Ask the birds and the bees – and the frogs and the snakes. It is not only that last year’s temperature was four tenths of a degree higher than the year before, but that the increase is an average – some really warm stretches alternating with days of true winter weather. Creatures basking in the sun one day may be at risk of temperatures suddenly plunging twenty-four hours later.
On the coast of Georgia, temperatures were in the 70s 25 times in December and January. For cold-blooded creatures like canebrake rattlesnakes, unseasonable warmth disrupted their winter rest and lured them out of their holes. According to Kimberly Andrews, an affiliate of the University of Georgia’s Savannah River Ecology Laboratory, a snake taking a January sun bath is expending energy he would normally save for spring and summer. “If predator reptiles start to change their habits,” Andrews says, “the entire ecosystem could see shifts in the competitive balance between predator and prey.”
Early sitings of migratory birds might cheer the winter-weary, but warmer temperatures may be forcing some species to leave their winter habitat before adequate food sources emerge at their destinations. A premature arrival could mean the avian travelers face nutritional shortages as they start to nest. That timing of migrations is shifting is more than casual observation and hearsay; a paperstudying records kept over the past century determined that the spring arrival dates of ruby-throated hummingbirds have advanced by as many as 18 days.
Indisputably, ecosystem relationships are dynamic and complex. Various species respond differently to stimuli; some species can adjust to earlier springtime warming by emerging sooner while other species rely on different cues to initiate seasonal behavior. A recent report published in the journal Ecology posits that an increase in a species’ abundance and spatial expansion relates to its ability “track” climate change. Although the author’s research focused on flora, a like phenomenon may occur among populations of hibernating mammals.
A paper published in Global Change Biology examined the relationships among climate change, phenology and populations of lesser snow geese in a subarctic region. Looking at body development and juvenile survival rates, the researchers found that warmer-than-average seasons degraded gosling body condition and reduced first-year survival rates, that phenological shifts in both goose and plant communities could disrupt nutritional availability, and that a warming climate could be detrimental to snow goose populations in the long run.
Understanding how plants and animals respond to later winters and earlier springs will help natural resource managers set goals and develop strategies. As a paper from the National Wildlife Federation states, “Determining which resources are most vulnerable enables managers to better set priorities for conservation action, while understanding why they are vulnerable provides a basis for developing appropriate management and conservation responses.”