Climate change ‘makes birds shrink’ in North America

“In biology, there is a general rule of thumb that animals tend to become smaller in warmer climates: an idea known as Bergman’s Rule.”


Using the logic of  Eco-Nazis – Dinosaurs lived and thrived during the great ice age. If you plan on going to India or Africa to view elephants be sure to take your parka. It must be cold in those countries because elephants are quite large. If it was warm in those countries, then obviously, elephants would be quite small – according to the Eco-Nazis

Thinking about  going to go to University to study science, you may want to reconsider.

Become a science fiction writer instead.

Science has completely lost its credibility.

Songbirds in the US are getting smaller, and climate change is suspected as the cause.

A study of almost half a million birds, belonging to over 100 species, shows that many are gradually becoming lighter and growing shorter wings.

This shrinkage has occurred within just half a century, with the birds thought to be evolving into a smaller size in response to warmer temperatures.

However, there is little evidence that the change is harmful to the birds.

Details of the discovery are published in the journal Oikos.

Many of these species are apparently doing just fine, but the individual birds are becoming gradually smaller nonetheless
Dr Josh van Buskirk
University of Zurich

In biology, there is a general rule of thumb that animals tend to become smaller in warmer climates: an idea known as Bergman’s Rule.

Usually this trend can be seen among animal species that live over a range of latitude or altitude, with individuals living at more northern latitudes or higher up cooler mountains being slightly larger than those below, for example.

Quite why this happens is not clear, but it prompted one group of scientists to ask the question: would animals respond in the same way to climate change?

To find out, Dr Josh Van Buskirk of the University of Zurich, Switzerland and colleagues Mr Robert Mulvihill and Mr Robert Leberman of the Carnegie Museum of Natural History in Rector, Pennsylvania, US decided to evaluate the sizes of hundreds of thousands of birds that pass through the Carnegie Museum’s Powdermill ringing station, also in Pennsylvania.

A black-capped chickadee has its wing chord measured

A black-capped chickadee has its wing chord measured

They examined the records of 486,000 individual birds that had been caught and measured at the ringing station from 1961 to 2007.

These birds belonged to 102 species, arriving over different seasons. Each was weighed. It also had the length of its wings measured, recorded as wing cord length, or the distance between the bird’s wrist to the tip of the longest primary feather.

Their sample included local resident bird species, overwintering species, and even long distance migrants arriving from the Neotropics.

Their explanation can be found here


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