From Dr. Bingham –
Pete and our adopted penguins will have left the warm sunny waters of Brazil to begin their long journey back home, ready for another season of egg-laying and chick-rearing. It is a very long journey, and the penguins are in no hurry. They travel a little bit further south each day, whilst taking time out to catch plenty of fish, and to float about in the open ocean resting and grooming. For penguins, the journey is as much a part of the vacation as where they visit, and they are not expected back in the colony until October.
Whilst the penguins are away from the colony it is impossible for us to give you a detailed report on Pete. Satellite trackers are sometimes used to follow the progress of penguins, but in addition to being very expensive (over US$1,000 each), they cause serious disturbance to the penguins.
A fully grown Magellanic penguin (like Pete) is so perfectly streamlined that it has about the same drag through the water as a medium sized coin. Even the smallest satellite transmitters are about the size of a packet of cigarettes, so they cause a very significant increase in drag to the penguin. This additional drag reduces the speed at which the penguin can swim, and causes the penguin to use more energy.
Putting a satellite transmitter on a penguin is like putting a small rucksack full of books on a person, to carry around 24 hours a day, 7 days a week, making every task slower and more tiring. Penguins hampered in such a way can never be as competitive at catching food or raising chicks as other penguins. Imagine a football or tennis player having to play with a rucksack. That is why satellite transmitters are very rarely used on penguins by reputable scientists.
So whilst we are waiting for our penguins to return home to begin a new season, it seems a good moment to share with you the results of last season’s research. I attach a series of graphs showing the progress of our penguins at our three main adoption sites, Argentina, Chile and the Falkland Islands.
Try not to be put off by the graphs, which are not too hard to follow using the following guidelines. Running along the bottom of each graph is the date, beginning in October 2010 and running until February or March 2011 (eg. 18/01 = 18th January 2011). (This is the average date for the colony as a whole, and may differ from the date for your actual penguin).
Up the left-hand side is the percentage of eggs and/or chicks surviving week by week, beginning at 100% when the eggs are first laid, and gradually dropping down as some eggs and then chicks are lost. The less the line drops below 100%, the higher the breeding success, with more chicks surviving.
The most successful colony by far last year was Cabo Virgenes in Argentina, with 77% of all eggs laid in the colony producing a chick that was successfully reared to leave the colony and begin life on its own. Since each penguin couple lays two eggs in their nest, that means an average breeding success of 1.54 chicks per nest for the colony (ie. 154 chicks successfully reared to begin life on their own for every 100 nests in the colony).
Just 1 chick per nest (50% of eggs surviving) would be considered good, so 1.54 chicks per nest (77% of eggs surviving) is exceptionally good. In fact it is the most successful season ever recorded in Argentina, and continues the successful trend of the previous 4 years (2006/07 = 1.40, 2007/08 = 1.40, 2008/09 = 0.98, 2009/10 = 1.30). It is clear that the colony at Cabo Virgenes in Argentina is in very good health, with plenty of food available, and high breeding success. The large numbers of chicks being reared each year are leading to an increase in population at this colony.
The second graph is for Chile. Here things are very different due to a severe drought that struck Magdalena Island during the last two years. In
While there was an average breeding success of only 0.80 chicks per nest (only 40% of eggs survived to produce a healthy chick that left the colony to begin life on its own). The cause of this low breeding success was a severe drought that caused the grass to die off, allowing the loose soil to be blown across the island day after day in the strong winds. The penguins live in burrows, and despite the best efforts of the adults, many burrows simply got filled up by the huge quantities of soil being blown around 24 hours a day, 7 days a week.
We worked around the clock freeing trapped penguins, but with around 65,000 penguin nests and only 3 people on the island, there was a limit to how much we could do. The drought lasted two years in all, and the season before was even worse, averaging just 0.46 chicks per nest (23% of eggs surviving).
Thankfully the drought is now over, and the grass has begun to grow back across the island, so hopefully, the crisis is now over. When not struck by drought, Magdalena Island has high breeding success, averaging well over 1 chick per nest, so the population is stable and not under threat unless climate change causes the drought to occur more frequently.
Finally, the Falkland Islands showed the lowest breeding success of any Magellanic penguin colony, as always, due to lack of control over the Falklands fishing industry. Here average breeding success for the colony was just 0.46 chicks per nest (23% of eggs surviving).
Commercial fishing vessels catch so much fish and squid that adult penguins are unable to find enough food to feed their chicks, leading to very low breeding success and a 90% population decline over the last 20 years. (Populations in Argentina and Chile have increased over the same period as a result of control over commercial fishing in these countries).
We have tried relentlessly since 1997 to persuade the Falkland Islands Government to establish no-fishing zones around penguin colonies, but they just refuse to do so, and the Penguins continue to decline For more information visit www.falklands.net, or view our scientific paper “Bingham (2002)
The decline of Falkland Islands penguins in the presence of a commercial fishing industry. Revista Chilena de Historia Natural 75: 805-818.” at www.seabirds.org/resume.htm#bookmark1, or view my book “The Falklands Regime” www.authorhouse.com/BookStore/ItemDetail.aspx?bookid=27877
I will write to you again at the end of October, by which time Pete should be back home in the nest and close to egg-laying.