Immune Condition and Blood Parasites in Three Sparrow Species with Different Migratory Status in Central Mexico

Abstract

A good immune condition imposes an energetic cost and depends on many factors such as stressful situations and extenuating activities, especially for migratory birds. The energetic demands during migration may be compromised due to limited food availability, higher predation risks or novel diseases. We collected blood samples in the adults of three species of sparrows with different migratory status in central Mexico: the Clay-coloured Sparrow Spizella pallida (long distance migrant), the Chipping Sparrow S. passerina (local and long distance migrant individuals present at the study site), and the Black-chinned Sparrow S. atrogularis (permanent resident). These were used to compare the immune condition through analyses of their leukocyte profiles, the heterophil/lymphocyte (H/L) ratio and the presence of blood parasites. We found differences in the immune condition: the resident species showed a lower percentage of lymphocytes than the long distance migrant, and also had more heterophils and a higher H/L than the two migratory species. We found that body mass was not related to the leukocyte parameters. Trypanosoma was recorded in the three bird species. The Chipping Sparrow was the most parasitised, followed by the Black-chinned Sparrow. Intensity of infection in the Chipping Sparrow and the Black-chinned Sparrow was correlated with changes in the abundance of lymphocytes. Our results suggest that the resident species had a reduced immune condition compared to the two migratory species, while the presence of parasites and the intensity of parasitism did not differ between species. This is the first study that evaluates and compares the immunological condition and blood parasitism in three congeneric species of birds with different migratory status.