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Siblicidal aggression and resource monopolization in birds.
Science (New York, N.Y.)
|August 17, 1984
Summary
Great egret chicks exhibit fatal siblicide due to monopolizing small prey, unlike great blue herons. Cross-fostering heron chicks to egret parents induced siblicide, confirming prey size as a key factor in avian aggression.
Area of Science:
- Behavioral Ecology
- Ornithology
- Evolutionary Biology
Background:
- Sibling aggression and siblicide are observed in some bird species, impacting chick survival.
- Great egret (Casmerodius albus) chicks frequently engage in siblicide, often fatally attacking younger nestmates.
- Great blue heron (Ardea herodias) chicks exhibit significantly less aggression towards siblings.
Purpose of the Study:
- To investigate the role of prey size in driving interspecific differences in siblicide between great egrets and great blue herons.
- To determine if prey size is the primary factor influencing aggression and siblicide in these two species.
Main Methods:
- Observational studies of natural siblicide rates in great egret and great blue heron populations.
- Experimental cross-fostering of chicks between the two species.
- Controlled feeding experiments manipulating prey size provided to cross-fostered chicks.
Main Results:
- Great egret chicks, fed small prey, displayed high levels of aggression and siblicide.
- Great blue heron chicks, when cross-fostered to egret parents and fed small prey, became siblicidal.
- Egret chicks, when cross-fostered to heron parents, did not show a reduction in aggression or siblicide, regardless of prey size.
Conclusions:
- Prey size is a critical determinant of sibling aggression and siblicide in great egrets and great blue herons.
- The ability to monopolize small prey facilitates aggressive behaviors in young birds.
- Behavioral plasticity in response to prey size influences the evolution of sibling conflict in avian species.
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