Behavioural ecologist Allert Bijleveld studies how animals adapt to the changing and dynamic tidal environment of the Wadden Sea. He is particularly interested in animal movement and spatial distributions. ‘Where do birds and fish go, and where do they find their food? How do birds adapt to sea level rise and land subsidence due to gas or salt extraction when intertidal mudflats become inaccesible for finding food? How long do fish stay in the Wadden Sea while migrating from lake IJssel to the English Channel? What are hotspots for biodiversity of worms, shellfish and shrimp living in and on the intertidal mudflats? The answers to questions like these will tell us what areas are crucial and what animals will get into trouble due to human activities, such as mining, fishing, and climate change.’
‘One of my study species are Red Knots. These are shorebirds that breed in the Arctic and winter in Europe and Africa. Because we have studied them for so long, they have now become an ideal model system that can also help us understand other animals, even fish. The interaction between an animal and its environment is, by definition, complex, and so it is good to work with a species that we already know a lot about. Red Knots feed on shellfish, such as small cockles and Balthic tellins, that they swallow whole and crush in their muscular gizzard. If there is one thing that we have learned in these years, it is the intricate relationship between Red Knots and their food. When less food is available, for instance due to shell fisheries or land subsidence, shorebirds will disappear. In the past decades, we have seen that the numbers of Red Knots in this part of the world - the so-called flyway population – have not changed. Red Knots that had settled in the Dutch Wadden Sea could so-far – thankfully – find an alternative elsewhere.'
To know how animals adapt to a changing world, you also need to know how they would normally behave in a steady environment. And this is almost a contradiction: the Wadden Sea is dynamic and per definition not steady. Moreover, we have learned that, even within species, there are huge differences between individuals. Some individuals are very cautious, and other fly huge distances per tide in search of food.
‘My research is mainly driven by an intrinsic fascination for the dynamic Wadden Sea. I am convinced that if one persists with that fundamental, curiosity-driven research for long enough, then practical applications will always emerge. For example, already Red Knots teach us about how nature responds to the changes that we cause in their world.’
More information about the work of Allert Bijleveld can be found here.Read more +
I am a behavioural ecologist focussed on studying consistent individual differences (animal personality), social behaviour, and trophic interactions in coastal ecosystems. Particularly, I am interested in studying how different phenotypes interact with the environment to shape movement, spatial distributions and fitness. In my studies, I combine experiments, modelling, field observations, and the latest tracking technologies. I have mainly studied marine macrozoobenthos and birds, but I will expand my research to include fish.
If you are interested in a project or a collaboration with me, please feel free to send me an e-mail or contact me on Twitter @AllertBijleveld.
2017 - present: Tenure-track scientist at NIOZ
2016 - 2017: Visiting academic at the University of Oxford
2015 - 2017: Post-doctoral researcher at NIOZ
2007-2009: Project-researcher at NIOZ
2003-2007: Teaching assistent at the University of Amsterdam
2009-2015: PhD - Untying the knot: Mechanistically understanding the interactions between social foragers and their prey. NIOZ / University of Groningen (cum laude)
2007: MSc Ecology & Evolution, University of Amsterdam with a specialization in Animal Ecology (cum laude)
2006: BSc General Biology, University of Amsterdam
2015: Wadden Academy Prize for best PhD thesis in the academic years 2013/14 and 2014/15 (5 k€)
Do Red Knots use each other to find their hidden food?
The video below shows an experiment that we designed to answer this question. In the Experimental Shorebird Facility we constructed two patches and burried food in only one. We then released two Red Knots on each patch. We also released a focal bird in a central cage that was located in between the two patches. This bird was then allowed to watch the two groups of foraging birds on both sides. After 2 minutes the central cage was opened and the focal bird was allowed to exit to either side. The results show that in 75% of the trials Red Knots chose that side of the experimental arena where the food was buried. This show that Red Knots can use social information to be more efficient in finding their hidden food. You can find the scientific publication here.
Red knot foraging experiment
Here is a movie that shows the experimental setup for a foraging experiment on Red Knots (Calidris canutus islandica). The experiment was designed to study patch departure decisions for red knots foraging in a patchy food environment. Foragers should not stay in a patch too long and waste time searching for that last prey item while other food patches have more to offer. On the other hand, foragers should not depart a patch too soon and leave many prey items behind. Depending on the density and distribution of food, one can calculate the optimal departure decision that foragers should use that maximises intake rate. We want to find out how and if red knots make optimal foraging decisions.
The movie below shows two golden plovers that we tracked with our novel 'time-of-arrival' methodology. This movie is part of our publication in LIMOSA.