  Ticks are important vectors of emerging zoonotic diseases. While adults of
many tick species parasitize mammals, immature ticks are often found on wild
birds. In the tropics, difficulties in species-level identification of immature
ticks hinder studies of tick ecology and tick-borne disease transmission,
including any potential role for birds. In Panama, we found immature ticks on
227 out of 3,498 birds representing 93 host species, about 1/8th of the entire
Panamanian terrestrial avifauna. Tick parasitism rates did not vary with
temperature or rainfall, but parasitism rates did vary with host ecological
traits: non-migratory residents, forest dwelling birds, bark insectivores,
terrestrial foragers and lowland species were most likely to be infested with
ticks. Using a molecular library developed from adult ticks specifically for
this study, we identified 130 immature ticks obtained from wild birds,
corresponding to eleven tick species, indicating that a substantial portion of
the Panamanian avifauna is parasitized by a variety of tick species.
Furthermore, we found evidence that immature ticks show taxonomic or ecological
specificity to avian hosts. Finally, our data indicate that Panamanian birds
are not parasitized regularly by the tick species responsible for most known
tick-borne diseases. However, they are frequent hosts of other tick species
known to carry a variety of rickettsial parasites of unknown pathogenicity.
Given the broad interaction between tick and avian biodiversity in the
Neotropics, future work on emerging tropical tick-borne disease should
explicitly consider wild birds as vertebrate hosts.
