|King penguins at Salisbury Plain, South Georgia. |
Photo credit: Liam Quinn. Some rights reserved.
The results, published this month in the open access journal PLoS ONE, showed that the juvenile penguins explored new habitat and eventually learned to find food in similar habitat to their parents.
For long-lived animals like penguins, it is important to look at their movements and distribution at all stages of their life cycle. This allows scientists to look at potential population trends and threats and, ultimately, ways to conserve the species.
After fledging, young animals generally disperse and forage on their own. During this period, in which they learn how travel and forage efficiently, they may not only have high mortality rates through natural causes, but may also be more susceptible to human-induced threats.
The most critical stage, often with a high risk of mortality, usually occurs during the first year when juveniles can spread out over relatively long distances compared with breeding season foraging trips made by adults, and across completely unknown ocean areas.
Previous studies have tracked emperor, gentoo and Adelie juvenile penguins after they fledge and leave the colony where they were born (their natal colony). But, surprisingly, little is known about this stage in king penguins' lives.
To better understand juvenile king penguin foraging behaviour, scientists tracked 18 juvenile kings – 10 from the Falkland Islands and 8 from South Georgia – for about 120 days in 2007/2008. The two South Atlantic sites have different climates and also differ in how close they are to the Antarctic Polar Front (APF). The APF is a line around Antarctica where the cold Antarctic waters sink beneath the relatively warmer waters of the sub-Antarctic. It is a key oceanographic feature generally thought to be important in determining how successful king penguins are in finding food.
The scientists found that king penguins travel large distances when at sea for the first time, ranging from a maximum distance of about 600 km to 4,000 km and averaging about 45 km per day. The greatest total distance travelled was an impressive 4,783 km by a penguin named Youngster from the Falkland Islands over 261 days.
The birds from the Falkland Islands and South Georgia moved similarly. More detailed analyses did reveal slight differences in habitat use, however. For example, juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height, and chlorophyll variability.
The study authors suggest that juvenile king penguins eventually use similar habitat to adult king penguins to find food. They said this may indicate that inexperienced king penguins develop their foraging skills progressively over time, regardless of the location of their natal site in relation to the position of the APF.
Study sheds light on penguins first year far from home [press release], 14 May 2014, PLOS
PLOS ONE citation
Putz K, Trathan PN, Pedrana J, Collins MA, Poncet S, et al. (2014) Post-fledging dispersal of king penguins (Aptenodytes patagonicus) from two breeding sites in the South Atlantic. PLoS ONE 9(5): e97164. doi:10.1371/journal.pone.0097164