Choice test snakes

A four-choice star maze, similar to that used by Kubie and Halpern (1978, 1979), was used as a two-choice Y maze for training the snakes. Snakes were trained to follow earthworm extract trails (IX = 6 gm earthworm per 20 ml dH20) in the apparatus until their performance exceeded chance behavior. (See Kubie and Halpern 1978 for details). At the termination of testing, snakes were videotaped during trailing at each earthworm concentration (IX, 1/9X, 1/8IX, Dry). Trials were repeated until a minimum of one minute of good, analyzable film had been obtained at each concentration. This usually involved one to three trials. For filming of animals from the side, a clear plastic maze of similar dimensions was used. 

Red-sided garter snakes from different regions of Manitoba, Canada show signs of isolation by chemical cues. In choice tests, males from a hiber-naculum (overwintering den) in central Manitoba preferred females from their own population to females from western Manitoba. Males from western Manitoba showed no preference. When confronted with experimental trails, males made the same choices. This demonstrated that a chemical factor is involved. Furthermore, the sexual attractiveness pheromone of females, a series of ty-9-cis-unsaturated methyl ketones, varies between the populations. Specifically, the... 

Table II. Preferences of red-backed salamanders exposed to substrate scent from garter snakes and red-backed salamanders in two-choice tests...

We examined the laboratory responses of red-backed salamanders to two predator diet treatments at two different time periods to determine whether the chemical label that identifies individual garter snakes as an elevated risk is conserved within the Plethodontidae, and to examine a possible temporal shift in red-backed salamander antipredator behavior. The early trials were conducted between 2100 and 2230 hours, and the late trials were conducted between 2330 and 0100 hours. In each of these trial periods, test salamanders were given the choice between T. sirtalis fed P. cinerem (TSp ) or E. bislineata (TSEb) versus distilled water. To assess the relative strength of each snake diet treatment, test salamanders also were given the choice between TSpc and TS. ... 

Amphibians are vulnerable to predation and show diverse predator defenses. We hypothesized that the common red-backed salamander should try to evade two common terrestrial predators, the garter snake and the spotted salamander, by avoiding locations containing their scent. When given a choice of clean substrates or those soiled by these predators, the red-backed salamander avoided the soiled substrates. To test whether they avoided the waste products and not the predator scent, we gave test subjects a choice between substrates soiled by predators and those soiled by red-backed salamanders. Salamanders pref-ered conspecific substrates to predator substrates, and in combination with other findings, our data show that red-backed salamanders probably reduce the likelihood of predation by avoiding locations with the chemical traces of predators. 

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