“
“Severe recent declines of amphibians around the world
have highlighted the need to identify factors that affect their population dynamics and viability. This study used a long-term (>30 years) dataset collected for a British population of natterjack toads Bufo calamita, a rare and endangered species in much of northern Europe. Modelling was employed to test a series of hypotheses concerning the effects of anthropogenic (conservation management) and climatic factors on toad demographics. The best models accounted for >72% of the variance in population size, as judged by spawn string counts, between 1975 and 2007. Conservation management (pond creation) was important, as were spring and summer climate variables relating to larval survival, and winter conditions associated with hibernation buy ITF2357 mortality. The implications
of trends associated with future climate change are also considered. “
“Predator selectivity for age and sex classes has large implications for their impact on prey populations. We FK506 nmr examined whether the Eurasian lynx Lynx lynx selects specific sex and age categories of roe deer Capreolus capreolus, and if this selection pattern differs between summer and winter. Data on sex and age of 194 roe deer killed by 44 VHF- and GPS-marked lynx were collected in southern Norway from 1995 to 2010. The sex and age distribution of the roe deer population was estimated using demographic parameters
estimated from radio-collared roe MCE公司 deer in the study area. We found that lynx selection differed between summer and winter. In both seasons, lynx selected adult roe deer of both sexes. In summer, there was a clear selection against yearlings, but in winter, lynx selected male yearlings. Compared with the availability, fawns of both sexes were under-represented during summer. Male and female lynx did not differ in their prey selection, but yearling lynx tended to kill a larger proportion of roe deer fawns than older lynx. We argue that seasonal differences in behaviour, activity and habitat use by roe deer may explain this variation in lynx selection patterns, supporting the view that prey selection is affected by the life cycle stage of both the predators and the prey. “
“Population-level distribution strategies, such as migration, nomadism or residency, form often as a result of spatio-temporal resource dynamics. While commonly a species will adopt a single strategy across its range, occasionally multiple strategies can be observed. In Australia, the eastern grass owl Tyto longimembris is considered nomadic over most of its range. However, resident populations have been reported along the eastern coastal zone. We collected and analysed regurgitated pellets of a coastal resident population across three seasons in a single year.