Abstract Integrating endocrine stress biomarkers with parasite community dynamics can help clarify how environmental and management-related pressures relate to host–parasite interactions in endangered wildlife. However, relationships between physiological stress and parasite dynamics remain poorly understood, particularly in high-altitude ecosystems. Here, we investigated the endangered Przewalski’s gazelle (Procapra przewalskii), endemic to the Qinghai–Tibet Plateau, by combining faecal cortisol quantification with amplicon sequencing of the internal transcribed spacer 2 region of ribosomal DNA from gastrointestinal nematodes. Seasonal patterns in physiological stress and nematode community composition were compared between wild and semi-captive populations. Both faecal cortisol concentrations and nematode community composition showed pronounced seasonal variation. Trichostrongylidae reached its highest relative read abundance in summer, whereas Molineidae reached its highest relative read abundance in spring. During spring, semi-captive gazelles exhibited higher faecal cortisol concentrations and greater relative representation of Trichostrongylidae than wild gazelles. Across samples, Trichostrongylidae and Molineidae showed nearly perfectly complementary relative read abundances. Generalized linear models with a Gamma error distribution showed significant associations between faecal cortisol concentrations and the relative read abundance of each dominant nematode family after accounting for season and population type, whereas relative read abundance × population type interactions were not statistically supported. These findings reveal pronounced seasonal associations between endocrine stress responses and gastrointestinal nematode dynamics in Przewalski’s gazelle, while providing no evidence that the parasite–cortisol association differed between wild and semi-captive populations. Our study advances the integration of stress endocrinology and disease ecology in conservation physiology and supports the value of combining non-invasive endocrine and parasitological biomarkers in wildlife health assessment.
Abstract Measures of protein balance, particularly changes in body mass, are important in understanding the health of wildlife populations but can be difficult or impossible to obtain from free-living animals. One potential biomarker, the δ15N value of bulk tissue, has had mixed associations with body mass. δ15N values of amino acids (AAs) have been shown to be more sensitive measures of trophic position than the bulk δ15N value and may also be more sensitive to changes in body mass. Here we evaluate AA δ15N values as a method to assess underweight status using archived serum samples from a captive population of muskoxen (Ovibos moschatus) that had decreased body mass resulting from an inadvertent dietary trace element deficiency. We predicted that AA δ15N values would be associated with deviations from the expected healthy body mass based on sex and age, and that they would be more sensitive than bulk δ15N values. We evaluated several linear mixed-effect models with δ15N values of bulk serum, AAs and other variables against deviations from expected body mass. In females, the δ15N values of glutamate/glutamine, leucine, aspartate/asparagine and serine, plus pregnancy status, were best associated with the difference from expected mass; in males, the δ15N values of glutamate/glutamine, leucine and proline were best associated with the difference from expected mass. Bulk δ15N values were not associated with the difference from expected mass. δ15N values of AAs have potential as a tool for researchers to evaluate body condition in animals.
Abstract Age of primiparity is a critical demographic parameter that influences lifetime reproductive success and fitness. Caribou (Rangifer tarandus) exhibit variation in age of primiparity but generally are considered sexually immature (i.e. do not ovulate or achieve pregnancy) until they are ≥2.5 years old, unless nutrition is exceptional. Using captive, female, yearling caribou, I tested the exceptional nutrition hypothesis, focusing on ovulation because caribou were not permitted to breed. I quantified faecal progesterone concentrations throughout the breeding season and compared those to estimates of body mass, body fat and body protein of caribou. Body mass of yearling caribou ranged from 90.9 to 122.7 kg, body fat varied almost 5-fold (6.3–31.1%) and body protein ranged from 13.7 to 21.2 kg. Faecal progesterone ranged from 89 to 3334 ng/mg (673 ± 13; mean ± SE). Despite highly variable nutritional condition, all n = 11 yearlings exhibited oestrus. Mean date of first oestrus among yearling females was 22 October (±3 days) and caribou initiated oestrus 3.8 days earlier for every 1 kg increase in body protein. Yearling caribou experienced 3–9 (5.6 ± 0.7) oestrous cycles and for every 1% point increase in ingesta-free body fat, number of oestrous cycles between October and March increased by 0.3. Yearlings ovulated even in relatively marginal nutritional condition, indicating exceptional nutrition was not required for ovulation. Population assessments assuming yearling caribou are largely sexually immature may require additional scrutiny or contextualization, particularly if they are used to gauge nutritional status of populations to inform alternative conservation and management strategies.
The early days of animal tagging and tracking using electronic tags were largely restricted to biologists who were electronics hobbyists capable of creating their own devices. Studies were typically characterized by low sample sizes due to lack of storage, large tags with short lifespans and fickle technology, yet those early studies were also important in revealing what was possible. Today, there is an ever-expanding array of commercially available biologging and biotelemetry tools that employ a wide range of sensors that enable us to study the behaviour and physiology of animals, from insects to whales, from the depths of the oceans to high in the atmosphere. The use of multiple sensors can allow us to explore animal-environment interactions and better inform conservation and management. From the identification of problems to the testing of solutions, biologging and biotelemetry are ideal for generating robust, ecologically relevant and management-relevant data. In this perspective article, we first briefly summarize the history of biologging and biotelemetry and consider the ethical aspects of the use of these tools. We then use the Conservation Measures Partnership IUCN Threat Classification and Conservation Action Classification to summarize the key ways in which these tools can be applied to support conservation and management. Finally, we identify opportunities to further advance the ability of those tools to generate effective and durable conservation solutions for the benefit of wildlife and people. This paper is not a comprehensive review but rather a forward-looking and practical perspective that spans applications, taxa, regions and issues.
