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Explosive increase in ectoparasites in Hawaiian forest birds
Leonard A Freed1, Matthew C Medeiros, Gustav R Bodner
1Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA. lfreed@hawaii.edu
The Journal of Parasitology
|June 26, 2008
Summary
An explosive increase in chewing lice (Phthiraptera) occurred in Hawaiian birds, linked to food limitation and potentially a new bird species. Infected birds showed signs of stress and lower recapture rates.
Area of Science:
- Ecology
- Parasitology
- Ornithology
Background:
- Chewing lice (Phthiraptera) are host-specific ectoparasites affecting bird populations.
- Historically, chewing lice populations have not shown significant increases over years.
Purpose of the Study:
- To investigate the cause of an unprecedented explosive increase in chewing lice prevalence in Hawaiian birds.
- To determine the ecological factors and host characteristics influencing louse infestation.
Main Methods:
- Long-term monitoring of bird populations and louse infestation from 1987-2005 on the island of Hawaii.
- Assessing host condition (fat levels, feather quality) and environmental factors (humidity).
- Correlating louse prevalence and intensity with host traits (bill overlap) and behaviors (molting, movements).
Main Results:
- Chewing lice prevalence increased explosively from 2003-2005 in all 12 studied bird species.
- The increase coincided with apparent food limitation and the presence of a nonnative bird.
- Infestation intensity correlated with feather damage (fault bars), indicating nutritive stress.
- Native species with greater bill overlap had lower infection prevalence and intensity.
- Birds with lice had lower recapture rates, suggesting increased mortality or reduced detectability.
Conclusions:
- Food limitation and potential introduction of a nonnative bird likely triggered the louse outbreak.
- Host traits like bill overlap and seasonal behaviors influence parasite transmission and control.
- Louse parasitism imposes indirect costs on birds, impacting their condition and survival.
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