Dutch House Martins Delichon urbicum gain blood parasite infections over their lifetime, but do not seem to suffer

Abstract

In a southern Spanish population of the colonial-breeding Afrotropical migrant House Martins Delichon urbicum, a high overall prevalence of (molecularly assayed) haemosporidian infections (in the non-parasitological literature usually denoted with the inclusive term ‘malaria’) was associated with negative fitness consequences for individuals carrying single or double infections. To verify this in a northern population, we here report on the occurrence of malaria in 112 fledgling and 358 adult House Martins from The Netherlands. Repeatability of molecular essays was 94.4% (n = 125). Malaria was not found in any of the fledglings, but 77% of the adults carried single or double infections of two Haemoproteus haplotypes (Delurb1, Delurb2) and five Plasmodium haplotypes (GRW2, GRW9, GRW11, COLL6 and Turdus1). The two Haemoproteus and two of the Plasmodium haplotypes overlapped with nine haplotypes observed in Spain, with Dutch birds showing another four. Haemoproteus infections were common (occurring in 70% of adult samples) and Plasmodium was rare (9%). Molecularly sexed females with blood parasite infections tended towards a higher chance of double infection (33%) than males (23%). Of 64 cases of birds captured in successive years, 23% showed no change in infection status, 5% lost infection, and there was an 85% chance for adults to gain a ‘malaria’ type. Within a single breeding season, infection status did not change in 6 of 13 cases (46%). However, in 6 of the 7 cases of change (86%), there was loss of a Haemoproteus infection. Infection status did not correlate with body mass or body size, tail asymmetry, occurrence of louse flies, nor with the likelihood of recapture in the subsequent year. The limited evidence so far suggests that House Martins get infected away from the European breeding grounds.