EXPLOSIVE INCREASE IN ECTOPARASITES IN HAWAIIAN FOREST BIRDS.
June 27th, 2008 | by admin |EXPLOSIVE INCREASE IN ECTOPARASITES IN HAWAIIAN FOREST BIRDS.
Ectoparasites, particularly chewing lice in the Phthiraptera (Insecta), affect the ecology of numerous host species. Most lice are highly host specific, and there are no documented cases of major increases of chewing lice within populations over years. During continuous study from 1987-2005 at upper elevation forests on the Island of Hawaii, chewing lice were exceedingly rare in 12 species of native and introduced birds until 2003. Between 2003-2005, there was explosive increase in prevalence of chewing lice in all host species. There was no change in humidity or behavior of hosts that could have caused ecological release of existing lice. Based on reduced fat levels and increases in broken wing and tail feathers for most host species, there was food limitation that preceded the increase. The increase coincided temporally with detection of a non-native bird recently found in elevations below the study sites. There were isolated sightings of this bird on the study sites, but seasonal movements and behavior of some species of native birds could have allowed greater transmission to study sites. Both prevalence and intensity of infection, indexed by number of body regions parasitized, were lower in native species with greater bill overlap, a character that could help birds control lice. Seasonality of prevalence indicated that low prevalence preceded molt and high prevalence followed molting of hosts. The number of major fault bars in wing and tail feathers, a sign of nutritive stress, was correlated with intensity of infection, indicating an indirect cost to the hosts of being parasitized. In addition, birds with lice were less likely to be recaptured than birds without lice.
Freed L, Medeiros M, Bodner G.