Robin A. Fordham

The annual diet of feral goats (Capra hircus L.) in lowland rimu-rata-kamahi forest on eastern Mount Taranaki (Mt Egmont)

Abstract The diet of the feral goat (Capra hircus) in rimu-rata-kamahi forest on Mt Taranaki was examined over 1 year from monthly rumen samples. Seasonal changes in diet, relative plant preference ratings, and differential fragmentation and digestion rates of plant species, were measured. Individual rumens contained 19 plant species on average and sometimes more than 30. Two species, (Asplenium bulbiferum and Ripogonum scandens), made up 44.8% of the total volume eaten over the year. Foods which were eaten in significantly different proportions by season included Coprosma grandifolia, Coprosma tenuifolia, Griselinia littoralis, Melicytus ramiflorus, Ripogonum scandens (fruit and vine), Weinmannia racemosa, and Dicksonia squarrosa. Goats selected or rejected different plant species largely independently of plant availability. Schefflera digitata was relatively scarce in the habitat, but was possibly the most preferred food. In contrast, the very abundant Microlaena avenacea, Uncinia spp., moss, Alsophila ...

Aspects of the breeding ecology of the North Island little shearwater Puffinus assimilis haurakiensis

Abstract Aspects of the breeding ecology of the North Island little shearwater Puffinus assimilis haurakiensis were studied on Lady Alice Island during the 1994 breeding season. Burrows with banded breeding birds were monitored throughout the breeding season to the fledgling stage. Details of the mating, pre‐laying exodus, incubation and chick rearing periods are presented. These include timing of breeding, length of incubation shifts, weight changes during incubation, and chick growth parameters. Little shearwaters showed a very high level of breeding asynchrony, and we suggest that this is due to their relatively short breeding season, and the fact that they are non‐migratory. Several aspects of the chick‐rearing stage, including frequent feeding of chicks, were not compatible with theories that fat deposits in Procellariiform chicks are an adaptation either to an unreliable food supply, or to stochastic food provisioning by individual adults. We suggest that, unlike other species of Procellariiformes, the little shearwater has access to a steady and predictable food supply.

Structure and composition of the subalpine forest on Mount Hauhungatahi, North Island, New Zealand, during the Holocene

Tree stumps of Holocene age were identified and measured at three sites above the present tree-line on Mount Hauhungatahi, Tongariro National Park, New Zealand. Wood and peat were radiocarbon dated and annual rings in stump cross-sections counted for growth-rates. Comparative measurements were made in three plots in the modern subalpine forests. Stem densities and basal areas in the ancient forest were within the range of the modern subalpine forest samples. The conifers Halocarpus biformis, Phyllocladus asplenifolius var. alpinus, and Libocedrus bidwillii were present in both sets of samples, but in different proportions. Modern forest plots also contained Podocarpus hallii and angiosperm trees. Tree-line forest, composed predominantly of Halocarpus bidwillii, reached 1340 m by c. 10000 cal. BP and c. 1390 m by 8700 cal. BP. These early- Holocene H. bidwillii trees were slower-growing and longer-lived than the same species in current subalpine forests. From c. 5400 to 3800 cal. BP woody vegetation was again preserved. The current irregularly depressed timberline appears to have been initiated before the Taupo eruption (c. 1700 cal. BP). Charcoal indicates infrequent fires in the subalpine bogs and scrublands in post-Taupo time.

Rearing conditions for lambs may increase tansy ragwort grazing.

Grazing by sheep is an accepted method of controlling tansy ragwort (Senecio jacobaea L.), but some flock members seldom eat it. Our objectives were to determine if pre-weaning exposure to tansy ragwort increases later consumption of the plant by lambs, and if confinement with ragwort-eating ewes after weaning facilitates ragwort eating. The sampling periods were Weeks 1, 3, and 12 following weaning. During each period grazing behavior was observed for 1-hour each day and the 24-hour reduction in ragwort volume measured on each of 4 or 5 consecutive days. Lambs exposed to ragwort before weaning removed more ragwort than ragwort-naive lambs during the first 2 sampling periods (P < 0.05). Lambs that grazed with ewes for 11 weeks following weaning ate ragwort more frequently during direct observation, than lambs without ewes during Weeks 3 and 12 (P < 0.05). The ragwort-eating of all lamb groups increased markedly between Weeks 1 and 12 (P < 0.05). This may indicate an increased ability of lambs to consume ragwort with increasing age or an acclimation period during which most lambs come to accept ragwort. Behavioral interventions aimed at increasing the consumption of weeds by lambs may need to take into account age-related differences in toxin tolerances. Exposing lambs to ragwort before weaning and grazing newly-weaned lambs with older ragwort-eating sheep after weaning may increase later ragwort-eating by lambs. DOI:10.2458/azu_jrm_v53i4_sutherland

The nitrogen and mineral content of seven native plant species preferred by feral goats (Capra hircus L.) in lowland rimu-ratakamahi forest on eastern Mount Taranaki (Mt Egmont)

Abstract The nitrogen and mineral content of seven plant species, preferred by feral goats in the lowland rimu-rata-kamahi forest on eastern Mt Taranaki, were determined. Asplenium bulbiferum, Coprosma grandifolia, and C. lucida were very low in Na; Coprosma lucida, Ripogonum scandens, and Weinmannia racemosa were low in P, in terms of meeting the goat’s estimated requirements. However, the animals were in good condition, implying that their nitrogen and mineral intakes were adequate — probably because they selected a range of plant species.

Comparative growth and seasonality of Vespula germanica (F.) and Vespula vulgaris (L.) (Hymenoptera: Vespidae) colonies in the Manawatu region of New Zealand

Data on the seasonality and growth of the German wasp (Vespula germanica (F.)) collected before and after the establishment, in the Manawatu, of the common wasp (V. vulgaris (L.)) were com- pared to investigate possible antagonistic interac- tions between the two species. Additional comparisons of seasonality and growth were made between the two species and between habitat (rural versus urban) and nest-site (ground versus building) categories within each species. There were no de- tectable differences in colony growth rate or nest size parameters in V. germanica before and after the ar- rival of V. vulgaris. This indicates either that, in the Manawatu, the two species do not compete, or that they do compete but without any measurable, dif- ferential effect on colony growth. Comparison of the two species indicated that both had similar rates of colony growth but V. vulgaris colonies were larger in January and February, presumably due to earlier initiation of nest building. V. germanica was first to begin producing drones, while V. vulgaris began building queen cells earlier. Urban V. germanica colonies were larger than those from rural habitats, but there was no difference between colonies built in the ground or in buildings. In contrast, V. vulgaris colonies in the ground were larger than those in buildings, but urban and rural colonies did not dif- fer in size.