Ralf Mullers PhD Student PhD Research Project

Qualifications

MSc in ecology at the University of Groningen, The Netherlands

Research interests

The most important study material for a goose researcher: droppings!

At the University of Groningen students have the opportunity to do several different projects during the last two years of their education. Ralf apparently likes to do work outside under harsh conditions, because for his first two projects he decided to work on the Dutch Wadden islands in the middle of winter.

The first project was on the island of Schiermonnikoog where he studied, together with his friend and fieldwork mate Jeroen Minderman, the competition and facilitation between herbivores on the salt marsh. The studied herbivores were the Brown Hare and the Barnacle Goose and the fieldwork mainly involved counting droppings, collecting droppings, weighing droppings, drying droppings and weigh them again… A lot of poo went trough their hands. Despite the fact that they were studying animals, a lot of the work was done on the grasses the herbivores were consuming, like measuring tiller length and vegetation density en height. They spend hours on their knees in the cold and wet vegetation and still enjoyed themselves. The problem with doing a "winter-project" is that when finally the weather gets nice and the sun comes out, you have to go to university and start analysing the data. So when everybody else started their fieldwork on breeding birds, Ralf and Jeroen had to sit inside behind a computer.

Sitting on the dike of De Cocksdorp (Texel), having little shelter from the car and making behavioural observations of the Oystercatchers.

However, not becoming much wiser during the summer, they decided to do another project during the winter. For decades the oystercatchers at Schiermonnikoog have been studied by the animal ecology group of the University of Groningen. Many PhD-students and Master-students did a project on these birds and during the winter of 2002/2003 Ralf and Jeroen also found a project on oystercatchers. Ralf was interested in the relation between body condition and intake rates, to find out whether intake rates are suitable to use as a 'currency of fitness'. During that winter they captured oystercatchers at 7 different sites in the Dutch Wadden Sea, measured their body condition, gave them individually encoded colour rings, and measured the intake rates while the oystercatchers were foraging at the mudflats. The observations were done in a very cold winter, resulting in the feeling that they would never warm up again, ever. But they survived and got warm again in the end.

Capturing a gannet chick for growth measurements

For his last research he again decided to do his fieldwork in winter. But he had a moment of clear thinking and was able to arrange a project on the Southern Hemisphere. And that is how he got involved with the ADU. Henk Visser was looking for a student to help René Navarro with his fieldwork on the Cape Gannets and Ralf "forced" himself into the project. The promising vision of doing fieldwork in South Africa, in the sun, with these beautiful seabirds was too tempting to let it pass. And it was well worth it. They deployed the Gannets with GPS-loggers to find out where they went foraging and they measured the growth of their chicks to see if there was any relation between the two. Together with the Doubly Labeled Water (DLW) technique, to measure energy expenditure, they hoped to get an insight in the breeding behaviour of the Cape Gannets.

During the fieldwork in South Africa, Henk Visser received a budget for a 4-years study on the Gannets and Ralf was offered the PhD-position involved in that project. His PhD-research involves a comparison between the Namibian colonies and the South African colonies of Cape Gannets. Over the last couple of decades, the Gannet colonies in Namibia decreased dramatically in numbers, whereas the colonies in South Africa increased or remained reasonably stable during the same period. By deploying the adult Gannets with GPS-loggers, measuring the growth of the chicks and measure energy expenditure with DLW, he hopes to find out what the exact relations are between these parameters and how they affect the breeding success at both sites.

Other interests

He is probably one of the few people of the ADU that is not a birder from origin, actually, he is still not a birder. He is able to distinguish a Gull from an Ostrich, but a Cape or a Crowned Cormorant already sort of look the same to him…

His main interests are music (listening to it and visiting festivals), spending time with his friends and write and read.

Publications

• Mullers, R.H.E. & R.A. Navarro (2003) How do Cape Gannets satisfy their young? Bird Numbers 12(2): 35-37

Conferences:

• Mullers, R.H.E. The relation between body condition and intake rate in oystercatchers (Haematopus ostralegus).
     Oral presentation at the 2003 International Wader Study Group Conference, 25-28 September 2003 in Cádiz, Spain
• Mullers R.H.E., Navarro R.A., Underhill L.G. & Visser G.H. How important is the timing of breeding in Cape Gannets?
     Poster presentation at the 8th International Seabird Group Conference, 2-4 April 2004 in Aberdeen, Scotland.
     Oral presentation at the Second European Conference on Behavioural Biology (ECBB), 28-31 August 2004, Groningen, The Netherlands.