Courtesy Terry Ord
Anoles change color as a means of regulating body temperature or as a form of visual signaling used in communicating with conspecifics. Males advertise territory ownership with repeated bobbing of their heads, along with the extension and retraction of a colorful pouch of skin known as a dewlap. These displays ultimately represent a compromise between costs associated with increased conspicuousness to predators and the benefits of effectively transmitting one’s ownership of a given territory to conspecifics. Beyond this trade-off, however, signal design and production are influenced by the medium through which the signal is broadcast. In noisy environments, signals are exaggerated, thus facilitating receiver access to signals. Both Puerto Rican crested anoles (Anolis cristatellus), shown in the video clip performing a dewlap display, and yellow-chinned anoles (Anolis gundlachi) increase the speed of body movements that they employ in dewlap displays to a degree that is commensurate with increasing visual noise caused by wind-blown vegetation.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 13, “Communication”; chap. 14, “Habitat Selection, Territoriality, and Migration.” T. J. Ord, R. A. Peters, B. Clucas, and J. A. Stamps, “Lizards speed up visual displays in noisy motion habitats,” Proceedings of the Royal Society, B Biological Sciences 274 (2007), pp. 1057–1062.
A. L. O’Loghlen and S. I. Rothstein, UC Santa Barbara, CA.
A female brown-headed cowbird (Molothrus ater) gives a copulation solicitation display in response to the playback of a conspecific male’s flight whistle song. Such courtship displays are given before and/or during copulation in a variety of species, indicating a female’s readiness to mate. In brown-headed cowbirds, females increase the frequency and duration of copulation solicitation displays when male songs conform to the dialect of the geographical area in which the females are breeding, demonstrating not only the females’ ability to discriminate among males, but also their preference for mating with local males. Female mating preferences, in turn, select for males to learn their local song dialect.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 7, “Sexual Selection”; chap. 13, “Communication.” A. L. O’Loghlen and S. I. Rothstein, “Female preference for the songs of older males and the maintenance of dialects in brown-headed cowbirds (Molothrus ater),” Behavioral Ecology and Sociobiology 53 (2003), pp. 102–109.
Courtesy James F. Hare
A dye-marked Richardson’s ground squirrel (Spermophilus richardsonii) juvenile detects an approaching terrestrial predator and utters a repeated alarm call, warning another nearby juvenile of the predator’s presence. Richardson’s ground squirrel’s repeated alarm calls communicate information encoding predator type, response urgency, caller location, and caller identity. Receivers use their ability to discriminate among callers to weight their response according to the past reliability of the alarm caller, just as vervet monkeys (Chlorocebus pygerythrus) discriminate among callers and come to ignore signals broadcast by unreliable signalers.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 12, “Antipredator Behavior”; chap. 13, “Communication.” J. F. Hare and B. A. Atkins, “The squirrel that cried wolf: Reliability detection by juvenile Richardson’s ground squirrels (Spermophilus richardsonii),” Behavioral Ecology and Sociobiology 51 (2001), pp. 108–112.
Tom Seeley, Cornell University
When a foraging honeybee (Apis mellifera) worker locates a productive source of food, it returns to its colony to recruit additional foragers to that food source. While the present video shows workers in an illuminated observation hive, such recruitment would normally occur in the darkness of the hive, where cues that would reliably communicate the location of food are limited, and thus bees have evolved a reliance on either mechanical/acoustic cues (dance language) or chemical cues (odor-search) to communicate the location of food. Here we see a worker performing a "waggle dance" in which the angular orientation of the waggle phase (the more-or-less straight run in which the abdomen is waggling back and forth) communicates the direction, and the duration of that waggle phase communicates the distance to the food source.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: Norton, 2013), Chap. 11, “Foraging”; Chap. 13, “Communication.” K. E Gardner, T. D. Seeley & N. W. Calderone, Do honeybees have two discrete dances to advertise food sources? Animal Behaviour 75 (2008), 1,291–1,300.
Female túngara frogs (Physalaemus pustulosus) preferentially mate with males that append low-frequency “chucks” to the end of the “whine” that constitutes their mating call. The broadcast of chucks, however, proves costly as both frog-eating bats and blood-sucking flies eavesdrop on calling frogs, and preferentially orient to callers that are incorporating chucks into their calls. Here, a male túngara frog broadcasts sexual advertisement calls that include chucks, attracting several blood-sucking flies (Corethrella spp.) in the process. Calling frogs lose time and energy in mounting a defense against flies, and they experience costs associated with blood feeding, including the potential transmission of blood-borne parasites.
FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 7, “Sexual Selection”; chap. 13, “Communication.” X. Bernal, A. S. Rand, and M. J. Ryan, “Acoustic preferences and localization performance of blood-sucking flies (Corethrella coquillett),” Behavioral Ecology 17 (2006), pp. 709–715.