Population Ecology and Reproductive Seasonality in Three Species of Antechinus (Marsupialia : Dasyuridae) in the Wet Tropics of Queensland

Abstract

The population and reproductive ecologies of three sympatric species of antechinus were examined in upland rainforests in the wet tropics of Queensland. The three species, Antechinus stuartii adustus, A. flavipes rubeculus and A. godmani, exhibited unusually low trapping success compared with that of sites in temperate regions of Australia. Spatial distributions were extremely patchy both between and within study sites. Comparison with trapping data for temperate populations of A. stuartii and A. flavipes suggests that densities in the wet tropics are among the lowest in Australia. The reproductive season was similar for the three species, commencing during the mid-dry season with juveniles weaned by the early to mid-wet season. The phenomenon of male die-off was observed in the three species. However, the highly synchronous two- week breeding season observed in temperate populations of A. stuartii and A. flavipes was not observed in the tropical populations. The breeding season of the tropical species extended over a six- week period. Timing of reproduction in A. s. adustus and A. f. rubeculus was more similar to temperate than to subtropical populations of A. s. stuartii and A. f. flavipes.

Photoperiod as a reproductive cue in the marsupial genus Antechinus: ecological and evolutionary consequences

“…2) ovulates between mid‐June and mid‐July (i.e. just around the winter solstice, Van Dyck, 1982a; Watt, 1997), up to 3 months before the populations of A. flavipes flavipes in southern Queensland which ovulate between early August and mid−late September. Antechinus flavipes rubeculus mates at a rate of change of photoperiod of −25 to +25 s/day and at absolute photoperiods of between 11 h and 11 h 20 min.…”

“…These three taxa can be found sympatrically within the rainforests of northern Queensland (Watt, 1997), and all mate around the winter solstice, where neither rate of change of photoperiod nor absolute photoperiod differ by much. Watt (1997) reported that there was little synchrony in the timing of births of A. flavipes rubeculus , although all males were dead by mid‐August, suggesting synchrony remaining in the male die‐off physiology. Because of scant data on the reproductive activity of all three species, it is difficult to know how clearly separated their reproductive efforts are.…”

“…Unusual aspects of the life history of members of the genus Antechinus are that females are synchronously monoestrous, and that after the conclusion of the short (usually 1–2 weeks and up to 3 weeks) annual mating period, there is abrupt mortality of all males (Woolley, 1966; Calaby & Taylor, 1981; Dickman, 1985; Watt, 1997). Hence males in all species live up to 11.5 months, whereas females may survive and produce young in often two, and exceptionally three, consecutive seasons.…”

Conservation of Australian insectivorous marsupials: biogeography, macroecology and life history

“…Our result that in insectivorous dasyurids, population density is lowest at low latitude supports Johnson's (1998a) finding that Australian forest mammals are rarest in the tropics. It also corroborates Watt's (1997) discovery that population densities of antechinus in the wet tropics are some of the lowest anywhere in their distribution. Our study suggests that antechinus populations, and likely other insectivorous dasyurids in forest habitats, are regulated by winter arthropod availability, which is driven by amount of winter rainfall (Figures 3.2, 3.3 and 3.4).…”

“…Antechinus have a short mating season (rut), which lasts for approximately one to three weeks during winter or early spring. The exact timing differs between species and sites (McAllan et al, 2006;Watt, 1997;Woolley, 1966). Evidence suggests that breeding timing is triggered by rate of change of photoperiod, and species in Queensland appear to have longer breeding seasons than species in southern Australia (McAllan et al, 2006).…”