Science News - June 30, 2012

Mammal makeup a shifting climate has brought changes to small-mammal communities in the northern parts of michigan’s lower peninsula. communities there have become dominated by species typically more common in southern climes, such as the white-footed mouse.

Nfs Wjm

Community composition

1857–1980

Rbv
Wdm
species with southern affinities
species with northern affinities

source: p. myers ET AL/ GLOBAL CHANGE BIOLOGY 2009

at Austin and economist Gary Yohe of Wesleyan University in Middletown, Conn., performed various analyses on data from independent studies on more than 1,700 animal, plant and lichen species. Parmesan and Yohe also found biological trends that matched climate change predictions. Butterflies, birds and other organisms had shifted their ranges northward by an average of 6. 1 kilometers per decade (or 6. 1 meters per decade upward to higher altitudes). Amphibians and migratory birds, among others, were breeding earlier in the spring by an average of two days per decade (SN: 3/8/03, p. 152).

Since then, researchers around the world have been piling up more and more examples of particular animals or suites of species showing changes that fit the same patterns (as well as some that don’t). On the range-shifting side of the story, more than half of 305 common North American birds are wintering farther north than they did in 1966, a National Audubon Society analysis showed in 2009 (SN Online: 2/10/09). The shifts, which average 56 kilometers and are as great as nearly 700 kilometers for individual species, coincide with warmer winter temperatures over the same period.

In Michigan, opossums, white-footed
mice and other mammals
once confined to the south-
ern part of the state have
rapidly expanded north-
ward, displacing some of
their counterparts in the
process. A 2009 paper
ruled out forest regenera-
tion and land-use changes
as possible explanations for
the expansion; the authors
concluded that warming,
documented in the area
over the same period, was
the probable cause. Mean-
while, chipmunks and other
small mammals in Califor-
nia’s Yosemite National
Park have moved to higher
ground as temperatures in
the park have increased in
the last century, a 2008 study showed.

new territory than they had been in the old home, researchers reported in Ecological Entomology in 2008. The par-asitoids were in the new place, too, but apparently more interested in a different butterfly species.

As for changes in seasonal activity, frogs are calling, birds are nesting, salmon are migrating, walleye are spawning, loggerhead turtles are laying eggs and bees and butterflies are appearing earlier in the spring. Plants too are responding by leafing out and flowering earlier (see Page 13).

Underscoring the individual reports, a 2010 study found that seasonal events in the United Kingdom have advanced for most of the 726 terrestrial, freshwater and marine plants and animals examined and that the rate of change has sped up in recent decades. What’s more, change was speediest in organisms at the bottom of the food chain — plants and plant-eaters — and slower in predators, a situation that could result in empty bellies for the planet’s top diners.

Mismatches can happen, too, when interacting species respond to different cues — say, one to day length and the other to temperature. That’s what’s happening with caribou in West Greenland, which synchronize their seasonal migration to calving grounds with day length. The food plants on which they depend respond to temperature, however, and as spring temperatures in the area have risen by more than 4 degrees Celsius, plants have started growing earlier. Caribou are now arriving after peak foraging time, fewer calves are being born and more calves are dying, a 2008 study found.

Out of sync
caribou birthing dates have
remained steady because
the schedule is timed to day
length. But the plants that
caribou feed on respond
to temperature, so they
have been emerging earlier
as temperatures in west
greenland have increased.
such mismatches could be
a common effect of climate
change.