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News from the Colonies 1
Life and Times of the African Penguin
1 November 2007
Animals in zoos are ambassadors for their counterparts in the wild. The interviews below aim to connect the African Penguins in the zoo which you support with the African Penguins living in their colonies in South Africa and Namibia.
This will be an occasional publication. Its format will vary, depending on how it is used. Feedback will be appreciated. If you have received this indirectly, please email me and ask to be put on the distribution list.
The global scene - Professor Rob Crawford
Rob, what was the outcome of the African Penguin census in 2007? Was it up on last year's, and do you think that the downward trend of the past few years had been reversed?
African Penguins breed in three discrete regions: Namibia, South Africa's Western Cape and South Africa's Eastern Cape. In 2007, some 21 000 pairs of African Penguins bred in the Western Cape, very close to the number of pairs recorded in 2006. In 2007, only 6 000 pairs bred in the Eastern Cape compared to more than 11 000 in 2006, a worrying decrease. The global population attained its lowest recorded value of about 31 000 pairs in 2007. Unfortunately, the downward trend in African Penguins has continued, and it has certainly not been reversed.
In a nutshell, what are the key conservation issues facing African Penguins now?
At present, the main threat to African Penguins is a scarcity of food. The main food of African Penguins are two species of fish, anchovy and sardine. Both have been scarce for 25 years off Namibia. In the Western Cape, these fish have moved to the east and are out of range of the breeding colonies. While they are breeding, penguins cannot travel far in search of food. Recent studies with satellite tracking devices have shown that breeding penguins cannot search much farther than 20 km from their colonies for food. Once colonies become small, local factors can have a big impact, including predation and pollution. It is necessary to attempt to manage all these factors.
What are the important things we need to do now to help the population of penguins to increase?
The view from Dyer Island - Lauren Waller
Lauren, as the 2007 breeding season draws to a close, has it been a productive year for the African Penguins on Dyer Island?
This time last year, adults were deserting their chicks and going into moult. Is this year proving a more normal year?
This year is more normal in the sense that the adults are going into moult at the same time as they usually do. There are however still many really small downy chicks on the island. I saw five dead chicks when we surveyed the island on 27 October, but there are probably more because we could not get close to some of the breeding colonies due to the breeding Cape Cormorants, and some of the small chicks would be hidden in rocks and vegetation. Our most recent counts estimated that there were about 350 chicks, which is less than the 700 last year. It's difficult to tell which chicks are abandoned because they have formed close bunches or crèches of downy chicks, which makes it difficult to determine those that are not being fed. Some of these groups have up to 15 chicks. We send obviously abandoned chicks off to SANCCOB for rehabilitation.
We removed the first batch of 99 chicks from the island on 28 October and took them to SANCCOB. A further 28 were removed on 30 October. These were chicks which were visibly underweight, standing alone unattended by an adult, in big creches which were obviously not being fed by the one or two adults with them, or in among small groups of moulting adults. Most adult penguins on Dyer Island are now moulting; from past experience we know that even the apparently well fed chicks will at some point start losing condition. It is likely that several hundred more chicks will be sent to SANCCOB over the next few days.
SANCCOB has a remarkable success rate with rearing these chicks. Of the 694 chicks from Dyer Island which were reared in captivity at SANCCOB last year, 646 (93%) were released. Follow-up studies of these "orphaned chicks" reared and released in this way indicates that the rate at which they return to breed does not differ from that of naturally raised chicks.
We will only know the fruits of our efforts in a few years time, because we won't see them on Dyer Island for a few years. Once chicks fledge they leave their island, they spend the next few years swimming around the coastline and sometimes even "visiting" other colonies. After 3-4 years, they usually go back to the island where they hatched, and join the breeding population there.
What seabird species are breeding on the island now?
As the African Penguin breeding season on Dyer Island draws to a close in October, it's the turn of the Cape Cormorants. The first birds started to pair up in September, and the island is now covered with tightly packed colonies of Cape Cormorant nests. There are already some chicks that have hatched, and we expect the island to be full of juvenile Cape Cormorants in November/December.
The African Black Oystercatchers will also be breeding soon. There are normally about 22 pairs on the island and we'll be starting to monitor their breeding from November.
With all this activity and extra food source, Kelp Gulls have also started to lay their eggs. Ever the opportunist, they are quick to snatch an egg or chick from an unsuspecting Cormorant. They are also masterfully successful at mobbing adult and juvenile Cormorants, inducing them to regurgitate their latest meal!
A Namibian view - Dr Jessica Kemper
Jessica, how did the African Penguins on Halifax Island fare in 2007?
This apparent food shortage seems to be quite widespread, because during the same week there were similar reports from three other islands in Namibia (along 150 km of coastline) - unusually high numbers of chick mortalities from starvation. Luckily this shortage does not seem to have affected any adults so far. During the first week of October, staff at Mercury Island noted that penguins were arriving back at the island with full bellies and that the chicks were already looking better! Let's hope that this food will soon also become available farther south to the Halifax penguins.
How many penguins do you currently have breeding on Halifax Island?
It is difficult to estimate the breeding population on Halifax Island because the breeding season extends almost all year round, and we suspect that quite a few of them breed more than once a year, while others may skip breeding altogether. We count all nests (containing eggs or chicks) once a month to get an idea of numbers of penguins breeding throughout the year. During peak breeding activities, when we assume that most pairs will breed, we have counted as many as 670 nests during the last decade. This year, we counted 530 nests in August and are hoping for another, perhaps bigger, wave of nests being initiated during December and January, if feeding conditions around the island improve.
What has been the trend in population numbers on Halifax Island in recent years and how does this compare with the other breeding colonies in southern Namibia?
Halifax Island is the only one of the four main breeding colony of African Penguins in Namibia where numbers are increasing (the other three colonies being Mercury, Ichaboe and Possession Islands; together these four islands account for about 96% of the Namibian penguin population). Although it is not clear why Halifax Island should be faring so much better, possible contributing factors to the declining population trend at the other three islands are likely to be the severe lack of food around Possession Island, where penguin diet is dominated by fish larvae and cephalopods, and a combination of poor food availability, competition for quality food (and possibly nesting space) with other seabirds, disturbance and seal predation on Mercury and Ichaboe Islands.
What are the biggest problems facing penguins in your area, and can anything be done to help solve them?
The main problem appears to be the availability of reliable, good quality food. The main prey of most penguins in Namibia is Pelagic Goby (at least north of Possession Island), which is far less palatable and nutritious compared to sardine and anchovy, their preferred food and the main prey of African Penguins in South Africa. Gobies are also more tricky to catch as they do not readily form shoals and tend to be demersal. After being heavily overfished during the 1960s and 1970s, the remaining sardine and anchovy stocks are now concentrated in central and northern Namibia and are generally not available to breeding Halifax penguins.
Breeding success is particularly poor on Halifax Island. Most of the penguins on Halifax Island nest on the surface, because the cement-like guano layer they used to burrow into got removed and sold as fertilizer until the early 1970s. Nesting on the surface exposes eggs and chicks to marauding Kelp Gulls. Large downy penguin chicks in surface nests are particularly vulnerable to heat exhaustion on Halifax Island, where air temperatures can occasionally exceed 35ºC (88ºF). In 2001 we attempted to improve breeding success by providing the Halifax penguins with artificial shelters. This strategy seems to work, with the penguins readily taking to their new accommodation and with breeding success of nests in shelters significantly higher than that of surface nests. I just wish that the shelter-breeding penguins would look after their shelters a little bit better and not cram them full of nesting material (mainly seaweed, shells and rocks) to the extent that they no longer fit inside!
What other seabird species are breeding on Halifax Island at present?
What can you do to help the penguins along the coastline of southern Africa? You can, through your zoo, purchase an artificial nest box, so the penguins can get underground, out of the sun and safe from predators. You can, through your zoo, make a donation to support one of the projects doing conservation research for African Penguins. You can also help to support the rearing of the current batch of abandoned chicks at SANCCOB.
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