Paper published!

Penguin measurements recorded during Robben Island foraging research featured in our recently published paper: 

Kate J Campbell, Danielle Farah, Sarah Collins & Nola J Parsons. 2015. Sex determination of African Penguins Spheniscus demersus using bill measurements: method comparisons and implications for use. Ostrich:1-9

Sexing birds in the field can be problematic for those with no sexual distinctive plumage or morphological features, as is the case with the endangered African Penguin. This methods paper clarifies different bill depth measurement techniques currently in use. It also presents a discriminant function that can be used with the traditional bill depth measurement for the species. 

One of the findings was that these two bill depth measurements are not interchangeable. When using discriminant functions to sex African Penguins, take care to use the appropriate measurement!

The bill morphology of DNA sexed penguins did not vary geographically, indicating that the discriminant functions described can be used throughout the African Penguins' range in South Africa. Further investigation is needed to see if  they can be applied in Namibia.

Reliable sexing methods are pertinent to research into sex ratios, population dynamics and identifying whether there are sex-specific differences in behaviour and survival. 

Note: Kate J. Robinson assumed her married name and is now Kate J Campbell. 

2nd World Seabird Conference

The second World Seabird Conference is coming to Cape Town!
Some of the African Penguin research conducted at Robben Island will be presented there. There is still time to register! Check out the website to learn more about this exciting conference World Seabird Conference.

The Forage Fish Impacts II session on Wednesday 28th at Room 1.60 will include the following talks focused on the African Penguin:

S10.2     14:10 - 14:20      
Changes in the abundance and distribution of small pelagic fish in the southern Benguela
Carl van der Lingen, Branch: Fisheries Management, DAFF

S10.3     14:20 - 14:30      
Evidence for a benefit of fishing closures around breeding colonies of African Penguins
Antje Steinfurth, University of Cape Town

S10.4     14:30 - 14:40      
Establishing suitable indices for the management of seabirds, fisheries and their prey: the case of African Penguins and purse-seine fisheries in Algoa Bay, South Africa.
Alistair McInnes, University of Cape Town

S10.5     14:40 - 14:50      
"Seas of plenty", a conundrum of sorts for African Penguins
Janet Coetzee, DAFF

S10.6     14:50 - 15:00      
African Penguin foraging behaviour and chick condition linked to local fish abundance
Kate Robinson, University of Cape Town

Then on Friday don't miss:

S23 Ecological/Evolutionary Rescue for Threatened Seabirds          Auditorium II

S23.2     14:15 - 14:30      
What drove the collapse of South Africa's penguin population and can we do anything to address it?
Richard Sherley, University of Exeter

Life in rain coats!

Winter is well and truly underway with storm fronts hauling around the Cape, and the African penguin’s breeding season is in full swing. The researchers on the island have been making use of their rain coats and water proof gear. Despite the occasional bout of bad weather, 38 deployments have been carried out so far and data collection is almost complete.

But Robben Island is not the only place where African penguin foraging behaviour is monitored at sea using GPS loggers. Deployments are also carried out at all other important penguin breeding sites including Dassen Island, St Croix and Bird Island. Amongst other things, the tracking data are used as part of an ongoing study to investigate the effects of fishing closures around penguin colonies. The study aims to assess whether preventing fishing in waters in close proximity to the main colonies can impact penguin breeding success and foraging behaviour, by reducing the penguins’ competition with fishermen for food. The project has been running since 2008, and if results can show that disallowing fishing has a positive impact on the penguin population, No-take zones may be implemented around the island colonies.

  

 Map showing some of the main African penguin breeding colonies, taken from Sherley et al. 2014.

In parallel with tracking the movements of penguins at sea using GPS loggers, foraging trip duration is also being measured at Robben Island by monitoring the penguins at the nest. At a number of nests, camera traps have been placed at the nest entrance, in order to capture when the penguins depart to forage, then at what time they return to feed their chicks. This information can then be used to determine the duration of the bird’s absence of the nest as a proxy for foraging trip length. When the chicks are small, one parent stays at the nest to keep the chicks warm, and to guard them from predators. However, once the chicks are old enough to thermoregulate themselves, both parents will go out to sea in order to provide enough food to satisfy their chicks increasing energy demand. At some nests, cameras are being used in combination with data-logging scales, which are able to record the weight of any penguin that stands on or walks over them. The information on the penguin’s weight can then be used to determine weight gain over the foraging trip, and to estimate the body condition of adult penguins. This method of collecting data is minimally invasive, measures were taken to minimise the stress of handling.

A camera trap image showing a penguin departing the nest.

This year’s tracking could not have been realized with the kind support, boundless help and effort of the Earthwatch team and the Robben Island Museum. Our special thanks however go to Mpumi, Phakamile Zungu, Davide Gaglio, Nola Parsons, Kerrie-Lee Dobbie, Sally Hofmeyr, Barbara Barham, Kate Robinson, Antje Steinfurth and Richard Sherley for their hard work and endeavors, companionship and invaluable assistance in the field.

For now the GPS logger deployments at Robben Island have finished for the season, but the penguins keep on swimming!

References:

Sherley RB, Waller LJ, Strauss V, Geldenhuys D, Underhill LG, et al. (2014) Hand-Rearing, Release and Survival African Penguin of Chicks Abandoned Before Independence by Moulting Parents. PLoS ONE 9(10): e110794. doi:10.1371/journal.pone.0110794

The 2015 field season begins...

With the start of April an increasing number of African penguins incubating eggs and brooding chicks can be seen throughout the colony. However, in recent years the African penguin has undergone a rapid population decline, which shows no sign of reversing.

Research suggests that a reduction in food availability is the largest factor influencing this decline. Therefore being able to determine the areas through which birds move and where they spend extended periods of time at sea to find their prey, is essential to shed some light on the mechanisms that are driving the penguin population trend. Although we still know surprisingly little about what the penguins do and where they are going when foraging for food at sea. The reason for this however, is relatively easy to understand: once they are at sea, they are out of sight and therefore much of what has been known of these birds was based on observations made on land, while their life at sea had stayed a well-kept secret.

Advances in logger technology have made it possible to achieve a glimpse of this other side of a penguin’s life. Advances in microchip technology have led to various devices being fitted to penguins (and other seabirds) to monitor their at-sea behaviour. Generally these miniature loggers fall into two categories: transmitters that emit a signal to a satellite and data loggers that store information on an embedded microchip. The latter often contains a GPS unit that records the penguin’s position. If these are used in combination with a Temperature Depth Recorder or TDR (a unit containing a pressure & temperature sensor), detailed information can be gained on how deep they dive, how often and long they dive, in what ambient temperatures they find their prey. Ultimately these devices provide a three-dimensional view on the bird’s movement at sea.

It may seem like an easy task to track penguins, as data collection is conveniently carried out by small electronic devices that are deployed on the bird’s back. Fieldwork however, and the all too common experience of sitting for hours (sometimes days) at the nest site waiting for the bird to return after its foraging trip, suggest otherwise.

Once the logger has been deployed, it must then be retrieved in order to collect the data. Hence, the penguin has to be captured not only once, but twice. For that reason breeding birds are a perfect target: you know where to find them (at the nest) and you know where they will return after foraging (to their nest)….in theory. However, if the bird fails to return or the logger falls off before the bird returns, all data are lost along with the logger.

Deploying a GPS logger.

This year Dr Antje Steinfurth is training MSc student Jennifer Grigg and Birdlife intern Mmatjie Mashaoto carry out logger deployments throughout the breeding season. To see how the loggers are deployed on each penguin, see the methods section of the site.

Programming one of the GPS loggers prior to deployment.

The first day of deployments got off to a sticky start, with the bakkie used for travelling between deployment nests getting stuck in the sand and Antje being attacked by a vicious branch, but ended with the first logger of the season being successfully deployed! During the ten days in April that Antje was training on the island 11 GPS loggers were deployed and retrieved successfully.

Some examples of African penguin foraging tracks, shown plotted in Google Earth.

To be continued……

2015 Field Season Starting

African Penguin brooding a small downy chick.

The EarthWatch African Penguin Project is already up and running, penguins are breeding on Robben Island and the foraging research for this year is about to begin. This year, MSc student Jenny Grigg is being trained by Dr. Antje Steinfurth to conduct this field work with GPS-TDlog logger devices at Robben Island.

The Robben Island lighthouse visible over the tops of the trees.

The analysis and write up of the foraging research conducted in 2011 to 2013 continues, in the middle of writing the last chapter draft at the moment. Looking forward to sharing our findings with you soon.

Note the 2nd World Seabird Conference will be taking place this upcoming 26-30 October in Cape Town! 

African Penguin brooding chicks.

Spot the two African Penguins in this photo of the north end of the colony.

Penguin tracking data gets a numbers crunch

Nature News - African penguins put researchers in a flap! This week a workshop in Cape Town funded by BirdLife South Africa took place in which seabird researchers, statisticians, ecologists, and modellers got together to discuss purse-seine fishing closures around African Penguin colonies. 

We took a dive into the ongoing debate and re-examined the evidence and what is known of this endangered species' life history and behaviour. Statistical models were run using African Penguin tracking data (including the data we have been collecting on Robben) and other indicators of reproductive success, colony health and population dynamics. New ideas were discussed, arguments explored, statistical issues were addressed, code ran, minds and processors whirred. Results are now being written into a report document and our recommendations will be presented at an international panel in early December.

2014 foraging data collection begins!

African Penguins entering the sea at the Stone Quarry.

Dr. Antje Steinfurth is on Robben Island looking for suitable nests where adult African Penguins are provisioning for small chicks for GPS Temperature Depth logger deployments.  Soon foraging penguin data collection at Robben Island will get underway. The current EarthWatch team, being led by Dr. Richard Sherley, is lending a hand with the start of data collection this year. The team has been working hard at nest monitoring over the last week and has identified some potential candidate adult penguins that  may be suitable to be equipped with a GPS device for one foraging trip.  The EarthWatch team is the 3rd one working on the African Penguin Project so far this year. The previous teams laid important ground work for this year's research. All the teams are monitoring penguin nesting success and chick condition in areas of the penguin colony, counting moulting birds, conducting rabbit and game censuses. Teams record the details of any banded or transpodered penguins as this is valuable information for survival analyses as well as immigration and emmigration rates to and from the colony. Thanks to all the team members and volunteers that assist with this research.
Good luck to Antje and the EarthWatch team with the field work. Swim well penguins!

Can you spot the small penguin chick this adult is brooding? Photo courtesy of Brian Hall.