Video by Hugh Drummond
Success or failure in aggressive encounters often has profound effects on an individual’s performance in subsequent interactions with conspecifics, and such effects are termed winner versus loser effects. Here, a secondhatched blue-footed booby (Sula nebouxii) chick (head painted yellow) threatens and ultimately attacks the third-hatched chick (head painted blue) while the first-hatched chick (head painted red) rests. Hatching asynchrony in birds promotes siblicide, and latter-hatched chicks often behave as losers, responding regularly to aggression with submissive behavior, such as the bill-down and face-away posture of the third-hatched chick in this video clip. While the third-hatched chick is rendered a loser, the experience of dominating its younger sibling does not promote the appearance of a winner effect in the second-hatched chick, exemplifying the asymmetrical expression of winner and loser effects in certain species
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 5, “Learning”; chap. 15, “Aggression.” T. Benavides and H. Drummond, “The role of trained winning in a broodmate dominance hierarchy,” Behaviour 144 (2007), pp. 1133–1146.
Kevin Judge, Department of Biology, University of Toronto at Mississauga
Two male fall field crickets (Gryllus pennsylvanicus) begin an interaction with antennal contact, and they mutually escalate aggression until a clear winner emerges. The winner then performs a victory display, engaging in both stridulatory chirping and shaking of the body. Such displays may advertise the winner’s prowess to bystanders, or they could serve to further intimidate the routed opponent, reducing the probability that the loser will challenge the victor in the future.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 13, “Communication”; chap. 15, “Aggression.” M. Mesterton-Gibbons and T. N. Sherratt, “Victory displays: A game-theoretic analysis,” Behavioral Ecology 17 (2006), pp. 597–605.
This clip is contributed by Yuying Hsu, National Taiwan Normal University
Contestants in aggressive interactions are seldom equally matched. Asymmetries may exist in their resourceholding potential, or even in the value of the resource to those individuals. Asymmetries may also arise as a result of the differential past experiences of the contestants in aggressive encounters, and such expriences may have drastic effects on the outcome of subsequent contests (i.e., winner and loser effects). Mangrove killifish (Kryptolebias marmoratus) are highly territorial, self-fertilizing hermaphroditic fish. In the first part of the clip, we see an individual with a recent win in a territorial contest pitted against an individual without any recent fighting experience, and the escalated aggressive contest that ensues. In the second part, the individual on the right, who had experienced a recent loss in a territorial contest, retreats and actively avoids an individual who has no recent fighting experience.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 5, “Learning”; chap. 15, “Aggression.” Y. Hsu and L. Wolf, “The winner and loser effect: Integrating multiple experiences,” Animal Behaviour 57 (1999) pp. 903–910.