Learn More
In the present study, we experimentally manipulated coccidian parasitism and dietary carotenoid availability in a fully factorial experiment in male house sparrows (Passer domesticus Linnaeus), and tested whether carotenoid supplementation reduces the cost of parasitism in terms of condition, moult and immune responses. We found that coccidians have a(More)
BACKGROUND The trade-off between current and residual reproductive values is central to life history theory, although the possible mechanisms underlying this trade-off are largely unknown. The 'molt constraint' hypothesis suggests that molt and plumage functionality are compromised by the preceding breeding event, yet this candidate mechanism remains(More)
Difference between sexes in parasitism is a common phenomenon among birds, which may be related to differences between males and females in their investment into immune functions or as a consequence of differential exposure to parasites. Because life-history strategies change sex specifically during the annual cycle, immunological responses of the host(More)
BACKGROUND Many animals display colorful signals in their integument which convey information about the quality of their bearer. Theoretically, these ornaments incur differential production and/or maintenance costs that enforce their honesty. However, the proximate mechanisms of production costs are poorly understood and contentious in cases of(More)
The preen gland is a holocrine sebaceous gland of the avian integument which produces an oily secretion that is spread on the plumage during preening. It has been suggested that birds may defend themselves against feather-degrading bacteria (FDB) and other potential pathogens using preen gland secretions. However, besides some in vitro studies, the in vivo(More)
Long-distance migratory birds have relatively smaller brains than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions suggested to play key roles in orientation during migration. Based on 152 bird species, belonging to 61 avian families from six(More)
Temporally changing environmental conditions occur in most parts of the world and can exert strong pressure on the immune defense of organisms. Seasonality may result in changes in physiological traits over the year, and such changes may be essential for the optimization of defense against infections. Evidence from field and laboratory studies suggest the(More)
Constitutive innate immunity is the first lined of defence against infections, but the causes determining its variability among species are poorly understood. The pace of life hypothesis predicts that species with a fast speed of life, characterized by high energy turnover and short developmental time, invest relatively little in defence in favour of growth(More)
Flight initiation distance (FID) is the distance at which an individual animal takes flight when approached by a human. This behavioural measure of risk-taking reflects the risk of being captured by real predators, and it correlates with a range of life history traits, as expected if flight distance optimizes risk of predation. Given that FID provides(More)
Migratory flight performance has direct or carry-over effects on fitness. Therefore, selection is expected to act on minimizing the costs of migratory flight, which increases with the distance covered. Aerodynamic theory predicts how morphological adaptations improve flight performance. These predictions have rarely been tested in comparative analyses that(More)