Over the past two decades, the resident communities of birds that attend eastern North America's backyard bird feeders in winter have quietly been remade, most likely as a result of a warming climate.
Writing this week in the journal Global Change Biology, University of Wisconsin-Madison wildlife biologists Benjamin Zuckerberg and Karine Princé document that once rare wintering bird species are now commonplace in the American Northeast.
Using more than two decades of data on 38 species of birds gathered by thousands of "citizen scientists" through the Cornell University Laboratory of Ornithology's Project FeederWatch, the Wisconsin researchers show that birds typically found in more southerly regions are gradually pushing north, restructuring the communities of birds that spend their winters in northern latitudes.
To the causal observer of backyard birds, the list of species becoming more common includes the readily familiar: cardinals, chipping sparrows and Carolina wrens. These birds and other warm-adapted species, according to Princé and Zuckerberg, have greatly expanded their wintering range in a warmer world, a change that may have untold consequences for North American ecosystems.
"Fifty years ago, cardinals were rare in the northeastern United States. Carolina wrens even more so," explains Zuckerberg, a UW-Madison assistant professor of forest and wildlife ecology.
An estimated 53 million Americans maintain feeding stations near their homes, according to the U.S. Fish and Wildlife Service, suggesting that increases in some species may be attributable to more readily available sources of food. However, that figure has remained constant, reflecting only a slight decline since 1991, indicating that environmental factors beyond the availability of food sources are at play.
The Wisconsin researchers measured the changes over time in the abundance of 38 bird species at feeders in eastern North America, specifically looking at the influence of changes in winter minimum temperature over a 22-year period on the flocks of birds that gather at backyard feeding stations.
"We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America," Princé and Zuckerberg write in their Global Change Biology report.
"People will likely start seeing new species in their backyards," says Princé, a UW-Madison postdoctoral fellow. "There can also be subtle changes in species abundance."
The changes in the mix of overwintering bird species is occurring against a backdrop of milder winters with less snow, more variable and intense precipitation events, and a shorter snow season, overall. Climate models predict even warmer temperatures occurring over the next 100 years, with seasonal climate effects being the most pronounced in northern regions of the world.
"We've been able to document in past studies that species are shifting in response to climate change," Zuckerberg says. "This study documents changes in the (winter bird) community structure. If you have a species coming into a new area, it can modify the composition of the community."
In any ecosystem, Zuckerberg notes, removing or introducing even a single species can have a cascade of ecological consequences, many of them unknown.
"These backyard birds are the canaries in the coal mine," Zuckerberg says. "Birds have always been very good indicators of environmental change. Whenever you have a reshuffling of a community of species, you have less of a sense of what change is going to be."
Princé notes that other environmental changes, such as the pervasive human impact on landscape, for example, may also be exerting an influence on the observed changes in the composition of birds attending winter feeding stations in eastern North America.
"Climate change should not be viewed as the sole driver of changes in winter bird communities, but this signal is a pretty strong one for climate change," she explains. "The changes we document are so broad in scope that anything that is occurring at a local level is swamped out by the scale of this analysis."
Terry Devitt, 608-262-8282, firstname.lastname@example.org
CONTACT: Benjamin Zuckerberg, 608-263-0853, email@example.com
Benjamin Zuckerberg | Eurek Alert!
Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung
Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences