Investigating Arctic warming-induced body shrinkage of long-distance migrants
Climate change is affecting life on Earth in various ways. Although recently discovered, body shrinkage is already considered a universal response to global warming. These body size reductions are likely to affect many ecological interactions, potentially affecting the fitness of the individuals involved in a variety of ways. As the Arctic is the most rapidly warming region on our globe, it is here where animal bodies are expected to be shrinking most dramatically.
Yet, species reproducing in the Arctic are often long-distance migrants spending the nonbreeding season at lower latitudes. The consequences of body shrinkages induced by rapid Arctic warming may thus become apparent at lower latitudes, thousands of kilometers away from where climate change was experienced and in regions where climate change may otherwise be much less noticeable. Indeed, a recent study on an avian migrant, the red knot, showed that the smallest individuals were born in the warmest Arctic summers (Science, 2016). Furthermore, it were these smallest birds that experienced the lowest survival chances, contributing to a population decline. However, both insights were gained during winter at their tropical wintering grounds in West Africa. The causes of body shrinkage, taking place in the Arctic during neonatal development, are completely not touched upon. As body shrinkage often precedes a population collapse, there is an urgent need to understand body shrinkage, insights which may be used when designing conservation programs.
This project will be the next step after the just described observational study. Here we aim to experimentally investigate the causes of body shrinkage in red knot chicks at their High-Arctic breeding grounds. In a nutshell, we will manipulate hatch dates and measure chick growth rate. At the same time, we will measure and manipulate the food supply (arthropod) in order to test the hypothesis that chick growth in a warmer Arctic is hampered due to a so-called ‘trophic mismatch’, i.e. chicks growing up after the peak food supply has already occurred. The project takes place on one of the most remote places on Earth, the most northern tip of Taimyr Peninsula in Russia (76° N, 98° E).
Photo's: Jan van Gils, Bethany Hoye and Benjamin Clock