Use of nest materials for skuas (Catharacta spp.) and kelp gull (Larus dominicanus) was studied in the Antarctic Peninsula during the 1992-1993 breeding season. Material from 126 skua and 51 gull nests found in 10 habitat types (HTs) was analyzed. Plant censuses were conducted to evaluate the availability of species commonly used as nesting material. Skuas used mainly Polytrichum alpestre, while gulls used mainly Deschampsia antarctica. No correlation was found in the use of different nest material in skuas and gulls, indicating that they differ in their use. The narrow range of resources found in nest material suggests a selective pattern of use restricted to a few plant species. However, use of nesting material also appears linked to its availability, although skuas and gulls’ preference for P. alpestre and D. antarctica, respectively was observed in HTs with a low and discontinuous covering of these plant species.
Conspicuousness of terrestrial birds from a distribution study using 100 ha squares based on the New Zealand map grid was investigated. Logistic regression was used to determine the amount of time observers should spend in each square to have a 50% chance of detecting any given bird species if it was present. The analysis was conducted for 3 habitats. For 14 species of native and introduced birds, the length of time necessary to determine presence was 1 – 631 min. To ensure that most species are accounted for in future distribution studies using similar grids, it is recommended that observers spend 1 h in each square.
The chick-rearing strategy of yellow-eyed penguins (Megadyptes antipodes) breeding on Otago Peninsula was examined in 12 pairs of adults, between 17 November 1996 and 31 March 1997, from time of hatching of chicks to parental moult. Differences in behaviour of both male and female parents towards one- or two-chick broods were not statistically significant, but behaviour towards all offspring changed significantly over time with respect to breeding phases. Differences observed resulted from a change in feeding procedure. “Food-walks” started significantly earlier in the course of a feeding session as time progressed, while major components (duration and number of individual feeds) decreased significantly. The changes observed are interpreted as resulting from the chicks’ growing independence in concert with the parents’ decreasing urge to spend time with their offspring outside the still necessary feeding encounters. An evolutionarily stable environment and reliable food source are suggested as the reason for the lack of development of different chick-rearing strategies for different numbers of offspring or for male and female breeders.
Patterns of white feathers on the heads of 10 female and 18 male wild and captive adult black stilts (Himantopus novaezelandiae) were quantified to determine whether the presence and location of white flecking was age- or sex-related. Eleven of the males, but none of the females had white flecking on their heads. Flecking occurred on 2-7 of 9 head regions described and an increased amount of flecking was positively correlated with increasing age. Males without white flecks were 2-7 years old, whereas males with flecks were aged 5-19 years. Most flecking was around the eyes, in the superciliary region and on the crown. We conclude that the presence of white flecking around the eyes or generally scattered on the head is a reliable indicator of a black stilt being old and male.