National Wildlife Research Center

FY 2019

Methods Development and Damage Management of Depredating Birds and Invasive Wildlife

Contact Information:

Dr. Bryan M. Kluever Research Wildlife Biologist Florida Field Station 2820 East University Avenue Gainesville, FL 32641

Phone: (352) 375-2229 Email: bryan.m.kluever@usda.gov Website: www.aphis.usda.gov/wildlifedamage/nwrc/

Groups Affected:

Air travelersAirlinesAirportsArchaeological site managersBroadcast and communicationtower owners and operatorsBusiness ownersCity managersElectric utility companiesEndangered speciesconservationists and managersHealth authoritiesHomeownersMilitary installationsNatural resource managersTouristsWater managers (managementdistricts)Wildlife managers

Major Cooperators:

BiosecurityQueensland/Department ofPrimary IndustriesFlorida Department ofEnvironmental Protection (or stateparks)Florida Fish and WildlifeConservation CommissionNational Park ServiceUniversity of California-DavisUniversity of Colorado School ofPublic HealthUniversity of FloridaUniversity of Southern QueenslandU.S. Air ForceU.S. Fish and Wildlife ServiceU.S. Geological SurveyU.S. NavyWildlife Services Operations

National Wildlife Research Center Scientists Address Problems Associated with Invasive and Overabundant Wildlife Populations

Wildlife Services' (WS) National Wildlife Research Center (NWRC) is the only Federal research organization devoted exclusively to resolving conflicts between people and wildlife through the development of effective, selective, and socially responsible methods, tools, and techniques. Scientists with NWRC's field station in Gainesville, Florida, conduct research to resolve problems caused by invasive species and overabundant native species. This 26-acre research facility includes large outdoor test pens and aviaries which allow research to be conducted under natural environmental conditions.

As land-use patterns change and people move into previously uninhabited areas, wildlife conflicts inevitably increase. Of growing concern are problems associated with some abundant native bird species, such as vultures, gulls and crows, which readily adapt to urban and suburban settings. Additionally, populations of invasive or non-native species, such as rose-ringed parakeets, monk parakeets, Burmese pythons, feral swine and Argentine tegu lizards, continue to grow with harmful impacts to native ecosystems and human health and safety.

Applying Science & Expertise to Wildlife Challenges

Trapping Invasive Lizards. Growing up to 4.5 feet in length, the invasive Argentine black and white tegu is the largest species of tegu lizard. It eats a variety of both plants and animals and has become a threat to many native species in Florida, including the gopher tortoise and Florida burrowing owl. Tegus were introduced through the pet trade and now populate south and west-central Florida from accidental and intentional releases. To help State wildlife officials in their tegu control efforts, researchers at the NWRC Florida field station evaluated the responses of 12 wild-caught captive tegus to several alternative live-trap and bait combinations. Trap types included commercial live-traps and 40-inch polyvinyl chloride (PVC) pipe traps. Bait options included chicken eggs, melon-oil scent, a commercial trapper lure (My-T Mouse Blackie's Blend), and no bait. The researchers videotaped and reviewed each trial to document how long it took the lizards to enter the traps and any other important behaviors. Results showed no significant difference between the alternative trap/bait combinations and their effectiveness. Tegus are willing to enter traps of various shapes and sizes baited with lures other than eggs. However, PVC traps are less expensive than commercial traps, can be constructed using items commonly found in hardware stores, and could be deployed in greater numbers to maximize capture rates.

Burmese Pythons as Hosts for Mosquitoes. The Burmese python is a well-established invasive species in southern Florida. It is likely that populations of Burmese pythons serve as hosts for native mosquito communities. To test this concept, NWRC and University of Florida researchers used mitochondrial cytochrome c oxidase subunit 1 DNA barcoding to determine the hosts of blood fed mosquitoes collected at the NWRC Florida Field Station where captive Burmese pythons are maintained in outdoor enclosures. Researchers recovered python DNA from the blood meal of three species of Culex mosquitoes. Results demonstrate that local mosquitoes will feed on invasive Burmese pythons, meaning the snakes may be involved in the transmission of mosquito-vectored pathogens. Researchers also note the techniques used have potential for detecting the presence of Burmese pythons in the field through screening mosquito blood meals for their DNA.

Chemical Ecology of Burmese Pythons and Tegus. Invasive Burmese pythons and black and white Argentine tegus are found in southern Florida, with the latter species being capable of spreading throughout much of the southeastern United States. Both species' behavior is driven by the animals' detection and reaction to chemosensory cues. The NWRC Florida Field Station, in cooperation with James Madison University, is examining the importance of scent trailing in these species, and how this behavior might be used to bolster management efforts. A recent study showed that male Burmese

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pythons track female scent trails, and efforts are currently underway to develop and test a python pheromone lure to help trap the snakes. A similar investigation found that female tegus track males during the breeding season. Since breeding female tegus are the drivers of this species’ invasive populations, researchers note the identification and development of a male-based scent lure could increase trapping efficiency.

Allowable Take of Black Vultures. The U.S. Fish and Wildlife Service (USFWS) issues permits for the lawful take of migratory birds, including black vultures, under various laws and treaties. These permits are used for a variety of purposes and are intended to balance human needs and the sustainability of migratory birds. The USFWS is committed to science-based approaches for estimating the take of migratory birds and is currently assessing alternatives for a take-permitting program for black vultures. To assist in this effort, NWRC and U.S. Geological Survey researchers have expanded an existing analysis used to estimate allowable black vulture take in Virginia to include the entire range of black vultures in the eastern United States. The combined population demographic rates, population size estimates, and management objectives to estimate allowable take at four different scales: 1) individual states, 2) Bird Conservation Regions, 3) USFWS administrative regions, and 4) flyways. Results showed the overall black vulture population in the Atlantic and Mississippi Flyways was estimated to be 4.26 million in 2015. Subsequent estimates for allowable take ranged from a few hundred individuals per year in states at the northern end of the species range to approximately 287,000 per year over the entire eastern United States. Researchers suggest that allowable take for the species be applied at a scale that reduces conflicts (e.g., livestock predation and property damage), ensures black vultures are not eliminated from local areas, and is efficient for administrative and monitoring purposes.

Path of Least Resistance for Feral Swine. Many wildlife species take advantage of dirt roads or tracks for easier travel. This behavior of using the “path of least resistance” comes in handy for researchers who want to determine animal abundances and record animal activity using road-based observation methods, such as camera traps and tracking plots. NWRC and university scientists placed GPS tracking collars on feral swine to investigate the frequency and timing of feral swine movements across roads in Florida pasturelands. Compared to natural Florida habitats, pasturelands offer little resistance for travel by feral swine. Results showed 17 of the 18 radio-collared swine (94 percent) were located on roads over half of the days they were monitored. Moreover, on days when collared swine were located on roads, they averaged 5.3 road crossings per day with a combined 76 road locations expected each day. Researchers conclude that although pasturelands are considered easy-to-traverse terrain, feral swine still frequently use roads, making road-based observation systems an efficient way to collect feral swine population monitoring data in a wide variety of habitats.

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Selected Publications:

Avery, M.L., J.S. Humphrey, and R,M. Engeman. 2106. Evaluating trap alternatives for removal of Salvator merianae (black and white tegu). Southeastern Naturalist 15 (special issue 8):107-113. doi: 10.1656/058.015.sp810

Boughton, R.K., B.L. Allen, E.A. Tillman, S.M. Wisely, and R.M. Engeman. 2019. Road hogs: implications from GPS collared feral swine in pastureland habitat on the general utility of road-based observation techniques for assessing abundance. Ecological Indicators 99:171-177. doi: 10.1016j.ecolind.2018.12.022

Reeves, L.E., K.L. Krysko, M.L. Avery, J.L. Gillet-Kaufman, A.Y. Kawahara, C.R. Connelly, and P.E. Kaufman. 2018. Interactions between the invasive Burmese python, Python bivittatus Kuhl, and the local mosquito community in Florida, USA. PloS ONE 13(1):e0190633. doi: 10.1371 journal.pone.0190633

Richard, S.A., E.A. Tillman, J.S. Humphrey, M.L. Avery, and M.R. Rockwell. 2019. Male Burmese pythons follow female scent trails and show sex-specific behaviors. Integrative Zoology 14:460-469. doi: 10.1111/1749-4877.12376

Zimmerman, G.S., B.A. Millsap, M.L. Avery, J.R. Sauer, M.C. Runge, and K.D. Richkus. 2019. Allowable take of black vultures in the Eastern United States. Journal of Wildlife Management 83(2):272-282. doi:10.1002/jwmg.21608

Major Research Accomplishments:

• WS research shows invasive tegus are willing to enter traps ofvarious shapes, sizes, and lures.

• WS research shows that Florida mosquitoes will feed oninvasive Burmese pythons, meaning the snakes may beinvolved in the transmission of mosquito-vectored pathogens.

• WS research shows that scent tracking occurs in invasivereptiles, meaning pheromone lures have the potential to beused in trapping efforts to increase capture efficiency.

• WS and U.S. Geological Survey estimates of allowable blackvulture in the Atlantic and Mississippi Flyways ranged from afew hundred a year in northern states to approximately287,000 per year over the entire eastern United States.

• WS research with radio-collared feral swine shows the animalsfrequently use and cross roads, making road-basedobservation systems an efficient way to collect feral swinepopulation monitoring data.