Virulence of avian brood parasites can trigger a coevolutionary arms race, which favours rejection of parasitic eggs or chicks by host parents, and in turn leads to mimicry in parasite eggs or chicks [1-7]. The appearance of host offspring is critical to enable host parents to detect parasites. Thus, increasing accuracy of parasites' mimicry can favour a newly emerged host morph to escape paras...

The ontogeny of shivering thermogenesis was investigated in the altricial red-winged blackbird (Agelaius phoeniceus). Two indices of heat production ­ the rate of oxygen consumption (V(dot)O2) of the bird and the electromyographic (EMG) activity of the pectoralis (PECT) and gastrocnemius (GAST) muscles ­ were measured simultaneously in adult and nestling red-winged blackbirds as they we...

Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding's ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bulle...

The solicitation behaviours performed by dependent young are under selection from the environment created by their parents, as well as wider ecological conditions. Here we show how mechanisms acting before hatching enable canary offspring to adapt their begging behaviour to a variable post-hatching world. Cross-fostering experiments revealed that canary nestling begging intensity is positively ...

Innate immune functions are proposed to develop rapidly post-hatch in altricial nestlings, compared with adaptive immune defenses that require development of receptor specifi city and memory. Studies of ontogenetic changes in altricial birds have been few until relatively recently and often do not encompass the entire developmental period. We examined the patterns of development in constitutive...