AboutZoos, Since 2008


Mam­mal species respond dif­fer­ent to cli­mate change, a recent study shows

pub­lished 26 Jan­u­ary 2014 | mod­i­fied 25 Decem­ber 2014

If you were a shrew snuf­fling around a North Amer­i­can for­est, you would be 27 times less likely to respond to cli­mate change than if you were a moose graz­ing nearby.

Raccoon in treeThat is just one of the find­ings of a new Uni­ver­sity of Col­orado Boul­der (CU-​Boulder) assess­ment led by Assis­tant Pro­fes­sor Christy McCain that looked at more than 1,000 dif­fer­ent sci­en­tific stud­ies on North Amer­i­can mam­mal responses to human-​caused cli­mate change. The CU-​Boulder team even­tu­ally selected 140 sci­en­tific papers con­tain­ing pop­u­la­tion responses from 73 North Amer­i­can mam­mal species for their analysis.

The stud­ies assessed by the team exam­ined seven dif­fer­ent responses to cli­mate change by indi­vid­ual mam­mal species:

Figure McCain mammals climatechange- local extinc­tions of species known as extir­pa­tions
- range con­trac­tions
- range shifts
- changes in abun­dance
- sea­sonal responses
- body size
- genetic diversity

The researchers used sta­tis­ti­cal mod­els to uncover whether the responses of the 73 mam­mal species to a chang­ing cli­mate were related to aspects of their phys­i­ol­ogy and behav­iour or the loca­tion of the study population.

The analy­sis showed only 52 per­cent of the mam­mal species responded as expected to cli­mate change, while 7 per­cent responded the oppo­site of expec­ta­tions and the remain­ing 41 per­cent had no detectable response. The two main traits tied to cli­mate change responses in the CU-​Boulder study were large mam­mal body size and restricted times dur­ing a 24-​hour day when par­tic­u­lar mam­mal species are active, McCain said. The study find­ings are pub­lished online on 22 Jan­u­ary in the jour­nal Global Change Biology.

This is the first time any­one has iden­ti­fied spe­cific traits that tell us which mam­mals are respond­ing to cli­mate change and which are not
Christy McCain, Depart­ment of Ecol­ogy & Evo­lu­tion­ary Biol­ogy, CU-​Boulder »

While body size was by far the best pre­dic­tor for response to cli­mate change – almost all of the largest mam­mals responded neg­a­tively – the new study also showed that mam­mals active only dur­ing the day or only at night were twice as likely to respond to cli­mate change as mam­mals that had flex­i­ble activ­ity times, McCain said. McCain said she and King were sur­prised by some of the find­ings. “Over­all the study sug­gests our large, charis­matic fauna – ani­mals like foxes, elk, rein­deer and bighorn sheep – may be at more risk from cli­mate change,” she said. “The think­ing that all ani­mals will respond sim­i­larly and uni­formly to tem­per­a­ture change is clearly not the case.”

The researchers also found that species with higher lat­i­tu­di­nal and ele­va­tion ranges, like polar bears, Amer­i­can pikas and shadow chip­munks, were more likely to respond to cli­mate change than mam­mals liv­ing lower in lat­i­tude and ele­va­tion. The abil­ity of mam­mals to hiber­nate, bur­row and nest was not a good pre­dic­tor of whether a species responded to cli­mate change or not. Amer­i­can pikas have been extir­pated from some of their pre­vi­ously occu­pied sites in the West, as have shadow chip­munks, which are in decline in California’s Yosemite National Park.

One of the most intrigu­ing study find­ings was that some small mam­mals may shel­ter from cli­mate change by using a wider array of “micro-​climates” avail­able in the veg­e­ta­tion and soil, she said. McCain com­pared the find­ings with the events at the Cre­ta­ceous – Ter­tiary extinc­tion 66 mil­lion years ago when an aster­oid smacked Earth, dras­ti­cally chang­ing the cli­mate and killing off the big dinosaurs but spar­ing many of the small mam­mals that found suit­able shel­ter under­ground to pro­tect them from the cat­a­clysmic event.

“I think the most fas­ci­nat­ing thing about our study is that there may be cer­tain traits like body size and activ­ity behav­iours that allow some smaller mam­mals to expand the range of tem­per­a­ture and humid­ity avail­able to them,” said McCain, also a cura­tor of ver­te­brate zool­ogy at the Uni­ver­sity of Col­orado Museum of Nat­ural His­tory. “These areas and con­di­tions are not avail­able to big­ger mam­mals that live above the veg­e­ta­tion and expe­ri­ence only ambi­ent temperatures.”

The new study builds on a grow­ing body of global infor­ma­tion doc­u­ment­ing the shift­ing behav­iours and envi­ron­ments of organ­isms like flow­ers, but­ter­flies and birds in response to a warm­ing world, said McCain.

“If we can deter­mine which mam­mals are respond­ing to cli­mate change and the ones that are at risk of dis­ap­pear­ing, then we can tai­lor con­ser­va­tion efforts more toward those indi­vid­ual species,” said McCain. “Hope­fully, this poten­tial loss or decline of our national iconic mam­mals will spur more peo­ple to curb cli­mate impacts by reduc­ing overuse of fos­sil fuels.”

(Source: Uni­ver­sity of Col­orado Boul­der news release, 22.01.2014)

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