Methodology:

We caught 33 adult penguins and pulled a canvas bag over their head, keeping the head free so that the individual could breathe; the bag minimised flipper movements and controlled the penguin during subsequent handling. We weighed each penguin to the nearest 0.5 kg using a suspended mechanical scale, and attached either a Wildlife Computers (n = 15) (model SPOT-275) or Sirtrack (n = 18) (Kiwisat K2G 273A rated to over 500 m; 95 g; 78 x 43 x 27 mm) satellite telemetry (ARGOS PTT) device to each individual. The Wildlife Computers tags were programmed to transmit at 60 s frequency, whilst the Kiwisat tags transmitted every 90 s. We attached devices on the dorsal mid-back of each penguin using Loctite 401 quick-setting glue and two plastic cold-resistant cable ties, which we sealed with glue. After release, we observed each penguin for as long as possible but did not detect any unusual behaviour. Data from the Sirtrack devices are also available from the AAD.

All PTT location data were analysed using R version 3.5.1 (R Core Team, 2018). Initially, fixes that would have required an average cruising speed of more than 2.2 m s-1 were removed using speedfilter (R package trip v1.6.0). We then used crwMLE (R package crawl v2.2.1) to fit continuous-time correlated random walk models and interpolated tracks at 5-minute intervals using crwPredict. Telemetry data are often incomplete or imprecise; as such these models allow for uncertainty in location. Location data from the 5-minute interpolated tracks were used for all subsequent analyses. The tracking data cover the period from deployment until the time when the penguin's annual moult was underway, although some tags ceased transmitting earlier.

Data collection:

We caught 33 adult penguins and pulled a canvas bag over their head, keeping the head free so that the individual could breathe; the bag minimised flipper movements and controlled the penguin during subsequent handling. We weighed each penguin to the nearest 0.5 kg using a suspended mechanical scale, and attached either a Wildlife Computers (n = 15) (model SPOT-275) or Sirtrack (n = 18) (Kiwisat K2G 273A rated to over 500 m; 95 g; 78 x 43 x 27 mm) satellite telemetry (ARGOS PTT) device to each individual. The Wildlife Computers tags were programmed to transmit at 60 s frequency, whilst the Kiwisat tags transmitted every 90 s. We attached devices on the dorsal mid-back of each penguin using Loctite 401 quick-setting glue and two plastic cold-resistant cable ties, which we sealed with glue. After release, we observed each penguin for as long as possible but did not detect any unusual behaviour. Data from the Sirtrack devices are available from the AAD.

Data quality:

The ARGOS quality flag was used by the crawl algorithm.