By Howard Meyerson
While global climate change reports often focus on iconic creatures like polar bears and penguins, species that would be in jeopardy if the polar ice cap melts, Michigan and Great Lakes scientists are looking to understand what else might get in trouble. Will Michigan moose thrive 40 years from now when average temperatures are expected to be five degrees warmer? What about the Boreal Chickadee, Tufted Titmouse, and Common Loon?
David Yarnold, National Audubon president and CEO, declared in an Audubon Magazine column last October that “climate change is the greatest threat to birds and biodiversity since humans have been on the planet.” He followed that by writing, “Scientists say we stand to lose one-quarter to one-third of all species on earth. And birds will be hit hard.”
That sweeping statement may raise doubt for some and give others reason for pause, but wildlife researchers say the evidence bears it out. “He is probably accurate with the caveat that there is still a lot of uncertainty,” says Chris Hoving, the Michigan Department of Natural Resources adaptation specialist, formerly the agency endangered species coordinator. “That one-third to one-quarter figure comes from a paper in the Journal of Science. It’s [based on] a simple model that looked at how much [home] ranges would change and how much biodiversity we would lose (due to climate shifts), but it is as good as we know. It could be more or it could be less.”
Data from citizen science projects like Audubon Christmas Bird Counts and Cornell Laboratory of Ornithology’s Project FeederWatch, along with projects like the Michigan Breeding Bird Atlas, have provided scientists with snapshots of the species that are moving northwards where winters are becoming less harsh and nesting seasons are growing longer.
“We already see evidence that birds are moving in Michigan and are adapting to the one degree Fahrenheit change we’ve had in the last 100 years,” Hoving said, pointing to the Least Bittern and Northern Cardinal as two examples. “We anticipate by mid-century, 2050, we will be looking at a three- to five-degree change and that the rate of change between now and then will be ten times as fast as the last 100 years.”
CHANGES COULD BE DEVASTATING FOR SOME BIRDS
Scientists across North America are largely in agreement about the predicted changes, and that the effects of climate-change driven drought, flooding, and habitat loss may be devastating for some birds. A 2010 State of the Birds Report, developed for the North American Bird Conservation Initiative, a collaboration of state, federal and Canadian wildlife agencies and scientific and conservation organizations across North America, concludes: “Some birds will adapt and succeed, others will struggle and decline, and some will disappear.”
Ben Zuckerberg, an assistant professor in the Department of Forest and Wildlife Ecology at the University of Wisconsin, said the “poleward shift” has already been documented in North America and Europe. Many birds are either moving north or into higher elevations.
Zuckerberg has spent several years studying bird movement in response to climate change. He is embarking on a two-year research collaboration with the Northeast Climate Science Center, hosted by the University of Massachusetts, Amherst. The study will look at grassland bird species in eastern half of the U.S. “We are trying to determine what species are most vulnerable and exposed to future climate change,” Zuckerberg said. “Some areas are getting cooler. Some areas are getting warmer. We want to understand how sensitive species are to extreme drought and extreme precipitation.”
Extreme rain events and flooding are predicted to occur with greater frequency. They can be devastating to ground-nesting birds. The rate of climate change is also predicted to be fastest in flat areas like the upper Midwest. Zuckerberg’s concern is that conditions will change faster than birds can adapt. “We are concerned that birds will increasingly find themselves in a climate space that is foreign to them in the future,” Zuckerberg said. “Many of the birds are adapted for variability in climate, but that adaptation is being pressed. We don’t know what’s ahead in the next 50 years for grassland bird species. It will be a mixed bag of results, but the elephant in the room will be habitat loss.”
Scientists agree that soils are expected to dry with the warmer temperatures. The upper Midwest is expected to face more droughts in the future. Grasslands may wither as a result, causing insect populations to decline. Birds would find less protein is available to feed young nestlings.
SEASON SHIFTS COULD CAUSE TIMING PROBLEMS
Researchers also worry about a timing problem called: “Phenotypic Mismatch,” a fancy name for saying: “You missed dinner.” Migratory birds that winter in the tropics decide when to fly north based day-length, Zuckerberg said. Historically they have arrived in Michigan when food was on the table. But milder winters are causing insects to come out earlier and earlier, though migratory birds continue to arrive at the same time. Over time, he worries, the gap may get larger and result in less food being available.
“In extreme situations you could have nest failure,” Zuckerberg said. “Studies in Europe of two species, the Great Pit and Pied Flycatcher, found population reductions of 80 to 90 percent in areas where the mismatch was particularly severe.”
In Michigan this becomes a concern for migratory grassland species such as Bobolinks,
Grasshopper Sparrows, and Dicktissel, all of which are susceptible to mismatch. Of less concern is the Savannah Sparrow and Henslow’s Sparrow, which migrate only to the southern regions of the U.S.
Dr. Alec Lindsay, incoming Michigan Audubon Society president and a professor of biology at Northern Michigan University, notes that the predicted warming trends could have an impact on boreal habitat in Michigan’s Upper Peninsula and the birds that rely on it. The Spruce Grouse, Three-toed Woodpecker, and Boreal Chickadee are three examples. All breed in northern Michigan, which is the southern end of their range.
“Those populations have moved north in the last 40 years,” Lindsay said. “They depend on boreal habitat. Spruce Grouse feed on needles in the winter, on jack pine and spruce. Those trees are projected to slowly disappear. If we start losing boreal forest that includes spruces, we will lose those species too.”
STATE OF MICHIGAN EXAMINES IMPACTS TO WILDLIFE
Hoving notes that whitetail deer may push north as temperatures warm, altering the landscape substantially with their browsing, in turn destroying habitat for birds that need a protective understory, which would no longer exist. The problem would be exacerbated in areas where the Great Lakes limit deer’s migratory movement north.
Michigan wildlife officials have been attempting to assess just what species will be vulnerable in the future. Hoving co-authored a report in 2013 called “Changing Climate, Changing Wildlife: A Vulnerability Assessment of 400 Species of Greatest Conservation Need.” It looked at birds, plants, mammals, reptiles, insects, and amphibians and found 61 percent of non-game species were vulnerable to climate change, as were 17 percent of game species.
Moose and American Martins were found to be vulnerable, along with Ruffed Grouse and snowshoe hare. Grouse would likely adapt on a global or regional scale, but the popular game bird could decline or disappear in Michigan because warmer temperatures are bad for aspen, which grouse need to thrive.
Non-game birds such as the Peregrine Falcon and Least Bitterns were found to be
“moderately vulnerable,” as are Cerulean Warblers, for a variety of reasons. But other species such as Le Conte’s Sparrows, Northern Flickers, and Olive-sided Flycatchers are predicted to increase in numbers, according to the report. Those species are “habitat generalists,” Hoving said. They are expected to adapt. The report also found Prairie Warbler and Kirtland’s Warbler populations would remain stable in a warming climate.
Only the Common Loon was listed as “highly vulnerable.” The threat is flooding and extreme rain events that could jeopardize nesting on low islands. Residential and other development on northern lakes is also expected to increase as temperatures warm, creating more disturbances.
Hoving warns that the assessment provides an incomplete picture when it comes to migratory birds. Its focus is only on the time that birds reside in Michigan. They may also be vulnerable along their migration path and on their wintering grounds.
NATIONAL AUDUBON WORKING ON NEW PREDICTIVE MODEL
Scientists at the National Audubon Society are also working on new methods for accurately determining the species most at risk by climate change. The organization will release a new report in spring of 2014 that discusses a new predictive model based on the bird and climate data collected from 49 continental states and Canadian provinces.
“The research goes beyond the 2010 State of the Birds report,” said David Ringer, the director of messaging for National Audubon. “It puts stronger parameters on what scientists have been saying for a long time and will help resource managers and agencies. We will have more specific information about which birds will be affected and where, rather than the broader strokes in the 2010 State of the Birds Report.”
This climate change report appears in the January/February 2014 issue of the Jack Pine Warbler published by Michigan Audubon Society.