Neuroendocrine control of song in the dark-eyed junco (Junco hyemalis)

Thesis (M.S.) University of Alaska Fairbanks, 2000This dissertation includes three discrete projects addressing various aspects of the neuroendocrine control of song in the Dark-eyed Junco (Junco hyemalis), a migratory songbird. Specifically, the roles of testosterone, photoperiodic condition, opioids, and age were investigated with respect to song production and neural plasticity in the regions of the brain that control song (vocal control regions, VCRs)." The author "found that, in males photoperiodic condition and testosterone interact to regulate seasonal VCR volume plasticity, whereas testosterone alone controls song production. The opioid system is probably not involved in VCR plasticity or song production, but is indicated to play a role in song learning or auditory processing. Finally, VCR volumes and song production do not differ with age in photostimulated adult male juncos

Fostering Coexistence Between People and Large Carnivores in Africa: Using a Theory of Change to Identify Pathways to Impact and Their Underlying Assumptions

Coexistence with large carnivores poses challenges to human well-being, livelihoods, development, resource management, and policy. Even where people and carnivores have historically coexisted, traditional patterns of behavior toward large carnivores may be disrupted by wider processes of economic, social, political, and climate change. Conservation interventions have typically focused on changing behaviors of those living alongside large carnivores to promote sustainable practices. While these interventions remain important, their success is inextricably linked to broader socio-political contexts, including natural resource governance and equitable distribution of conservation-linked costs and benefits. In this context we propose a Theory of Change to identify logical pathways of action through which coexistence with large carnivores can be enhanced. We focus on Africa’s dryland landscapes, known for their diverse guild of large carnivores that remain relatively widespread across the continent. We review the literature to understand coexistence and its challenges; explain our Theory of Change, including expected outcomes and pathways to impact; and discuss how our model could be implemented and operationalized. Our analysis draws on the experience of coauthors, who are scientists and practitioners, and on literature from conservation, political ecology, and anthropology to explore the challenges, local realities, and place-based conditions under which expected outcomes succeed or fail. Three pathways to impact were identified: (a) putting in place good governance harmonized across geographic scales; (b) addressing coexistence at the landscape level; and (c) reducing costsand increasing benefits of sharing a landscape with large carnivores. Coordinated conservation across the extensive, and potentially transboundary, landscapes needed by large carnivores requires harmonization of top-down approaches with bottom-up community-based conservation. We propose adaptive co-management approaches combined with processes for active community engagement and informed consent as useful dynamic mechanisms for navigating through this contested space, while enabling adaptation to climate change. Success depends on strengthening underlying enabling conditions, including governance, capacity, local empowerment, effective monitoring, and sustainable financial support. Implementing the Theory of Change requires ongoing monitoring and evaluation to inform adaptation and build confidence in the model. Overall, the model provides a flexible and practical framework that can be adapted to dynamic local socio-ecological contexts. large carnivore conservation, African semi-arid, community-based conservation, human wildlife conflict, community-based natural resource management, adaptive co-management, rangeland management, climate change adaptationpublishedVersio

Offspring Hormones Reflect the Maternal Prenatal Social Environment: Potential for Foetal Programming?

Females of many species adaptively program their offspring to predictable environmental conditions, a process that is often mediated by hormones. Laboratory studies have shown, for instance, that social density affects levels of maternal cortisol and testosterone, leading to fitness-relevant changes in offspring physiology and behaviour. However, the effects of social density remain poorly understood in natural populations due to the difficulty of disentangling confounding influences such as climatic variation and food availability. Colonially breeding marine mammals offer a unique opportunity to study maternal effects in response to variable colony densities under similar ecological conditions. We therefore quantified maternal and offspring hormone levels in 84 Antarctic fur seals (Arctocephalus gazella) from two closely neighbouring colonies of contrasting density. Hair samples were used as they integrate hormone levels over several weeks or months and therefore represent in utero conditions during foetal development. We found significantly higher levels of cortisol and testosterone (both P < 0.001) in mothers from the high density colony, reflecting a more stressful and competitive environment. In addition, offspring testosterone showed a significant positive correlation with maternal cortisol (P < 0.05). Although further work is needed to elucidate the potential consequences for offspring fitness, these findings raise the intriguing possibility that adaptive foetal programming might occur in fur seals in response to the maternal social environment. They also lend support to the idea that hormonally mediated maternal effects may depend more strongly on the maternal regulation of androgen rather than cortisol levels

Female reproductive competition explains variation in prenatal investment in wild banded mongooses

PublishedArticleFemale intrasexual competition is intense in cooperatively breeding species where offspring compete locally for resources and helpers. In mammals, females have been proposed to adjust prenatal investment according to the intensity of competition in the postnatal environment (a form of ‘predictive adaptive response’; PAR). We carried out a test of this hypothesis using ultrasound scanning of wild female banded mongooses in Uganda. In this species multiple females give birth together to a communal litter, and all females breed regularly from one year old. Total prenatal investment (size times the number of fetuses) increased with the number of potential female breeders in the group. This relationship was driven by fetus size rather than number. The response to competition was particularly strong in low weight females and when ecological conditions were poor. Increased prenatal investment did not trade off against maternal survival. In fact we found the opposite relationship: females with greater levels of prenatal investment had elevated postnatal maternal survival. Our results support the hypothesis that mammalian prenatal development is responsive to the intensity of postnatal competition. Understanding whether these responses are adaptive requires information on the long-term consequences of prenatal investment for offspring fitness.ER

Using camera traps to study hyenas: challenges, opportunities, and outlook

The use of remote camera traps has accelerated rapidly in the field of large carnivore science since the 1990s. Members of the Hyaenidae are important components of functional ecosystems in Africa and parts of the Middle East and South Asia, and make good candidates for study using camera traps. However, camera trap studies of hyenas remain rare in the literature when compared to species like tigers Panthera tigris, leopards Panthera pardus, and snow leopards Panthera uncia. In this paper, we examine the published use of camera traps for hyenas (n = 34 studies implemented between 2007 and 2020) and examine the logistical challenges of using camera traps, such as individual identification, limited sexual dimorphism, and complex social structures, for studies of hyena population biology, behavioral ecology, and conservation. We highlight what these challenges may mean for data analyses and interpretation. We also suggest potential benefits of further camera trap studies of this taxonomic family, including new insights into social behavior, range extensions, and robust density estimates

Testes size, testosterone production and reproductive behaviour in a natural mammalian mating system

1. Testosterone (T) is a key mediator in the expression of numerous morphological and behavioural traits in mammals, but the factors underlying individual variation in circulating T levels are poorly understood. 2. The intimate structural integration of sperm and T production within the testes, alongside the dependency of sperm production on high levels of T, suggests that T requirements for spermatogenesis could be an important driver of individual differences in T. 3. To test this hypothesis, we examine how male capacity for sperm production ( as indicated by their testes size) is associated with T levels in a feral population of Soay sheep, resident on St. Kilda, Scotland, during their rutting season. 4. We found a strong positive relationship between an individual's testes size ( as measured before their seasonal enlargement) and the levels of circulating T during their rut, suggesting that T requirements for spermatogenesis has a prominent influence on the production of this androgen. 5. In contrast, body condition and competitive ability did not independently predict T levels, findings that are inconsistent with conventional 'condition-dependent' and 'challenge' hypotheses of T production. 6. This influence of male's capacity for sperm production on T appeared to be substantial enough to be biologically relevant, as testes size also predicted male aggression and mate-seeking behaviour. 7. Our results suggest that a male's inherent capacity for sperm and T production is tightly phenotypically integrated, with potential consequences for a wide range of other T-mediated reproductive traits

Fecal glucocorticoids reflect socio-ecological and anthropogenic stressors in the lives of wild spotted hyenas

Our aim was to identify natural and anthropogenic influences on the stress physiology of large African carnivores, using wild spotted hyenas ( Crocuta crocuta) as model animals. With both longitudinal data from a single social group, and cross-sectional data from multiple groups, we used fecal glucocorticoids (fGC) to examine potential stressors among spotted hyenas. Longitudinal data from adult members of a group living on the edge of the Masai Mara National Reserve, Kenya, revealed that fGC concentrations were elevated during two periods of social upheaval among adults, especially among younger females; however, prey availability, rainfall, and presence of lions did not influence fGC concentrations among hyenas. Our results suggested that anthropogenic disturbance in the form of pastoralist activity, but not tourism, influenced fGC concentrations among adult male hyenas; rising concentrations of fGC among males over 12 years were significantly correlated with increasing human population density along the edge of the group's home range. As hyenas from this social group were frequently exposed to anthropogenic disturbance, we compared fGC concentrations among these hyenas with those obtained concurrently from hyenas living in three other groups undisturbed by pastoralist activity. We found that fGC concentrations from the undisturbed groups were significantly lower than those in the disturbed group, and we were able to rule out tourism and ecological stressors as sources of variation in fGC among the populations. Thus it appears that both social instability and anthropogenic disturbance, but not the ecological variables examined, elevate fGC concentrations and represent stressors for wild spotted hyenas. Further work will be necessary to determine whether interpopulation variation in stress physiology predicts population decline in groups exposed to intensive anthropogenic disturbance

Review of the global research on Hyaenidae and implications for conservation and management

1. Despite the ecological importance of the four extant species of Hyaenidae, and the threats they face globally, there has been no review of the nearly 100 years of published research on hyaenas, nor has there been a synthesis of management-related literature regarding these species. 2. We reviewed 907 studies on Hyaenidae, summarized broad temporal, geographic and topical trends, and evaluated findings from management-related research to determine ways forward for hyaena conservation management. Since the first known study in 1939, most have focused on spotted hyaena (Crocuta crocuta; 75% of all studies), yet overall publications for Hyaenidae have increased by 372% in recent decades. 3. Only 44 of the 67 hyaena range states were represented across publications, with nearly half of all studies conducted in Kenya (18%), South Africa (16%) and Tanzania (13%). Twenty-eight countries had fewer than five studies. Ecology and diet were the most-studied topic areas. The least-studied topics were disease and physiology. 4. Studies on human–hyaena interactions were highly variable in topic, with infrastructure impacts and Hyaenidae benefits to people covered the least. All species were reported to have consumed anthropogenic diet items. Mortality data were included within 11% of publications, with 79% of recorded hyaena mortality constituting anthropogenic causes, although there were few targeted studies on the subject. Lastly, 12% of publications involved community engagement in their methods. 5. There is a significant bias among species, topics and range states across Hyaenidae studies, and little data explicitly related to human–hyaena coexistence. Our management-focused synthesis suggests that research on Hyaenidae could better reflect large carnivore conservation and management inquiry by increasing studies focused on human interactions with Hyaenidae. To address research gaps and inform Hyaenidae management, we recommend increasing applied research outside of protected areas and using interdisciplinary, community-involved methods to increase foundational knowledge on understudied hyaena species, habitats and locations