The IUCN Red List cites the rapid decline of the northern rockhopper penguin population, approximately 57% over the past 30 years, as justification for placing them on the Endangered Species List. But without a better understanding of the reasons for this decline, the northern rockhopper penguin may never recover.
Northern Rockhopper Penguins Found Only on a Few Remote Islands
Until 2005, all rockhopper penguins were considered to be a single species. Since then northern (Eudyptes moseleyi) and southern (Eudyptes chrysocome) rockhoppers have been divided into separate species. Although the southern species is more widespread, even they are listed as Vulnerable to Extinction under IUCN guidelines.
Northern rockhopper penguins breed on a few remote islands in the Atlantic and Indian Oceans. 80% of the entire population of this endangered species is found in the Atlantic, on Gough Island and the Tristan de Cunha Island group. The other 20% breeds in the Indian Ocean, on Amsterdam and St. Paul Islands in the French Southern Territories.
Possible Causes for the Decline of Northern Rockhopper Penguins
The reasons for the decline in northern rockhopper penguins are not completely understood. Some possible factors include overfishing for krill, squid and octopus near breeding colonies, the increasing presence of fur seals reducing available space for nesting, and the presence of introduced mice on breeding islands, which predate on eggs and chicks on the nest.
An oil spill in the Tristan de Cunha Islands in the Atlantic in 2011 resulted in the loss of many northern rockhopper pengions as severe weather and the remote location of the breeding islands hampered rescue and rehabilitation efforts. Over 1,500 birds died after being rescued but the total number lost can only be estimated over the course of several years as birds return to the islands for breeding season.
Penguin Conservation Efforts Slowed by Lack of Information
While there are multiple factors which may be affecting northern rockhopper penguin populations, without clear indications of which are causing the greatest impact it is difficult to develop a recovery program. Reducing commercial fishing pressure, particularly in areas near breeding colonies, may improve reproductive success. In other species it has been found that when adults have to travel further to find food, fewer chicks survive.
In addition to continuing to assess populations on the major breeding islands – Tristan de Cunha, Gough, Amsterdam and St. Paul, work is being done to eliminate rodents on the islands. Predation on eggs and chicks by these rodents affects several other seabirds, including some endangered albatross species, making controlling the rats and mice a high priority for overall biodiversity conservation.
The recovery of fur seal populations, which are no longer hunted, is having a secondary effect on the penguins of Nightingale Island where the two species compete for space on land and possibly food resources in nearby waters. There is also some suggestion that climate change may be playing a role. Rising sea levels may reduce the available land for breeding and changing sea temperatures may be affecting food sources.
At this time, more research is being suggested to determine how each of these factors impacts the penguins. Given how quickly the population is dropping, however, it will be important to implement whatever changes are possible as quickly as possible in an attempt to reduce the loss of more northern rockhopper penguins even as further research is being conducted.
Resource:
R. CUTHBERT, et al. 2009. Population trends and conservation status of the Northern Rockhopper Penguin (Eudyptes moseleyi) at Tristan da Cunha and Gough Island. Bird Conservation International 2009:19:1-12
Dawn M. Smith - A vet nurse, Dawn has worked in wildlife rehabilitation and conservation around the world in addition to her veterinary hospital ...
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