Immunity, growth and begging behaviour of nestling Barn Swallows Hirundo rustica in relation to hatching order

Abstract

2001.Immunity, growth and begging behaviour of nestling Barn Swallows Hirundo rustica in relation to hatching order. -J. Avian Biol. 32: 263 -270.In altricial birds, asynchronous hatching often results in a size hierarchy among nestlings. However, laying order and hatching order may affect components of offspring condition differentially. Since parasites can have a heavy impact on their hosts, strategies may have evolved that allow parents and offspring to allocate critical resources to immunity depending on hatching order. In this study of the Barn Swallow Hirundo rustica we (1) analyse the relationship between laying and hatching order of eggs, (2) compare morphological, serological and immunological traits between early-and late-hatched siblings, and (3) compare the begging behaviour of early-and late-hatched nestlings. Hatching order strictly reflected laying order. Late-hatched chicks begged more for food but had smaller body mass throughout the nestling period. Immunoglobulin concentration and intensity of T cell-mediated immunity were larger in late-hatched nestlings. Large concentration of immunoglobulins in late-hatched nestlings may reflect transfer of immunity from the mother via the egg. Alternatively, in association with larger T cell-mediated immunity, immunoglobulin production may indicate larger investment in immunity by latehatched nestlings. Laying order and hatching order may therefore affect components of nestling condition differentially.

Birth order, individual sex and sex of competitors determine the outcome of conflict among siblings over parental care

“…It has been shown that seniority and the sex ratio of siblings both affect the condition of barn swallow chicks around fledging [19,37,38]. More studies are required to validate further predictions about the effect of the covariation between sex and seniority on chick phenotype.…”

Experimental manipulation of egg carotenoids affects immunity of barn swallow nestlings

“…Size hierarchy probably results from the fact that the first laid eggs in a clutch hatch first (see also Saino et al 2001). …”

Relationship between avian growth rate and immune response depends on food availability

“…Saino et al, 1997;Saino et al, 2001;Christe et al, 1998;Merino et al, 1999;Merino et al, 2000;Szép and Møller, 1999;Szép and Møller, 2000). They frequently face periods of food shortage incurred by unfavourable weather conditions (Bryant, 1975;McCarty and Winkler, 1999;Lifjeld et al, 2002), which adversely affect their immune function (Christe et al, 2001;Lifjeld et al, 2002).…”