Climate change 'makes birds shrink' in North America

March 12, 2010

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.

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.

[atsimg]http://files.abovetopsecret.com/images/member/79cf81ce31e6.jpg[/atsimg]
Scarlet tanagers are more than 2% smaller today than in the 1960s

news.bbc.co.uk...

More species discussed at the link, good to hear that these beautiful birds are not in danger and size shrinkage doesn't seem to do any damage to them.

reply to post by Aquarius1

with the birds thought to be evolving into a smaller size in response to warmer temperatures.

Ah, more evidence of evolution at work, or better defined as regional adaptations due to climate change & changes in our environment. Interesting, but maybe not so good for the birds if there's unforeseen health risks.

Originally posted by Aquarius1

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.

Dinosaurs contradict this, but they are cold blooded. Thought I would say this before anybody starts screaming about the dinosaurs, and how this is a bunch of hogwash. I know they will use Dinos as an example... but they are cold blooded, so they are left out of this.

But the simple fact is that we have had a much colder and longer winters over the last few years, and RECORD LOWS all over the Northern Hemisphere over this winter, so how can they make the claim that birds are getting smaller because of global warming?

What a lot of hogsawash!

if animals are shrinking then whats happening to humans?

reply to post by togetherwestand


Humans don't reproduce as often as songbirds, so the changes to us will take a lot longer to appear, and might not appear at all.

reply to post by dampnickers


Shrinkage happens over a long period of time, nothing to do with the past few years..same with any species.

so your saying that there is indeed some underlying change happening, just not as detectable in comparison to birds on a evolutionarily scale..

reply to post by togetherwestand


Well, I don't actually know that. But if there is a change which is going to occur, it will be slow.

US citizens don't starve to death in winter because they are to small and lose to much heat to the environment. Also body fat is today no longer a benefit against cold temperatures. We have clothes and houses. Climate-adaption is no longer a selective trait for the human species.

Also it is not sure if dinosaurs were warm- or cold-blooded. Small theropod species (like the Velociraptor were likely warm-blooded, large sauropoda like Brontosaurus were likely cold-blooded)
dinosaurs.about.com...

I believe the shrinkage may be a result of our modern agriculture and also a result of pollution. Pesticides are designed to kill pests and many plants on our fields. Less insects and seeds are available for the birds. This is an selection advantage for smaller birds which need less food to survive and successfully reproduce. Chemicals have also a negative impact on animal populations which don't live in the agricultural landscape.

reply to post by Drunkenshrew

I believe the shrinkage may be a result of our modern agriculture and also a result of pollution. Pesticides are designed to kill pests and many plants on our fields. Less insects and seeds are available for the birds. This is an selection advantage for smaller birds which need less food to survive and successfully reproduce. Chemicals have also a negative impact on animal populations which don't live in the agricultural landscape

I think you have it right, that same negative impact is effecting humans also, if this were evolution it would be a very slow process over a long time.

there are billions of new unknown chemicals introduced every year and polluted. I dont think it is a slow change, until in starts effecting human genetics (probably already does) things will get crazy, like humans shrinking, growing multiple body parts, deformitys, etc.

also humans are more adaptable to the climate then to chemicals.

Originally posted by togetherwestand
there are billions of new unknown chemicals introduced every year and polluted. I dont think it is a slow change, until in starts effecting human genetics (probably already does) things will get crazy, like humans shrinking, growing multiple body parts, deformitys, etc.

also humans are more adaptable to the climate then to chemicals.

You are right, it already has. Pollution has already affected our sperm count. This is also true for many animal species.

The study, by Brunel University, the Universities of Exeter and Reading and the Centre for Ecology & Hydrology, shows for the first time how a group of testosterone-blocking chemicals is finding its way into UK rivers, affecting wildlife and potentially humans. The research was supported by the Natural Environment Research Council and is now published in the journal Environmental Health Perspectives.

www.innovations-report.de...

Here something about the drop in sperm count:

There have been a number of studies over the past 15-20 years (1, 2, 3, 4, 5, 6 and 10), which suggest that sperm counts in man are on the decline. Since these changes are recent and appear to have occurred internationally, it has been presumed that they reflect adverse effects of environmental or lifestyle factors on the male rather than, for example, genetic changes in susceptibility. If the decrease in sperm counts were to continue at the rate that it is then in a few years we will witness widespread male infertility. To date it remains unknown why this is happening and the available preventative measures, which can be taken to avoid a continuation of this trend, are not common knowledge.

www.ispub.com.../iju/vol2n1/sperm.xml