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High moon brightness and low ambient temperatures affect sloth predation by harpy eagles
Everton B P de Miranda1, Caio F Kenup2, Edwin Campbell-Thompson3,4
1School of Life Sciences, Centre for Functional Biodiversity, University of KwaZulu-Natal, Pietermaritzburg, Pietermaritzburg, KwaZulu-Natal, South Africa.
Peerj
|September 11, 2020
Summary
Harpy eagle predation on sloths is influenced by nocturnal light and cool temperatures. Brighter moonlight reduces predation, while cooler weather forces sloths to forage in daylight, increasing their vulnerability to these top predators.
Area of Science:
- Tropical ecology
- Vertebrate predator-prey dynamics
- Behavioral ecology
Background:
- Climate significantly impacts tropical vertebrate life histories, even with weak seasonality.
- Sloths, limited thermoregulators, rely on behavior for thermoregulation and crypsis.
- Harpy eagles (Harpia harpyja), a sloth specialist, exert top-down control, but environmental influences on this interaction were unknown.
Purpose of the Study:
- To investigate the role of environmental variables on predator-prey interactions between harpy eagles and sloths.
- To understand the seasonal prey profile of harpy eagles.
Main Methods:
- Field study conducted from 2003-2009 in Soberanía National Park, Panamá.
- Systematic recording of prey species killed by telemetered harpy eagles.
- Analysis of climatic and vegetation phenology effects on prey profiles using generalized linear mixed models.
Main Results:
- Harpy eagle predation on sloths decreased with increased nocturnal ambient light (moonshine).
- Predation on sloths increased with seasonally cool temperatures, potentially forcing diurnal foraging.
- Seasonal temperature variations significantly influence this keystone predator-prey relationship.
Conclusions:
- Environmental factors like moonlight and temperature subtly modulate tropical predator-prey dynamics.
- Seasonal effects on sloth predation by harpy eagles may impact sloth demographics and distribution.
- Understanding these interactions is crucial for conservation efforts, especially for the Near Threatened harpy eagle.
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