A semi-annual publication of manomet

Climate Change is Driving Birds North
By: Ashley Daniels

Walking through the trails at the Manomet Center headquarters Campus, a bird bander spots a flapping, angry, red blur tangled in a Mist net.

Climate Change is Driving Birds NorthThe bander knows that the blur is sure to be a Northern Cardinal and she looks on the ground for a small twig, an old banding trick to appease the bird's instinctive reflex to bite down and hold tight. She gives the bird the twig and starts to carefully extract it from the net. inevitably, the cardinal drops the twig at the moment the bander is most preoccupied with removing the bird. The cardinal clamps down on her finger with what feels like a pitbull's jaws.

The banders at Manomet today bear the brunt of cardinal retaliation much more than banders in the 1970s, 80s and 90s. In an unmistakable and striking natural phenomenon, the numbers of Northern Cardinal captures at Manomet has significantly increased over time.

A 2004 Wilson Bulletin article by ornithologistsTrevor Lloyd-Evans, who has directed Manomet's banding program since 1972, and Jonathan Atwood, found that Northern Cardinal numbers from 1970-2001 showed some of the greatest increases of any species banded at Manomet. The species saw 168 percent spring and 135 percent fall increases from early to recent seasons over the 32 years. According to Lloyd-Evans, "numbers of cardinals banded in both seasons are still increasing as this southern and rather non-migratory, resident species takes advantage of climate change."

They're not the only species that has seen dramatic increases in numbers since the early years of the program. The Red-bellied Woodpecker, Tufted Titmouse, and Carolina Wren have also significantly increased in capture numbers. According to researchers, Manomet is seeing more of these southern species because the birds are shifting their ranges in response to climate change.

Banding

Clockwise from the left: A Tufted Titmouse captured at the Manomet Center banding station.
A Red-bellied Woodpecker captured at the Manomet Center banding station.
Turkey Vulture photographed by former Manomet bander Laura Koloski.

Last year was the hottest on record in the contiguous United States. A report released by NOAA's National Climatic Data Center in January 2013 announced that the average U.S. temperature for 2012 was 55.3 degrees Fahrenheit, the highest average since records started in 1895.

The record temperatures are weather, not climate, but they fit with the overall warming trend. A 2007 report by the Intergovernmental Panel on Climate Change (IPCC) determined that "warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures."

In fact, according to a 2008 NASA report, the 10 warmest years in documented history took place between 1997 and 2008.

The response of birds to climate change across species and habitats has been unmistakable. Bird enthusiasts and scientists alike have reported easily observable northward shifts in range.

Manomet researchers can draw significant conclusions from the increased captures, especially when compared to complementary data from various sources across the state. Mass Audubon's Breeding Bird Atlas, the North American Breeding Bird Survey and annual Christmas Bird Counts all show similar changes.

Mass Audubon's 2011 State of the Birds Report confirms the expansion of various southern species including southern forest dwelling birds, including Red-bellieding the Red-bellied Woodpecker, Tufted Titmouse, Northern Cardinal, Carolina Wren and Northern Mockingbird northward across the state with the warming climate and increased urbanization. In fact, urban dwelling southern species are experiencing the highest gain in abundance amongst all habitat groups, with a 10 percent annual gain according to the Breeding Bird Survey. A comparison of Mass Audubon's Breeding Bird Atlases from 1979 and 2011 supports this data, showing a 400 percent gain in distribution for southern urban nesting species across the state since 1979.

An analysis of Christmas Bird Count data finds that southern species have not only increased in distribution and abundance, but have also increased in winter population size since 1980. Turkey Vultures have increased by 26 percent, Carolina Wrens by 15 percent, and Red-bellied Woodpeckers by 21 percent. Red-bellied Woodpeckers have colonized more than half of the state of Massachusetts since 1979, increasing in northward distribution and abundance according to the Atlas and Breeding Bird Survey respectively.

A comparison of the 1979 Atlas and the 2011 Atlas shows a 560 percent increase in 10 species of southern forest dwelling birds, including Red-bellied Woodpeckers.

Banding

The number of northern cardinals captured in Manomet's fall banding season has steadily increased since 1970 and
peaked in 2012. cardinals, like other species, are extending their range northwards in response to climate change.
the data are corrected for the number of nets and number of hours they are open. the annual number of northern
cardinals captured is displayed as a proportion of seasonal catch in relation to highest year.

In its 2011 report, Mass Audubon concluded that "the impacts of warming are particularly evident for birds that formerly occurred only south of Massachusetts or were at the northern edge of their range in the commonwealth."

"If you look at Manomet's capture data, along with data from Mass Audubon's Breeding Bird Atlases, the Breeding Bird Surveys, and the Christmas Bird Counts, you see strong evidence of a significant shift in northern distribution and increased abundance of southern species in the state," said Lloyd Evans.

Massachusetts is not an isolated example, but serves as a microcosm for trends in range shift north throughout the country and across the world. An analysis of the Audubon Christmas Bird Count over a period of four decades found 177 of 305 studied species (58 percent) to have significantly moved northward by an average of 35 miles. From the analysis, Audubon also determined "that species' populations grew the most in the states experiencing the greatest warming."

A 2007 article published in Conservation Biology by research biologists Alan Hitch and Paul Leberg examined the distribution of 56 species of birds, and found an average shift of 2.35 km (1.46 mi)/year of the northern limit of birds with a southern distribution. Similar results were found for species in Great Britain from a study published in Nature by Drs. Chris Thomas and Jack Lennon. They estimated that during a time of warming climate "the northern margins of southerly species moved north by an average of 18.9 km in 20 years," while "southern margins of northerly species did not shift consistently."

While numerous species have successfully responded to warming temperatures through range expansion and growth, others meet with obstacles to expanding north and as a result face a bleaker future in a changing environment. Specialist species are limited in their ability to adapt to differing habitats, food sources and nest sites and face greater consequences to survival.

Banding

Clockwise from bottom left: A male Northern Cardinal captured at the Manomet Center banding station.
A Carolina Wren captured at the Manomet Center banding station.
A female Northern Cardinal bites down on a bander's finger.

The natural world is faced with two options when confronted with change, adaptation or extinction, and while many species will not have the resources torecover from the effects of a changing climate, others will successfully adjust, and some will even thrive. The 2007 IPCC report has predicted that the average rate of warming over the next century will be twice that experienced during the 20th century, and that ultimately by the end of the 21st century, the surface temperature of the Earth will have increased to their best estimate by 3.2 to 7.2ºF. In the face of changing global temperatures, bird species have already begun to adapt. Scientists do not know, however, if they will they be able to keep pace with rapidly increasing temperatures.

"There are so few long-term datasets that it is difficult to make a prediction to stand behind," Hitch said. "Most species can adapt to change in temperature on a distributional level, but the big issue and where you'll see declines is the lack of habitat north. We need to be more focused on identifying critical factors that might make or break suitable habitat when shifts north do happen."

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