The ecology of the dama wallaby (Macropus eugenii, Desmarest) in forests at Rotorua, with special reference to diet : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science, Massey University, Palmerston North

Abstract

The dama wallaby (Machopu eugenll, Desmarest, 1817), tammar or Kangaroo Island wallaby is present in high numbers throughout the Okataina Scenic Reserve and common elsewhere in the Rotorua Lakes region. Little is known of the animals' ecology in the area although its present status is that of a pastoral and forest pest. Major aims of the present study were to investigate feeding habits and general ecology of the dama.

Between November 1983 and March 1985 1076 wallabies were shot and autopsied; results have confirmed that the dama is a preferential grazer and where there is access to managed pasture, upwards of 70% of identifiable stomach material is likely to consist of pasture species. However wallabies also live and successfully breed within indigenous forest of the Okataina Scenic Reserve, with access to meagre amounts of grass. Here preferred foods include foliage of Melicytus ramiflorus, Weinmannia racemosa, Geniostoma rupustre, Coprosma spp., Hedycarya arborea and Leptospermum spp.

Some seasonal variation in plant species selected is evident, as are some minor differences in diet between adults and juveniles; however there are no significant differences in foods eaten between males and females.

Wallabies in exotic forest consume largely grass and weed species but relatively little Pinus radiata.

Molar indexing appears to be an excellent method of aging M. eugenii up until at least three years of age.

Wallabies in general attain the largest size where they have access to managed pasture and it is suggested that a pasture/forest margin is very suitable wallaby habitat. This is supported by kidney fat assessment, which shows that male and female wallabies with access to pasture are in better condition than those in nutritionally

poorer areas. Breeding data suggests that yearling wallabies from pasture margins may be more fecund than those from other areas.

Kidney fat reserves of males drop considerably during the rut and take several months to reach previous levels. Whereas for females considerable stress is imposed during the late spring when energy demands of the pouch young are greatest.

In general female damas breed in their first year and as in Australia the breeding season is very short; however in New Zealand it is marginally earlier.

Sex ratios of pouch young, with one exception were found to be not significantly different from 1:1. Nevertheless there was a significant and consistent bias towards males in shot samples. It is suggested that this is a result of males being more active within their home­ range.

Rhodamine trials revealed that wallabies may travel at least 500m from within the forest to pasture margins, presumably to feed.

Evidence is presented which suggests that wallabies are detrimentally influencing the structure of forests within the Okataina Scenic Reserve, however it is also held that there is considerable doubt as to how much blame is directly attributable to wallabies.