Changes in Fecal Glucocorticoid Metabolites in Captive Coyotes (Canis latrans): Influence of Gender, Time, and Reproductive Status

Reproduction is considered an energetically and physiologically demanding time in the life of an animal. Changes in physiological stress are partly reflected in changes in glucocorticoid metabolites and can be measured from fecal samples. We examined levels of fecal glucocorticoid metabolites (fGCMs) in 24 captive coyotes (Canis latrans) to investigate responses to the demands of reproduction. Using 12 pairs of coyotes (five pairs produced pups, seven pairs did not), we analyzed 633 fecal samples covering 11 biological periods (e.g., breeding, gestation, and lactation). Levels of fGCMs showed high individual variability, with females having higher fGCM levels than males. The production of pups showed no statistical effect on fGCM levels among females or males. Among females, fGCM levels were highest during 4-6 weeks of gestation compared to other periods but were not significantly different between pregnant and nonpregnant females. Among males, the highest fGCM levels were during 1-3 weeks of gestation compared to other periods, but were not significantly different between males with a pregnant mate versus nonpregnant mate. Of females producing pups, litter size did not influence fGCM levels. Given that they were fed ample food throughout the year, we found that the demands of producing pups did not appear to statistically influence measures of fGCM concentrations in captive coyotes.

Seasonal Variations of Faecal Cortisol Metabolites in Koalas in South East Queensland

The Koala (Phascolarctos cinereus) is an endemic marsupial inhabiting four states of Australia. Urbanisation, declining habitat, drought and fires are threatening the survival of this flagship species. These threats may cause acute and chronic stress in koalas, which might also be associated with occurrence of infectious diseases in koala populations. Stress may induce an increase in cortisol reflected in increased faecal cortisol metabolite (FCM) values. To be able to use faecal cortisol metabolites to measure stress levels in this species, our aim was to determine baseline values for males and females during breeding and non-breeding season. A total of 351 defecations were collected fortnightly, twice a day, for 12 months from koalas at a wildlife facility in South East Queensland. Samples were analysed with three different enzyme immunoassays (EIAs): a cortisol, 5α-pregnane-3β,11β,21-triol-20-one (37e) and tetrahydrocorticosterone (50c) EIA. The latter, which also reacts with tetrahydrocortisol, the main metabolite in koala faeces, was found to have the highest biological sensitivity and, therefore, is the most suitable EIA to measure stress levels in koalas. Utilising this EIA, we found significant differences (p < 0.05) in FCM values between males and females, breeding and non-breeding season, and between morning and evening samples. Values of faecal cortisol metabolites established in stress-free koalas in this study can serve as a reference for future studies in koalas.

Fur Color and Nutritional Status Predict Hair Cortisol Concentrations of Dogs in Nicaragua

This study examined the relationships between hair cortisol concentrations (HCC) and sex, age, nutritional status (as determined by body condition scores, or BCS), and body mass (geometric mean calculated from morphometric measurements), as well as the potential influence of hair pigmentation (light, dark, or agouti/mixed) on HCC in dogs of the Bosawas Biosphere Reserve, Nicaragua. The dogs examined in this study live in a marginal environment where disease, malnutrition, and mortality rates are high. For fur color, HCC was significantly higher in light fur than in than dark and mixed fur (p < 0.001). In addition, BCS scores were found to have a negative effect on HCC (p < 0.001). Measures of sex and body size exhibited inconclusive effects on HCC, and when compared to adult dogs, juvenile dogs did not exhibit significantly different HCC. Repeated measures of dogs over time reveal a moderate intra-class correlation, suggesting that there are unmeasured sources of individual-level heterogeneity. These findings imply a need to account for fur color in studies of HCC in dogs, and the study suggests an overlooked relationship between cortisol and body condition scores in undernourished dogs in diverse settings.

Human–dingo interactions on Fraser Island: an analysis of serious incident reports

Wild predators that attack people represent a significant challenge to the management authorities charged with conserving populations whilst minimising human safety risk. Fraser Island is home to an iconic population of dingoes (Canis dingo). However, conflict stemming from negative human–dingo interactions (incidents), some resulting in serious human injury and in one case, a fatality, is an ongoing concern. In an effort to highlight important factors influencing incident dynamics, we investigated the most serious incident reports gathered by the Queensland Parks and Wildlife Service for the period 2001–15. We found a consistent pattern of incidents peaking in March/April and also July, corresponding with dingo breeding and whelping seasons (respectively). Monthly vehicle permit numbers (a proxy for visitation) were not positively correlated with incident rates, except during the breeding season. Male dingoes, particularly subadult males, featured heavily in incidents. Despite the fatality being highly publicised and the advent of copious on-site warning messages and other management interventions, serious incidents continue to occur annually, including some involving children. This suggests that risks are either not always understood, or are otherwise being ignored. While our results demonstrate that dingoes generally pose minimal risk to humans, some risk remains, particularly where poorly supervised children are concerned.