The initial journey of an Endangered penguin: implications for seabird conservation

Abstract

Seabirds can disperse widely in search of prey, especially during non-breeding periods. Conservation measures predominately focus on protecting breeding colonies, but juvenile survival and recruitment can have critical impacts on population dynamics. We report the first deployment of satellite transmitters to track the dispersal of fledgling African penguins Spheniscus demersus, a step towards determining the at-sea behaviour of post-fledging birds and identifying the key non-breeding habitats for this species. Five hand-reared fledglings dispersed from their release sites in the Western Cape, South Africa, in a north-westerly direction. Birds moved >100 km within 6 d and reached a mean distance of >1000 km from their release sites. Two key foraging areas were identified in regions of high and reliable primary productivity, one around Swakopmund, Namibia, and one north of Lambert's Bay, South Africa. Neither site has protected status, underlining the importance of adaptive strategies to preserve key foraging hotspots and the need for further information on post-fledging dispersal to improve seabird conservation.

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

“…Juvenile African Penguins initially forage in nursery grounds of small pelagic fish, probably targeting Anchovy recruits (Sherley et al . ). Juvenile survival increased at all three localities from 1994–95 to 1999–2000, coinciding with an increase in the recruitment biomass of Anchovy from ca.…”

“…, Sherley et al . ), these movements are generally migratory in nature, rather than representative of permanent emigration (Whittington et al . ), and, in the past, most inter‐colony movement of birds banded in the Western Cape has been to other colonies within that province (Randall et al .…”

“…In contrast, juveniles may move over large distances (Sherley et al . ) and stay at sea for up to 24 months after fledging (Kemper & Roux ). They then return to breeding colonies to moult into adult plumage (Kemper & Roux ) but usually do not breed until 4–6 years of age (Whittington et al .…”

Penguins’ perilous conservation status calls for complementary approach based on sound ecological principles: reply to Butterworth et al. (2015)

“…However, they neglect to mention that chicks are only reared for ∼2-3 months post-hatching-during which time they depend on being fed (by their parents) from prey available in relatively close proximity to their colony. After this, they leave the breeding colonies (there is no post-fledging parental care) and search for food over a far larger area (Sherley et al, 2013b). Indeed, analyses in Weller et al (2016) (TRACE appendix) indicate that post-fledgling (like adult) survival at Robben Island may well be best explained by the availability of adult sardine west of Cape Agulhas rather than by anchovy recruitment.…”

“…Indeed, analyses in Weller et al (2016) (TRACE appendix) indicate that post-fledgling (like adult) survival at Robben Island may well be best explained by the availability of adult sardine west of Cape Agulhas rather than by anchovy recruitment. Moreover, satellite tracking of fledglings departing Robben Island shows that young penguins do not follow the migration of anchovy recruits southwards along the west coast (Sherley et al, 2013b;RBS, unpubl. data), but move north towards Namibia, where, before overfishing collapsed the stock, they may traditionally have relied on the abundant sardine resources of the northern Benguela.…”