Courtesy of Jesse E. Purdy, Southwestern University, Georgetown, TX, and Randall W. Davis, Texas A and M University at Galveston
A male Weddell seal (Leptonychotes weddellii) defends his territory under the ice against an intruder male. Aggressive responses to intruders, including physical attacks (like those seen here) and loud vocalizations, are common in territorial animals. Territoriality can be costly in terms of energy and risk of injury, but territorial individuals have sole access to the resources available in their territory.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 14, “Habitat Selection, Territoriality, and Migration”; chap. 15, “Aggression.” J. M. Terhune, “Geographic variations in underwater male Weddell seal trills suggest breeding area fidelity,” Polar Biology 31 (2008), pp. 671–680).