Growth curves were fitted to data collected by L.E. Richdale on Yellow- eyed Penguin (Megadyptes antipodes) chicks during three seasons in the 1930s, and compared statistically with curves fitted to data collected at the same locality over two seasons in the 1980s. Interseasonal variation also was compared across the five decades. Although the variation was similar, chicks from Richdale’s poorest season had higher fledging weights than chicks from two out of the three seasons monitored during the 1980s. Growth rates were significantly different for all comparisons except between the 1939-40 and 1983-84 seasons, with contemporary chicks tending to grow faster at 30 – 50 days of age, i.e. during the period of maximum growth. The slower growth of Richdale’s chicks during this period was not reflected in lower fledging weights. As growth rates are more likely to be affected by diet than by other factors, this difference may be due to a change in the availability or quality of prey items during the chick-rearing period, perhaps in response to long-term commercial fishing pressure in the area.
Behaviour of Kingfishers (Halcyon sancta vagans) was studied at three nests in Canterbury. Courtship feeding was observed. Chicks were fed by both parents, predominantly on lizards, crabs and insects. No difference was found in the proportion of prey sizes fed to chicks of different ages ((2=0.02, p>0.05). Chicks were fed about every 20 min in the first week, the rate increasing to every 10 min in the latter stages of nesting. Kingfishers were aggressive during nesting and attacked a wide variety of species as well as other Kingfishers. Mortality during nesting of adult Kingfishers was heavy in suburban habitats.
During a trip to Adams Island in the Aucklands group in November- December 1989, 5 Auckland Island Rails (Rallus pectoralis Muelleri) were caught and 43 heard calling. Several hundred rails are probably on Adams Island, where they are widespread in vegetation that provides good cover near ground level. They were not found on other islands in the Aucklands group, though they may occur on Disappointment Island, which was not visited. The calls of Auckland Island Rails are recognisably similar to those of the same species in Australia but easily distinguished from those of other Auckland Island bird species. During November and December rails readily responded to tape recordings of their own calls, and they called, both spontaneously and in response to tapes, throughout the daylight hours. Two nests were found, one active with two eggs and one old. Chicks were heard at two places. Auckland Island Rails probably lay in October and November, and their nests are built in thick vegetation dominated by tussocks and sedges. Auckland Island Rails seem consistently smaller than Lewin’s Rail (R. pectoralis) from south-eastern Australia, and their subspecific status is appropriate.
Differences in the time of onset of breeding, morphology, egg size, plumage and vocalisations of Dark-rumped Petrels (Pterodroma phaeopygia phaeopygia) were investigated on four islands in the Galapagos. Comparisons were made with P. p. sandwichensis in Hawaii. In Galapagos, breeding cycles differed among islands, and on San Cristobal there were two populations that bred at different times. On Floreana, colonies at different altitudes bred at different times. Eggs were laid on Santiago over four consecutive months; on Santa Cruz the egg-laying period was shorter. Analyses of morphological measurements and notional volume separated Galapagos Dark-rumped Petrels into three groups. Birds on Santa Cruz and those breeding in the middle of the year on San Cristobal were the smallest; birds on Santiago and those breeding at the end of the year on San Cristobal were of intermediate size; and those on Floreana were the largest. There was a similar size trend in the breadth and volume of eggs. No relationship was found between variable plumage patterns on head and chest or between plumage and island populations. Evidence is presented that supports sexual dimorphism in vocalisations, and it is suggested that males make Sweet calls and females make Coarse calls. There were statistically significant interisland differences among Sweet calls and among Coarse calls. Dialects probably exist within the archipelago. Calls had either one or two introductory syllables. When present, the second introductory syllable was very similar to the single introductory syllable, and these may serve the same function. Discriminant analysis of Sweet calls correctly classified 82.296 of these into island of origin. A similar analysis of morphology correctly classified 58.6% of birds from five populations. A theoretical combination of these two analyses indicates a potential classification rate of 92.6%. Although there are differences among Galapagos populations, there is not yet sufficient evidence to warrant subspecific status. Vocalisations of the Hawaiian birds were quite different from those in Galapagos, and Galapagos birds were bigger. Dark-rumped Petrels in Galapagos and Hawaii might be more distant taxonomically than currently recognised and they may be different species.