CCAMLR

Discriminant analysis can use morphometric differences between known male and female birds to predict the sex of unknown individuals in field studies. Geographic variation in size and shape often limits the predictive value of a discriminant function to the population from which it was derived. Specific discriminant functions for populations of five species of fulmarine petrels (Northern Fulmar, Fulmarus glacialis; Southern Fulmar, F. glacialoides; Antarctic Petrel, Thalassoica antarctica; Cape Petrel, Daption capense; and Snow Petrel, Pagodroma nivea) assigned 81 to 98% of birds in the samples to the correct sex, but the validity of each discriminant applied to alternative populations remained questionable. Our approach to overcome this limitation is to combine data from the different species into a single discriminant. Adequate performance of this generalized discriminant in samples of different species shows its validity for use in other populations of any of these species. The generalized function calculates the discriminant scores for individual fulmarine petrels as: Y = HL + 2.38BD + 0.41TL – 0.21CL, where HL is head length, BD is bill depth, TL is tarsus length and CL is bill length (measurements in millimeters). The cut point to split sexes is different in each sample and may be calculated directly from discriminant scores, without reference to sexed birds, by using a maximum-likelihood method. Depending on species, the generalized method results in 84 to 97% correct classifications and can be applied to other populations of fulmarine petrels without requiring samples of birds of known sex.

Observations of nesting Adélie Penguins (Pygoscelis adeliae) were made at Ardley Island during spring 1990 when snow cover was unusually thick at some subcolony sites. Adélie Penguins at these sites had to delay egg laying until the snow melted. Maximum length of fasting periods comprising pre-breeding and incubation was 50 days. Long fasting seemed to have no detrimental effect on breeding. Furthermore, there was no relationship between penguin arrival mass and duration of fast. Even birds with small mass had sufficient reserves to undergo long fasting periods.
In spring 1990, when we started with a monitoring study for CEMP (CCAMLR 1990) at Ardley Island, there were still high quantities of snow at the subcolony sites. Adélie Penguins at Ardley Island inhabit both small rocky outcrops and flat, stony hillocks (storm bars). The latter had a distinctly thicker snow cover this time so that the pebbles necessary for nest building were unattainable. Consequently, we observed the behaviour of the penguins in this situation, recorded the laying dates and lengths of fasting periods

Indices of predator reproductive status are calculated for CEMP parameters such as adult weight on arrival at breeding colony, duration of foraging trips, breeding population size and success, chick weight and diet, and fur seal pup growth rates (Methods A1-A9, Bl-B2 and C1-C2) using data held at the CCAMLR Data Centre. Preliminary statistical and graphical analyses of the trends shown by indices are also present. Information of the ice cover within CEMP study regions is also provided (Method F2).

Published in: J. Zool., Lond. (1994) 234, 000-000