Nutritional ecology of brushtail possums (Trichosurus vulpecula Kerr) in New Zealand

Morley, Jenny (2018) Nutritional ecology of brushtail possums (Trichosurus vulpecula Kerr) in New Zealand. Doctoral thesis, University of East Anglia.

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In this thesis, a combination of field observations and laboratory experiments are used to address the question: how do the nutritional strategies of brushtail possums enable this alien pest species to obtain a balance of nutrients at native forest-pasture margins in New Zealand?

Possums had a polyphagous diet with a core of leaves from three species, supplemented by flowers in spring and summer, fruits in autumn and invertebrates in winter. Graphical models confirmed that possums were polyphagous in all seasons, although diet width and the extent to which individual species of food dominated the diet varied between seasons.

Four nutrient characteristics of potential foods were analysed: total nitrogen, available nitrogen, soluble organic matter and total digestible dry matter. They varied significantly between food species and between seasons but were not significantly associated with either proportion by mass, or frequency of occurrence in the diet.

In laboratory experiments relative preferences between leaves of three woody species changed when the basal leaf diet was supplemented by flowers or by pasture species. Intake rates of nutrients also varied according to diet. The target nutrient intake ratio of available nitrogen to digestible dry matter was calculated. Predictions from optimal foraging, nitrogen limitation and mixed diet theories were compared but mixed diet theory was supported most strongly.

Home ranges were delineated using data from GPS telemetry. Nocturnal foraging pathways were characterised and divided to distinguish between searching within patches and travelling between them. Possums travelled further per night and travelled faster between search patches in winter than they did in autumn. Selection ratios showed that native forest and native shrub/scrubland were preferred habitats for both travelling and searching.

The implications of applying mixed diet theory to possum nutritional ecology, for improving the efficiency of control programmes and reducing interactions between possums and cattle are explored.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Users 9280 not found.
Date Deposited: 14 May 2019 12:42
Last Modified: 14 May 2019 12:42


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