Alligator Encounter

© Jack P. Hailman

Animals trade off foraging for vigilance, as early detection of predators allows individuals to behave in a manner that reduces their risk of predation. Here, a tricolored heron (Egretta tricolor) detects and withdraws from a juvenile American alligator (Alligator mississippiensis), which swims forward and encounters both a snowy egret (Egretta thula) and a white ibis (Eudocimus albus). These birds similarly withdraw as the alligator advances, but they keep the potential predator in sight. Predator inspection serves to reduce the probability of attack by advertising to the predator that it has been detected, and such inspection provides presumptive prey with information that allows them to take appropriate evasive action.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 12, “Antipredator Behavior.” L. A. Dugatkin and J.-G. J. Godin, “Prey approaching predators: A cost-benefit perspective,” Annales Zoologici Fennici 29 (1992), pp. 233–252.

Embryo Escape via Early Hatching

Karen M. Warkentin

A parrot snake (Leptophis ahaetulla) attacks a clutch of red-eyed treefrog (Agalychnis callidryas) embryos, stimulating many of them to hatch early and thereby escape predation. Treefrog embryos use attackcharacteristic vibrational cues, including the duration and spacing of snake-induced vibration events, as well as the presence of vibrations within a certain low frequency range, to discriminate snake attacks from benign vibration-inducing stimuli. Other aspects of the vibrational signatures modify the escape hatching response, resulting in roughly an 80 percent escape success rate on average.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 12, “Antipredator Behavior.” K.M. Warkentin, “How do embryos assess risk? Vibrational cues in predator-induced hatching of red-eyed treefrogs,” Animal Behaviour 70 (2005), pp. 59–71.

Meerkat Alarm Response

L. I. Hollén and M. B. Manser, University of Zurich, Switzerland. Footage from the Kalahari Meerkat Project, South Africa.

Alarm signals can communicate information about both the specific nature (i.e., referential information such as predator type) and extent of threat (i.e., motivational information such as response urgency) posed in an encounter with a potential predator. Here, a juvenile meerkat (Suricata suricatta) responds to the playback of an aerial, high-urgency call by running to and entering a burrow, while other meerkats stand alert scanning for the presumptive predator. Young meerkats reliably encode information regarding the extent of threat a predator presents, but relative to adults, the young are unreliable in terms of encoding predator type in their alarm calls. Thus, motivational signaling precedes the development of referential signaling in this species.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 12, “Antipredator Behavior”; chap. 13, “Communication.” L. I. Hollén and M. B. Manser, “Motivation before meaning: Motivational information encoded in meerkat alarm calls develops earlier than referential information,” American Naturalist 169 (2007), pp. 758–767.

Meerkat Experience with Potential Threat

L. I. Hollén and M. B. Manser, University of Zurich, Switzerland. Footage from the Kalahari Meerkat Project, South Africa.

Experience with predators is sometimes critical to the development of adaptive antipredator behavior. In the initial segment of this video clip, a juvenile meerkat (Suricata suricatta) finds, investigates, and ultimately abandons a piece of African wildcat (Felis silvestris lybica) hair. When that same tuft of hair is discovered by an adult meerkat in the latter part of the clip, alarm calls are issued and conspecifics are recruited to mob the potential threat.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York: W. W. Norton, 2013), chap. 5, “Learning”; chap. 12, “Antipredator Behavior.” L. I. Hollén, T. Clutton-Brock and M. B. Manser, “Ontogenetic changes in alarm-call production and usage in meerkats (Suricata suricatta): Adaptations or constraints?” Behavioral Ecology and Sociobiology 62 (2008), pp. 821–829.

Coccinellid Pupa Chemical Defense

Scott Smedley

Organisms have often evolved chemical defenses that deter predators. Here, we see a worker ant (Crematogaster lineolata) investigating a coccinellid beetle (Subcoccinella vigintiquatuorpunctata) pupa. The ant initially contacts the pupa's posterior, which has retained the adhering larval cuticle with its long spines. There are no defensive secretor hairs in this region and therefore no immediate cleaning after the ant makes contact. Only after the ant contacts the pupal cuticle proper, with its glandular hairs, does it start self-grooming. This consists initially of brushing the antennae with the forelegs and then running the forelegs through its mouthparts, which prompts the worker to expel its gut contents, leaving a distinctive streak on the arena floor.

FURTHER READING: Lee A. Dugatkin, Principles of Animal Behavior, 3rd ed. (New York:  Norton, 2013), Chap. 12, “Antipredator Behavior.” F. C. Schroeder, S. R. Smedley,  L. K. Gibbons,  J. J. Farmer, A. B. Attygalle, T. Eisner & J. Meinwald, Polyazamacrolides from ladybird beetles: Ring-size selective oligomerization, Proceedings of the National Academy of Sciences U.S.A. 95 (1998), pp. 13,387–391.