Immunocompetence and nestling survival in the house martin: the tasty chick hypothesis

In altricial birds post-fledging survival is usually positively related to nestling body mass. A large number of studies have shown that the latest hatched chick is the more likely to die, even if food is abundant. Here we suggest that ectoparasites may be a key factor in the evolution and the maintenance of the establishment of weight hierarchies within broods. We prepose the hypothesis that weight hierarchies within broods may be adaptive if the chick in poor condition is the one with the least efficient immune system within a nest. In this case parasites would preferentially feed on such a "tasty chick", because it would allow high reproductive rates for the parasites, without negatively affecting the survival of the other nestlings. This could prevent entire nest failure of the brood or allow the other chicks to grow more efficiently. This hypothesis was investigated in a colony of house martins Delichon urbica. We predicted that immunocompetence was positively correlated with body condition, and that nestlings dying before hedging should have lower immune responses when challenged with an antigen. T-cell immune response to an experimentally injected antigen was strongly positively related to body condition. Non-surviving chicks had low body condition and a weak immune response. The implications of these results are discussed in the context of the adaptive significance of hatching asynchrony.

Cloona Oasis Centre - Davette Martin

The organisation helps those with mental ill health and those suffering addiction. This is their second community-pharmacy project. The first focussed on men and this project will move on to work with women. Women who have been referred to Cloona Oasis have been through hardship. The Pharmacist will work with them to develop their confidence, explain their medication and break down barriers so that they can access other services.

Martin Heidegger

Nota biogràfica sobre el filòsof Martin Heidegger on es fa, per una banda, un breu repàs dels principals fets de la seva vida com a filòsof i, per una altra banda, un breu repàs de la seva obra

Noyon, cathédrale [Notre-Dame] vue de la rue St Martin [dégâts dus à la guerre] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57125

Ypres, les halles [i. e. la cathédrale Saint-Martin, ruines] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57808

Ypres, les halles [i. e. la cathédrale Saint-Martin, ruines] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57807

Ypres, les halles [i. e. la cathédrale Saint-Martin, ruines] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57806

28-01-20, Ypres [la cathédrale Saint-Martin en ruines] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57797