Spatial variation in haemoglobin concentration of nestling Blue Tits (Cyanistes caeruleus): a long-term perspective

Abstract

An understanding of the influences of anthropogenic disturbance and variation in habitat quality on organism condition and breeding success may improve future management and conservation decisions. Some authors consider haemoglobin concentration to be a simple biochemical indicator of bird condition. The main goal of this paper is to examine if the level of haemoglobin displays any consistent pattern of variation across habitats differing in quality. We present results concerning long-term variation in haemoglobin concentration in the blood of about 14-day-old nestling Blue Tits (Cyanistes caeruleus) in central Poland in an 11-year period (2003–2013), in two landscapes (an urban parkland and a deciduous forest). The most important findings of the study are: (1) the concentration of haemoglobin of the nestlings from the same brood tended to be consistently similar, with most variation occurring between broods, (2) mean levels of haemoglobin varied between years, and were correlated with caterpillar abundance peaks in the forest study site, (3) mean haemoglobin concentration was significantly higher in the forest area than in the parkland area, (4) haemoglobin levels were positively correlated with breeding and fledging success. We confirmed that haemoglobin concentration displays a spatio-temporal pattern and that the level of haemoglobin is a reliable condition and habitat quality indicator in nestling Blue Tits in the study populations. Although, strictly speaking, the analysed differences are between two particular sites, we think that they reflect differences between urban and non-urban habitats.