The Effects of Snake Predation on Metamorphosis of Western Toads, Bufo boreas (Amphibia, Bufonidae)

• Published in: Ethology Vol. 104; no. 3; pp. 185 - 193
• Main Authors: Devito, Jill, Chivers, Douglas P., Kiesecker, Joseph M., Marco, Adolfo, Wildy, Erica L., Blaustein, Andrew R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.1998; Blackwell
• Subjects: Amphibia and reptilia; Animal ethology; Biological and medical sciences; Bufo boreas; Fundamental and applied biological sciences. Psychology; Psychology. Psychoanalysis. Psychiatry; Thamnophis sirtalis; Vertebrata; Laboratory study; Bufonidae; Emersion; Defensive behavior; Amphibia; Salientia; Ophidia; Aggregation; Thamnophis sirtalis; Vertebrata; Social interaction; Bufo boreas; Development; Reptilia; Developmental stage; Antipredator behavior; Predation; Time analysis; Metamorphosis
• ISSN: 0179-1613; 1439-0310
• DOI: 10.1111/j.1439-0310.1998.tb00061.x

For some anuran species, synchronous metamorphosis may function as an antipredator adaptation by swamping predators during the period of transformation. We examined the levels of synchrony of emergence from the water of metamorphosing western toads (Bufo boreas) in the presence and absence of a live snake predator, the common garter snake (Thamnophis sirtalis) in a laboratory experiment. To compare between the treatments, we measured the time to emergence from the water, the number of metamorphs emerging together, and the level of aggregation (before and during emergence) of the toads in each treatment. There was a difference between the treatments when all three factors were considered. We attributed these differences to a behavioral response in which B. boreas emerged sooner in the presence of the predator, regardless of whether individual toads had reached the point at which they were physically better suited to the terrestrial environment than the larval environment.