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Managing wildlife populations for conservation, control or harvesting involves uncertainty. Nevertheless, decisions need to be made based on the available evidence. The two main sources of uncertainty in population modelling are parameter estimates and structural uncertainty. Structural uncertainty in models is not included as often as parameter uncertainty.We present an approach where parameter and structural uncertainty (strength of density dependence) is included within a model, using the over-wintering English population of cormorants Phalacrocorax carbo L. Because of the damage caused to inland fishery interests by cormorants, there was a change in UK government policy in autumn 2004, increasing the numbers of birds that can be shot under licence.A stochastic Monte Carlo annual population model was produced to examine the effect of changes to the numbers of birds shot each year. Indices of annual population size were converted to population estimates and used to determine annual growth rates and strength of density dependence.There is strong evidence for density dependence in the data, which suggests the population is currently slightly above carrying capacity, with a mean growth rate of 4–6% per annum. The 1300 birds shot under licence in 2004/05 represent about 4·5% of the English population, and if this level of culling continues, the population would be expected to decline by 9% by 2007, compared to the long-term average. The a priori preferred model, which included all uncertainty, gave predictions for 2004/05 and 2005/06 in close agreement with field data.The model was used to produce short-term population projections, with the understanding that Adaptive Resource Management (ARM) will be adopted to iteratively update the parameters and model each year, feeding back into the numbers of available licences.Synthesis and applications. We recommend the approach used in this study of including parameter and structural uncertainty within a single model, where possible, with the proportion of iterations that ...

A total of 1487 observations of nine species of arboreal mammal, Acrobates pygmaeus, Phascolarctos
cinereus, Petauroides volans, Petaurus australis, P. breviceps, P. norfolcensis, Pseudocheirusperegrinus,
Trichosurus caninus and T. vulpecula, were made during surveys of the vertebrate fauna of northeastern
Victoria. Habitat use by each species was examined in relation to eight forest types that occur
along an environmental gradient ranging from sites at high elevation with a high annual rainfall, to
sites on the dry inland and riverine plains. Arboreal mammals were not evenly distributed between forest
types. Three species (P. australis, P. volans and T. caninus) were mainly associated with moist tall
forests; two species (P. norfolcensis and T. vulpecula) were primarily associated with drier forests and
woodlands of the foothills; the remaining three species (A. pygmaeus, P. breviceps and P. peregrinus)
occurred widely throughout the forests. The composition of the arboreal mammal assemblage changed
along the environmental gradient, but species displayed gradual changes in abundance with forest type
rather than marked discontinuities in distributional pattern. The highest overall frequencies of occurrence
of arboreal mammals were in forests typically dominated by a mixture of eucalypt species. The position
at first sighting of an animal, and the relative height in the forest stratum, were used to describe the
micro-habitats utilised. In general, the microhabitats occupied by each species are consistent with the
distribution of their known food resources.