Lizards perceived abiotic and biotic stressors independently when competing for shade in terrestrial mesocosms

Hormones such as glucocorticoids and androgens enable animals to respond adaptively to environmental stressors. For this reason, circulating glucocorticoids became a popular biomarker for estimating the quality of an environment, and circulating androgens are frequently used to indicate social dominance. Here, we show that access to thermal resources influence the hormones and behavior of male […]

Aggressive behavior and stress response after oxytocin administration in male Norway rats selected for different attitudes to humans

Oxytocin (OXT) is known to influence on social behaviors, including intermale aggression and hypothalamic-pituitary-adrenal (HPA) axis activity. However, there are no data on the effects of oxytocin on intermale aggression and HPA axis activity in rats selected for elimination and enhancement of aggressiveness towards humans. The aim of this study is to elucidate the role […]

Stress in Broiler Chickens Due to Acute Noise Exposure

Stress effects from acute noise exposure were monitored in a group of ROSS 308 broiler chickens (n = 80), aged 42 days. The experiment simulated slaughterhouse sounds to which the broilers were exposed for 10 min in the test enclosure. Effects of acute noise exposure at two different levels (80 dB and 100 dB) were […]

Behavioral and hormonal responses of Magellanic penguins (Spheniscus magellanicus) to tourism and nest site visitation

One of the results of human disturbance at seabird colonies may be the provocation of the typical vertebrate adrenocortical response to stressors, but there have been few studies that demonstrate this. The present study demonstrates that simple human presence at the nest site, without effects of capture or handling, is physiologically stressful for breeding Magellanic […]

Spontaneous egg or chick abandonment in energy-depleted king penguins: A role for corticosterone and prolactin?

Various exogenous or endogenous factors may induce an emergency response in birds, redirecting current activity towards survival. In fasting, breeding penguins, the achievement of a critical energy depletion was suggested to induce egg abandonment and departure to sea for re-feeding. How such a behavioral shift is hormonally controlled remains unknown. The possible involvement of corticosterone […]

Physiological and Behavioral Differences in Magellanic Penguin Chicks in Undisturbed and Tourist-Visited Locations of a Colony

Studies examining anthropogenic effects on wildlife typically focus on adults and on behavioral responses rather than the physiological consequences of human disturbances. Here we examined how Magellanic Penguin ( Spheniscus magellanicus) chicks living in either tourist-visited or undisturbed areas of a breeding colony were affected by human visitation by comparing the baseline and stress-induced levels […]

Noninvasive monitoring of adrenocortical activity in carnivores by fecal glucocorticoid analyses

Measurement of glucocorticoid metabolites in feces has become an accepted method for the noninvasive evaluation of adrenocortical activity. The objective of this study was to determine if a simple cortisol enzyme immunoassay (EIA) was suitable for monitoring adrenocortical activity in a variety of carnivore species. Performance of the cortisol EIA was gauged by comparison to […]

Housing and welfare in laboratory rats: effects of cage stocking density and behavioural predictors of welfare

Using male and female Alderley Park (Wistar-derived) rats housed in single-sex groups in standard laboratory cages, we looked at the effect of group size (one, three, five or eight) on competitive behaviour and time budgeting (initial and longer term), changes in their serum testosterone (males), corticosterone and antibody concentrations, and organ pathology at age 16 […]

In search of relationships between the acute adrenocortical response and fitness

The assumption that the acute response to stress is adaptive is pervasive in the literature, but there is little direct evidence regarding potential positive fitness consequences of an acute stress response. If acute glucocorticoid (GC) elevation increases lifetime reproductive success (fitness), in what contexts does this occur, and through what combination of effects on annual […]

Actions of glucocorticoids at a seasonal baseline as compared to stress-related levels in the regulation of periodic life processes

For decades, demands associated with the predictable life-history cycle have been considered stressful and have not been distinguished from stress that occurs in association with unpredictable and life-threatening perturbations in the environment. The recent emergence of the concept of allostasis distinguishes behavioral and physiological responses to predictable routines as opposed to unpredictable perturbations, and allows […]