Aspects of the life history and breeding biology of the Mountain Pygmy-possum (Burramys parvus), (Marsupialia: Burramyidae) in alpine Victoria.

Abstract

From February 1982 to November 1989, a trapping and captive breeding program was undertaken to examine the life history of the vulnerable Mountain Pygmy-possum (Burramys parvus), the only Australian mammal restricted to the alpine and subalpine region. During the active season (Oct.-Apr.) over 38 000 trapnights in the habitat throughout Victoria yielded over 900 individual B. parvus captured on over 3 800 occasions. Burramys parvus is a polyoestrous species (mean cycle period of 20.3 days) and produces supernumerary young, up to twice the number of available teats (4). In the wild, breeding is highly synchronised to spring and a single litter is carried p.a. (x = 3.6; mode = 4). Whilst B. parvus retains the capacity to produce a second litter, this is a rare event in the wild and would be selected against as there would be insufficient time to obtain fat reserves for hibernation. At birth and independence the sex ratio of the cohort is at parity, yet at any time the sex ratio of the B. parvus population is always biased toward females due to differential survival of the sexes (at breeding I M: 4-6 F). In autumn, females that would survive winter were on average > 12 % heavier than those not retrapped. One female was at least 11 years old whilst the oldest male recorded was 4 years. Burramys parvus is the longest lived small terrestrial mammal known. Aspects of the life histo ry are discussed in the context of adaptions to the alpine environment and are compared to other small mammals in the habitat and in other cold climates, and to other small marsupial diprotodonts.