Falklands Conservation

Where Do Falkland Penguins Go in Winter?

Dr. Klemens Putz reports on the results of our Satellite Tracking Study of the Winter Migration of Magellanic and Rockhopper Penguins breeding in the Falkland Islands

This study forms part of an overall plan to gain more information about the Falklands offshore ecosystem, a particularly important priority in view of the current hydrocarbon exploration and exploitation activities.

Fifteen Penguins Were Tagged at the Beginning of the Winter
A pilot study was initiated in late 1997 to study the winter migrations of Magellanic and Rockhopper Penguins breeding in the Falkland Islands. At the end of March 1998, ten Magellanic and five Rockhopper Penguins were successfully equipped at the end of their moult with satellite transmitters (platform transmitter terminals, PTT's) at Seal Bay in the north-east of the Falklands, using the method described by Wilson et al. (1997). The PTT's were programmed to transmit for eight hours only every three days and included a saltwater switch to suppress transmission while underwater.

The Performance of Each Penguin was Analysed
The data collected was analysed with respect to migration routes, travelling speeds and the overall performance of the trip. Values calculated for travelling speed are minimum values as they are based on the assumption that the penguins move in a straight line between two locations. Furthermore, the analysis of the quantity and quality of the locations revealed relationships between time of day and activity of the birds.

During the migration of the birds, all PTT's stopped transmitting after different time periods. Locations were received for periods of between 15 and 99 days from Magellanic and for periods of between 54 and 111 days from Rockhopper Penguins. The failures are most likely to be linked to a detachment of the devices rather than being due to other reasons such as predators or starvation. However, one Magellanic Penguin was found dead on the beach near Puerto Madryn, Argentina, and the PTT was recovered.

Magellanics are 'Long Haul' Travellers
All Magellanic Penguins initially headed north-west swimming either offshore over the Patagonian Shelf or in coastal waters of the South American continent. The birds migrating offshore typically had higher travelling speeds than those swimming inshore. The Magellanic Penguins finally reached an area around 35oS, 54oW, more than 1,800km (1,125 miles) away from the colony, where they stayed for some time before transmissions stopped. Another bird remained for several weeks in an area at 42oS, 60oW, about 1,000 km (625 miles) north of the breeding site. The highest total distance travelled for a single bird was calculated to be 2,661km (1663 miles) within a time period of 75 days.


Figure 1:
Click on image to enlarge: Warning! Large file size

Rockhoppers Stay Closer to Home
The movements of the Rockhopper Penguins did not follow such a clear pattern. At least three birds travelled in a more westerly direction compared to that of Magellanic Penguins and stayed for some time close to the mainland at about 48oS, 65oW before returning to the Islands during which time the signals stopped. The highest distance to the colony was calculated to be less than 700km (437 miles) for these birds. Two Rockhopper Penguins stayed to the north of their colony, one bird close inshore, even returning several times to the colony. The other penguin remained offshore and travelled a total distance of 2,119 km (1,324 miles) within 75 days.


Figure 2:
Click on image to enlarge: Warning! Large file size

Travelling Speeds
The different performance of the winter foraging trips in the two species is further reflected in the individual travelling speeds. On average, the Magellanic Penguins travelled at about 35km/day (22miles/day) nearly twice as fast as the Rockhopper Penguins with average speeds of some 20km/day (12miles/day). In contrast to this, the highest speeds calculated did not differ between the two species.

Potential for Improving and Increasing Data Collection
However, although transmission periods were much longer than in a comparable study (Stokes et al. 1998: average 24 days, maximum 36 days), the devices did not stay on the birds long enough to cover the whole period. Based on the experience gained in this study further improvements of the method of attachment, as well as a reduction in the hydrodynamic drag, were proposed and are very likely to enable us to track individual birds over longer time periods. The alterations will be integrated in the PTT's to be deployed during the next breeding season and their effectiveness can be considered.

In the next breeding season Magellanic and Rockhopper Penguins will again be equipped with PTT's to follow their movements during the incubation period, during which time both sexes alternate foraging trips of a duration of up to two weeks. It is not reasonable to continue this study over the chick-rearing phase as birds have to feed their chick daily, thus being time limited and unable to reach offshore areas. However, in the coming winter period it would be reasonable to deploy PTT's on penguins from different colonies in order to be able to compare the findings from different places.

Pilot Project Provides Vital Information for Penguin Protection
The results of this pilot study provide for the first time highly valuable insights into the winter foraging patterns and migrations of Magellanic and Rockhopper Penguins breeding in the Falkland Islands. It could be shown that there is a clear potential for both species to be impacted by activities in the northern tranche areas licenced for exploration of oil. Consideration of how to limit any such impact will now have to be addressed. It has also provided us with a more precise picture of the areas of the Patagonian Shelf on which these species depend during winter. Greater knowledge of the role these areas play in the life of Falkland penguins through the collection of additional data is an important priority and will be a focus of future work for the Tagging Project.

Falklands Conservation gratefully acknowledge the financial support from the Falkland Operators Sharing Agreement (FOSA) and the Antarctic Research Trust (ART). Peter and Melanie Gilding kindly provided access to the penguin colonies at Seal Bay.

References:
Stokes, D L, Boersma P D, and Davis J S. 1998. Satellite Tracking of Magellanic Penguin Migration. The Condor 100: 376-381.

Wilson, R P, Putz K, Peters G, Culik B, Scolaro J A, Charrassin J-B & Ropert-Coudert Y. (1997). Long-term Attachment of Transmitting and Recording Devices to Penguins and Other Seabirds. Wildlife Society Bulletin 25: 101-106.

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