Delay in arrival: lineage-specific influence of haemosporidians on autumn migration of European robins

Abstract

Haemosporidian blood parasites are widely used in evolutionary ecological research when exploring the effects of parasites on different life-history traits of their bird hosts. However, their roles in bird migration are less studied. If these parasites deteriorate the body condition of the birds strongly, they might negatively affect the whole migration phenology and the survival of the birds as well. In our study, we tested the relationships between infection for parasite genera (Haemoproteus or Plasmodium), the three most frequent parasite lineages and body condition (body mass, fat deposit), and the timing of autumn migration in the European Robin (Erithacus rubecula). We found that mean body mass and fat scores did not differ between parasitized and non-parasitized individuals, but infected juveniles arrived later than their non-infected counterparts. The difference in the arrival time of parasitized and non-parasitized birds was greater in the case of Haemoproteus infections. However, when we analysed the effects of the distinct parasite lineages separately, we found that prevalence of parasite lineages correlated with the body mass, fat storage, and timing of autumn migration of the birds in a different direction. Our results therefore emphasize the importance of testing the impacts of the different parasites individually, because possible lineage-specific effects on bird condition during migration might exist.

Keywords: Autumn; Body condition; European Robin; Genetic lineages; Haemoproteus; Plasmodium; Timing of migration.

Fig. 1

Body mass in relation to the most common parasite lineages in all age and sex groups merged. Box plots show the median, lower and upper quartiles and the whiskers representing data within the 1.5 × interquartile range and were calculated from the data. The black dots represent the mean body mass in each category with SE, estimated from the final model

Fig. 2

Ratio of having visible subcutaneous fat deposit in relation to different infection categories in adult (left) and juvenile (right) birds. Dots and whiskers show the estimated ratio of having visible fat deposit and the 95% confidence intervals, respectively, both calculated from the model

Fig. 3

Arrival date in relation to infections with the most common parasite lineages separately for adults (left) and juveniles (right). Box plots show the median, lower, and upper quartiles and the whiskers representing data within the 1.5 × interquartile range. The black dots represent the mean arrival time in each category