Annual rhythm of body weight in Prezwalski horses
The live-weight of female Przewalski horses in a semi-natural reserve has been recorded continuously over 6 years by means of an automatic weighing machine and automatic identification. Data were tested for cyclic as well as for linear trend effects and a mathematical model was developed. A clear annual rhythm of live-weight with the maximum in […]
Puberty in female cavies (Cavia aperea) is affected by photoperiod and social conditions
In many environments, photoperiod is a reliable predictor of ecological conditions. Such predictability generally declines towards low latitudes as the yearly cycle becomes less marked. It has been claimed that photoperiodic effects are small in cavies and guinea pigs that reproduce throughout the year. We here investigated photoperiodic influences on the onset of puberty in […]
Plasma corticosterone increases during migratory restlessness in the captive white-crowned sparrow Zonotrichia leucophrys gambelli
Plasma corticosterone increases during the period of spring migration in a variety of bird species. Long-distance migrants show elevations in corticosterone specifically in association with the stage of flight, suggesting that corticosterone may support flight-related processes, for example, locomotor activity and/or energy mobilization. The pattern of corticosterone secretion as it relates to migratory flight has […]
Social and Environmental Factors Influence the Suppression of Pup-Directed Aggression and Development of Paternal Behavior in Captive Meadow Voles (Microtus pennsylvanicus)
During summer, female meadow voles (Microtus pennsylvanicus) maintain territories and males do not engage in paternal care. As day length shortens, territories dissolve and males nest with females and young. Because paternal behavior has never been studied in free-living meadow voles during colder months or in the laboratory under short photoperiods, the authors examined whether […]
The effects of the light regimen imposed during lactation on the performance and behaviour of sows and their litters
The objective of the present study was to highlight the possible effects of an extended photoperiod throughout lactation on the performance and behaviour of sows and their piglets. Sows were randomly assigned to two light regimens: (1) standard (n = 12) consisting of 8 h of light (0700–1500) daily from day 111 of gestation until […]