Scientists point to a lack of their favorite prey resource due to climate change
Red knots, a bird species that makes an impressive migratory journey, are getting smaller in size, and researchers blame a lack of food. Red knots (Calidris canutus) travel 10 thousand kilometers every year from their breeding grounds in Arctic Russia to their wintering grounds in West Africa. In recent years, scientists have documented the birds shrinking. In a study published in Global Change Biology, researchers compared the birds and their insect food source in the 1990s with 2018 and 2019. Their findings showed that the chicks in the later years grew at a slower pace. In addition, they found that chicks fed primarily on crane flies that emerge after snow melts. But a recent warmer climate caused earlier snowmelt and earlier crane fly presence. As a result, red knot chicks missed out on their prey, and their growth slowed. “Earlier snowmelt, an earlier emergence of crane flies and fewer crane flies when the chicks need them thus cause young red knots to grow slower,” said lead author Tim Oortwijn from the Royal Netherlands Institute for Sea Research. “This effect remains visible throughout their life, resulting in smaller red knots every generation.”
