reproduction biology in grey wolves canis lupus in belarus

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Vadim Sidorovich and Irina Rotenko Reproduction biology in grey wolves Canis lupus in Belarus: Common beliefs versus reality MINSK CHATYRY CHVERСI 2018

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Vadim Sidorovich and Irina Rotenko

Reproduction biology in grey wolves Canis lupus in Belarus:

Common beliefs versus reality

MINSKCHATYRY CHVERСI

2018

ISBN 978-985-581-173-3

UDC 599.742.11:591.16(476)

© Sidorovich V., Rotenko I., text,illustrations, 2018

The monograph was reviewed by Prof. Dr. Luigi Boitani,

Sapienza University of Rome, Italy; Prof. Dr.Włodzimierz Jędrzejewski,

Instituto Venezolano de Investigaciones Cientificas, Venezuela Dr. Ilpo Kojola,

Finish Game and Fishers Research Institute, Finland

This scientific monograph gives a detailed information about reproduction biology in thegrey wolf Canis lupus in Belarus. This topic includes the wolf breeding (mating and denning)behavior, fertility of the species and mortality of its pups. The initial material was notcollected occasionally from wolf hunters and wolf pup searchers, but mainly gained byauthors first-hand according to a well-set research design and long-term. By analyzing thegathered data, we became convinced that in the wolf reproduction biology there are moreexceptions than rules. Therefore, the standard patterns of reproduction biology in wolvesthat are wide-spread in the published literature about the species we call as common beliefsthat are given versus the wolf reality that we have found in Belarus. Concerning the non-standard features in the wolf reproduction biology, we revealed that multiple breeding inwolf pack is a common phenomenon, breeding of yearling females and wolf-doghybridization were found to be irrespective the food base and strongly depending on thespecies population density i.e. they are reproduction regulations. Wolf pup mortality wasinvestigated and the crucial role of deliberate predation of lynxes on wolf pups wasrevealed.

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Contents

Preface by Luigi Boitani

Chapter 1. Introduction

Chapter 2. Study areas

2.1. Paazierre Forest

2.2. Naliboki Forest

Chapter 3. Methods3.1. Method of wolf census and approach to estimate the species population den-sity3.2. Snowtracking of wolves and identification of wolf tracks3.3. Collecting information from the individual wolves that were marked with aclipped finger3.4. Wolf pup searching and study on wolf denning behavior3.5. Estimation of wolf fertility parameters3.6. Investigation of wolf pack composition3.7. Study on the interference between wolves and lynxes3.8. Gathering of scats of wolf pups and their parents, analysis of the scats in orderto estimate the pup and parent diets3.9. Determination of wolf age 3.10. Estimation of the population density of the main prey species3.11. Statistical methods

Chapter 4. Breeding behavior in wolves4.1. Mating in wolves4.2. Wolf denning and tending of early days pups4.3. Raising of pups after weaning

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4.4. Some behavioral traits of wolf-stray dog pairs at denning and raising pups

Chapter 5. Fertility and reproduction regulations in wolves5.1. Frequency of breeding in female wolves and its density-dependent variation5.2. Fecundity and its density-dependent variation5.3. Pack multi-breeding as a density-dependent reproduction regulation in wolves5.4. Hybridization with stray dogs as an overexploited population response to com-pensate the loss

Chapter 6. Mortality in wolf pups with implication for the species populationstructure6.1. Mortality causes and estimates of mortality rate in wolf pups6.2. Decline in the wolf reproduction with implication for wolf pack compositionBasic results

Literature

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Wolves are not an easy research subject.Elusive, often nocturnal, moving fastacross huge areas and often difficult ter-rain, wolves have challenged researchers,hunters, nature lovers who have been tryingto observe them in the wild. The difficultyto track them is part of the fascination thathas attracted humans to this speciesthroughout human history. In the early 70s,the irruption of radiotelemetry among thesuite of technicalities used by wildlife biol-ogists dramatically increased the wealth ofdata and insights collected on many aspectsof the biology of wolves as well as otherpredators. Several thousands of wolveshave been radio-collared in many parts oftheir large range across the northern hemi-sphere and all aspects of their biology havebeen investigated. One would easily con-clude that there is very little left to be stud-ied and learned on wolves but this would bea great error, as clearly shown by this bookby Sidorovich and Rotenko. There are atleast two main reasons making this bookexceptionally interesting to wolf scientists. The first reason is that this book revealspreviously unknown aspects of wolf repro-duction, such as the high frequency ofyearling reproducing females and of multi-ple litters in the same pack. It is true that

wolves are extremely adaptable to a varietyof habitat types, prey base, human pres-sures to the point that every new study in anew geographic area is likely to yield newresults. However, none really knows thelimit of this ecological and behaviouralflexibility and this book reports on wolfbiology in a very unusual setting: for exam-ple, wolves in Belarus are heavily hunted

Preface

Luigi Boitani, professor, doctor of biolog y,Sapienza University of Rome, Italy, 2015.

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and have to face the fierce competition oflynxes preying on their litters.The second reason is that this book is theresult of the incredibly intensive field workdone by Vadim Sidorovich and IrinaRotenko for many years and in two studyareas. The number of litters found, of kilo-metres of snow and mud-tracking, ofhours of observation, the numbers ofwolves followed throughout their lives and,in general, the quantity of data gatheredduring so many years has little or no com-parison among wolf research projects. Theauthors reveal an unusual capacity for thefield work and a natural sense for the reallife of wild wolves. Their exceptional dedi-cation to gathering first hand data in thefield has produced excellent sample sizesfor many of their analyses even where qual-itative statements are privileged over datamunching and modelling. The result is abook to be read as a combination of a sci-entific report and a personal account of liv-ing in the forest in close companion ofwolves. Among hundreds of anecdotes, aconsistent and forceful story of the life ofwolves in the forests of Belarus emerges tobe compared with the well-established sci-entific information available for wolves ofNorth America and western Europe.Scientists will have some difficulties in

using this book, because data are oftenoffered in unconventional formats.However, the quantity of data and theobvious great knowledge and practice ofthe authors on their subject provide strongsupport to their conclusions.

Luigi Boitani

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The introduction of this book about thegrey wolf Canis lupus reproduction biologywas mostly written by one of the authors,Vadim Sidorovich, who initiated, designedand carried out the main part of thebelow-given studies on wolves in Belarus.Irina Rotenko, who is the second author,helped me with wolves really a lot. From2005 until 2010 all work was done togeth-er with her. From 2011 until 2017 she stillassisted me with the studies on wolvesdespite the fact she was busy with othermatters. Many other persons, who assistedsomehow in the wolf studies are men-tioned in the acknowledgements.

This introduction consists of three parts.The first part is about our aims and moti-vations to write this book. The second parthighlights the new knowledge and skillsrepresented in the book. Finally, I wouldlike to thank those who really helped me inthis study in the acknowledgements.

Thinking about the aims and motivations,as well as about the originality in the bookmessages, I would like to say the followingin several theses.

Being an amateur of wildlife and a profes-sional zoologist, I was caught by passion of

learning reproduction in wolves, first of all,the species denning and family life. Overtwo decades we quite successfully searchedfor the wolf dens in Belarus (mainly inPaazierre Forest and Naliboki Forest) andmarked many of the found wolf pups byfinger clipping, then we traced the markedwolves for as long as possible. All theseallowed us to collect a quite unique data setin relation to reproduction in wolves. So,the first and main idea for the book was justto share the gained knowledge and skillswith wolf colleagues and amateurs.

Chapter 1. Introduction

(1) Vadim Sidorovich, predator researcher of theNaust ecostation, doctor of biology since 1989, pro-fessor since 2008. Naliboki Forest, 2017.

In accordance with the main idea for thebook, I have no ambitions to analyze andsynthesize on the topic for the whole (largeand ecologically various) distribution rangeof the species. Therefore, in this book youwill not find a comprehensive review inrelation to the wolf reproduction andsocial behavior, which combine our owndata with data and knowledge gatheredworldwide. Although I could do this, I pre-fer to study the species in the wild, getting

answers on small questions about behav-ioral and ecological details. An analysis ofall the published results on the topic simplydemands too much time at a computerscreen, which is not how I wish to studywolves as well as is not my life choice gen-erally.

As to the absence of such a review, I alsodid not that because of my evident prob-lem with English. I hope the readers of this

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(2) Irina Rotenko, predator researcher of the Naust ecostation, Naliboki Forest, 2017.

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book will take into account I am not anative English speaker and have never vis-ited any English courses even for a day. Isimply had other priorities, and one ofthem brought this book. Moreover nowa-days, when there are so much informationpublished on most of questions, a reviewof results up-to-date is getting more andmore as a separate job in relation to areporting of a study results.

One may ask why we have written thisbook, without publishing a series of arti-cles for zoological journals. There are sev-eral reasons for that, and I would like to tellabout them. Nowadays, articles in suchjournals are under such heavy reviewing,and, in turn, they demand too much time,leaving not enough time for the study itself.It appears a temptation to economize lifetime and neglect such journal system.Therefore, in order to advance in myresearch and life objectives I chose an alter-native way. To share research results withcolleagues, we chose to create books andmake them available for everyone, free onthe Web. It seems to be a good alternativeway and web stats support this choice.

Moreover, some other peculiarities of ourapproach do not facilitate publishing inzoological journals. We avoid excessive useof statistics, mathematical simulation etc.

Instead we try to provide enough proofnot with abundance of figures and compli-cated statistics, but by using many suitabledocumented examples. We limit the use ofestimates and statistics to a minimum, butattach great importance to detailed andhigh quality basic data. This is how webelieve zoology should be. We have noaffinity with zoologists, who hide their lackof knowledge behind too many estimates,statistics and mathematical modeling. Toour regret, such zoologists are getting moreand more common in the modern city-biased world.

Also, we avoid ambiguous and too sophis-ticated terms for a still unclear phenome-non. Therefore, for instance, in this bookabout the wolf reproduction we did not usethe terms ‘rendezvous site’ or ‘adoptee’.

On the other hand, by comparing the cre-ation of a book and the writing of a scien-tific article, we immediately realize the mainadvantage of books. In a book one candescribe or illustrate something thoroughlyand without limitations, and give the readeraccess to all results in one.

There was another aim and motivation todo this book. By investigating the publica-tions in relation to the grey wolf, wenoticed that our results may bring quite a

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lot of new knowledge on the species repro-duction biology in the region of theEuropean forest zone, and this encouragedus to publish the results.

There is a lot of knowledge about the wolfbreeding behavior and denning in NorthAmerica, but the behavioral patterns differa lot from those in Europe (Mech &Boitani, 2003 and references therein;Sidorovich et al., 2017). Reading the litera-ture about grey wolves and talking with col-leagues about the species in NorthAmerica, comparing that with my experi-ence and knowledge gained in Belarus, Ibecame convinced that wolves in NorthAmerica and Europe are very distinctive intheir behavior, almost as if they are two dif-ferent species.

We may mention two simple examples.

As to the wolf breeding behavior, in NorthAmerica breeding wolves permit humansto observe them at the den by keeping asecurity distance (e.g. Mech, 1988; Mech &Boitani, 2003). Quite opposite, in Belarusbreeding wolves often immediately escapewith their pups from the denning area, ifpeople enter from a road into their denninghabitats. Even, if people pass still quite far(300-700 meters) from the wolf den, theymove their pups to another denning area, at

least, several kilometers away. In Belarus,breeding wolves never use one den for along time like in North America. Quiteopposite, during the first 30-50 days of pupraising, parent wolves keep pups in severaldenning sites with many used dens in eachdenning site (up to 79, usually 15 to 30) byreplacing pups frequently (Sidorovich et al.,2017).

Concerning the intraspecific aggression, inNorth America wolves are often aggressivetowards each other and it’s not rare if awolf gets killed by another wolf (Mech &Boitani, 2003). In Belarus and seemingly inthe whole of Eurasia such strong aggres-sive encounters are rare. After almost fourthousand kilometers of snowtracking ofwolves in Belarus we never faced with this.Moreover, among almost seven hundredcarcasses of wolves inspected, we foundvery few wolves with traces of fights withother wolves. However, once in winter (lateJanuary) at a forest road, we discovered arelatively small male wolf with an injuredhind paw, which was killed by another wolf.

We will briefly discuss the possible causesfor such differences in the wolf traits inEurasia and North America. Wolves inNorth America and in Europe or wider inEurasia were isolated for an evolutionary

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long enough time to be distinctive; thespecies lived and evolved in different habi-tats with different prey stock. Moreover,wolves were extirpated over most of theirNorth-American range, later followed byreintroduction and spontaneous recolo-nization of large areas (e.g. Paquet &Carbyn, 2003). During wolf expansion inNorth America hybridization of wolf withstray dogs and coyotes could frequentlyhappen. Another great difference is thatthe indigenous people, i.e. native NorthAmericans have never persecuted wolves,and only the European invaders and thenthe new Americans began extirpatingwolves in North America about two cen-turies ago.

Conversely in Belarus, Eastern Europe andfurther eastwards wolves were stronglypersecuted for a considerably longer time:at least since the 16th century. At the sametime, despite of the longer and heavy wolfpersecution by humans, wolves in Eurasiahave never been extirpated on such a largespatial scale as in North America. Anotherexample is hybridization of wolves withstray dogs. Again conversely to NorthAmerica, hybridization was a rare phe-nomenon in Belarus, at least, until theearly 2000’s. A European study on wolfgenetics revealed that at that time the wolf

population in Belarus displayed very littlegenetical contamination by hybridizationwith stray dogs; none of the geneticallyinvestigated wolves from Belarus showeddog ancestry (Stronen et al., 2013). Variousother differences between North Americanand European wolves were already dis-cussed in earlier literature (Jędrzejewski etal., 2010).

Published studies on wolves in otherregions of Europe such as Eastern Poland,Russia, Fennoscandia, Italy (e.g. Bibikov,1985 and references therein; Jędrzejewskaet al., 1996; Jędrzejewska & Jędrzejewski,1998; Jędrzejewski et al., 2000, 2001, 2002,2007; Mech & Boitani, 2003 and refer-ences therein for Italy and Fennoscandia)are basically characterized by detailedresults on foraging and diets, impact on theprey populations, home range and territori-ality, movement and population dynamics.

Concerning studies on the wolf breedingin Europe, there are several publicationson the topic (Bibikov, 1985; Theuerkauf etal., 2003; Schmidt et al., 2008). Wolf den-ning behaviour in the European forestzone was described in two articles for thearea of Bielaviezha (Białowieża in Polish)Forest, the Polish part (Theuerkauf et al.,2003; Schmidt et al., 2008). However, the

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articles were based on telemetry study withfew breeding females (n=6) and a rathersmall number of investigated dens (n=8and 16). Therefore, in our point of view,the mentioned results might bring a simpli-fied and biased knowledge on the topic (seeChapter 4 for details).

A lot of information on the wolf breedingin Russia has been published (e.g. Bibikov,1985; items and references therein, first ofall, Danilov et al., 1985 ), but those studieswere mainly based on data that was gainedfrom hunters and wolf pup searchers. Forour part, there is no doubt that data collect-ed by hunters are not sufficient and may begreatly biased. Having both our own dataand data from hunters in Paazierre Forest,we became convinced of this. For instance,if a hunter reports a discovered wolf litter,it’s hard to be sure, if the possibility of mul-tiple breeding in the wolf pack was suffi-ciently checked.

The results on wolf denning behavior in theEuropean part of Russia (Danilov et al.,1985) are of short descriptive nature.Actually, the authors (Danilov et al., 1985)did not consider denning behavior as themain aim of their study on wolf reproduc-tion. Their research was targeted on theeffect of the wolf breeding on theirdemography as well as on fertility in wolves.

On these questions the results gained bythe Russian authors were a great advance inthe study on the wolf reproduction.

Anyway, taking everything into account, wecan conclude that before the given study inEurope and even in Eurasia nobody fromzoologists investigated the grey wolf breed-ing and overall reproduction systematicallyon a large set of own-gained data that weregathered through a scientifically soundapproach. Therefore, despite of the pres-ence of the above-mentioned publicationswe state that actually there is not much cor-rect knowledge about denning in wolves inthe European forest zone.

Our data on the wolf breeding in Belaruswas collected from two local populations ofwolves (in Paazierre Forest and NalibokiForest), on a regular basis during a longperiod. In effect, a very extensive set ofdata on wolf reproduction, in particular onaspects such as fertility, denning behavior,reproductive regulations, diet of pups, sur-vival and mortality of pups were collected.Quite a lot of interesting information wasgained by pup finger clipping and subse-quent tracing of such marked wolves withtheir specific footprints. In addition, smartuse of many camera traps during just fouryears brought some exciting results.

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One of the motivations to prepare thisbook about the wolf breeding was that inEurope and wider in Eurasia there is awidely spread belief that the species isstrictly monogamous with a certain way ofbreeding and pack formation in family pat-tern (e.g. Bibikov D.I., 1985 and referencestherein; Jędrzejewska & Jędrzejewski,1998).

Actually, in our study in Belarus since thelate 1990s we have found so many abnor-malities, that we start thinking about whatactually prevails in the wolf reproduction:the “rules” or “exceptions”. Such "abnor-malities" occurring often is a very interest-ing phenomenon. To describe and analyzethese was another important goal of thebook.

There are several commonly accepted andseemingly ‘normal’ features of the wolfreproduction and the species pack formingin the Eurasian forest zone (Bibikov, 1985;Mech & Boitani, 2003 and referencestherein). Below a list of these “rules”, orshould we say “common beliefs”?

(1) The first breeding of female wolveshappens, when they are about two yearsold or older.

(2) During breeding season, a wolf packhas merely one litter or there are no pups.

(3) Usually a wolf pack consists of parentwolves and their pups of the current andprevious biological years as a normal max-imum; additionally, such a pack may subor-dinate some non-relative wolves.

(4) Usually offspring disperse from theirmaternal pack around mating season, in thesecond year of their life, when they are 20-22 months old.

(5) When wolves are more or less common,wolves usually kill and even consume straydogs, but do not incorporate them into apack and do not interbreed with them.Pairing with stray dog happens in a rarefiedwolf population; and both sexes of straydog may be paired with both sexes ofwolves, respectively.

(6) There is nearly nothing mentionedabout a great negative role of the Eurasianlynx Lynx lynx and wild ungulates (mostlyelk Alces alces, red deer Cervus elaphus andbison Bison bonasus) on the survival of wolfpups. There is a common belief that theseanimals do not markedly impact wolfreproduction.

In our study we found that (2), (3) and (4)are only partially correct, there are excep-tions of (1) and (5), while (6) is entirely theopposite.

The following ‘abnormalities’ were foundin Belarus:

(1) Pack multiple breeding appeared to bea common phenomenon in Belarus.Indeed, during about 20 years of investi-gating wolf breeding in Naliboki Forestand Paazierre Forest and having found 72dens with pups ourselves, we revealed 13cases of double breeding and 2 cases oftriple breeding in a wolf pack. So, in 39%of the investigated denning cases therewas registered a multiple breeding phe-nomenon in the pack. The main reasonfor multiple breeding was mating of thedominant (founding) male not only withthe founding female (mother), but withdaughters or other subdominant females.Taking into account that not in all casesthe possibility of multiple breeding waschecked sufficiently, i.e. when other possi-ble litters could be not discovered, weassume that actually multiple breeding inwolf packs occurs even more often thancan be derived from our data.

(2) Pup survival may be extremely low, andquite often whole litters die.

(3) Out of 72 wolf dens with pups, breed-ing of yearling females was revealed fortwo times (3%). Considering the ratiobetween yearling and other females in the

wolf population, the data suggests thatapproximately 5-8% of yearling femalesalready breed.

(4) Timing of parturition in the wolf pop-ulation seems to be getting prolonged orthere are just many exceptions. In the2000’s among 61 well-documented parturi-tions, we registered one parturition in mid-January, 4 parturitions in late March-earlyApril and 4 parturitions in the last ten daysof May. The majority of the registered par-turitions in wolves were dated within a nor-mal seasonal period, i.e. the last ten days ofApril till mid-May.

(5) Also, we gained enough proofs thatlynxes suppress the wolf reproduction a lotby deliberately hunting on vulnerable indi-viduals such as pups of the year, yearlingfemales and heavily pregnant females. Wildungulates kill many wolf pups, as well.

(6) We frequently found peculiarities ofpack formation. One of them is offspringthat stayed with their parents for 3 to 5years without breeding. The opposite trendis pack formation by mostly unrelatedwolves (without direct family ties). This isconnected with pack deterioration throughwolf persecution by humans or/andbecause of extremely low survival of pups.Both situations lead to pack formation with