Kathreen E. Ruckstuhl

Sexual segregation in vertebrates : ecology of the two sexes

Preface Part I. Overview: 1. Sexual segregation and the ecology of the two sexes Kathreen E. Ruckstuhl and Tim H. Clutton-Brock Part II. Concepts and Methodology: 2. Definitions, hypotheses, models and measures in the study of animal segregation Larissa Conradt Part III. Foraging Ecology: 3. Sex differences in the foraging ecology of large mammalian herbivores Johan T. du Toit 4. Sexual segregation in seals Ian J. Staniland 5. Sexual differences in foraging behaviour and diets: a case-study of wandering albatrosses Jose C. Xavier and John P. Croxall 6. Differences in foraging behaviour and feeding ecology in giant petrels Jacob Gonzales-Solis and John P. Croxall Part IV. Predator Avoidance and Reproductive Strategies: 7. Predation risk as a driving factor for size assortative shoaling and its implications for sexual segregation in fish Darren P. Croft, Jens Krause and Richard James 8. Differences in habitat selection and reproductive strategies of male and female sharks David W. Sims 9. Sex differences in reproductive strategies affect habitat choice in ungulates Martin B. Main and Johan T. du Toit Part V. Sex-related Activities and Social Factors: 10. Activity asynchrony and social segregation Kathreen E. Ruckstuhl and Peter Neuhaus 11. Sexual segregation in ungulates: from individual mechanisms to collective patterns Richard Bon, Jean-Louis Deneubourg, Jean-Francois Gerard and Pablo Michelena 12. Sexual segregation in humans Anthony D. Pellegrini, Jeffrey D. Long and Elizabeth A. Mizerek Part VI. Sexual Differences in Ecology: Comparisons within Different Taxa: 13. Ecological divergence between the sexes in reptiles Richard Shine and Mike Wall 14. Sexual segregation in Australian marsupials Abigail M. MacFarlane and Graeme Coulson 15. Social systems and ecology of bats John D. Altringham and Paula Senior 16. Sociality and ecology of the odontocetes Robert Michaud 17. Sexual segregation in non-human primates David P. Watts Part VII. Implications for Conservation: 18. Sexual segregation in birds: patterns, processes and implications for conservation Paulo Catry, Richard A. Phillips and John P. Croxal 19. Sexual segregation: a necessary consideration in wildlife conservation Esther S. Rubin and Vernon C. Bleich Part VIII. Outlook: 20. Conclusions and future directions Peter Neuhaus, Kathreen E. Ruckstuhl and Larissa Conradt References Index.

Parasite infection and host group size: a meta-analytical review

SUMMARY Many studies have identified various host behavioural and ecological traits that are associated with parasite infection, including host gregariousness. By use of meta-analyses, we investigated to what degree parasite prevalence, intensity and species richness are correlated with group size in gregarious species. We predicted that larger groups would have more parasites and higher parasite species richness. We analysed a total of 70 correlations on parasite prevalence, intensity and species richness across different host group sizes. Parasite intensity and prevalence both increased positively with group size, as expected. No significant relationships were found between host group size and parasite species richness, suggesting that larger groups do not harbour more rare or novel parasite species than smaller groups. We further predicted that the mobility of the host (mobile, sedentary) and the mode of parasite transmission (direct, indirect, mobile) would be important predictors of the effects of group sizes on parasite infection. It was found that group size was positively correlated with the prevalence and intensity of directly and indirectly transmitted parasites. However, a negative relationship was observed between group size and mobile parasite intensity, with larger groups having lower parasite intensities. Further, intensities of parasites did not increase with group size of mobile hosts, suggesting that host mobility may negate parasite infection risk. The implications for the evolution and maintenance of sociality in host species are discussed, and future research directions are highlighted.

Cortisol and corticosterone independence in cortisol-dominant wildlife

Species have traditionally been defined as cortisol-dominant or corticosterone-dominant, depending on the glucocorticoid that is reported. To assess the degree of covariance versus independence between cortisol and corticosterone, 245 serum samples belonging to 219 individuals from 18 cortisol-dominant, non-domesticated species (6 mammalian orders) were compared by mass spectrometry. In these samples, which were elevated above baseline, concentration ranges were overlapping for cortisol and corticosterone although cortisol was dominant in every sample except one of 17 bighorn sheep with a corticosterone-biased cortisol-to-corticosterone ratio of 0.17. As expected, cortisol and corticosterone were strongly associated among species (r(2)=0.8; species with high absolute cortisol tend to have high absolute corticosterone concentrations), with wide variation in the species-average cortisol-to-corticosterone ratio (range 7.5-49) and an even wider ratio range across individuals (0.2-341). However, only 9 out of 13 species with >7 individuals showed a positive association between cortisol and corticosterone among individuals, and repeated measures of the cortisol-to-corticosterone ratio within individuals were weakly associated (CV range 3-136%). We conclude that corticosterone, although at lower concentrations, has the potential to signal independently of cortisol, and should be included in integrated endocrine models of stress responses.

Spatial heterogeneity and temporal variations in Echinococcus multilocularis infections in wild hosts in a North American urban setting

Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, has the potential to circulate in urban areas where wild host populations and humans coexist. The spatial and temporal distribution of infection in wild hosts locally affects the risk of transmission to humans. We investigated the spatial and temporal patterns of E. multilocularis infection in coyotes and rodent intermediate hosts within the city of Calgary, Canada, and the association between spatial variations in coyote infection and the relative composition of small mammal assemblages. Infection by E. multilocularis was examined in small mammals and coyote faeces collected monthly in five city parks from June 2012 to June 2013. Coyote faeces were analysed using a ZnCl(2) centrifugation and sedimentation protocol. Infection in intermediate hosts was assessed through lethal trapping and post-mortem analysis. Parasite eggs and metacestodes were morphologically identified and molecularly confirmed through species-specific PCR assays. Of 982 small mammals captured, infection was detected in 2/305 (0.66%) deer mice (Peromyscus maniculatus), 2/267 (0.75%) meadow voles (Microtus pennsylvanicus), and 1/71 (1.41%) southern red backed voles (Myodes gapperi). Overall faecal prevalence in coyotes was 21.42% (n = 385) and varied across sites, ranging from 5.34% to 61.48%. Differences in coyote faecal prevalence across sites were consistent with local variations in the relative abundance of intermediate hosts within the small mammal assemblages. Infections peaked in intermediate hosts during autumn (0.68%) and winter (3.33%), and in coyotes during spring (43.47%). Peaks of infections in coyote faeces up to 83.8% in autumn were detected in a hyper-endemic area. To the best of our knowledge, our findings represent the first evidence of a sylvatic life-cycle of E. multilocularis in a North American urban setting, and provide new insights into the complexity of the parasite transmission ecology.

Occurrence, diagnosis, and strain typing of Mycobacterium avium subspecies paratuberculosis infection in Rocky Mountain bighorn sheep (Ovis canadensis canadensis) in southwestern Alberta.

The role that wildlife may play in the transmission of Mycobacterium avium subspecies paratuberculosis (Map), the causative agent of Johne’s disease (JD), and the potential consequences of infection in these populations are being given increasing consideration. A yearling male Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from southwestern Alberta, Canada, was found infected with Map in August 2009. Clinical signs of emaciation and diarrhea and histologic findings of diffuse granulomatous enteritis of the distal ileum, lymphadenitis of the mesenteric lymph nodes, and lymphangitis of the ileum were similar to previously described cases of JD in bighorn sheep. Infection with Map was confirmed by bacterial isolation through fecal culture, acid-fast staining, and polymerase chain reaction (PCR) of IS900. The Map1506 gene was sequenced, and the isolate was identified as a Cattle (Type II) strain. In a follow-up herd-level survey, three of 44 fecal samples (7%) from individual bighorn sheep from the same herd as the index case were PCR-positive and identified as Type II Map strains. Twenty-five samples from a distant bighorn population were negative. Additional strain typing of the isolates from the index case and the positive fecal samples was done by sequencing three discriminatory short sequence repeat (SSR) regions. All four SSR profiles differed from one another, suggesting multiple introductions or a long-existing circulation of Map within this bighorn population. Detailed molecular analyses are essential for understanding and managing diseases at the wildlife-livestock interface.

Spatial and Social Sexual Segregation Patterns in Indo-Pacific Bottlenose Dolphins (Tursiops aduncus)

Sexual segregation seems to be common in bottlenose dolphins, whereby males and females live in different pods that mix mainly for mating. Male dolphins often use aggressive behaviour to mate with females, while females with calves may have different activity and dietary requirements to males and different susceptibility to predation. We investigated the degree of spatial and social sexual segregation in Indo-Pacific bottlenose dolphins (Tursiops aduncus) in a subtropical estuary in Australia. Based on surveys completed over three years, dolphin groups were mostly mixed-sex or female. Mixed-sex groups were found in larger groups in mostly deeper water, whereas, female groups were foraging across all water depths in smaller groups. Aggressive coercive behaviour by males towards females was high, occurring mainly in deeper water, at higher tides, and outside the breeding season. Habitat use by female dolphin groups suggests that shallow tributaries may provide a sanctuary from aggressive males, access to suitable prey items and density for mothers and their calves, or a combination of these factors.

Development and availability of the free-living stages of Ostertagia gruehneri, an abomasal parasite of barrenground caribou (Rangifer tarandus groenlandicus), on the Canadian tundra.

Climate change in the Arctic is anticipated to alter the ecology of northern ecosystems, including the transmission dynamics of many parasite species. One parasite of concern is Ostertagia gruehneri, an abomasal nematode of Rangifer ssp. that causes reduced food intake, weight loss, and decreased pregnancy rates in reindeer. We investigated the development, availability, and overwinter survival of the free-living stages of O. gruehneri on the tundra. Fecal plots containing O. gruehneri eggs were established in the Northwest Territories, Canada under natural and artificially warmed conditions and sampled throughout the growing season of 2008 and the spring of 2009. Infective L3 were present 3-4 weeks post-establishment from all trials under both treatments, except for the trial established 4 July 2008 under warmed conditions wherein the first L3 was recovered 7 weeks post-establishment. These plots were exposed to significantly more time above 30°C than the natural plots established on the same date, suggesting a maximum temperature threshold for development. There was high overwinter survival of L2 and L3 across treatments and overwintering L2 appeared to develop to L3 the following spring. The impact of climate change on O. gruehneri is expected to be dynamic throughout the year with extreme maximum temperatures negatively impacting development rates.

The Effect of Cattle Grazing on Native Ungulates: The Good, the Bad, and the Ugly

The effect of cattle grazing on native ungulates: the good, the bad, and the ugly. DOI:10.2458/azu_rangelands_v28i3_Chaikina

Efficacy of a Portable Oxygen Concentrator with Pulsed Delivery for Treatment of Hypoxemia During Anesthesia of Wildlife

Abstract:  Portable battery-driven oxygen concentrators provide an alternative to the use of oxygen cylinders for treatment of hypoxemia during field anesthesia. The aim of this study was to evaluate the use of the EverGoTM Portable Oxygen Concentrator (Respironics®, Murrysville, Pennsylvania 15668, USA) with pulse-dose delivery for improvement of arterial oxygenation during anesthesia of wildlife. This concentrator delivers oxygen in a pulsed flow with pulse volumes from 12 to 70 ml, up to a maximum capacity of 1.05 L/min. The pulse-dose setting shall be adjusted according to the respiratory rate of the animal, e.g., setting 6 for a respiratory rate ≤15/min. The study included 16 free-ranging brown bears (Ursus arctos), 18 free-ranging bighorn sheep (Ovis canadensis), and five captive reindeer (Rangifer tarandus). Oxygen was administered via two nasal lines that were inserted through the nostrils to the level of the medial canthus of the eyes. Arterial blood samples were collected before, during, and after oxygen therapy and immediately analyzed. When providing oxygen from the portable concentrator, the arterial oxygenation markedly improved in all brown bears and some reindeer, whereas no or minor improvement was seen in the bighorn sheep. The mean ± SD (range) PaO2 during oxygen supplementation was 134 ± 29 (90–185) mmHg in the brown bears, 52 ± 11 (32–67) mmHg in the bighorn sheep, and 79 ± 19 (61–110) mmHg in the reindeer. The efficacy of the evaluated method may be influenced by ambient temperature, altitude, pulse-dose setting on the concentrator, the animals respiratory rate, and species-specific physiology during anesthesia. Advantages of the portable oxygen concentrator included small size and low weight, ease of operate, and rechargeablity.

Mixed-sex group formation by bighorn sheep in winter: trading costs of synchrony for benefits of group living

Animals commonly form groups and most sexually dimorphic ungulates form sex-specific groups outside the breeding season. Differences in diet, in vulnerability to predation, and in behaviour between the sexes are hypothesized to drive sexual segregation; however, low-density conditions sometimes favour aggregation. This may occur because larger groups provide greater antipredator benefits that overcome the cost of association between the sexes. In this study we sought to determine whether bighorn rams and ewes (Ovis canadensis) aggregate during winter as an antipredator strategy and whether they alter their behaviour to maintain mixed-sex groups. We compared the occurrence of mixed-sex groups during winter against the population size and sex ratio, and assessed vigilance as an indication of predation risk. We also analysed activity budgets to determine whether group cohesion required departure from sex-specific time budgets. We observed a low proportion of mixed-sex groups in all years of our study except one, in which the population size was very small and the proportion of females was the smallest on record. Mixed-sex groups were larger than single-sex groups, and vigilance was lower in larger groups, indicating that mixed-sex groups provided greater antipredator benefits. However, there was evidence of the oddity effect for older females, which displayed greater vigilance in groups composed primarily of males. Females modified their activity budgets in mixed-sex groups by spending less time foraging and travelling and more time bedding, providing support for the activity budget hypothesis. The costs of mixed-sex group formation limit the circumstances under which aggregation of the sexes is favourable.