Penguins share incubation duties between the male and female of a pair. The one left on the nest must fast while its partner is foraging at sea. Nest attendance patterns during the incubation period reflect the way time is allocated between the conflicting demands of incubation and foraging. We conducted daily nest checks for little penguins (Eudyptula minor) at two localities in New Zealand (Motuara Island in the Marlborough Sounds and Oamaru, Otago) in the 1998/99 breeding season and found significant variation in nest attendance between the two areas. Penguins breeding at Motuara Island made significantly longer foraging trips and were in poorer body condition than those breeding at Oamaru. Foraging trip durations were significantly correlated with the body condition of birds at both areas: the poorer the condition, the longer the foraging trip durations. The increased risk of egg desertion observed at Motuara Island is probably a consequence of the prolonged foraging trips that limit the time available for incubation.

The density of a ferret population in South Island pastoral farmland was estimated by live capture, mark and release, and by removal trapping, during March and April 1997. An estimate of 6.3 ferrets per km 2 (5.5-8.4, 95% CI) was obtained after 8 days of mark and release, whereas 10 days of removal trapping provided an estimate of 5.3 ferrets per km 2 (5.3-5.9, 95% CI). There was significant variation in individual trappability. Proportionally more unmarked ferrets were captured as population density was reduced during removal trapping. Four person-days effort were required to remove 50% of the ferret population from an area of 1254 ha, while removal of 80 or 95% of the population took considerably greater effort. Trapping provided a reliable relative index of ferret abundance. While there is a need to replicate this study in order to confirm its validity, it confirms the use of a relative index as a valuable tool for measuring the efficacy of control operations and estimating ferret abundance.

Little penguins breeding on Motuara Island, New Zealand, went on longer foraging trips during the incubation period compared with those breeding at Oamaru, Otago, resulting in higher rates of egg desertion at Motuara (Numata et al. 2000). In this paper, we report on the differences at these two sites in growth and survival of penguin chicks. During the guard stage at both study areas, parents alternated chick-brooding duties on average every day, and lost 1-2% of their body mass after every trip. However, the duration of the guard stage was significantly shorter at Motuara (15.1 ± 1.0 days) than at Oamaru (20.0 ±1.0 days). Body condition of parents was poorer at Motuara than at Oamaru. The poorer food supply available to parents during chick rearing probably caused the lower growth rates and higher risks of desertion and starvation of chicks observed at Motuara.

The temporal stability of trace element concentrations in fertilized, artificially incubated anadromous brown trout Salmo trutta eggs and newly hatched fry was investigated. The anadromous status of the parental fish was confirmed using strontium isotopic analysis of otoliths. Whilst manganese concentrations in eggs varied over time, concentrations of aluminium, potassium, magnesium, strontium, barium and calcium were all unchanged 1 week and 6 weeks post-fertilization as well as in recently hatched larvae. The results clearly suggest that the distinctive trace element signature present in the eggs and newly hatched larvae of anadromous S. trutta (typically characterized by high strontium, low barium) is stable over time. Therefore analysis of the trace element composition of eggs is concluded to be a cost-effective and reliable method for determining the spatial and temporal extent of upstream spawning migration by anadromous salmonids. The temporal variability of at least one element in this study suggests the stability of untested multi-element signatures cannot automatically be assumed.

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