Breeder aggression does not predict current or future cooperative group formation in a cooperatively breeding bird

Area of Science:

• Behavioral Ecology
• Evolutionary Biology
• Ornithology

Background:

• Cooperative breeding involves subordinates helping breeders raise young.
• In facultative systems, breeders may or may not receive help.
• Nest defense against predators is a key role for helpers, but its link to group formation is unclear.

Purpose of the Study:

• Investigate if breeder aggression towards nest predators affects helper recruitment in facultative cooperative breeders.
• Test if less or more aggressive breeders are more likely to form cooperative groups.
• Examine correlations between breeding partner aggression and helper recruitment.

Main Methods:

• Studied facultative cooperative breeding in brown-headed nuthatches (Sitta pusilla).
• Measured breeder aggression using a nest predator model.
• Assessed aggression's correlation with current and future helper recruitment.

Main Results:

• No sex differences in breeder aggression were observed.
• Breeder aggression scores did not correlate with breeding partner aggression.
• Aggression levels were unrelated to forming cooperative groups in the current year.
• Male breeder aggression did not predict helper recruitment in subsequent years.

Conclusions:

• Breeder aggression towards nest predators is not linked to cooperative group formation in brown-headed nuthatches.
• Both sexes exhibit similar aggression levels.
• Helper recruitment is independent of breeder anti-predator aggression in this species.