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Seasonal and diurnal time budgets and feeding intensity of the white-faced heron in pasture

Notornis, 33 (4), 233-245

P.L. Lo; R.A. Fordham (1986)

Article Type: Paper

Time-activity budgets and feeding rates were compiled for white-faced herons (Ardea novaehollandiae) on pasture near Pukepuke Lagoon, Manawatu, from March 1980 to February 1981. Indices of the hourly strike, catch and step rates were calculated. The direction of the bill during strikes was recorded to indicate the kind of prey being hunted. Time spent foraging increased from summer through to spring. Feeding rates were highest in spring, less in summer and winter, and lowest in autumn. Herons fed most actively early and late in the day. Adults were more efficient at foraging than juveniles. Herons spent longer foraging and fed at a faster rate when energy demands were high owing to cool temperatures, breeding or moult, and when more food was available. Areas of pasture in which herons fed, and some that they avoided, were sampled with a sweep net and soil quadrat to determine the seasonal availability of potential prey. Earthworms were most abundant in winter and scarcest in summer, whereas larger insects were common in summer and autumn. Herons fed on whatever prey was most available, taking earthworms in winter and less often in autumn and spring, but concentrating more on insects in summer and autumn.

Habitat use and spring movements of New Zealand pigeons at Lake Rotoroa, Nelson Lakes National Park

Notornis, 33 (1), 37-44

M.N. Clout; P.D. Gaze; J.R. Hay; B.J. Karl (1986)

Article Type: Paper

Monthly counts of New Zealand pigeons (Hemiphaga novaeseelandiae) in lakeside habitat at Lake Rotoroa (Nelson Lakes National Park) over 20 months showed that they were most abundant from June to September. Pigeons were seen to feed exclusively on fruits from February to May, but mainly on foliage from June to January, when kowhai (Sophora microphylla) leaves were the main food (96 of 126 observations). Kowhai leaf fall in October/November coincided with a marked drop in pigeon counts, which was possibly caused by birds leaving the area. Two pigeons captured while feeding in lakeside kowhai in June and August 1984 were fitted with radio transmitters. Both were initially sedentary, but they left the lakeside area in October/ November 1984 and travelled at least 2.8 km and 11 km respectively, outside the National Park, to areas of silver beech (Nothofagus menziesii) forest at over 1100 m a.s.l. One of the radio-tracked birds nested unsuccessfully at this altitude, where it fed on strawberry fungus (Cyttaria gunnii) parasitising silver beech. Both radio-tracked birds returned to the kowhai at Lake Rotoroa in 1985 (by July and September respectively). The lakeside habitat may be an important overwintering area not only for local pigeons, but also for some which breed in forests outside the National Park.
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