Detection of the sexual identity of conspecifics through volatile chemical signals in a territorial salamander

Following on the work of Page and Jaeger (2004), Dantzer and Jaeger (Dantzer and Jaeger, 2007) continued experiments addressing chemical communication in territorial and mating contexts of red-backed salamanders. Previous studies have indicated the use of nonvolatile chemicals from feces and skin secretions in the territorial behavior of these salamanders. However, as mentioned in the previous summary, volatile advertisement chemicals may serve as an attractant between the sexes. As previously mentioned, red-backed salamanders use a chemoreceptive behavior (nose tapping) to detect nonvolatile chemicals, but they also have an olfactory system that is receptive to volatile chemicals.

Experiments were performed separately with males and non-gravid females. Each focal salamander was given chemical, but not physical, exposure to six treatments: four experimental (filter paper from other [“source”] males and females) and two controls (unaltered filter paper). In order to determine the effect of chemical concentration, experimental treatments included two time lengths: filter paper that had been in contact with source salamanders for one day and filter paper that had been in contact with source salamanders for five days. Filter papers were rolled and placed in open-ended plastic tubes capped with vinyl screening. Behavioral monitoring of the focal salamander included time spent in threat posture, number of nose taps to the substrate, number of nose taps to the tube, and time spent touching the tube.

Time spent in threat posture and number of nose taps to the substrate were significant for both focal males and focal females. For one-day treatments, males spend more time in threat posture in response to both male and female stimuli than in response to controls; females spent more time in threat posture in response to female stimuli than in response to males or controls. For five-day treatments, males spent more time in threat postures in response to male than to female stimuli, and in response to both male and female stimuli than to the control; females spent more time in threat posture in response to female than to male stimuli, and in response to both male and female stimuli than controls. Results were similar for numbers of nose taps.

Aggressive behavior of red-backed salamanders toward volatile chemical stimuli thus differed with respect to the sex of the source salamander, and varied with the inferred chemical concentration, supporting the role of volatile chemical signals in territorial and mating behavior of these animals.

Dantzer BJ, Jaeger RG. Detection of the sexual identity of conspecifics through volatile chemical signals in a territorial salamander. Ethology (2007) 113:214-222.