In South Africa, penguin ‘podcasts’ expose threats to breeding colonies
Scientists studying endangered penguins in South Africa have devised a new way of assessing threats to their breeding colonies -- recording and analysing sound files of their daily chatter.
African penguins vocalise mainly during two periods of the day: four hours in the early morning and four hours in the evening, according to a new study.
With such predictable timing the sounds can be recorded and downloaded, giving conservationists vital insights into the health of penguin breeding colonies. There are 27 penguin colonies in South Africa and Namibia.
Data collected from these sound files can indicate how many breeding pairs there are; how efficient they’ve been at finding food and therefore, how effective they will be at rearing their chicks.
Previously, assessing the health of a penguin colony has involved people picking their way through colonies to count individual birds and their nests. That is time-consuming and can disturb the birds.
Penguin display calls
“Bird calls can be collected (remotely) relatively easily and with a lot less disturbance than doing actual counts,” said Katrin Ludynia, who co-authored the new study into penguin colony soundscapes at Stony Point, home to 1,200 pairs of African penguins at Betty's Bay, in the Western Cape.
“This is especially true for colonies or areas of colonies that are difficult to access or for birds that breed in thick vegetation or in burrows for example,” said Ludynia, who is also research manager at the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) in Cape Town.
Ludynia and colleagues attached a recording device equipped with two in-built microphones high up on a pole in the middle of Stony Point.
The device was set to record at 15-minute intervals over 55 days during the 2019 breeding season, and more than 1,600 usable sound files were obtained and analysed with minimal disruption to the birds.
Penguin calls can be broadly divided into two main types, the scientists wrote in their study published in the journal Ibis: ecstatic display calls, mostly made during the morning when penguins defend their territory and mates; and mutual display calls -- made when foraging penguins greet their partners on their return from feeding trips out at sea.
Threat of extinction
These calls are especially instructive. Earlier studies conducted on African penguins show that shorter foraging trips by the birds indicate better food availability closer to the colony, said Ludynia.
“If we record mutual display songs earlier in the day, we know that birds are finding food close by,” she explained.
“If they start to return late and we record songs much later than usual, that indicates to us that there is a problem in terms of food availability.”
Using the birds themselves is the best way to monitor fish abundance near colonies, the University of Kiel-trained marine biologist said.
“Research has shown that limiting fishing around colonies can have a positive impact on the breeding success of penguins, an important factor in saving this species from extinction.”
Not enough food
Experts say that numbers of African penguins have declined from around 1.5 million pairs in the early 1900s, to fewer than 13,000 pairs now.
Initially their numbers were driven down by the unsustainable collection of their eggs by egg collectors, as well as their droppings for fertilizer. Now commercial fishing operations are depleting the penguins' main source of food -- anchovies and sardines.
Conservationists in South Africa plan to entice the birds to new potential breeding sites along its southern coastline that have healthier stocks of fish. Penguins are wary about starting new colonies if other penguins aren’t already breeding there, so lifelike decoys and sound recordings will be used to create the impression the sites are in use.
Christina Hagen, a penguin conservationist with BirdLife South Africa who was not part of the soundscape study, is responsible for that project. “It is becoming increasingly important to develop non-invasive ways to monitor African Penguins,” she told RFI.
“With further work and development in understanding the timing and number of calls, this study could be very useful in monitoring the foraging effectiveness and reproductive success of penguin colonies.”
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