Leptin, a protein hormone secreted by fat cells, is best known for its role as an adiposity signal; however, leptin has diverse physiological roles ranging from regulation of feeding behavior and body weight, to effects on reproduction and immune function. Although leptin has been extensively studied in mammals, the identification and function of leptin in birds remains controversial, and studi...

Avian Borna virus (ABV) has been shown to be a causative agent of Proventricular Dilatation Disease in birds. The avian Bornaviradae represent a genetically diverse group of viruses that are widely distributed in captive and wild populations around the world. They are widely distributed in tissues of affected birds and generally produce a non-suppurative ganglioneuritis in the gastro-intestinal...

Carotenoid-based skin colorations vary seasonally in many bird species and are thought to be honest sexually selected signals. In order to provide more insight in the potential signal function and underlying mechanisms of such colorations we here quantified patterns of variation of leg coloration in adult male and female Eurasian kestrels (Falco tinnunculus tinnunculus) over the breeding season...