Dale M. Madison

Space use and social structure in meadow voles, Microtus pennsylvanicus

SummaryFree-ranging, sexually mature meadow voles (Microtus pennsylvanicus) were tracked by using radiotelemetry from June through August in Front Royal, Virginia, U.S.A. Estimates of intraspecific spacing were derived from the concurrent movements of up to 16 voles. Positions were recorded hourly for 24 h, twice per week. A total of 16 male and 15 female voles were studied during sixteen 24-h sessions.The daily ranges of males (192.3±109.7 m2) were larger and more variable than those of females (68.6±39.4 m2). Males also changed locations more frequently (Fig. 2).Adult females usually maintained territories free of other females; males overlapped considerably among themselves (Fig. 2). Males temporarily moved into the areas occupied by estrous females, indicating intrasexual competition among males for access to receptive females (Fig. 3). M. pennsylvanicus appears to be promiscuous, is socially organized into territorial, maternal-young units during the breeding season, and fits the female territorial model of population regulation.

Social organization of a free-ranging population of pine voles, Microtus pinetorum

SummaryFree-ranging pine voles (Microtus pinetorum) were radiotracked on four separate occasions between August 1980 and July 1981 in an apple orchard in Ulster County, New York USA. Positions were recorded hourly for a total of five 24-h periods during each of the four telemetry sessions. A total of 76 voles were radiotracked

A chemically mediated trade-off between predation risk and mate search in newts

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Individual recognition in salamanders: Cloacal odours

over the course of the study.Pine voles existed in non-overlapping extended family units with a mean of 4.2 (range 2–9) individuals per unit (Figs. 1 and 3). All family members utilized one or two nest sites within the groups exclusive territory (Fig. 2), regardless of sex or reproductive condition. Home range areas (range=6 m2–102 m2) estimated for males and females were not significantly different.Based on telemetry revealed associations between reproductively active individuals, the pine vole mating system appears to be monogamous. However, cooperative polyandry in multi-male units is a distinct possibility.

Dryness increases predation risk in efts: support for an amphibian decline hypothesis

Live-trapping and radiotelemetry were used to monitor weight changes and movements of free-ranging female meadow voles ( Microtus pennsylvanicus ) through the reproductive cycle. Body weight increased markedly from day 8 of gestation. Seven measures of space use and movement were quantified weekly from 4 weeks before to 2 weeks after parturition. These included total, maximum, and secondary clustering, home area size, average radius, average movement per hour, and the change in center of activity between observation periods. All measures showed a significant decrease associated with parturition, except total and maximum clustering, which showed a significant increase. The findings are discussed in relation to maternal care of altricial young in mammals, and relative to a possible role in population regulation.

Effects of Predator Chemical Cues and Behavioral Biorhythms on Foraging, Activity of Terrestrial Salamanders

Previous studies have demonstrated that adult male red-spotted newts, Notophthalmus viridescens, are attracted to female sexual pheromones and avoid conspecific alarm substances that signal predation. In this study, we tested the response of red-spotted newts to different concentrations and combinations of macerated male newt extract (MNE) and gravid female odour in the laboratory and field. In the laboratory, males decreased their activity in response to MNE and showed an intermediate attraction (a trade-off) to female odour when paired with MNE. The intermediate attraction indicates that predators may inhibit mate search, and that male newts apparently take greater risks during the breeding season. Results from tests conducted at two sites within the same pond complex demonstrated plasticity in response to MNE. One site showed the laboratory trade-off between mate search and predator avoidance for males, while at the second site, no significant avoidance of MNE was detected for either sex. To explain the discrepancy in MNE avoidance between the sites we propose a trade-off that incorporates risk and resource sensitivity.  2001 The Association for the Study of Animal Behaviour

Premigratory autumn foraging forays in the green frog, Rana clamitans

Poeciliid fishes are live bearers that may cannibalize their young, both in their natural habitat and in the aquarium. Time dependency and non-kin-related cannibalism have not been studied in poeciliid fishes. The object of this study was to observe the frequency of cannibalism during the days following parturition and to determine whether kin recognition is involved during cannibalism. The two species of fish observed were Poecilia reticulata (the common guppy) and Poecilia sphenops (the black molly). Females who had just given birth to fry were observed for 6 days, with daily exposures to their own young and the young of another female. There was no variation in the occurrence of cannibalism during a day (morning vs afternoon); however, there was a significant decrease in the occurrence of cannibalism between the 2nd and 4th day following parturition. In addition, female poeciliids preferentially cannibalized the young of another female rather than their own. Growth changes in the young and kin recognition by both the mother and the young are postulated to account for these results.

Sex ratio shifts within litters of meadow voles (Microtus pennsylvanicus)

Abstract Male red-backed salamanders ( Plethodon cinereus ) were studied to determine the origin of the chemical cues allowing for individual odour recognition between conspecifics. Individual males showed a preference for substrates with their own faecal and cloacal odours rather than those marked by unfamiliar conspecific males. This discriminatory ability did not depend on recent differences in food consumed. These scent marks might be used to define breeding territories in the field.