Haematological variables are good predictors of recruitment in nestling pied flycatchers (Ficedula hypoleuca)

Abstract

Abstract:The number of different types of circulating leucocytes may provide information about the health state of birds in the wild. We counted the number and proportions of circulating leucocytes in blood smears of nestling pied flycatchers (Ficedula hypoleuca) shortly before fledging. We studied the relationship between these haematological measures and environmental factors like parasitism, body mass, hatching date, and brood size. The heterophils-to-lymphocytes ratio was higher in nestlings whose nests suffered from mite infestation and in lighter individuals, heterophils being the cells that responded preferentially to malnutrition. Recruited birds had lower lymphocyte and heterophil counts when nestlings than non-recruited ones. Our results show that heterophil count is a better predictor of local recruitment than other variables widely used for nestlings as survival predictors, like body mass or hatching date, supporting the hypothesis that low heterophil counts reflect a good individual health state in nestlings. Keywords: health state, leucocytes, nestlings, parasitism, pied flycatchers, recruitment.Résumé : Le nombre des différents types de leucocytes en circulation dans le sang peut fournir de l'information au sujet de l'état de santé des oiseaux dans la nature. Nous avons compté le nombre et déterminé les proportions de leucocytes circulant dans des frottis sanguins provenant d'oisillons gobemouches noirs (Ficedula hypoleuca) peu de temps avant leur premier envol. Nous avons de cette façon étudié la relation entre ces mesures hématologiques et des facteurs environmentaux, comme le parasitisme, la masse corporelle, la date de l'éclosion et la taille de la couvée. Le rapport entre les leucocytes neutrophiles et les lymphocytes est plus élevé chez les oisillons dont les nids sont infestés par des mites et chez les individus les plus légers, les leucocytes neutrophiles étant les cellules sanguines qui se manifestent le plus lors d'une malnutrition. Les oiseaux qui ont recruté dans la population avaient des numérations de lymphocytes et de leucocytes neutrophiles moins élevées au stade de jeunes au nid que ceux qui n'ont pas recruté. Ainsi, la numération des leucocytes neutrophiles serait un meilleur prédicteur du recrutement local que d'autres variables féquemment utilisées, comme la masse corporelle ou la date d'éclosion. En somme, nous appuyons l'hypothèse que les numérations de leucocytes neutrophiles constituent de bons indicateurs de santé chez les oisillons.

Is oxidative status influenced by dietary carotenoid and physical activity after moult in the great tit (Parus major)?

“…Repeatability scores of our counts were highly significant (H/Ly ratio F 91,92 =8.28, P<0.01, intraclass correlation coefficient=0.78; Lessells and Boag, 1987). A high H/Ly ratio is often interpreted as a sign of physiological stress Lobato et al, 2005;Campbell and Ellis, 2007) and, for example, sustained flight has been shown to increase the H/Ly ratio (Matson et al, 2012).…”

Why fly the extra mile? Using stress biomarkers to assess wintering habitat quality in migratory shorebirds

“…H/L ratios have been used to assess susceptibility to disease and infection (e.g., Davis et al 2004;Al-Murrani et al 2006) and to indicate immune challenge ). These ratios are also known to be affected by growth and reproduction (e.g., Moreno et al 2002;Lobato et al 2005). The use of eosinophil counts as an indicator of stress is not as common, although studies have demonstrated that stress-induced glucocorticoid secretion leads to a reduction in eosinophil numbers in mammals (Gordon 1955) and amphibians (Belden and Kiesecker 2005).…”

Foraging effort does not influence body condition and stress level in little auks

“…Golet et al 2000, Kitaysky et al 2001b, Kitaysky et al 2003) and a subsequent increase in H:L ratio (e.g. Hoi-Leitner et al 2001, Suorsa et al 2004, Lobato et al 2005.…”