Biology subjects

Brown, J. L.

Publications and source records attributed to Brown, J. L..

4 recordsLinked to original sources

bioRxiv2019

Short-term effects of GPS collars on the activity, behavior, and adrenal response of scimitar-horned oryx (Oryx dammah)

GPS collars have revolutionized the field of animal ecology, providing detailed information on animal movement and the habitats necessary for species survival. GPS collars also have the potential to cause adverse effects ranging from mild irritation to severe tissue damage, reduced fitness, and death. The impact of GPS collars on the behavior, stress, or activity, however, have rarely been tested on study species prior to release. The objective of our study was to provide a comprehensive assessment of the short-term effects of GPS collars fitted on scimitar-horned oryx (Oryx dammah), an extinct-in-the-wild antelope once widely distributed across Sahelian grasslands in North Africa. We conducted behavioral observations, assessed fecal glucocorticoid metabolites (FGM), and evaluated high-resolution data from tri-axial accelerometers. Using a series of non-standard regression models, we illustrate clear but short-term effects to animals fitted with GPS collars. Behavioral observations highlighted a significant increase in the amount of headshaking from pre-treatment levels, returning below baseline levels during the post-treatment period (>3 days post-collaring). Similarly, FGM concentrations (i.e., stress hormones) increased after GPS collars were fitted on animals but returned to pre-collaring levels within 5 days of collaring. Lastly, tri-axial accelerometers, collecting data at eight positions per second, indicated a > 480 percent increase in the amount of hourly headshaking immediately after collaring. This post-collaring increase in headshaking was estimated to decline in magnitude within 4 hours after GPS collar fitting. These effects constitute a handling and/or habituation response (model dependent), with animals showing short-term responses in activity, behavior, and stress that dissipated within several hours to several days of being fitted with GPS collars. Importantly, none of our analyses indicated any long-term effects that would have more pressing animal welfare concerns.

ecology↗

bioRxiv2019

Effects of arthropod prey turnover on the chemical traits of poison frogs: a landscape ecology approach to assess the phenotypic consequences of biotic interactions

Ecological studies of species pairs demonstrated that biotic interactions promote phenotypic change and eco-evolutionary feedbacks. However, we have a limited understanding of how phenotypes respond to interactions with multiple taxa. We investigate how interactions with a network of prey species contribute to spatially structured variation in the skin toxins of the Neotropical poison frog Oophaga pumilio. Specifically, we assess how beta-diversity of alkaloid-bearing arthropod prey assemblages (68 ant species) and evolutionary divergence among populations (from a neutral genetic marker) contribute to frog poison dissimilarity (toxin profiles composed of 230 different lipophilic alkaloids sampled from 934 frogs at 46 sites). We show that ant assemblage turnover predicts alkaloid turnover and unique toxin combinations across the range of O. pumilio. By contrast, evolutionary relatedness is barely correlated with toxin variation. We discuss how the analytical framework proposed here can be extended to other multi-trophic systems, coevolutionary mosaics, microbial assemblages, and ecosystem services.

ecology↗

bioRxiv2019

Environmental, social, management and health factors associated with within- and between-individual variability in fecal glucocorticoid metabolite concentrations in zoo-housed Asian and African elephants

Identifying links between environmental, social, management, and health factors as they relate to physiological stress in captive elephants is crucial for the improvement of welfare and husbandry practices in North American zoos. Studies have examined the effects of short-term and chronic elevations in glucocorticoids in small groups of elephants, but few have examined adrenal activity on a large scale. This study evaluated 106 Asian (Elephas maximus) and 131 African (Loxodonta africana) elephants housed at 64 accredited facilities across North America. Fecal samples were collected every other week for 12 months and analyzed for glucocorticoid metabolite (FGM) concentrations. Risk factors for mean and individual variability (CV) in FGM were subjected to univariate and multivariable analyses using epidemiological methods. Independent variables that included individual traits, social environment, housing and management factors were chosen based on their identification as risk factors in previously published models for the same North American population of elephants. Results indicate that African elephants are more responsive to social stressors than Asians, and that poor joint health is a stress-related welfare problem for Asian, but not African elephants. For both species, higher FGM concentrations were associated with zoos located at more northern latitudes and having free access to indoor/outdoor spaces, whereas spending more time in managed interactions with staff were associated with lower FGM concentrations. Also important for captive management, elephants having diverse enrichment options and belonging to compatible social groups exhibited lower mean and reduced intra-individual variability in FGM. Our findings show that aspects of the zoo environment can be potential sources of stress for captive elephants, and that there are management activities that can facilitate coping and adapting to zoo conditions. Given species differences in factors that affected FGM, targeted, species-specific management approaches likely are needed to ensure good welfare for all elephants.

zoology↗

bioRxiv2018

Influence of season, tourist activities and camp management on body condition, testicular and adrenal steroids, lipid profiles, and metabolic status in captive bull elephants in Thailand

We previously found relationships between body condition and physiological function affecting health and welfare of female tourist camp elephants in Thailand, and used that approach to conduct a similar study of bulls elephants in the same camps (n = 13). Elephants received a body condition score (BCS) every other month, and fecal glucocorticoid metabolite (FGM) concentrations were measured in twice monthly samples for 1 year. Effects of season, camp management and tourist activity on lipid profiles [total cholesterol (TC), low density lipoproteins (LDL), high density lipoproteins (HDL), triglycerides (TG)] and metabolic factors [insulin, glucose, fructosamine, glucose to insulin ratio (G:I)] were determined and correlated to measures of body condition, testosterone and adrenal function. Positive correlations were found between BCS and TG, between FGM and TG, HDL and glucose, and between testosterone and HDL (p<0.05), whereas BCS and testosterone were both negatively associated with the G:I (p<0.05). Elevated FGM concentrations were associated with altered lipid profiles and metabolic status and were higher in winter compared to summer and rainy seasons. Insulin and glucose levels were higher, while the G:I was lowest, in the winter season. Strong positive associations (p<0.001) were found between TC and HDL, LDL and HDL and glucose, and glucose and insulin. By contrast, negative relationships (p<0.001) were found between the G:I and HDL and glucose, and between insulin and G:I. Differences also were found between High and Low tourist season months for FGM, insulin, and G:I, which may be related to tourist activities. Last, there was notable variation among the camps in measured parameters, which together with the tourist season effect suggests camp management related to tourism may affect physiological function and welfare; some negatively like feeding high calorie treats, but others are positively, like exercise. Last, compared to females, bulls elephants appear to be in better physical health.

zoology↗