Affected Species: The Bicknell's Thrush

Gahbauer 2005

While many species of birds have relatively wide breeding ranges, the Bicknell's thrush, a longtime resident of the Vermont and New England mountain top conifer forests, "has one of the most restricted breeding ranged of any North American bird." (Reynolds & Wolff 2011) Although the Bicknell's thrush is a migratory bird, it relies on these mountain top forests as its breeding ground. The Bicknell's thrush survives on a diet that consists mainly of insects. Their biggest threat comes from the red squirrel, a species that typically consumes spruce and fir cones, but is known to raid the nests of the Bicknell's thrush to prey on both eggs and young birds. The gradual Northeastern climate change that has been occurring has had a negative impact on the Bicknell's thrush in more ways than one. Not only is the structure of the forest they rely on slowly changing, but their food supply as well. In addition, there is the looming threat of increased red squirrel populations in years to come as weather patterns shift. (Dettmers)

Bicknell's Thrush Breeding Range - Cornell

How as climate change affected the Bicknell's thrush so far?

• Warming conditions have allowed for deciduous tree species to grow higher and higher up on the mountains that were previously covered only in evergreen tree species.

• Increased numbers of deciduous trees in these forests have lead to the thinning and shrinking of the conifer forests that are crucial breeding grounds for the Bicknell's thrush.

• Increased numbers of deciduous trees in the Bicknell's thrush breeding range promote the arrival of more species of birds, leading to increased food competition.

• Changes in weather patterns have affected the arrival of the insect species that the Bicknell's thrush relies on for food, which arrive in response to climate, while the Bicknell's thrush arrives in response to day length.

• Warmer climates have lead to the potential for increased, more robust cone crops from the spruce and fir trees that remain in the conifer forests, which, in turn, lead to the potential for increased red squirrel populations and a higher threat to the Bicknell's thrush.

(Dettmers)

Pfieffer

While forest management can play a minor role in controlling what tree species inhabit the Vermont and New England mountain tops, it is difficult to control a rapidly changing environment. Currently, the Bicknell's thrush is being studied and monitored by a number of organizations including the U.S. Fish and Wildlife Service to study and determine the bird's ability to adapt to predicted ecological changes. The Bicknell's thrush is just one of the innocent victims of the ongoing threat of climate change.