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Activity patterns and escape behavior of the slender salamander (Batrachoseps attenuatus)

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Title: Activity patterns and escape behavior of the slender salamander (Batrachoseps attenuatus)
Author: Meneghin, Gary R.
Abstract: Seasonal surface activity patterns and predator escape behavior of the California slender salamander(Batrachoseps attenuatus) were studied from March through August 1971, near Crannell, California. The habitat types investigated included: 1) second growth coast redwood (Sequoia sempervirens)forest, 2) grassland and 3)the forest/grassland edge. Surface activity was positively correlated with rainfall and ground temperatures. From March through August the monthly mean number of animals found during the diurnal sample decreased by 50.0 percent in grassland habitats. Nocturnal surface activity remained relatively constant in all habitats from March through August. Limited data suggest that this species becomes nocturnal during the drier summer months. With relative humidity greater than 70 percent, this species' temperature preference ranges from 100 to 15.50 C. From March through August 61.9 percent of the animals collected in the field were found within this temperature range. During this same period, the monthly percentage of animals with absent or regenerating tails increased from 24.3 to 45.2 in the redwood forest, 26.9 to 73.9 in the edge and 28.9 to 73.9 in the grassland habitats. Slender salamanders exhibited protean displays when presented with tactile and olfactory stimuli. Protean behavior is defined as that behavior which is sufficiently unsystematic to prevent a predator from predicting in detail the position or actions of the prey. Direction of movement of the protean display from a consistent tactile stimulus contact point appeared to be random. The mean distance and time of movement were 11.5 cm and 1.02 s respectively. Chemical extracts of potential predators elicited protean responses only in slender salamanders with regenerating tails. Animals with regenerating tails exhibited protean displays when exposed to chemical extracts of these species: Pacific giant salamander (Dicamptodon ensatus), arboreal salamander (Aneides lugubris), ringneck snake (Diadophis punctatus), common garter snake (Thamnophis sirtalis), western terrestrial garter snake (T. elegans) and western aquatic garter snake (T. couchi). Exposure to the chemical extracts of these species followed by a tactile stimulus resulted in a 22.5 ± 9.3 percent increase in the mean distance moved during the protean display. No difference was noted in the distance moved by animals with regenerating or complete tails. Predator-prey interactions of 22 potential vertebrate predators and slender salamanders indicated the following: 1) variable prey palatability but no lethal effects when prey was ingested, 2) successful attacks on salamanders were made to the head and body area, 3) unsuccessful attacks were made on the tail, 4) the protean display was observed in 10.0 percent of successful attacks and 79.2 percent of unsuccessful attacks, and 5) tail autotomy occurred in 0.01 percent of successful attacks and 63.2 percent of unsuccessful attacks. The protean display delayed the predator's reaction time and thereby reduced the effectiveness of the predatory response. The protean display probably insures against learned counter measures by incorporating unpredictability as a basic behavior component. Prey which employ behavior patterns unfamiliar to the predator will be at a selective advantage.
Description: Thesis (M.S.)--Humboldt State University, 1977
Date: 1977-12

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  • Masters Theses [874]
    A collection of selected Masters Theses in electronic format.

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