Honey, I Shrunk the Red Knots

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Red Knots (Calidris canutus) is the common name for a suite of shorebirds that are known for their brownish-red plumage during breeding season and their globe-trotting ways. These birds breed near the Arctic and winter in warmer climates such as Argentina or West Africa (depending on the subspecies). In the May 13th issue of Science magazine researchers reported on the the possible impacts of climate change on Calidris canutus canutus, the Red Knot subspecies that winters in West Africa.

As snow melts earlier and earlier in the Arctic due to rising temperatures, insect populations also follow this changing time table and peak earlier than they did in the past. Unfortunately, the Red Knot breeding season does not follow that course and peak hatching of Red Knot chicks no longer overlaps with peak insect abundance. Reduced food supplies for young Red Knots leads to juveniles that are smaller in size.

Regardless of their condition these birds continue to migrate to warmer destinations as Red Knots have done for years and years. However, trouble follows these smaller birds as their shorter beaks (remember everything gets smaller) make it difficult to dig out the bivalves (clams) that are their main food source. Instead, they consume sea grasses which are not a proper alternative. Many of these malnourished juveniles never survive the winter and therefore do not have an opportunity to breed. And a vicious cycle continues that could lead to the extinction of Calidris canutus canutus.

About This Illustration: Watercolor and micron pens. I was thinking about Russian stacking dolls when I did this illustration. Appropriate, considering this particular subspecies breeds in Russia.

For More Information: 

Climate Change and the Case of the Shrinking Red Knots By Carl Zimmer NYT

Climate Change is Shrinking Earth’s Far-Flying Birds By Ed Yong The Atlantic

 

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