prioritization and management of pennsylvania’s bat...

Chapter 14

Prioritization and Management of Pennsylvania’s Bat Hibernacula after Pervasive Contamination with the Fungus Causing White-nose Syndrome

BRENT J. SEWALLDepartment of Biology, Temple University, 1900 N. 12th Street,

Philadelphia, PA 19119 USA

MICHAEL R. SCAFINIPennsylvania Game Commission, 2001 Elmerton Avenue, Harrisburg, PA 17110 USA

GREGORY G. TURNERPennsylvania Game Commission, 2001 Elmerton Avenue, Harrisburg, PA 17110 USA

ABSTRACTEfforts by the Pennsylvania Game Commission (PGC) over nearly 2 decades toresearch, monitor, and manage bats have been guided by a hibernacula prioriti-zation plan. Under this plan, increased monitoring and management attention istriggered at hibernacula meeting any of 4 key criteria: 1) large total count; 2) highspecies richness; 3) presence of federally endangered species; and 4) presence ofexceptional populations of species of special concern. This plan has had broadapplication in Pennsylvania, but has never been systematically evaluated. Theneed for such an evaluation has become pressing since the recent invasion of anemerging infectious disease of hibernating bats, White-nose Syndrome (WNS),which has dramatically changed hibernating bat colonies and affected their use ofhibernacula. In this study, we use data from the PGC’s long-term program of batmonitoring to evaluate the plan’s utility both before and after the onset of WNSin the state. Our evaluation indicates that some criteria and thresholds are redun-dant and others – especially since the onset of WNS – are exceedingly restrictive.In addition, some species now requiring heightened conservation attention arelargely ignored under the plan, and the plan does not provide clear guidance tomanagers on resource allocation. We present here a new prioritization plan that

Conservation and Ecology of Pennsylvania’s Bats. Edited by Calvin M. Butchkoski, DeeAnn M. Reeder, Gregory G. Turner, and Howard P. Whidden. © 2016. The Pennsylvania Academy of Science.

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more explicitly states criteria and quantitative thresholds, avoids unnecessarycomplexity, is more adaptable, is more inclusive of all hibernating bat species,and provides clearer guidance to managers. This new plan uses 2 evaluation criteria (high species richness and important populations of any hibernatingspecies) and establishes several tiers of conservation priority (including the 3highest priority ones: Critical Hibernacula, Special Concern Hibernacula, andPotential Recovery Hibernacula). We also specify management interventions forhibernacula in each tier to be completed by the PGC and its partners. This newplan, to be known as the Pennsylvania Hibernacula Prioritization and Manage-ment Plan, replaces the previous plan, and will be implemented by the PGCbeginning in 2017. It is expected to serve as a durable strategy to prioritize hiber-nacula for monitoring, research, and management attention, with the overall goalof facilitating the continued persistence of hibernating bats in Pennsylvania.KEY WORDS — bats, Eptesicus fuscus, hibernacula, Myotis leibii, Myotislucifugus, Myotis septentrionalis, Myotis sodalis, Perimyotis subflavus, manage-ment, prioritization, Pseudogymnoascus destructans, White-nose Syndrome

Over the past several decades, the Pennsylvania Game Commission (PGC) has engagedin intensive efforts to identify, monitor, research, and manage bat hibernacula – the criti-cal winter habitat of hibernating bats. Important successes of these efforts in Pennsylvaniahave included: the inventory of caves, mines, and tunnels used as winter hibernacula;establishment of a long-term monitoring program; maintenance of a long-term monitoringdataset on bat populations collected since about 1985; research to improve understandingof abiotic and biotic conditions favoring bat survival during hibernation; attempts to ame-liorate potential habitat to better meet species’ hibernation requirements; the installation ofbat-friendly gates at cave, mine, and tunnel entrances to minimize human disturbance ofbats at prioritized sites; work with developers to avoid, minimize, and mitigate projectimpacts to hibernacula; the establishment of a requirement that abandoned mines be sur-veyed for bats prior to closure; the imposition of seasonal restrictions on recreational entryinto important hibernation sites to minimize disturbance; and public awareness efforts toeducate the caving community and broader public about hibernation sites for bats and thepotential harms that may arise from disturbance (as detailed in PGC annual unpublishedreports on its Indiana Bat Hibernacula Surveys from 2000 to 2014, hereafter referred to as‘PGC Annual Reports’1). Due to limited resources, however, the PGC has concentratedsuch management efforts at a few dozen sites in Pennsylvania – a relatively small portionof the over 2000 recognized caves and over 4000 known mine openings in the state thatcould potentially serve as underground habitats for bats (PGC Annual Report 71401-14z).Thus, the effectiveness of the PGC efforts for hibernating bat populations is dependent onwhether the most appropriate sites have been selected for management attention.

210 Conservation and Ecology of Pennsylvania’s Bats

1PGC Annual Reports on Indiana myotis, labeled ‘Indiana Bat Hibernacula Surveys’, are 71401-XX reports, withthe last two digits referring to the year in which surveys were completed. Sometimes the letter ‘z’ is appended.These reports are available by request to the PGC Bureau of Wildlife Management from [email protected],or online at http://www.pgc.pa.gov/InformationResources/ MediaReportsSurveys/AnnualWildlifeManagementReports/Pages/default.aspx

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Selection of sites for priority management attention by the PGC has previously beenaccomplished in accordance with a prioritization plan that was first established in the late1990s (PGC Annual Report 71401-99) and that has guided management efforts ever since(e.g., PGC Annual Report 71401-06z). The development of a formalized prioritizationplan is both in accordance with best practices for management (because prioritizationefforts are critical to management success when conservation need exceeds resourcesavailable for conservation; Sarkar & Illoldi-Rangel 2010) and rare (to our knowledge, thePGC is the only state agency in the U.S. that has attempted such a standardized approachto prioritization of bat hibernacula). Thus, efforts by the PGC to establish a prioritizationplan for Pennsylvania’s bat hibernacula are commendable. However, the utility of this planhas never been systematically evaluated. Further, the need to evaluate the plan has becomeincreasingly urgent since the recent invasion of a devastating fungal pathogen of hibernat-ing bats.

In the winter of 2008–2009 Pseudogymnoascus destructans (Pd, formerly Geomycesdestructans), the fungal agent of White-nose Syndrome (WNS; Lorch et al. 2011, Warnecke et al. 2012), was found in Pennsylvania. Infection with Pd affects hibernationphysiology such that hibernating bats with WNS have greater energetic and evaporativewater loss (Reeder et al. 2012, Cryan et al 2013), leading to mass mortality events at hiber-nacula during winter (Frick et al. 2010, Turner et al. 2011). WNS was already widespreadwithin the state by 2012, by which time it had been confirmed at 57 hibernacula in 24 ofPennsylvania’s 67 counties (PGC Annual Report 71401-12z, Heffernan & Turner 2016). Itis now thought to have affected bats at all known large hibernacula in the state (PGCAnnual Report 71401-14z, Heffernan & Turner 2016). Further, the prevalence of WNS in Pennsylvania’s remnant bat populations may remain high for the foreseeable future;contamination of hibernacula with Pd appears highly persistent once established (e.g.,Lorch et al. 2013).

WNS has already contributed to a number of important changes in hibernating bat pop-ulations. Most dramatic has been severe population declines in at least 4 species: Indianamyotis (Myotis sodalis), northern long-eared myotis (M. septentrionalis), little brownmyotis (M. lucifugus), and tri-colored bat (Perimyotis subflavus). These declines haveoccurred both at a large regional scale across the eastern and Midwestern United States(Thogmartin et al. 2012, Ingersoll et al. 2013, Ingersoll et al. 2016) and statewide withinPennsylvania (Turner et al. 2011, Thogmartin et al. 2012, PGC and PFBC 2015, Ingersollet al. 2016, B.J. Sewall, G.G. Turner, and C.M. Butchkoski, unpublished data) (Table 1). Inaddition, the optimal temperature and humidity profile of bats’ preferred roosting sites maydiffer from the period before the onset of WNS (Grieneisen et al. 2015, Lilley et al. 2016,Johnson et al. 2016). Further, bats may be becoming more aggregated at fewer sites, whichmay suggest that a relative handful of sites are exceptionally important (Langwig et al.2012). Such WNS-driven changes to bats and bat habitats call into question whether long-established management approaches remain appropriate for remnant populations afterwidespread contamination of hibernacula with Pd.

A reevaluation of the previous prioritization plan that has been used by the PGC for nearly 2 decades is therefore needed to ensure effective protection of Pennsylvania’sremnant populations of hibernating bats. Our objectives in this chapter are to evaluate theprevious prioritization plan for Pennsylvania’s bat hibernacula, and if needed, revise this

Sewall et al.: Hibernacula Prioritization & Management Plan 211


plan. Although successful management of Pennsylvania’s bat populations will require amulti-pronged effort for bat conservation across the state in habitats used throughout the year, we limit our focus here to prioritization of bat hibernacula and steps that will benefit bats during the hibernation period (roughly the end of September to mid-April formost Pennsylvania species).

UTILITY OF PREVIOUS PRIORITIZATION APPROACH

Previous Prioritization PlanA prioritization plan was presented for Pennsylvania’s bat hibernacula by the PGC in

several annual reports beginning in the late 1990s (e.g., PGC Annual Report 71401-99). A somewhat different plan was presented soon thereafter, in a detailed draft developed in2001 and submitted to the PGC (J. Hart, The Nature Conservancy, unpublished report;hereafter referred to as the Draft Hibernacula Management Plan). However, the DraftHibernacula Management Plan was apparently never published or formally accepted bythe PGC. Further, criteria presented in the earlier annual reports of the PGC (PGC Annu-al Report 71401-99) remained the same in subsequent annual reports (e.g., PGC Annual Reports from 2000–2010). We therefore focus in this study on evaluating the plan


Table 1: Hibernating bat species of Pennsylvania, with hibernacula use, conservation status,and population trends. Hibernacula use: C = cave, M = mine, T = tunnel, R = rock crevicesexterior to caves and mines, B = buildings. Data are from the Draft Hibernacula ManagementPlan, PGC Annual Report 71401-05, Turner et al. (2011), Thogmartin et al. (2012), PGC andPFBC (2015), Ingersoll et al. (2016), B. J. Sewall, G. G. Turner, and C. M. Butchkoski, unpub-lished, and G. G. Turner and M. R. Scafini, pers. obs.

PA Recent WNS-estimated pre-WNS prevalent

Federal pre-WNS PA population populationHibernacula conservation population conservation trends trends

Species types used status size status within PA within PA

Indiana C, M, T Endangered rare PA Slight Severemyotis Endangered increase decline

northern C, M, T, R, B Threatened rare PA Steady Severelong-eared Responsibility decline declinemyotis Species

little brown C, M, T, R Petitioned common None Stable Severe myotis decline

eastern small- C, M, T, R None rare PA Stable Declinefooted myotis Threatened

tri-colored bat C, M, T Petitioned common None Stable Severe decline

big brown bat C, M, T, B None common None Slight Declinedecline


presented in these PGC Annual Reports, because of its use in practice by the relevant management authority for Pennsylvania’s bats, the PGC. Hereafter, we refer to the plandocumented in the PGC Annual reports as the “previous prioritization plan.”

The previous prioritization plan identified Special Concern Hibernacula as those sitesof high priority for bat conservation relative to all other actual or potential undergroundhabitats for bats. A set of criteria and associated quantitative thresholds was selected to guide conservation attention to the most important sites. The intended result was theidentification of a manageable number of sites that could be protected, with the greatestpossible benefit for the bat community as a whole and for species of conservation concernin particular. Specifically, under the previous prioritization plan, Special Concern Hiber-nacula were those sites that had: 1) a large total number of hibernating bats; 2) a highspecies richness of hibernating bats; 3) a federally endangered species present; or 4) anexceptional population of a special concern species present (PGC Annual Report 71401-99).

Quantitative thresholds were presented for the first 3 criteria: Special Concern Hiber-nacula should have ≥1000 bats, ≥4 species of bats, or ≥1 Indiana myotis present (PGCAnnual Report 71401-99). For the last criterion, special concern species were identified asthe northern long-eared myotis (due to its rarity in hibernation sites) and the eastern small-footed myotis (Myotis leibii) (due to its status as a state-threatened species) (Genowaysand Brenner 1985, Kirkland and Krim 1990, PGC Annual Report 71401-05), but a specif-ic threshold (i.e., what constitutes an exceptional population of one of these species) wasnot specified. If a site met the quantitative threshold for any one of the 4 criteria, it wasconsidered a Special Concern Hibernaculum (PGC Annual Report 71401-99).

Classification of a hibernaculum as being of Special Concern triggered several management and monitoring actions by the PGC. Specifically, all Special Concern Hiber-nacula were to be surveyed no less than once every 5 years (or typically every 2 years if Indiana bats were present), baseline environmental data (temperature and humidity) collected, the condition of the hibernaculum assessed, changes in this condition noted(e.g., changes in airflow or temperatures, or repeated entry by people), and means to control access by the public during the hibernation season (e.g., via landowner agreementsand bat-friendly gate installation) established (PGC Annual Report 71401-00z).

Data Collection MethodsFor this study, no new field data were collected. Rather, data are from the PGC’s bat

monitoring database (PGC, unpublished data), which is the accumulation of all field datacollected by trained bat biologists from the PGC since the mid-1980s. Data were counts ofbats from standardized winter surveys inside hibernacula, or from capture efforts duringfall swarm or spring emergence at hibernacula entrances; these survey and capture effortswere conducted broadly on a range of known or potential hibernacula sites to obtain base-line data on suitability. Repeated surveys in subsequent years focused primarily on SpecialConcern Hibernacula, or other sites with large colonies, diverse communities, or rarespecies.

Winter surveys were conducted along consistent internal survey routes within knownhibernacula. These surveys were performed during the hibernation period, typicallybetween early January and mid-March. Out of concern for negative effects of disturbing




hibernating bats (Thomas 1995), due to limited personnel and resources for monitoring(Kunz 2003), and in accordance with federal guidelines for Indiana myotis (USFWS2016a), winter surveys were conducted on a biennial or less frequent basis. Bats werevisually counted where they hibernated on walls and ceilings (Kunz 2003, Tuttle 2003).

Fall swarm surveys were typically conducted in late September or early October, andspring emergence surveys were typically conducted during the second half of April.Selected trap nights targeted the warmest evenings in the trapping window without highwinds or rain. Trapping began at sunset, and ceased after 5 hours, or if consistent or heavyrain occurred. To trap hibernacula, entrances were covered in plastic cut with square harp-trap-sized holes. Harp traps (Faunatech AustBat and Bat Conservation and Management,Inc.) were then placed flush with the plastic. Secondarily, in the fall, an additional harp trapwas often placed perpendicular to the opening and proximate to the other harp trap to catch bats circling at the entrance. Bats were gathered every ≤30 minutes at traps, and individuals were tallied. Indiana myotis were always banded and little brown myotis and tri-coloredbats were often banded, but other bat species that use tight crevices (eastern small-footedmyotis, northern long-eared myotis) were typically not banded out of concern the bandwould become jammed in the crevice. Big brown bats were only banded for specialresearch objectives. All measurements and banding were performed following the currentversion of the United States Fish and Wildlife Service (USFWS) standard protocols for thecapture, handling, and banding of federally endangered Indiana myotis (e.g., USFWS2016a). Prior to WNS, bats were removed from traps and placed in a holding cage untildata could be recorded. Following the first confirmation of WNS in Pennsylvania, all indi-viduals were placed in individual paper bags to avoid cross-contamination with Pd, andprocessed individually, following the current version of the USFWS guidelines for decon-tamination (e.g., USFWS 2016b). Uniquely numbered bands (Darvic bands from AvinetInc. for Indiana myotis or 2.9 mm split-metal alloy bands with lips from Porzana Ltd. forlittle brown myotis and tri-colored bats) were applied to the right forearm of males and theleft forearm of females. Darvic bands were slightly spread and sharp edges were filed withan emory board prior to application. Individuals recaptured on the same night (as deter-mined by band numbers) were only included once in count totals.

Analysis Methods for the Previous Prioritization PlanPrioritization improves management by guiding allocation of scarce resources to priority

conservation targets of greatest need, ensuring management effort is focused on the mostimportant conservation goals (Margules & Sarkar 2007, Sewall et al. 2011). To be effec-tive, however, prioritization approaches must systematically evaluate clear criteria andspecific, quantitative thresholds with standardized data (Margules & Sarkar 2007, Sewallet al. 2011). Thus, we began by evaluating to what extent the previous prioritization planfit such guidelines.

Then, we quantitatively assessed the utility of the previous prioritization plan, compar-ing quantitative thresholds in the previous prioritization plan against data from the PGC’sbat monitoring database in 2 ways. First, to evaluate the set of criteria employed, we quantified the extent to which each criterion contributed to the identification of hiber-nacula as Special Concern. Second, to investigate the continuing relevance of the previousprioritization plan, we evaluated whether prioritization criteria and thresholds established


during the period prior to the known onset of WNS in the state (hereafter, the pre-WNSperiod) were still suitable for the identification of priority hibernacula in the period sinceWNS has become prevalent in hibernacula across Pennsylvania (hereafter, the WNS-prevalent period).

For evaluations of criteria in the WNS-prevalent period, we used the 5-year period from2012–2016. At sites where WNS was first detected in 2012, counts used from that yearwere from surveys after mass mortality had occurred. Although the criteria were initiallyapplied in PGC Annual Reports (e.g., PCG Annual Report 71401-99) without reference toa particular time frame, for comparability in this analysis, we restricted survey data usedin the pre-WNS period to a 5-year period as well; the pre-WNS period analyzed was2002–2006. The restriction of the pre-WNS analysis to a limited time frame could resultin the identification of fewer sites as being of Special Concern than identified by PGCAnnual Report 71401-06z, but allows for a more rigorous comparison of the 2 periods.Further, since all Special Concern Hibernacula are to be monitored at least once every 5 years (PGC Annual Report 71401-99), every Special Concern Hibernacula should haveat least one survey during both 5-year periods examined. A total of 237 surveys at 115hibernacula were conducted during 2002–2006, and 275 surveys at 119 hibernacula wereconducted during 2012–2016. Specific quantitative thresholds used for the evaluation in both time periods are presented in Table 2. For this analysis, we only counted a site


Table 2. Previous criteria and quantitative thresholds for identification of Special ConcernHibernacula in Pennsylvania, with number meeting this threshold in pre-WNS period(2002–2006) and the WNS-prevalent period (2012–2016).

Numbers of hibernacula

pre-WNS WNS prevalent period period

Criteria for the Thresholds for Meeting Meetingdetermination of Special the determination single singleConcern Hibernacula of Special Concern Meeting threshold Meeting threshold

Hibernacula threshold only threshold only

Large total number A total of ≥1000 22 3 0 0of hibernating bats bats (any species)

High species richness ≥4 bat species 34 9 19 11of hibernating bats present

Presence of a federally Indiana myotis 15 0 5 1endangered species present

Exceptional population ≥ 3 eastern small- 30 9 10 3of a special concern footed myotis, orspecies ≥ 10 northern myotis

Number of hibernacula — 48 21 23 15meeting any threshold or meeting only one threshold in each period


as fulfilling Special Concern criteria if it did so during these defined periods. Further, to qualify as a Special Concern Hibernaculum in our analysis, a hibernaculum must havemet or exceeded the threshold for at least one of the criteria listed during at least one fall,winter, or spring survey conducted during a time period.

Evaluation of the Previous Prioritization PlanThe previous prioritization plan was not explicit about quantitative thresholds in at least

3 ways that may limit its effectiveness and reproducibility. First, PGC Annual Reports(e.g., 71401-99) did not indicate an explicit quantitative threshold for determining whatconstituted an exceptional population of a special concern species. It was unclear whetherthis represented an oversight in describing the plan or whether exceptional populationswere simply determined subjectively on a case-by-case basis. Further, due to personnelturnover at the PGC, it is possible the standard used may have changed over time. To retainthe rigorous quantitative nature of the analysis in this chapter, we assumed that an excep-tional population of eastern small-footed myotis was a colony where at least 3 individualswere counted in a survey, and an exceptional population of northern long-eared myotis wasa colony where at least 10 individuals were counted in a survey. It is unknown how ourthresholds compare to those used by the PGC in practice, but our thresholds include rough-ly the largest half of all known colonies of each species in the state during the pre-WNSperiod. Second, the relevant time frame (i.e., the window during which the meeting of a threshold needed to be documented) was not explicitly stated. The time frame used inpractice by the PGC was clearly longer than the 5-year period we used in this analysis,however. The PGC had identified 69 Special Concern Hibernacula within Pennsylvania by 2006 (PGC Annual Report 71401-06z), whereas our analysis of the five-year periodending in 2006 period uncovered only 48 (Table 2). Third, it was unclear how hibernacula were to be added to or removed from state lists of Special Concern Hibernacula. Appar-ently only one site (11-001-M) was ever removed from the list; this was because “it was incorporated into the Rails to Trails program and became unsuitable for bats” (PGC Annual Report 71401-04). Thus, it was implicit that once listed as a Special Concern Hibernacu-lum, it would remain so until conditions were documented to have substantially deterio-rated. That such a standard was not consistently followed, however is evident: hibernacula whose conditions deteriorated substantially as a result of Pd contamination were notremoved from the list.

Our quantitative evaluation of the relative importance of prioritization criteria suggestsan important role for the high species richness and exceptional population criteria in classification of hibernacula as Special Concern. This high species richness criterionwould have, by itself, accounted for 71% of hibernacula classified as Special Concern inthe pre-WNS period, and 43% of all hibernacula that were so classified on the basis of asingle criterion during that period (Table 2). The criterion for exceptional population ofspecial concern species would have, by itself, accounted for 63% of hibernacula classifiedas Special Concern in the pre-WNS period, and 43% of all hibernacula that were so classified on the basis of a single criterion. Together these 2 criteria identified all but 3 (ora total of 94%) of the Special Concern Hibernacula in the pre-WNS period. The criterionfor presence of a federally endangered species was satisfied at 15 hibernacula in the pre-WNS period, but all of these sites would have been classified under the high species



richness and exceptional population criteria (Table 2), suggesting that this criterion wasfully redundant in the pre-WNS period.

Several important changes were also observed in our quantitative analysis of differ-ences between the pre-WNS and WNS-prevalent periods. First, more than half (52%) of all sites classified as Special Concern in the pre-WNS period would no longer be classified as such if evaluated for the first time in the WNS-prevalent period. This isdespite a 16% increase in survey effort in the WNS-prevalent period relative to the pre-WNS period. Second, a single criterion – the high species richness criterion – is nowclearly the dominant reason hibernacula would be classified as Special Concern in theWNS-prevalent period. Although the number classified as Special Concern under this criterion was down 44%, it still accounted for the large majority of both of the sites thatremained so classified (83%) and of the sites (73%) that were so classified on the basis ofa single criterion. Further, few sites now meet the other thresholds in the previous plan,and some thresholds are now impossibly restrictive: while in the pre-WNS period, 22 sitesin the state met the large total number threshold and 23 harbored exceptional populationsof northern long-eared myotis; none do now (exceptional populations of eastern small-footed myotis were not as affected, with 11 exceptional populations in the pre-WNS period and 10 now). Cumulatively, while 39 hibernacula met thresholds for at least 1 of the 3other criteria in the pre-WNS period, only 12 (31% of the original number) would do sotoday. Third, there was a reduction of redundancy in the classification of hibernacula asSpecial Concern: the percentage of sites so classified on the basis of more than 1 criteriondecreased from 56% in the pre-WNS period to 35% in the WNS-prevalent period (Table2).

PRIORITIZATION OF HIBERNACULA FOR MANAGEMENT ATTENTION IN THE WNS-PREVALENT PERIOD

Need for Updating the Previous Prioritization PlanThe results of our evaluation suggest a need for improvement and updating of the pre-

vious prioritization plan (PGC Annual Report 71401-99). First, the thresholds should bemade more explicit. Specifically, what constitutes an exceptional population, the timeframe for documentation, and procedures for adding or removing a hibernaculum from thelist of Special Concern Hibernacula should be clarified. Doing so would improve consis-tency and remove elements of subjectivity in selection of Special Concern Hibernacula.

Second, communication with the public and stakeholders about the prioritization planand consistency in its implementation will both be improved if unnecessary complexity isavoided where possible. Our results suggest an opportunity exists for simplification of theclassification system via the removal of fully redundant criteria. While redundancy by criteria is not problematic in a prioritization plan per se, complete or near-complete redun-dancy suggests certain criteria are simply not needed. Because 2 criteria (high species rich-ness and exceptional populations of species of special concern) accounted for most of thesites classified as Special Concern, the set of criteria used for classification could bereduced while still reaching largely the same classification outcome.

Third, the previous criteria (PGC Annual Report 71401-99) are not inclusive of allspecies that now require conservation attention for persistence. Three of the previous cri-



teria are largely focused on 1 or 2 species each. The large total number criterion had been,in practice, solely focused on large aggregations of the little brown myotis, formerly themost common species in Pennsylvania. This was the only species to ever meet the 1000-bat threshold required for Special Concern status under the large total number criterion.The federally endangered species criterion focused exclusively on the Indiana myotis(PGC Annual Report 71401-99). And the exceptional population criterion focused exclu-sively on the eastern small-footed myotis and the northern long-eared myotis (PGC AnnualReport 71401-99).

In contrast, the tri-colored bat, which does not form large aggregations, and is not federally endangered or of special concern in Pennsylvania, did not figure into any of these3 criteria. This is despite great conservation need for this species: Pennsylvania popula-tions of tri-colored bats have collapsed by more than 90% since the onset of WNS in thestate (Turner et al. 2011, B. J. Sewall, G. G. Turner, and C. M. Butchkoski, unpublisheddata). Tri-colored bats’ hibernacula were only included in the prioritization scheme if theirpresence enabled a hibernaculum to reach the threshold for high species richness. Further,as the high species richness criterion is based on presence, not numbers, the most impor-tant hibernacula for tri-colored bats could easily be overlooked. This oversight may haveset back conservation efforts after the onset of WNS in Pennsylvania: important hibernac-ula for tri-colored bats would not be included as Special Concern unless they also happened to have been important for other species. Such a fortunate coincidence often did not occur: hibernacula for 5 of the 8 largest colonies of tri-colored bats in the WNS-prevalent era, including the 2 of the 3 largest, would not be classified now as Special Concern using the criteria in the previous prioritization plan. This oversight may have obscured conservation needs for tri-colored bats in Pennsylvania and slowed management response for the species after the onset of WNS. This may have led to missed opportunities for important conservation actions, such as the installation of bat-friendly gates, establish-ment of landowner agreements, or implementation of access restrictions at importanthibernacula for tri-colored bats.

Fourth, some of the criteria formerly used to distinguish hibernacula of Special Concern are now exceedingly restrictive, and it has therefore become evident that the criteria were not adaptable to the kinds of unforeseen radical changes in bat populationsthat have occurred since the onset of WNS in Pennsylvania. In particular, the threshold forthe large total number criterion has become a completely unrealistic one since colonies oflittle brown myotis have collapsed by more than 98% since the onset of WNS in Pennsyl-vania (Turner et al. 2011; B. J. Sewall, G. G. Turner, and C. M. Butchkoski, unpublisheddata) and other species have also declined substantially (Table 1). As a result, no hiber-nacula remain in Pennsylvania that have colonies anywhere close to reaching the samethreshold that 22 hibernacula were known to have met just a decade ago (Table 2). Further, it seems unlikely that any substantial number of colonies will reach these levelsin the near future. To respond to the onset of WNS, one possible strategy would be to retainhibernacula as Special Concern on the basis of historical counts meeting established criteria, but the previous plan does not specify a suitable time frame during which suchcontinued classification would be appropriate. In addition, while historical data provideimportant context and indications of habitat suitability in the absence of Pd, as time goesby, it could become increasingly difficult from a practical standpoint to justify conserva-



tion efforts to stakeholders solely on the basis of bat counts from years or even decadesago. Further, because knowledge of past use by hibernating bats is generally not availablewhen evaluating a hibernaculum for the first time, the current criteria would not normallybe sufficient for assessing the conservation priority of such hibernacula. Moreover, whilehistorical data can suggest the potential of a now little-used site for recovery of bat popu-lations, especially if survivors develop a resistance to WNS, a prioritization plan fullyreliant on historical data could inhibit a dynamic management response to a changing situation. This could occur if WNS drives surviving bats to shift their habitat preferences(Lilley et al. 2016, Johnson et al. 2016), to aggregate at fewer or different sites (Johnsonet al. 2016), or to use a greater diversity of sites. Thus, criteria and thresholds will need tobe modified to be more adaptable to the WNS-prevalent landscape.

Fifth, the previous criteria suggest a substantial decrease in number of hibernacula thatwould classify as Special Concern during the WNS-prevalent period (Table 2). Yet, weargue that the severe declines in hibernating bat populations over the past decade (Table1) and their deteriorating conservation status (Table 1; PGC and PFBC 2015) suggest aneed for more, not fewer, conservation efforts, or at least smarter approaches to using thesame limited conservation resources. For instance, a tiered prioritization scheme couldhelp ensure that the greatest conservation and monitoring efforts are directed toward thehighest priority sites for conservation. Further, by explicitly linking management to the priority level of hibernacula, managers could ensure that the amounts and types ofmanagement interventions are well suited to conservation needs at particular sites. Suchtargeted approaches could help to ensure that the limited available conservation resourcesare oriented to achieve the greatest effect.

A New Prioritization PlanOur evaluation suggested a need to modify the previous prioritization approach to

provide more explicit quantitative thresholds, reduce unnecessary complexity, be moreinclusive of all species needing conservation attention, be more adaptable to a changingconservation landscape, and enable managers to more efficiently allocate conservationresources and monitoring efforts for the continued persistence of hibernating bat popula-tions in Pennsylvania. To address these needs, we present here a new prioritization planfor hibernacula conservation in Pennsylvania. This new plan, to be known as the Pennsyl-vania Hibernacula Prioritization and Management Plan, will replace the previous prioriti-zation plan, and will be used to guide prioritization and management of hibernacula by thePGC beginning in 2017.

In this new plan, criteria and quantitative thresholds are described explicitly (Tables 3and 4). Prioritization of the most important hibernacula for conservation will be on thebasis of just 2 criteria: high species richness and important populations for each species(Table 3). The high species richness criterion is retained under the new prioritization planbecause of its success under the previous prioritization plan in identifying a suite of impor-tant sites in both the pre-WNS and WNS-prevalent periods. Including this criterion in thenew prioritization plan is also strategic from a prioritization perspective because scarceconservation resources may often have greater effect if efforts to protect a single site cansimultaneously benefit multiple species. The other 3 criteria in the previous prioritizationplan are combined into a single criterion in the new plan: the identification of important



220 Conservation and Ecology of Pennsylvania’s BatsTable 3. Revised criteria and quantitative thresholds for identification of priority hibernacula for conservation in WNS-prevalent period in

Pennsylvania. Evaluation time frame for CR and SC criteria is 2012–2016; for PR any PGC survey in the database can be used. Each hiber-

naculum receives only one classification, of the highest priority status for which criteria are met. Numbers of hibernacula classified under each

criterion may differ from those listed in the threshold when there are multiple species, when hibernacula are redundantly classified, or in the

case of ties when ranking colonies by size. Numbers in parentheses indicate the number meeting a single threshold only.

Number of

Number of

Number of

hibernacula

hibernacula

hibernacula

meeting CR

meeting SC

meeting PR

Criteria

CR Threshold

threshold

SC Threshold

threshold

PR Threshold

threshold

Hig

h sp

ecie

s Re

cent

surv

ey10

(0)

Rece

nt su

rvey

with

12 (7

)A

ny su

rvey

with

≥5

8 (3

)ric

hnes

sw

ith ≥

5 hi

bern

atin

g ≥

3 hi

bern

atin

g ba

thi

bern

atin

g ba

t ba

t spe

cies

spec

ies

spec

ies.

App

ropr

iate

cond

ition

s rem

ain

or re

stora

ble.

Impo

rtant

pop

ulat

ion

Rece

nt su

rvey

with

31

(9)

Rece

nt su

rvey

with

0 (0

)A

ny su

rvey

with

one

15 (8

)(s

tate

- or f

eder

ally

on

e of

the

20 la

rges

t≥

1 in

divi

dual

of t

heof

the

20 la

rges

tlis

ted

spec

ies)

colo

nies

of t

he sp

ecie

ssp

ecie

sco

loni

es o

f the

spec

ies.

App

ropr

iate

con

ditio

ns

rem

ain

or re

stora

ble.

Impo

rtant

pop

ulat

ion

Rece

nt su

rvey

with

22 (5

)Re

cent

surv

ey w

ith9

(5)

Any

surv

ey w

ith o

ne6

(2)

(spe

cial

con

cern

or

one

of th

e 10

larg

est

one

of th

e ne

xt 1

0on

e of

10

larg

est

seve

rely

dep

lete

d co

loni

es o

f the

spec

ies

larg

est c

olon

ies o

fco

loni

es o

f the

spec

ies.

spec

ies)

the

spec

ies

App

ropr

iate

con

ditio

ns

rem

ain

or re

stora

ble.

Impo

rtant

pop

ulat

ion

Rece

nt su

rvey

with

one

5 (1

)Re

cent

surv

ey w

ith3

(2)

Any

surv

ey w

ith o

ne

1 (0

)(o

ther

non

-liste

d of

the

5 la

rges

t col

onie

s on

e of

the

next

5

one

of 5

larg

est

spec

ies)

of th

e sp

ecie

sla

rges

t col

onie

s of

colo

nies

of t

he sp

ecie

s. th

e sp

ecie

sA

ppro

pria

te c

ondi

tions

re

mai

n or

resto

rabl

e.

Num

ber o

f hib

erna

cula

37

(15)

19 (1

4)20

(13)

mee

ting

any

thre

shol

d


Sewall et al.: Hibernacula Prioritization & Management Plan 221Table 4. Hibernacula management and monitoring effort linked to the new priority classifications. Each site receives only one classification, of

the highest priority for which criteria are met. CR, SC, and PR classifications are further detailed in Table 3.

Number

of sites

meeting

Priority classification

Criteria

threshold

Management

Monitoring

Criti

cal H

iber

nacu

la

Rece

nt su

rvey

with

ver

y hi

gh

37H

ighe

st pr

iorit

y fo

r bat

-frie

ndly

gat

ing.

PGC

bat s

urve

y ev

ery

2 ye

ars.

(CR)

spec

ies r

ichn

ess o

r ver

y Cr

eate

pla

ns fo

r: sit

e m

anag

emen

t, M

onito

ring

of a

biot

icim

porta

nt p

opul

atio

n.la

ndow

ner a

gree

men

t, co

nditi

ons.

distu

rban

ce m

inim

izat

ion.

Spec

ial C

once

rn

Rece

nt su

rvey

with

hig

h19

Seco

ndar

y pr

iorit

y fo

r bat

-frie

ndly

PGC

bat s

urve

y ev

ery

5 ye

ars.

Hib

erna

cula

(SC)

spec

ies r

ichn

ess o

r im

porta

nt

gatin

g. C

reat

e pl

ans f

or: l

ando

wne

rpo

pula

tion,

but

insu

ffici

ent

agre

emen

t, di

sturb

ance

min

imiz

atio

n.fo

r CR

statu

s.

Pote

ntia

l Rec

over

y Fo

rmer

ly h

igh

spec

ies r

ichn

ess

20Te

rtiar

y pr

iorit

y fo

r bat

-frie

ndly

PG

C ba

t sur

vey

ever

y 10

yea

rs.

Hib

erna

cula

(PR)

or im

porta

nt p

opul

atio

ns.

gatin

g. C

reat

e pl

ans f

or: l

ando

wne

r A

biot

ic c

ondi

tions

via

ble

or

agre

emen

t.re

stora

ble.

Suita

ble

Hib

erna

cula

≥1

bat

obs

erve

d at

≥1

surv

ey

320

Eval

uate

util

ity o

f man

agem

ent

Inve

stiga

te b

at a

bund

ance

(SH

)(fa

ll, w

inte

r, or

sprin

g).

actio

ns, a

nd fe

asib

ility

and

vi

a PG

C su

rvey

, inf

orm

atio

nA

biot

ic c

ondi

tions

unk

now

n,

effe

ctiv

enes

s of m

icro

clim

ate

shar

ing

with

cav

ers.

Mon

itor

suita

ble

or re

stora

ble.

mod

ifica

tion.

sites

to b

e m

odifi

ed b

efor

e an

daf

ter m

odifi

catio

n.

Unk

now

n Su

itabi

lity

No

bat s

urve

ys c

ondu

cted

. 5,

400

Pres

erve

hab

itat s

uita

bilit

y un

tilIn

vesti

gate

bat

pre

senc

eSi

te (U

N)

Abi

otic

con

ditio

ns u

nkno

wn,

su

rvey

ed.

via

PGC

surv

ey, i

nfor

mat

ion

poss

ibly

suita

ble,

or r

esto

rabl

e.sh

arin

g w

ith c

aver

s.

Like

ly U

nsui

tabl

e Si

te≥1

fall/

win

ter/s

prin

g su

rvey

s 18

4Ev

alua

te u

tility

of m

anag

emen

t, N

o m

onito

ring

plan

ned

(LU

)an

d ba

ts no

t obs

erve

d or

abi

otic

fe

asib

ility

and

effe

ctiv

enes

s of

unle

ss n

ew in

form

atio

n ar

ises.

char

acte

ristic

s sug

gest

lack

of

mic

rocl

imat

e m

odifi

catio

n.M

onito

r site

s to

be m

odifi

ed

suita

bilit

y.be

fore

and

afte

r mod

ifica

tion.


populations of each species of hibernating bats. Thresholds for this criterion are scaled bythe conservation status of the bat species: greater numbers of sites will be prioritized forstate- and federally listed species than for severely depleted non-listed species, and greaternumbers of sites for these species in turn will be prioritized than for other non-listedspecies (Table 3).

In addition, the plan is designed to be responsive to changing conservation needs. Here,rather than setting static numeric thresholds for numbers of bats, we identify the largestcolonies of each species for conservation attention, as documented during a defined timeframe. The time frame for documenting hibernacula with the highest status is limited tothe use of counts from both within the last 10 years and since the onset of the WNS-preva-lent period in 2012. However, hibernacula identified for other statuses can be identified onthe basis of PGC counts from any time frame.

Finally, unlike the previous prioritization plan, which only identifies a single tier ofconservation importance (Special Concern), the new plan includes several tiers. The 3main tiers implying high conservation priority are ‘Critical Hibernacula’ (CR) for the high-est priority sites, ‘Special Concern Hibernacula’ (SC) for other sites of high conservationvalue, and ‘Potential Recovery Hibernacula’ (PR) for sites that do not currently meet thesecriteria but did in the past and could allow for eventual recovery of bat populations in thefuture. Specific descriptions of these criteria and associated thresholds are presented inTable 3, and associated management and monitoring efforts triggered by a given classifi-cation in Table 4. In addition to the 3 higher-priority categories of conservation status forhibernacula, 3 other lower-priority categories are also identified for underground sites onthe basis of bat presence and habitat suitability; these categories are Suitable Hibernacula(SH), Unknown Suitability Sites (UN), and Likely Unsuitable Sites (LU) (Table 4).

Data Collection and Analysis Methods for the New Prioritization PlanTo evaluate the new prioritization plan, we used the same database (the PGC’s bat mon-

itoring database; PGC, unpublished data) as described for the previous prioritization plan.Again, analysis began by evaluating to what extent the new prioritization plan fit recom-mended guidelines for prioritization approaches (Margules & Sarkar 2007, Sewall et al.2011).

Then, we quantitatively assessed the utility of the new prioritization plan, also largelyas described for the previous prioritization plan. In this analysis, hibernacula were assessedto determine whether they met quantitative thresholds for CR and SC status in a recent(since 2012) standardized survey by state biologists. Hibernacula that did not meet CR orSC status were then evaluated for other conservation statuses with data from the entirePGC bat monitoring database. To qualify for a particular status, a hibernaculum had tomeet or exceed quantitative thresholds for at least one of the criteria listed. For the impor-tant population criterion, these related to rankings of the largest colonies for each species.Where ties among colonies occurred in such rankings, all hibernacula with the tiedcolonies were assigned the higher priority conservation status. A hibernaculum could not be listed as having 2 conservation statuses; where thresholds were met in multiple categories, the hibernaculum was accorded the higher status. Some thresholds refer toappropriate conditions for hibernation; these include a variety of abiotic and biotic condi-tions of the hibernaculum and surrounding landscape (e.g., as described in Raesly and



Gates 1986, Draft Hibernacula Management Plan, and Johnson et al. 2016). Currently,state- or federally-listed species include Indiana myotis, northern long-eared myotis, andeastern small-footed myotis; other species of special concern or other severely depletedspecies include little brown myotis and tri-colored bats; and other non-listed speciesincludes only big brown bats.

A list of hibernacula meeting the top 3 statuses (CR, SC, and PR) was generated. Specific hibernacula names were not provided to protect the identities of the highest priority sites. Instead PGC’s unique codes for each hibernaculum were provided. To provide finer-grained information on relative priority, within-category rankings weredetermined, with the order of individual sites corresponding to the number of thresholdsmet (species richness and important populations) at the site.

Comparisons with the previous prioritization plan were accomplished by comparingthose identified under the new criteria (Tables 5, 6, and 7) to previous Special ConcernHibernacula as listed in the 1999 report (PGC Annual Report 71401-99). Tables 5–7 alsobreak out thresholds by species, to provide clarity on where important populations of eachspecies are found.

Evaluation of the New Prioritization PlanOur evaluation suggests several advantages of the new prioritization plan over the pre-

vious one. First, the new prioritization plan explicitly states all criteria and quantitativethresholds employed (Tables 3, 4), enabling unambiguous identification of priority sites.Specifically, our analysis suggests that 76 sites are now recognized as high priority hiber-nacula: 37 CR, 19 SC, and 20 PR hibernacula (Table 3). The classification of particularsites differs substantially from the previous prioritization plan, reflecting a combination ofboth changing conditions in the field (e.g., WNS impacts) and changes in criteria andthresholds from the previous prioritization plan to the new one. Of the 76 high priorityhibernacula now identified, 32 (42%) – including 14 CR Hibernacula (Table 5), 7 SCHibernacula (Table 6), and 11 PR Hibernacula (Table 7) – were not classified as SpecialConcern Hibernacula in the previous prioritization plan. In particular, some sites nowranked most critical to hibernating bat species (such as the third-highest ranked site over-all; Table 5) were not included in the previous prioritization plan, whereas others formerly ranked as Special Concern have been down-ranked to other categories. These differenceshighlight the value of developing criteria appropriate to the WNS-prevalent landscape oversimply retaining historical lists of important bat hibernacula.

Second, the new plan focuses on the essential elements needed for effective prioritiza-tion, by removing both the completely redundant and the now impossibly restrictive criteria (Tables 2 and 3). In so doing, the new plan reframes 3 of the formerly disjointed criteria (high species richness, presence of a federally endangered species, and exceptional popula-tion of a special concern species, Table 2) into a more coordinated framework focused onmaintaining the most critical populations of hibernating bat species (important populationcriterion, Table 3).

Third, these revised criteria are also more inclusive than those in the previous prioriti-zation plan, because they represent important hibernacula for all hibernating species – inparticular including tri-colored bats, a species severely affected by WNS that was largelyexcluded from the previous prioritization plan. Unlike in the previous plan, the top 20



224 Conservation and Ecology of Pennsylvania’s BatsTable 5. List of Critical Hibernacula (CR) under new prioritization plan, with hibernaculum data and thresholds met. Hibernacula are listed

in order of the relative conservation value, with sites meeting the most CR thresholds ranked highest. Ties are broken by highest number of

Special Concern (SC) thresholds met. Hibernacula types: CM = Coal Mine, LC = Limestone Cave, LM = Limestone Mine, OM = Other Mine,

OS = Other Structure, RR = Inactive Railroad Tunnel, SC = Sandstone Cave.

Important Population

N. long-

E. small-

Little

Hibernaculum

HibernaculumPrevious

Indianaeared

footed

brownTri-colored

Big

Species

code

County

type

status

myotis

myotis

myotis

myotis

bat

brown batrichnessRank

26-0

01-M

Faye

tteLM

SCCR

CRCR

SCCR

CRCR

156

-004

-MSo

mer

set

LMSC

CRCR

CRSC

CRCR

CR1

17-0

02Cl

earfi

eld

RRCR

CRCR

CRCR

SC3

07-0

18-M

Blai

rLM

SCCR

CRCR

CRCR

431

-001

-MH

untin

gdon

LCSC

CRCR

CRCR

CR4

41-0

06-M

Lyco

min

gLC

SCCR

CRSC

CRCR

640

-007

-MLu

zern

eCM

CRCR

CRCR

SC6

14-0

32-M

Cent

reRR

SCCR

CRSC

CRCR

656

-012

-MSo

mer

set

RRSC

CRCR

SCCR

SC9

44-0

09-M

Miff

linLC

SCCR

CRSC

CR10

65-0

01-M

Wes

tmor

elan

dLC

CRCR

SCCR

1007

-015

-MBl

air

LCSC

CRCR

CRSC

1044

-008

-MM

ifflin

LCSC

CRCR

SCCR

1037

-006

-MLa

wre

nce

LMSC

CRCR

SCSC

1403

-008

-MA

rmstr

ong

LMSC

CRCR

SCSC

1426

-008

-MFa

yette

LCCR

CRSC

1656

-015

Som

erse

tSC

CRCR

SC16

56-0

05-M

Som

erse

tLM

CRCR

SC16

03-0

01-M

Arm

stron

gLM

SCCR

CRSC

1614

-009

-MCe

ntre

LCSC

CRCR

SC16

65-0

05-M

Wes

tmor

elan

dLC

SCCR

CR21

44-0

18-M

Miff

linLC

SCCR

CR21

09-0

01-M

Buck

sO

MSC

CRSC

SCSC

2344

-017

-MM

ifflin

LCSC

CRSC

SC24

29-0

02-M

Fulto

nO

SCR

SCSC

2465

-006

Wes

tmor

elan

dLC

CRSC

26


colonies of this species would be accorded a high prior-ity conservation status (CR or SC). Even importanthibernacula for a non-listed species that is not con-sidered of special concern or severely depleted – specif-ically, the big brown bat (Eptesicus fuscus) – are included. This is beneficial because this species may havedeclined, though to a more limited degree than the otherspecies (Turner et al. 2011, PGC and PFBC 2015, B.J. Sewall, G.G. Turner, and C.M. Butchkoski, unpub-lished data, Table 1), and because limited data makefuture trajectories difficult to predict for all species.However, to avoid diverting resources from morethreatened species, only 10 important hibernacula forthis species are prioritized as CR or SC (Table 3).

Fourth, the use of site rankings and limited timeframe for comparison together enable a more dynamicresponse to current realities of bat conservation in theWNS-prevalent era, and allow greater ability to adapt tofuture changes in the conservation landscape. Focusingon ranking sites avoids setting thresholds with arbitrarypopulation sizes that may become obsolete over time.The approach is also selective, enabling targeted man-agement effort and avoiding undue restrictions on thecaving community or industry: the complete list of allCR, SC, and PR Hibernacula represents only a smallfraction (13%) of the total number of underground habi-tats that have been surveyed in Pennsylvania, and a tiny fraction (1.3%) of the ~6000 known underground sitesin the state (Table 4). Given the similar numbers of prioritized sites (76 under the new plan, 69 under theprevious one; PGC Annual Report 71401-06z), thePGC should have adequate capacity to manage the toppriority hibernacula, assuming similar levels ofresources remain available for this purpose over time.Further, management effort can now be scaled to con-servation priority through tiered rankings (Table 3, 4)enabling management effectiveness to increase. Simi-larly, the 10-year time frame for evaluation of hibernac-ula fits with the planned schedule for monitoring ofPennsylvania’s hibernacula – all of the top 3 tiers ofconservation are to be monitored at least once every 10years (Table 4) – facilitating continual updating of thelists of priority hibernacula and avoiding excessivereliance on historic counts.

Fifth, the new prioritization plan will enable man-agers to more closely allocate management, monitoring,


-005

-MLa

wre

nce

LMCR

SC26

07-0

16-M

Blai

rLC

CRSC

2605

-003

-MBe

dfor

dLC

SCCR

SC26

26-0

27-M

Faye

tteO

MSC

CRSC

2640

-002

-MLu

zern

eRR

SCCR

SC26

31-0

17-M

Hun

tingd

onLC

SCCR

SC26

14-0

26-M

Cent

reRR

CR33

29-0

04-M

Fulto

nLC

SCCR

3309

-004

Buck

sO

SCR

3306

-010

Berk

sO

MCR

3321

-006

Cum

berla

ndLC

CR33



Table 6. List of Special Concern Hibernacula (SC) under new prioritization plan, with hibernaculum data and thresholds met. Hibernacula are

ranked in order of relative conservation value, with sites meeting the most SC thresholds ranked highest. Hibernaculum type codes are as in

Table 5.


N. long-

E. small-

Little

Hibernaculum


Indianaeared

footed

brownTri-colored

Big

Species

code

County

type

status

myotis

myotis

myotis

myotis

bat


26-0

02-M

Faye

tteLC

SCSC

107

-008

-MBl

air

LMSC

SC1

45-0

01-M

Mon

roe

LCSC

SCSC

161

-009

Vena

ngo

RRSC

SC1

04-0

01-M

Beav

erLM

SCSC

SC1

44-0

11-M

Miff

linLC

SC6

07-0

06-M

Blai

rLC

SC6

65-0

04-M

Wes

tmor

elan

dLC

SCSC

607

-005

-MBl

air

LCSC

SC6

07-0

01-M

Blai

rLC

SCSC

667

-003

-MYo

rkO

MSC

SC6

67-0

06-M

York

OM

SCSC

661

-003

-MVe

nang

oRR

SC6

56-0

03-M

Faye

tteLC

SCSC

644

-016

-MM

ifflin

OM

SCSC

644

-006

-MM

ifflin

LCSC

SC6

65-0

15-M

Wes

tmor

elan

dLC

SCSC

637

-004

-MLa

wre

nce

LMSC

611

-001

Cam

bria

RRSC

SC6



Table 7. List of Potential Recovery Hibernacula (PR) under new prioritization plan, with hibernaculum data and thresholds met. Hibernacula

are ranked in order of the relative conservation value, with sites meeting the most PR thresholds ranked highest. Hibernaculum type codes are

as in Table 5.


N. long-

E. small-

Little

Hibernaculum


Indianaeared

footed

brownTri-colored

Big

Species

code

County

type

status

myotis

myotis

myotis

myotis

bat


56-0

01-M

Som

erse

tLM

SCPR

PRPR

PRPR

PR1

37-0

08-M

Law

renc

eLM

SCPR

PRPR

PR2

14-0

01-M

Cent

reLC

SCPR

PRPR

307

-033

-MBl

air

LCSC

PRPR

435

-002

-MLa

ckaw

anna

CMPR

PR4

14-0

04-M

Cent

reLC

SCPR

PR4

07-0

11-M

Blai

rLC

SCPR

PR4

65-0

16W

estm

orel

and

LCPR

849

-001

Nor

thum

berla

ndO

MPR

842

-003

McK

ean

OS

PR8

44-0

03M

ifflin

LCPR

807

-020

-MBl

air

LMSC

PR8

56-0

03-M

Som

erse

tO

SSC

PR8

62-0

02W

arre

nLC

PR8

07-0

31Bl

air

LCPR

844

-002

Miff

linLC

PR8

40-0

04Lu

zern

eCM

PR8

44-0

27-M

Miff

linO

MSC

PR8

13-0

03Ca

rbon

CMPR

844

-030

Miff

linLM

PR8


and research effort in accordance with conservation need. This has been done in 3 ways.One way is by setting thresholds to ensure a greater number of hibernacula are identifiedfor more threatened species (e.g., among CR Hibernacula, 9 are uniquely designated for astate- or federally listed species, 5 for another species of special concern or severelydepleted species, and one for the other non-listed species; Table 3). A second way isthrough the use of the tiered approach. The different tiers of conservation priority will pro-vide clearer guidance to managers on how to scale the amount of and direct the types ofconservation effort in accordance with conservation need, with greater attention paid tosites with a higher priority status. Guidance is also expanded to cover less critical under-ground sites through classification with a lower priority status (SH, UN, or LU Sites). Ineach case the classification is linked to specific management actions (Table 4). The thirdway the new prioritization plan facilitates efficient allocation of conservation resources isby enabling a relative ranking of individual hibernacula on the basis of the number ofthresholds they meet (Tables 5-7). For instance, the 2 highest-ranked hibernacula overall(hibernacula 26-001-M and 56-004-M) included not only high species richness but har-bored important populations of all 6 focal species (Table 5). Protection of these and otherhigh-ranking hibernacula will allow managers to address multiple conservation impera-tives simultaneously. Such rankings of hibernacula will also enable finer-scale prioritization even within a single classification category (Tables 5–7), and thus greaterefficiencies in allocation of resources.

PRIORITIZATION AND EFFECTIVE MANAGEMENTPrioritization without planning or implementation does not result in improved conser-

vation outcomes (Knight et al. 2006, Sewall et al. 2011). Prioritization, however, can orient management, leading to more efficient allocation of limited conservation resourcesand more effective conservation interventions. Thus, the new prioritization plan we present here can serve as a beginning point for improving the effectiveness of the ongoingconservation program for bat hibernacula, with the goal of maintaining hibernating batpopulations over time.

To that end, building on guidelines initially proposed in the Draft Hibernacula Man-agement Plan, we envision specific monitoring, research, and management efforts that arelinked to the conservation status of a hibernaculum. Under the new plan, the greatest mon-itoring and management attention is to be focused on CR Hibernacula, and especiallythose ranked most highly within this category (Table 5). CR sites are to be monitored every2 years (Table 4) unless contraindicated by specific conditions at a hibernaculum (e.g.,specific hazards like roosting over water that might incur heightened risk of bat mortalityduring disturbance), as a means to closely track the status of the most important popula-tions and most diverse assemblages of bats in the state (Table 3). Monitoring will involveinternal winter surveys where the sites are accessible, and fall or spring surveys otherwise.The CR Hibernacula also represent the first targets for implementation of new techniquesthat are known to improve the accuracy of monitoring efforts, but that have not yet beenregularly implemented during hibernacula surveys in Pennsylvania (see below). For acces-sible sites classified as CR Hibernacula, abiotic conditions including temperature will alsobe measured, either during the internal winter survey or with dataloggers. Some of theimproved bat monitoring methods described below, especially the mapping effort, will



allow for the targeting of the most important roosting areas for collection of data on abiotic conditions.

Several other specific steps are to be completed as soon as feasible at CR Hibernacula,including the creation of a site-specific management plan, the formulation of landowneragreements, and efforts to minimize bat disturbance (Table 4). The site-specific manage-ment plan would include a description of the site, the identification of potential risks to hibernating bat populations, and the presentation of key conservation steps and a time-line to complete them. Such steps may include education of the public via signage or outreach (to indicate the importance of bats to the economy and environment, to highlightthe threats bats face, and to avoid actions that could disturb bats during hibernation), collaboration with commercial caves and mines with active tourism or mining operations to reduce disturbance to bats, education or agreements with local recreational cavers to encourage responsible practices including decontamination of caving gear, or moreintensive management interventions. Intensive management interventions could take several forms, such as the installation or maintenance of bat-friendly gates at the hiber-naculum entrance that allow bat passage and maintain abiotic conditions in the under-ground habitat, but prevent human entry. The imposition of seasonal closures and otherrestrictions also take on a greater importance in the era since the onset of WNS becauseenergetically expensive arousals may compound the effects of energy loss from WNS(Reeder et al. 2012). Another possible management intervention for the future would bethe application of treatments to bats or hibernacula surfaces that reduce the incidence ofWNS or slow its progression (should such treatments be developed and determined safefor bats and cave fauna). Again, CR Hibernacula represent priority sites for such inter-ventions, though it is important to note that not all such intensive management interven-tions or other steps are appropriate to each hibernaculum; such site-specific concernsshould be clarified in the site-specific management plan.

Targeting research efforts to CR Hibernacula will often be desirable, as in many casessuch research will be beneficial to improve knowledge of the most critical sites for hiber-nating bats, and – given the management focus on these sites – ensure a tight connectionbetween field research and its management application. However, intrusive research, suchas research involving mortality of bats or modification of internal conditions may be better directed to other categories of hibernacula, to reduce the potential for detrimentalimpacts on the state’s most critical hibernation sites.

The next most important set of hibernacula are the SC Hibernacula, especially thoseranked most highly within this category (Table 6). These hibernacula are to be monitoredat least once every 5 years (Table 4), to ensure that these sites maintain their diverse batcommunities or important populations of one or more bat species (Table 3) over time. It isrecommended that monitoring occur even more frequently at hibernacula that have a historic record of monitoring (these sites have hibernacula codes ending with ‘M’ in Tables5-7), as a means to maintain long-term continuous datasets. Key management steps for SCHibernacula include the formulation of landowner agreements and a plan to minimize batdisturbance (Table 4). These sites would have secondary priority for large managementinterventions, such as bat-friendly gate installation and maintenance or possible futuretreatments of WNS.

The next conservation priority is the PR Hibernacula, and especially those ranked mosthighly within this category (Table 7). While these sites do not currently maintain substan-



tial bat populations, they may be critical to future recovery. For such sites, a bat survey isto be completed at least once every 10 years and landowner agreements are to be formu-lated. These sites would have tertiary priority for large management interventions, such asbat-friendly gate installation and maintenance (Table 4).

The next 2 categories, SH and UN Sites, imply lower conservation value than the 3highest priority rankings (CR, SC, or PR Hibernacula), but SH and UN sites may havesome potential current or future value for bats. Thus, in terms of monitoring, it would beuseful to survey UN sites (especially in areas with high capture rates during netting oracoustic surveys) and track bat presence and habitat suitability over time at both types ofsites where possible. Such data can be used to identify sites with potential to become occu-pied in the future, to identify target sites that could be modified to improve suitability, andto orient management efforts more broadly (Table 4). In many cases, monitoring of these2 categories of sites could be done via information sharing with recreational caver groups;such groups could note the presence of bats during the hibernation season, or even sendphotos of hibernating bats or bat clusters to enable the PGC to gain information on speciesidentity and abundance. Particular attention should be paid to those sites with stable winter temperatures, as such sites may be particularly suitable as hibernacula (Raesly andGates 1986, Draft Hibernacula Management Plan). This is especially true for those withtemperatures just above freezing, as these sites may take on heightened importance forhibernating bats in the WNS-prevalent period (Johnson et al. 2016).

In contrast, sites for which winter surveys discover no bats, or sites with unfavorableabiotic characteristics, such as temperatures outside the optimal range for bats and no airflow, are likely to be unsuitable (Draft Hibernacula Management Plan), and provide evidence for LU status. It is important to note, however, that all underground sites in thestate have minimum levels of protection. For instance, no cave or mine closure is allowedin Pennsylvania without following the state’s guidelines for determining unsuitable sites(PGC and USFWS unpublished, Appendices to 2012 Memorandum of Understandingbetween the United States Fish and Wildlife Service and the United States Office of Sur-face Mining), and such guidelines are more rigorous than the threshold used here for LUSites (Table 4). The state guidelines outline a procedure to determine if a site is clearlyunsuitable for bats and ensure that corporations or other parties interested in permanentlyor temporarily closing access to underground sites do not inadvertently entomb live batsor close off potential hibernacula from future use.

Underground sites can sometimes be modified through simple changes to features of theentrance and surrounding landscape that affect airflow into or out of the sites. Such modi-fications – which could range from clearing of rockfalls or dense brush at the entrance tocreation of a cold air trap at the entrance or even opening of new entrances – may, in somecases, make the sites more suitable for hibernating bats. Careful evaluation of potentialeffects of cave or mine modification are needed prior to initiation of the work, along withbaseline monitoring of the effects of such efforts that begins before the modification andcontinues after its completion. The goal of such a modification effort would be to createappropriate conditions for hibernation where they did not exist before or to improve condi-tions at sites where they are marginal. Appropriate conditions include a variety of abioticand biotic conditions of the hibernaculum and surrounding landscape (e.g., as described inRaesly and Gates 1986, Draft Hibernacula Management Plan). These may vary by species



and may have changed since the onset of WNS (Johnson et al. 2016). Where possible, itmay be prudent to favor multiple microclimates within a single hibernaculum. Such anapproach can provide habitat to multiple species, allow bats to select optimal roosting habi-tat from among a variety of possible roost sites, and/or to enable individual bats to movebetween roosts within the hibernaculum during a single winter as their needs change (e.g.,across the hibernation season, or during progressive infection with WNS).

Environmental modification may not be needed (or even possible) in all circumstances.For instance, given the precipitous recent declines in bat populations, the availability ofsuitable hibernacula may no longer be a limiting factor. If so, the creation of additionalunderground habitats may not substantially benefit hibernating bat populations. For thisreason, modification may be most successful in areas far from known CR, SC, or PR hiber-nacula, where ideal conditions are not otherwise available. Modification may also enablethe creation of ‘insurance’ hibernacula in cases where there is uncertainty about the con-tinued viability of a critical winter habitat. It is also important to note that environmentalmodification could have unexpected negative consequences for bats and other cave fauna.Thus, tunnels and mines that are classified as SH and LU Sites may be particularly appro-priate candidates for environmental modification. Such anthropogenic sites may harborfew or no bats and few endemic cave fauna, so the potential negative impacts of environ-mental modification may be reduced.

CONCLUSION AND FUTURE DIRECTIONSIn this chapter, we have presented a new plan, the Pennsylvania Hibernacula Prioriti-

zation and Management Plan, with the goals of providing more explicit criteria and thresh-olds; reducing unnecessary complexity; being more inclusive of all species needing conservation attention; being more adaptable to a changing conservation landscape; andproviding more useful guidance to managers for the efficient allocation of conservationresources, research, and monitoring efforts. Our evaluation suggests the new plan haslargely met these goals, though there will still be room for improvement in the future.

Three potential future enhancements were identified during the development of the prioritization plan as important goals for the future. First, improvements in the accuracy ofcount data are needed. Several techniques already exist that can either improve raw countsor enable better estimation of observer errors. These include the use of high-resolution digital photography for improved estimation of numbers of bats in clusters (Meretsky etal. 2010), double-observer methods that distinguish between observer error and naturalvariability (Nichols et al. 2000, Williams et al. 2002, Duchamp et al. 2006), the regularcollection and analysis of standardized data on detection covariates such as survey effortand distance from observer to bat clusters (Williams et al. 2002, Royle and Dorazio 2008),mapping of survey routes and recording of abundance data by hibernaculum section andordered movement through the hibernaculum to increase consistency and to track varia-tion in roosting sites in hibernacula over time (Tuttle 2003), the standardization of surveydate at each hibernaculum in each year it is surveyed (Ingersoll et al. 2013), and otherapproaches known to improve the accuracy of bat counts (O’Shea and Bogan 2003). Ultimately, prioritization efforts depend on accurate data, and the implementation of someor all of these techniques would improve prioritization, and thereby help ensure the hiber-nacula of greatest importance for bat populations are targeted for management.


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Second, the collection of other kinds of data at hibernacula may also improve prioriti-zation. Similar to the previous plan, the new plan relies extensively on numbers of batssurveyed at hibernacula as the primary data source for the prioritization effort. This is animperfect approach: the highest counts are not necessarily representative of the largest truecolony sizes. This is due to the observer errors inherent in standard bat count techniques(as discussed just above), but it is also due to heterogeneities in detection rate by batspecies (Ingersoll et al. 2013) and the inability of surveyors to count bats inhabiting inaccessible areas of hibernacula. In some cases, bats may also be misidentified even byhighly experienced technicians, such as in mixed-species clusters. Further, even if everybat in every hibernaculum were accurately counted and identified, so abundance wasknown precisely, the near-complete reliance on counts would still be less than ideal. Thisis because hibernacula with high bat abundances are not necessarily the best hibernaculafor population growth, due to the presence of attractive but poor quality habitat(Schlaepfer et al. 2002). We have nonetheless relied on counts in this plan since few otherhabitat or colony data are widely available, and because of the importance of protectingthe largest aggregations of bats in the state. An important goal for the future would be tocollect data on habitat quality or population growth rates, to complement count data in theprioritization plan. A first step in this regard could be to downweight the prioritization ofsites for management with known unavoidable but significant threats to hibernatingcolonies, such as those with a history of periodic winter flooding.

Third, a greater recognition of bat population structure is needed. The new plan focuses on the most important populations statewide, as determined by maximum counts withinthe applicable time period. This ensures that large colonies are prioritized for management,but if all the largest colonies are in close proximity, regional variation may not be adequately captured. Specifically, population genetic structure varies spatially within thestate for some species (e.g., Miller-Butterworth et al. 2014), and therefore representationof hibernacula across wide geographic areas would be desirable in future iterations of theprioritization plan. A useful first step in this regard would be a mechanism to ensure representation of sites both to the southeast, and to the north and west of the AppalachianMountains, a potentially important barrier to bat movement in the state (Miller-Butter-worth et al. 2014).

Beyond these enhancements to the prioritization plan, additional basic research on bathibernation ecology and cave ecology is needed. For instance, it is unclear to what extentthe number and diversity of bats captured outside of hibernacula vary with trapping date,and whether the timing of fall swarms and spring emergences may have changed since theonset of WNS in the state. Research into such topics could help clarify the best times and strategies for fall or spring trapping at the entrances to inaccessible hibernacula. Similarly, investigations of how sampling effort (number of hours and number of netting nights) during spring or fall trapping affects species detection would be beneficial. Similarly, thestudy of how results from trapping compare to results from interior surveys is needed tobetter compare data collected with the different techniques and ensure even treatment ofall hibernacula in the prioritization process. Even for accessible hibernacula, bat detectionrates vary for most species across the hibernation season (Ingersoll et al. 2013). This sug-gests a need to standardize survey timing and improve understanding of optimal timing ofsurveys. Another important question relates to modification of hibernacula entrance areas



and areas above hibernacula. While it is clear that changes to the entrance structure andvegetation can affect interior environmental conditions, clarification of the direct relation-ship between them would enable more targeted interventions and greater certainty that themodification would improve interior microclimates for hibernating bats. Finally, surveysto locate populations of rare troglobites, woodrats, and other rare cave-associated faunawould be beneficial. Consideration of the management needs of these species alongsidethose of bat species could facilitate broader community-level conservation within cave andmine environments. These are just a few of the many topics for which targeted researchcould improve management and monitoring efforts at hibernacula.

To our knowledge, Pennsylvania is the only state with such a detailed prioritization andmanagement plan for hibernacula. This new plan and resulting list of priority hibernaculahas the potential to undergird management efforts, serve as a durable strategy to guidehibernacula management, and to provide a valuable tool to reinforce the overall goal ofsupporting the continued persistence of hibernating bat populations in Pennsylvania.

ACKNOWLEDGMENTSWe thank all landowners of hibernacula, all grottos assisting with management of and

access to underground sites, and all PGC biologists and volunteers participating in fieldsurveys of hibernacula and data entry. This research was supported in part by a grant fromthe PGC’s White-nose Syndrome Escrow Fund to B. J. Sewall.

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