If you have measured more than 486,203 birds over a period of several
decades, then you might be in a position to throw stones, Ian.
Declining body sizes in North American birds associated with climate
change
Josh Van Buskirk 1 , Robert S. Mulvihill 2 and Robert C. Leberman 2
1 Inst. of Zoology, Univ. of Zürich, CH-8057 Zürich, Switzerland, and:
Dept of Zoology, Univ. of Melbourne, 3010 Victoria, Australia 2
Powdermill Avian Research Center, Carnegie Museum of Natural History,
Rector, PA 15677-9605, USA
Oikos Early View Published Online: 2 Mar 2010 DIGITAL OBJECT
IDENTIFIER (DOI) 10.1111/j.1600-0706.2009.18349.x
Recent climate change has caused comparatively rapid shifts in the
phenology and geographic distributions of many plants and animals.
However, there is debate over the degree to which populations can meet
the challenges of climate change with evolutionary or phenotypic
responses in life history and morphology. We report that migrating
birds captured at a banding station in western Pennsylvania, USA, have
exhibited steadily decreasing fat-free mass and wing chord since 1961,
consistent with a response to a warmer climate. This confirms that
phenotypic responses to climate change are currently underway in
entire avian assemblages. Declines in body size were not explained by
an index of habitat condition within the breeding or wintering
distributions. Instead, size was negatively correlated with
temperature in the previous year, and long-term trends were associated
with the direction of natural selection acting on size over the
winter: species undergoing the strongest selection favoring small wing
chord showed the most rapid long-term declines in wing. Phenotypic
changes are therefore in line with the prevailing selection regime.
Paper manuscript accepted 12 November 2009
On 13/03/2010, at 6:28 PM, Ian May wrote:
C'mon Laurie! It's not April 1 yet. Didn't we read last year
that birds forced up the mountains by higher temperatures are
becoming smaller too. If this keeps going, crows will be smaller
than blow flies.
Are these climate change findings an example of robust peer reviewed
science or just quotes from grey literature?
Regards
Ian
Laurie Knight wrote:
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8560000/8560694.stm
Climate linked to smaller birds
By Matt Walker
Editor, Earth News
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.
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