Captive Wolves Research Articles

Feeding Enrichment in a Captive Pack of European Wolves (Canis Lupus Lupus): Assessing the Effects on Welfare and on a Zoo's Recreational, Educational and Conservational Role.

Simple SummaryFeeding enrichment is widely used to improve the welfare of zoo animals, but it may also affect zoo visitors’ experience and perception of the animals. The objective of this study was to assess the effects of a naturalistic and a non-naturalistic feeding enrichment program, on both wolf behaviour and visitors’ interest in the exhibit. A questionnaire was administered to visitors with the aim of assessing whether our feeding enrichment programs might affect their perception of captive wolf welfare as well as their attitude towards wolf conservation issues. Our findings suggest that, although wolves seemed to benefit from enrichment, their behavioural responses were highly variable among individuals. Visitors’ interest in the exhibit and perception of captive wolf welfare improved by observing the wolves interacting with food, especially when novel feeding objects were provided. Finally, their attitude towards wolf conservation issues did not change in relation to enrichment, but improved when they observed the wolves performing feeding-related behaviours. These findings may help zoos implement enrichment programs that are effective for enhancing their wolves’ welfare as well as their recreational and educational role.This study investigated the effects of two feeding enrichment programs on the behaviour of a captive pack of European wolves (Canis lupus lupus) and their correlation with both zoo visitors’ interest towards the exhibit and their overall perception of the species. Behavioural data (exploration, stereotypies, social interactions, activity/inactivity rates) were collected on four male wolves during four two-week long phases: initial control, hidden food, novel object, final control. Three observation sessions were performed daily: before, during and after feeding. Number of visitors and their permanence in front of the exhibit were recorded. After watching the wolves, visitors were asked to fill out a brief questionnaire in order to investigate their perception of captive wolf welfare, as well as their attitude towards wolf conservation issues. Despite the high inter-individual variability in their behavioural response, all wolves seemed to benefit from feeding enrichment. With regard to visitors, interest in the exhibit increased when enrichment was provided. Visitors’ perception of the level of welfare of wolves improved if they attended a feeding session, especially during the novel object phase. Visitors’ attitude towards wolf conservation issues also improved during feeding sessions, regardless of enrichment provision.

Parasite survey on a captive wolf population using classical techniques and ELISA coproantigen detection, USA.

As laws change around the United States, wildlife that were once kept as companion animals are now often confiscated by local authorities. They are then euthanized unless a home is found for them at a sanctuary. Wolf sanctuaries are, therefore, becoming increasingly important for their conservation and management. However, little data is available on best practices for the health management of captive wolves, including data on parasitic diseases. Our objective was to assess the prevalence of parasites of captive wolves combining classical coprological techniques and immunoassays based on the detection of coproantigen of selected canid parasites. Fecal samples of 39 animals were collected upon observation of individual animals defecating. All samples were processed using the Fecal Dx® tests, a suite of coproantigen ELISAs for detection of ascarid, hookworm, whipworm, and Giardia (IDEXX Laboratories Inc.). Out of the 39 samples, 38 were processed using the double-centrifugation sugar flotation (DCSF) and 34 using a modification of the Baermann technique. Twenty-eight samples (71.8%) were positive for hookworm, and none positive for the other parasites tested using coproantigen ELISA. Ancylostoma sp. (26, 68.4%), Eucoleus boehmi (13, 34.2%), and Trichuris sp. (2; 5.3%), and Sarcocystis sp. (13, 34.2%) were detected using DCSF. No metastrongyloid lungworm larvae were found. The Cohen's kappa index (0.97) showed excellent agreement between the hookworm coproantigen ELISA and the DCSF using feces preserved in ethanol for a short period of time. This study provides a baseline on the parasites of captive wolves, and shows that recent innovative diagnostics in veterinary parasitology, developed and optimized for dogs, may be used for assessing the health of wolves.

Evidence of individual discrimination in the maned wolf long-distance extended-bark

The acoustic channel is an efficient long-distance signalling system that may be especially effective for animals moving in the dark in a vast home range. The maned wolf’s extended-bark is a long-range vocalization that functions as a mechanism to increase spatial distance among conspecifics as well as to enable pair-mate reunion. Individual variations in this vocalization have been reported, but the possibility that they can be perceived and used by the species has never been tested. In our study, we used ABAB playback experiments to test if captive maned wolves could perceive individual variations. We ran 19 playback sessions with ten different subjects from six different zoos. After discarding nine sessions that did not fulfil minimal experimental conditions, in all except two of the ten valid trials, the subjects responded with displaying Oriented Attention. To our knowledge, this is the first demonstration that the maned wolf is capable of discriminating among extended-barks of different individuals.

Wolf howls encode both sender- and context-specific information

Loud, long-distance calls serve varied functions across animal species including marking territory, attracting mates and signalling one's identity. Here, we examined the types of sender- and context-specific information encoded in the howls of captive timber wolves, Canis lupus. We analysed 913 howls from nine individuals across three packs and investigated whether howl structure varied consistently as a function of phenotypic factors (age class, sex, pack and identity of the caller) in addition to the context in which the call was produced: specifically, whether the call was produced in a ‘spontaneous’ context just after sunrise or was ‘elicited’ by the absence of a group member. Calls were correctly classified by individual identity and production context, but not by any other factors. Principal components analyses indicated that individual differences were primarily associated with frequency-based measures, whereas acoustic variation between production contexts was associated with a variety of frequency-, intensity- and energy-based measures. Recognition of individual differences in vocalizations is likely to be important for navigating social relationships in wolves and further work is required to determine which life history factors may shape these individual differences. Differences resulting from production context are suggestive that these howl variants may serve different functions. The extent to which these individual and contextual differences are understood by receivers remains an open question.

Food preferences of similarly raised and kept captive dogs and wolves.

Food preferences may be driven by a species’ ecology. Closely related species such as dogs and wolves may have evolved preferences for different foods owing to their differing foraging styles. Wolves have been shown to be more persistent in problem-solving experiments and more risk-prone in a foraging task. A possible element affecting these (and other) results is a potential wolf-dog difference in food preferences. To address this possibility, we tested similarly raised and kept dogs and wolves in two different food choice tasks, a classic two-choice task and a multiple-choice paradigm. We predicted that if dogs have adapted to a more opportunistic, scavenging foraging style, they would show a weaker preference for meat over starch rich foods (such as kibble) and be less affected by hunger than wolves. Alternatively, given the recentness of the new niche dogs have created, we predicted no substantial differences between dogs’ and wolves’ food preferences. We found that our subjects did not differ in their preference for meat over kibble in either paradigm. However, wolves’ (but not dogs’) choice patterns were affected by satiation, with wolves being less “selective” when hungry. Furthermore, when fed before testing, wolves were more selective than dogs. These differences were more noticeable in the multiple-choice paradigm than the two-choice task, suggesting that the former, novel paradigm may be more sensitive and better capable of evaluating food preferences in a diverse range of species. Overall, we found that the distinct differences in wolves’ and dogs’ ecology and foraging styles do not appear to have affected their food preferences and thus, differences in food preferences are unlikely to have influenced results of previous experiments demonstrating wolf-dog differences in cognitive skills.

Clinical, morphological, and molecular characterization of an undetermined Babesia species in a maned wolf (Chrysocyon brachyurus)

A possible novel Babesia species infection of a maned wolf (Chrysocyon brachyurus) was first reported in 2012. The current case details a confirmed report of a maned wolf with infection by an undetermined species of Babesia. As the mortality and morbidity of babesiosis is high, this may become a significant concern to captive maned wolves, which are considered a near-threatened species by the World Association of Zoos and Aquariums. The aim of this study is to report the clinical, morphological and molecular characterization of this Babesia species. A 2.5-year-old, intact female maned wolf was found laterally recumbent with pale mucous membranes and jaundice the morning of presentation. Hematological and serum biochemical data were consistent with babesiosis and showed a regenerative severe anemia, leukocytosis, thrombocytopenia, hyperbilirubinemia, azotemia, increased creatine phosphokinase and increase alanine aminotransferase. On blood film review, inclusion bodies were seen in the red blood cells with cytomorphological features that were most consistent with a small form Babesia species. A blood sample was sent for polymerase chain reaction (PCR) testing and multi-locus sequence analyses. These findings suggested a unique Babesia species that is most closely related to a Babesia species (Babesia sp. AJB-2006) that has been found to infect raccoons (Procyon lotor) in North America. Although the cytomorphological features of the piroplasms and the clinical presentation were similar in both the current and 2012 case, when comparing the 18S melt curve temperature of the two Babesia isolates, the peak temperature was different. Unfortunately, genetic material from the 2012 case was not available so comparison of multi-locus gene sequences could not be performed, excluding the possibility to definitively state if the Babesia spp. from both cases were distinct from each other. The maned wolf was treated with a whole blood transfusion, dexamethazone (0.28 mg/kg IM), azithromycin (10 mg/kg in NaCl SC), atavaquone (1.5 cc PO), and 2 imidocarb (6.6 mg/kg IM) injections, and clinically improved. These findings demonstrate the need to further characterize the molecular and epidemiological differences of the Babesia species in this case report and the Babesia species known to infect raccoons.

The effect of domestication on post-conflict management: wolves reconcile while dogs avoid each other.

Highly cooperative social species are expected to engage in frequent reconciliation following conflicts in order to maintain pack cohesiveness and preserve future cooperation. By contrast, in social species with low reliance on cooperation, reconciliation is expected to be less frequent. Here, we investigate the pattern of reconciliation in four captive wolf packs and four captive dog packs. We provide evidence for reconciliation in captive wolves, which are highly dependent on cooperation between pack members, while domestic dogs, which rely on conspecific cooperation less than wolves, avoided interacting with their partners after conflicts. Occurrence, intensity, latency, duration and initiation of wolf reconciliations appeared to vary as a consequence of a compromise between the costs (e.g. risk of further aggression) and the benefits (e.g. restoring relationship with opponents) of such interactions. Our results are in line with previous findings on various wolf packs living under different social and ecological conditions, suggesting that reconciliation is an important strategy for maintaining functional relationships and pack cohesiveness. However, current results on dogs are in contrast to the only other study showing that reconciliation can occur also in this species. Therefore, the occurrence of reconciliation in dogs may be influenced by social and environmental conditions more than in wolves. Which factors promote and modulate reconciliation in dogs needs to be further investigated.

An ounce of prevention: Quantifying the effects of non-lethal tools on wolf behavior

Human-carnivore conflict is presently on the rise as human populations continue to grow and carnivore conservation efforts gain precedence. The behaviors exhibited by carnivores that cause conflict are often learned; therefore, reducing learning potential though the use of non-lethal tools is important for coexistence. In this study we measured how prior experience (i.e., conditioning) influenced the motivation and persistence of captive wolves (Canis lupus) seeking a food reward by quantifying latency to first behavior and duration of behavior for two behavior groups: investigative and work behaviors. Latency to first behavior was faster in conditioned wolves for both investigative (11 times faster; P = 0.0491) and work (4 times faster; P = 0.0112) behaviors, indicating prior experience motivated wolves to overcome neophobic behaviors and facilitated learning to access rewards more quickly. We found little difference in duration for both investigative (P = 0.3194) and work behaviors (P = 0.7016), indicating conditioned and non-conditioned wolves will spend similar amounts of time trying to obtain a reward once a behavior is initiated. When wolves were unable to attain food rewards, we found that the duration of both investigative (P = 0.0631) and work (P = 0.0609) behavior declined over the course of three weeks for both non-conditioned (37.3% and 92.6% decline in investigative behaviors and work behaviors, respectively) and conditioned (59.5% and 88.2% decline in investigative behaviors and work behaviors, respectively) wolves, indicating decreased persistence with the application of a secure prevention measure. Overall, our results indicate that the use of non-lethal tools that prevent animals from attaining anthropogenic food can effectively curb learning in carnivores and help reduce human-carnivore conflict.

Ultrasonographic characteristics of the reproductive tract and serum progesterone and estradiol concentrations in captive female red wolves (Canis rufus) with and without reproductive tract disease.

OBJECTIVE To describe ultrasonographic characteristics of the reproductive tract and serum progesterone and estradiol concentrations in captive female red wolves (Canis rufus) with and without reproductive tract disease. DESIGN Prospective study. ANIMALS 13 adult female red wolves. PROCEDURES Wolves with varying parity and history of contraceptive treatment were anesthetized to facilitate ultrasonographic examination and measurement of the reproductive tract and blood collection for determination of serum progesterone and estradiol concentrations in December 2011 and June 2012. Additionally, during the December evaluation, fine-needle aspirate samples of the uterus were obtained for cytologic evaluation. Measurements were compared between wolves with and without reproductive tract disease and between wolves that had and had not received a contraceptive. RESULTS 7 of 13 wolves had or developed reproductive tract disease during the study. Ranges for measurements of reproductive tract structures overlapped between ultrasonographically normal and abnormal tracts, but measurements for abnormal tracts were generally greater than those for normal tracts. The ultrasonographic diagnosis was consistent with the histologic diagnosis for reproductive tracts obtained from wolves that were sterilized, were euthanized, or died during the study. Cytologic results for fine-needle aspirate samples of the uterus and serum progesterone and estradiol concentrations were unable to distinguish wolves with and without reproductive tract disease. Reproductive tract disease was not associated with parity or contraceptive administration. CONCLUSIONS AND CLINICAL RELEVANCE The ultrasonographic images, reproductive tract measurements, and descriptions of reproductive tract lesions provided in this study can be used as diagnostic guidelines for the treatment and management of red wolves with reproductive tract disease.

Helminth Fauna in Captive European Gray Wolves (Canis lupus lupus) in Germany.

Captive as well as free-ranging wolves, which are currently recolonizing Germany, may harbor a variety of gastrointestinal parasites. This study investigated endoparasites in captive European gray wolves (Canis lupus lupus) using coproscopical methods. Fecal samples were collected monthly between October 2012 and November 2013 from 18 wolf enclosures in 14 German zoological gardens, representing 72 individual wolves. In total, 1,041 fecal samples including 26 bulk samples were analyzed by the sedimentation and flotation method. The most frequently detected egg morphotypes included five nematodes [Ancylostomatidae (Ancylostoma or Uncinaria spp.), Toxocara canis, Toxascaris leonina, Trichuris vulpis, and Capillaria/Eucoleus spp.], one cestode (Taeniidae) and one trematode (Alaria alata). 44.76% of all samples were positive for at least one of these egg morphotypes. Overall, Ancylostomatidae showed the highest frequency (30.84% of all samples), followed by Capillaria/Eucoleus spp. (19.88%), Toxocara canis (5.19%), taeniids (3.75%), Trichuris vulpis and Alaria alata (3.65% each), and Toxascaris leonina (1.25%). As fecal samples were collected from the environment and could not be assigned to individual wolves, sample results were combined per zoo and month. General linear mixed models were employed to analyze the effect of season and management factors on the occurrence of Ancylostomatidae, Capillaria/Eucoleus spp., Toxocara canis and taeniids. No statistically significant effect of season was found, whereas anthelmintic treatment negatively affected Ancylostomatidae egg excretion. Detected parasites and their prevalences are comparable to previous studies on wolf parasitism conducted elsewhere in Europe. As many of the most prevalent helminths are of zoonotic importance, routine anthelmintic treatment of captive wolves should be recommended.

Managed movement increases metapopulation viability of the endangered red wolf

ABSTRACTMovement connects otherwise isolated populations, influencing demographic persistence and promoting gene flow. We evaluated the effect of movement on the genetic and demographic viability of the red wolf (Canis rufus) and tested the application of metapopulation theory to management of this endangered predator. The establishment of a captive subpopulation in the 1970s allowed persistence of the species and facilitated a reintroduction program that supported 2 wild subpopulations, one of which persists today. We assessed the effect of historical and potential future movement between the wild and captive subpopulations on the genetic and demographic viability of the metapopulation. We analyzed approximately 30 years of individual‐level data to quantify the effects of historical movement among subpopulations and constructed an individual‐based metapopulation model to predict the effects of future potential movement (i.e., releases of captive wolves) on the species’ persistence and genetic diversity. Counter to theory, increased movement has had positive demographic effects, with higher per capita movement rates leading to increased metapopulation growth and decreased subpopulation synchrony. These counter‐theoretical results are likely due to differences in reproduction and survival rates among subpopulations and the small size of the metapopulation. Furthermore, higher rates of movement did not increase retention of genetic diversity, likely because of the active pedigree‐based breeding management of the species already maximizing gene retention. Our model indicates that future releases of captive wolves are necessary, but not sufficient, for the survival of the species, and must be combined with changes to demographic rates in both the captive and northeastern North Carolina subpopulations. Our results highlight the need for models and field data that more adequately describe the viability of small metapopulations. © 2017 The Wildlife Society.

Post-conflict opponent affiliation reduces victim re-aggression in a family group of captive arctic wolves (Canis lupus arctos).

Post-conflict affiliative interactions have been widely investigated in primates but not extensively in other species. Using the Post Conflict-Matched Control (PC-MC) comparison method, this study investigated the patterns of post-conflict opponent affiliation (POA) of a captive family group of 19 arctic wolves (Canis lupus arctos), investigating the correlation with various factors. We found that POAs occurred mainly in the non-feeding context and more often when the victim was dominant and the aggressor subordinate. Furthermore, POAs were more likely to have been initiated by the victim than the aggressor. Victims’ stress related behaviours occurred more in PC than MC periods, and more after high vs. low intensity aggressions but they were not more likely to occur after conflicts between wolves with a stronger social bond and POAs did not reduce their rate of occurrence. Our results showed that re-aggression was twice less frequent when a friendly interaction occurred between the aggressor and the victim, and consistent with this, victims engaged in POAs more often than the aggressor. Overall, our results support the hypothesis that POAs in wolves may have been selected for as a mechanism to avoid conflict escalation, which could lead to social disruption and hence jeopardize cooperative activities. The high relatedness among individuals in the pack and the greater dependence of all members on cooperation in breeding and hunting may reduce the importance of ‘relationship quality’ as a mediating factor of POAs, although dominance relationships, which are directly linked to the risks of further conflicts, do play an important role.

The effects of domestication and ontogeny on cognition in dogs and wolves

Cognition is one of the most flexible tools enabling adaptation to environmental variation. Living close to humans is thought to influence social as well as physical cognition of animals throughout domestication and ontogeny. Here, we investigated to what extent physical cognition and two domains of social cognition of dogs have been affected by domestication and ontogeny. To address the effects of domestication, we compared captive wolves (n = 12) and dogs (n = 14) living in packs under the same conditions. To explore developmental effects, we compared these dogs to pet dogs (n = 12) living in human families. The animals were faced with a series of object-choice tasks, in which their response to communicative, behavioural and causal cues was tested. We observed that wolves outperformed dogs in their ability to follow causal cues, suggesting that domestication altered specific skills relating to this domain, whereas developmental effects had surprisingly no influence. All three groups performed similarly in the communicative and behavioural conditions, suggesting higher ontogenetic flexibility in the two social domains. These differences across cognitive domains need to be further investigated, by comparing domestic and non-domesticated animals living in varying conditions.

Free-ranging dogs show age related plasticity in their ability to follow human pointing.

Differences in pet dogs’ and captive wolves’ ability to follow human communicative intents have led to the proposition of several hypotheses regarding the possession and development of social cognitive skills in dogs. It is possible that the social cognitive abilities of pet dogs are induced by indirect conditioning through living with humans, and studying free-ranging dogs can provide deeper insights into differentiating between innate abilities and conditioning in dogs. Free-ranging dogs are mostly scavengers, indirectly depending on humans for their sustenance. Humans can act both as food providers and as threats to these dogs, and thus understanding human gestures can be a survival need for the free-ranging dogs. We tested the responsiveness of such dogs in urban areas toward simple human pointing cues using dynamic proximal points. Our experiment showed that pups readily follow proximal pointing and exhibit weaker avoidance to humans, but stop doing so at the later stages of development. While juveniles showed frequent and prolonged gaze alternations, only adults adjusted their behaviour based on the reliability of the human experimenter after being rewarded. Thus free-ranging dogs show a tendency to respond to human pointing gestures, with a certain level of behavioural plasticity that allows learning from ontogenic experience.

The prevalence and impact of Babesia canis and Theileria sp. in free-ranging grey wolf (Canis lupus) populations in Croatia

BackgroundBabesia spp. and Theileria spp. are important emerging causes of disease in dogs. Alongside these domesticated hosts, there is increasing recognition that these piroplasms can also be found in a range of wild animals with isolated reports describing the presence of these pathogen in foxes (Vulpes vulpes) and captive grey wolves (Canis lupus). The prevalence and impact of these infections in free-ranging populations of canids are unknown. To gain a better insight into the epidemiology and pathogenesis of piroplasm infections in free-ranging grey wolves, pathological and molecular investigations into captive and free-ranging grey wolves in Croatia were performed.ResultsThe carcasses of 107 free-ranging wolves and one captive wolf were the subjects of post-mortem investigations and sampling for molecular studies. A blood sample from one live captured wolf for telemetric tracking was also used for molecular analysis. PCR amplification targeting the 18S RNA gene revealed that 21 of 108 free-ranging wolves and one captive animal were positive for Theileria/Babesia DNA. Subsequent sequencing of a fragment of the 18S RNA gene revealed that 7/22 animals were positive for Babesia canis while the other amplified sequence were found to be identical with corresponding 18S rDNA sequences of Theileria capreoli isolated from wild deer (15/22). Haematological and cytological analysis revealed the presence of signet-ring shaped or pear-shaped piroplasms in several animals with the overall parasite burden in all positive animals assessed to be very low. Pathological investigation of the captive animal revealed fatal septicemia as a likely outcome of hemolytic anaemia. There was little or no evidence of hemolytic disease consistent with babesiosis in other animals.ConclusionImportantly, the presence of B. canis in free-ranging grey wolves has not been described before but has been reported in a single fox and domestic dogs only. That B. canis infections cause disease in dogs but have little impact on wolf health possibly suggests that the wolf is the natural and the domestic dog is a secondary host. Surprisingly, the frequent finding of Theileria capreoli in wolves suggests that this Theileria species is not restricted to ungulates (cervids) but commonly infects also this carnivore species. Nevertheless, the potential role that these asymptomatically infected animals may play in the dispersal of these pathogens to susceptible sympatric species such as domesticated dogs requires further investigation.

Unravelling dominance in dogs

Aggression is the canine behaviour most likely to lead to relinquishment or euthanasia. Understanding how dogs socially interact and manage conflict is therefore of particular importance to veterinary professionals. Traditional approaches to the prevention and management of canine aggression advocated owners assert themselves as ‘pack leader’ through routine control of all resources and correction of any perceived challenge for them. At its most extreme this included physical punishment and steps to inhibit any initiative by the dog, including free movement and social interaction. The theory evolved from early to mid 20th century research into captive wolf behaviour, embellished by subsequent generations of dog trainers and behaviourists. However, more recent research into the behaviour of non-captive wolves and domesticated dogs, both in the home and living ferally, has brought the dominance theory into question. Perhaps more importantly, progress in the fields of animal welfare and training have highlighted ethical concerns and risks associated with the punitive methods of handling and training recommended by advocates. Modern approaches to modifying and managing the behaviour of the domestic dog use scientific principles to understand the motivation for their behaviour. Change is then facilitated through management of triggers, changing the dog's emotional response to them and manipulating things the dog wants, to encourage preferred behaviour.

Piroplasmosis in a Grey Wolf (Canis lupus) Population in Croatia

Introduction: Infection with Babesia canis is common in Croatian dogs suffering from haemolytic anaemia, but also in asymptomatic dogs. Captive wolves can develop babesiosis as well, while the role of free-ranging wolves in the piroplasms life cycle and impact on their health status hasn’t been investigated. Materials and Methods: Blood or different organ samples from one live-trapped wolf and 108 carcasses were screened for presence of Babesia/Theileria DNA. Wolf W1 was captured for movement monitoring, blood-sampled and traced for one year. Wolf W2 was euthanized after car collision. Samples from W2 were submitted for haematology, biochemistry and pathology. Results: Theileria sp. closely related to T. capreoli was confirmed in 13.8%, while B. canis was found in 5.5% of animals, which presents the first report of these pathogens in free- ranging grey wolves. Haematological and biochemical findings in W1 and W2 were within reference values although merozoites were present in 0.03% and 0.09% of erythrocytes, respectively. Majority of necropsied wolves were autolytic, but no signs of hepatosplenomegaly, jaundice, anaemia, pigmenturia or DIC were found. In W2 tissue analysis revealed discrete spleen histocytosis and merozoites within erythrocytes in brain and myocardium capillaries, without other signs specific for babesiosis. Conclusions: B. canis and Theileria sp. maintain sylvatic cycle within wolf population in Croatia. Wolves, although closely related to dogs, don’t develop disease and probably serve as asymptomatic carriers. Free-ranging wolf pups most likely have developed mechanisms for piroplasm clearance like foals infected with B. caballi in which maternal antibodies aid in protective immunity development.

Evidence for sex-specific reproductive senescence in monogamous cooperatively breeding red wolves

Sex-specific senescence has been construed as a function of mating system and differential investment in parental care, with males exhibiting low parental investment predicted to have more rapid senescence due to costly reproductive behavior. In monogamous mating systems, however, where parental investment may be more evenly distributed, rates of senescence are predicted to be more equivalent between the sexes than in polygynous mating systems. While many polygynous species do appear to support this pattern, evidence from monogamous species, particularly mammals, is scarce. Wolves are an excellent system with which to test this hypothesis, as they exhibit both monogamy and cooperative breeding, where parental investment is distributed across both breeders and non-breeders of both sexes. We examined patterns of age-specific reproduction in red wolves and red wolf-coyote hybrids. We found no evidence of decline in pup production with age in male wolves; among females, the production appeared better explained by hybrid status and age at first reproduction than age per se. Remarkably, however, there was strong evidence of sex differences in pup recruitment, with males, but not females, showing a steep decline in recruitment with age. Combined with previous work on aging in captive wolves, our findings contribute not only to the current understanding of the relationship between mating system and senescence but also to the plasticity of aging and the dynamics of female mate choice in the wild. In this study, we test for signs of reproductive aging in red wolves using a 20-year dataset documenting age-specific reproduction in the wild. We find evidence that reproductive aging in males is evident for number of pups recruited, though not for number of pups born; we find no evidence for reproductive aging at either stage in wild female wolves. This sex difference stands in contrast to the general prediction that patterns of aging would be more monomorphic among monogamous species. Furthermore, this is especially of interest given that red wolves are cooperative breeders, with costs of reproduction spread across family groups. In general, this study constitutes a valuable contribution to an emerging literature geared at understanding patterns of aging in the context of diverse social and ecological variables.

Dominance relationships in a family pack of captive arctic wolves (Canis lupus arctos): the influence of competition for food, age and sex.

BackgroundDominance is one of the most pervasive concepts in the study of wolf social behaviour but recently its validity has been questioned. For some authors, the bonds between members of wolf families are better described as parent-offspring relationships and the concept of dominance should be used just to evaluate the social dynamics of non-familial captive pack members (e.g., Mech & Cluff, 2010). However, there is a dearth of studies investigating dominance relationships and its correlates in wolf family packs.MethodsHere, we applied a combination of the most commonly used quantitative methods to evaluate the dominance relationships in a captive family pack of 19 Arctic wolves.ResultsWe found a significant linear and completely transitive hierarchy based on the direction of submissive behaviours and found that dominance relationships were not influenced by the competitive contexts (feeding vs. non-feeding context). A significant linear hierarchy also emerges amongst siblings once the breeding pair (the two top-ranking individuals) is removed from analyses. Furthermore, results suggest that wolves may use greeting behaviour as a formal signal of subordination. Whereas older wolves were mostly dominant over younger ones, no clear effect of sex was found. However, frequency of agonistic (submissive, dominant and aggressive) behaviours was higher between female–female and male–male dyads than female–male dyads and sex-separated linear hierarchies showed a stronger linearity than the mixed one. Furthermore, dominance status was conveyed through different behavioural categories during intra-sexual and inter-sexual interactions.DiscussionCurrent results highlight the importance of applying a systematic methodology considering the individuals’ age and sex when evaluating the hierarchical structure of a social group. Moreover, they confirm the validity of the concept of dominance relationships in describing the social bonds within a family pack of captive wolves.

Spondylosis deformans in three large canids from the Gravettian Předmostí site: Comparison with other canid populations

Spondylosis deformans is a common degenerative condition of the spinal column, especially in modern domestic dogs. The presence and severity of lesions are related to age and physical activity, but they can be influenced by genetics, with some modern breeds being particularly predisposed. Spondylosis deformans also has been reported in prehistoric dogs. Here, we describe three affected vertebrae, likely from three individuals, in a large canid assemblage from the Gravettian Předmostí site, Czech Republic. We compare the proportion of affected individuals from the Předmostí assemblage with that of affected individuals among recent wild Northern wolves, inbred wolves, captive wolves, and recent Northern dogs. The proportion of affected individuals among the captive wolves differs significantly from the other wolf groups. The proportion in the Předmostí assemblage does not differ significantly from that of the wild wolf groups.