Methodology:

The mass of individual breeding chinstrap penguins are measured annually on first return to their colonies at Signy Island in November following CCAMLR (CEMP) Standard Method A1A. A random sample of adult penguins are captured on the beach as they leave the sea. Any birds already occupying territories are not sampled. Each bird is weighed to the nearest 50g. The sex of each bird is determined using bill length and depth and applying appropriate discriminate function analyses. Ideally, counts are made every fourth or fifth day, starting with the first available five day period after adults are first observed in the chinstrap chronology colony (C69 and later C66, see CCAMLR (CEMP) Standard Method A9). The weighing procedure continues until either 4 weighing sessions have been carried out or chronology colony counts indicate most/all penguins have arrived.

Arriving penguins are captured when travelling on patches of snow from the beach to the colony or when resting on the beach, suggesting they are newly arrived. They are then firmly but gently put into a secure weighing jacket where bill length and depth measurements are taken before being weighed using a spring balance. Once measured, each bird is marked with non-permanent, animal-friendly stock marker on their chest to avoid recapture, and released. Handling time should not exceed 1 minute.

Data collection:

Instruments:

- weighing bag

- hand-net

- 10kg spring balance

- callipers

- non-permanent, animal-safe stock marker

Data quality:

Accuracy within 50-100 g

Sessions are ideally repeated every 4-5 days - the number of sessions vary between years depending on the time it takes for all penguins and researchers to arrive. Years with no data indicate personnel had not arrived to Signy in time to carry out this activity.