Leukocyte profiles are associated with longevity and survival, but not migratory effort: a comparative analysis of shorebirds

1. Assessment of leukocyte profiles has become an increasingly popular tool in the fields of ecology and ecophysiology. The ratio of heterophils to lymphocytes (H/L ratio) is of special utility, as it reflects physiological adaptation of an organism to cope either with an infection through injury (via heterophils) or a communicable disease (via lymphocytes). Thus, elevated H/L ratios may constitute an adaptation to risky environments (i.e. associated with high risk of injury). While intra-population variation in avian H/L ratio has been extensively studied, we are aware of no studies that linked this trait to life-history components at the inter-specific level.
2. We measured H/L ratio in over 400 shorebirds from 19 species during their autumn migration through Central Europe. Phylogenetically informed comparative methods were used to test whether H/L ratio was related to: i) annual survival and lifespan; ii) migratory effort, as measured with total migration distance and migratory en...