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Aspects of the population ecology of the long-nosed potoroo, Potorous tridactylus (Kerr, 1792), in Southeastern Tasmania


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Hird, Donald Geoffrey 1996 , 'Aspects of the population ecology of the long-nosed potoroo, Potorous tridactylus (Kerr, 1792), in Southeastern Tasmania', Unspecified thesis, University of Tasmania.

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Aspects of the Population Ecology of the Long-Nosed Potoroo.
The aim of this study was to describe the population parameters of a natural population of
the long-nosed potoroo. The study was designed to be longitudinal in order to collect data
over the entire lifespans of at least some individuals. Parameters of special interest were
body mass and its relation to seasonality and home-range, survivorship, female
reproductive activity in relation to maternal age, seasonality and breeding interval, and
capture rates in relation to microhabitat.
Capture / recapture data was systematically collected from a study area of approximately
35 ha at Porter Hill, five km southeast of Hobart. The study was designed to be
longitudinal, potentially across generations of potoroos, and to also collect data for two
syntopic species, the brown bandicoot and eastern bettong.
A grid of ten transects, each of 20 sites, was trapped. Each trapping session was comprised
of a transect trapped on two successive nights, with distant transects being trapped at
successive sessions to minimise potential trapping impact on individual animals. Data
from 134 such sessions form the basis of the thesis, some subsidiary data was also
collected to supplement individual longevity data.
Trappability of potoroos at Porter Hill was high compared with studies of potoroos on
mainland Australia. Adult potoroos had a persistent male-biassed sex ratio over time.
Sexual dimorphism was evident, with males having significantly greater body mass (based
on both mean adult and maximum body mass) than females. Captures in traps occupied at
a trapsite on a previous night were sex-biassed, with intra-sex avoidance of traps. Breeding
in potoroos was aseasonal. Mean population density based on known-to-be-alive data for
each sex was estimated to be 0.7 individuals ha -1 . A life table and survivorship curve are
presented. Longevity patterns indicated uneven survivorship, with first-year mortality of
around 80%, and some individuals living to eight years of age.
Microhabitat selection was examined in relation to floristic diversity and vegetation
structure. Sites were grouped on the basis of an agglomerative classification of floristic data, and analysis of variance was used to determine whether significant between-group
differences in capture rates occurred. Vegetation groups were described, and appeared to
vary with physical attributes of the local area. Significantly higher potoroo capture rates
were obtained from one of the ten groups; a group comprised of floristically depauperate
sites of open vegetation structure.
Home range was examined using kernel analysis. A threshold number of captures which
yielded a range asymptotic to the full home range area was determined by taking repeated
random samples of differing sizes from individual capture-site data. Individuals with at
least the threshold number of captures were examined further. Males had significantly
larger home ranges than females, although considerable individual variation in home-range
was also evident. Considerable overlap of both male and female home ranges occurred.
The implications of these and related data for mating systems in the potoroo are discussed.
The results are discussed in terms of the imputed mating system and trophic ecology of
potoroos. Potoroos exploit a dispersed food resource, primarily hypogeal fungi. This,
together with aseasonal breeding, is suggested to have led to a mating system where males
have undergone sexual selection in body mass and home-range behaviour in order to search
for and compete for access to receptive females. This social system is discussed in relation
to that of other potoroids and comparable marsupials.

Item Type: Thesis - Unspecified
Authors/Creators:Hird, Donald Geoffrey
Keywords: Potoroos, Potorous tridactylus
Copyright Holders: The Author
Additional Information:

Thesis (M.Sc.)--University of Tasmania, 1996. Includes bibliographical references

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