Diel and infradian (7-day) activity rhythms in Mexican spider monkeys (Ateles geoffroyi) kept with and without visitor contact

Diel activity rhythms in mammals are regulated by an endogenous (circadian) timing system which is synchronized by environmental 24-hr periodicities called zeitgebers. Additional direct responses to stochastic environmental factors ensure the fine-tuning to the actual situation and may mask the circadian time course. Following an observational study on behavioral effects of visitor activities in a […]

Social influences on circadian behavioural rhythms in vertebrates

Although photoperiodic cycles are known to be the most powerful entraining agent of circadian rhythms in homeotherms, social factors can also play a role in synchronizing activity rhythms. Here we review social influences on circadian behavioural rhythms in vertebrates, focusing on the types of possible effects and the types of stimuli eliciting these effects. Social […]

Variation of the phase of the 24-h activity period in different large herbivore species under European and African conditions

The variation of daily rhythms were analysed in relation to environmental factors. Activity phases were determined for Przewalski horses (Equus ferus przewalskii), feral domestic horses (Equus caballus), and mouflon (Ovis orientalis musimon) in Europe under semi-natural conditions by storage telemetry (ETHOSYS 1 ) and compared to samples from plain zebra (Equus burchelli) and blesbok (Damaliscus […]

A note on the circadian rhythm and feeding behaviour of heep fitted with a light weight GPS collar

The circadian rhythm and feeding behaviour (bite rate) of 16 Scottish Blackface ewes of which eight were fitted with a lightweight (863 g) GPS collar were examined. The collar consisted of a leather harness and a 0.5 l aluminium box and represented 2.2% of the average body mass of the study ewes. No differences in […]

Circadian rhythms in metabolic variables in Caenorhabditis elegans

Circadian rhythms govern a wide variety of physiological and metabolic functions in most organisms through neural networks, hormones and gene expression. In this work, we studied the circadian variation in metabolic variables of adult C. elegans such as food consumption, pharyngeal contractions, defecation and oxygen consumption. Feeding behavior was clearly rhythmic under LD conditions, with […]

The circadian body temperature rhythm of Djungarian Hamsters (Phodopus sungorus) revealing different circadian phenotypes

Djungarian hamsters (Phodopus sungorus) of our breeding stock show three rhythmic phenotypes: wild type (WT) animals which start their activity shortly after “lights-off” and are active until “lights-on”; delayed activity onset (DAO) hamsters whose activity onset is delayed after “lights-off” but activity offset coincides with “lights-on”; and arrhythmic hamsters (AR) that are episodically active throughout […]

Effects of environmental enrichment on behavioral responses to novelty, learning, and memory, and the circadian rhythm in cortisol in growing pigs

Previously we showed that pigs reared in an enriched environment had higher baseline salivary cortisol concentrations during the light period than pigs reared under barren conditions. In the present experiment, it was investigated whether these higher baseline salivary cortisol concentrations were a real difference in cortisol concentration or merely represented a phase difference in circadian […]

Analyzing corticosterone metabolites in fecal samples of mice: a noninvasive technique to monitor stress hormones

In small animals like mice, the monitoring of endocrine functions over time is constrained seriously by the adverse effects of blood sampling. Therefore, noninvasive techniques to monitor, for example, stress hormones in these animals are highly demanded in laboratory as well as in field research. The aim of our study was to evaluate the biological […]

Behavioral thermoregulatory responses of single- and group-housed mice.

The ambient temperature (Ta) to house and study laboratory rodents is critical for nearly all biomedical studies. The ideal Ta for housing rodents and other animals should be based on their thermoregulatory requirements. However, fundamental information on the behavioral thermoregulatory responses of single- and group-housed rodents is meager. To address this issue, thermoregulatory behavior was […]

Contrasting activity patterns of two related octopus species, Octopus macropus and Octopus vulgaris

Octopus macropus and Octopus vulgaris have overlapping habitats and are exposed to similar temporal changes. Whereas the former species is described as nocturnal in the field, there are conflicting reports about the activity time of the latter one. To compare activity patterns, the authors tested both species in the laboratory. Octopuses were exposed to a […]