Territorial pheromone salamanders

Jaeger, R. G., Goy, J., Tarver, M., and Marquez, C., 1985, Salamander territoriality Pheromonal markers as advertisement by males,... 

Jaeger, R.G., J.M. Goy, M. Tarver, C.E. Marquez. 1986. Salamander territoriality pheromonal markers as advertisement by males. Anim. Behav. 34 860-864. 

Horne, E. A. and Jaeger, R. G. (1988). Territorial pheromones of female red-backed salamanders. Ethology 78,143. 

Nothing is known about the biochemistry of the pheromones used in territorial advertisement. This is unavoidably true partly because the study of territoriality in salamanders is so new, partly because the existence of pheromones has been inferred only from behavioral responses of individuals under experimental conditions, and partly because none of the glands producing the suspected pheromones have been conclusively identified. In short, there is so little background information about territorial pheromonal communication in salamanders that sophisticated studies probably will not be conducted for several years yet. 

Virtually all tests of territorial pheromones have involved the response of a receiver salamander in the presence or absence of presumed pheromones from a sender. Four basic experimental designs have been used. 

In summary, virtually all of the information on territorial pheromones (through behavioral inferences of their existence) comes from single species, Plethodon cinereus. Evidence to date indicates that at least males (and perhaps females) place chemical substances on the substrate, that these substances are contained in fecal pellets and are produced in or near the cloaca (though other glandular sources are not ruled out), that these substances tend to deter intruders from entering a marked (territorial) area, and that the aggressive and submissive interactions of territorial residents and intruders are governed in part by these substances (and in part by visual displays). Thus, pheromones, whatever they are, are used by Plethodon cinereus (and perhaps other species of salamanders) to advertise territorial possession. 

In general, the same techniques are used to collect stimuli for tests of pheromones used in reproduction as for tests of territorial pheromones. It is possible that in many cases the same pheromones may serve both functions advertisement to potential competitors and to potential mates. Although the collection techniques are similar for both types of pheromones, many studies of sexual advertisement pheromones have focused on aquatic animals (primarily newts) and the techniques described above for terrestrial salamanders have been modified for use in aquatic environments. For example, test animals might be exposed to water from a chamber that had contained another salamander (Dawley 1984b) or from sponges soaked with secretions from other salamanders (Twitty 1955). 

Jaeger, R. G. (1986). Pheromonal markers as territorial advertisement by terrestrial salamanders. In Chemical Signals in Vertebrates, vol. 4, ed. D. Duvall, D. Miiller-Schwarze, and R. M. Silverstein, pp. 191-203. New York Plenum. 

PHEROMONAL MARKERS AS TERRITORIAL ADVERTISEMENT BY TERRESTRIAL SALAMANDERS... 

Two attempts have been made to identify the source of the pheromones used in territorial communication by salamanders. The first was by Simon and Madison (1984), using experimental procedure (4) and Plethodon cinereus. They provided each male salamander with a choice of two substrates, each marked with either fecal pellets or cloacal washes. On one side, the pellets (or washes) were the test animal s own on the other side, the pellets (or washes) were from a conspecific. None of the salamanders had prior experience with each other. For both pellets and washes, salamanders significantly chose their own marked substrates over those of conspecifics. This was the first indication that fecal pellets are used to place pheromones in territories. In addition, the data from cloacal washes suggest that pheromones are produced by glands in or around the cloaca, and are not a by-product of the chemical composition of the feces per se. 

The fourth case indicated no position bias in the experiment. These data demonstrate, then, that male salamanders of this species are not only attracted to areas marked with their own pheromones, but are repulsed (and threatened) by areas marked by pheromones of other males. Territorial advertisement is inferred from these data. Parallel tests with females are now being performed. 

Apparently the nares are the principal centers for receiving pheromonal information. Olfactory receptors in the nares are able to discriminate among a variety of odors in salamanders of the family Ambystomatidae (Kauer, 1974 Kauer and Moulton, 1974 Kauer and Shepherd, 1975, 1977). However, members of this family are not known to be territorial (Martin et al., in press). 

The purpose of this scant review of homing and courtship is to emphasize that salamanders produce a variety of pheromones, probably from a variety of glands, and having a diversity of functions. However, there is not a single case where the composition and origin of a pheromone is well known, a factor that severely inhibits the study of pheromonal communication during territorial defense by salamanders. 

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