[Tweeters] Birds are shrinking

Randy Robinson rwr.personal at gmail.com
Wed Dec 4 15:37:08 PST 2019

There is an interesting article in the Washington Post about a recently
published paper documenting a 40 year trend in the morphology of birds
found dead in Chicago. One ornithologist has collected 70,716 dead birds
since 1978 and measured them. He found that over that time, on average,
birds weigh less, have shorter legs and longer wings. The article is here:

I have a subscription but I think you can get access to a few free articles
without paying. The paper was published in Ecology Letters and a logon is
required to view the paper at that website.

Re: the weight, the speculation is that smaller birds have a larger surface
to volume ratio, are better able to cool themselves in hot weather and
therefore have a better survival rate. Also studies on zebra finches and
house sparrows show that young birds raised in hotter conditions tend not
to grow as large.

Especially interesting to me is that such a simple idea, to measure dead
birds, can provide evidence of climate change after 40 years.

Randy Robinson
Seattle, WA
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