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Posted 5/17/2013

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CHAMPAIGN, Ill.—Installation training ranges’ future sustainability could be affected if increasingly warm temperatures due to climate change alter the regional ecosystem.  Global climate change is influencing the distribution and abundance of many species and is predicted to drastically increase extinction risk.   As such, ERDC’s Construction Engineering Research Laboratory (CERL) is participating in studies to identify potential impacts among different species within their ecosystems to revise environmental management strategies if necessary. 

In one recently published study, research to determine effects of warming temperatures on ratsnakes reveals that the reptile may actually benefit, rather than being stressed in the ways predicted for many other species.  CERL scientists teamed with experts at the University of Illinois at Urbana-Champaign (UIUC), Fort Hood, Texas, and other partners to design a 10-year study using data collected from the snake in three distinct geographic regions: Canada, Illinois and Texas.

The ratsnake is an ectotherm, or “cold-blooded” creature whose internal temperature mostly depends on its habitat’s external temperature, as opposed to endotherms, or “warm-blooded” species like humans, whose internal metabolic processes produce body heat.  The snake can help control its internal temperature through different behaviors, such as hibernating in winter, spreading out in the sun for warmth or seeking cooler, shady areas, or switching between night and day foraging.

Officials at Fort Hood, Texas, were interested in research on snake behavior because ratsnake predation is the major cause of reproductive failure for two species of endangered birds at the fort – the golden-cheeked warbler and black-capped vireo.  For this reason, Fort Hood wanted to develop new management strategies that could decrease nest predation and had participated in research designed to better understand the relationship between snake activity and nest predation risk.  The data collected during the course of this work was then combined with similar data, collected across a 1,500 kilometer latitudinal gradient, to predict effects of climate change.

“Because the ratsnake populates a broad area representing different temperature ranges, we were able to use these conditions as a ‘surrogate’ climate change model,” said CERL Researcher Dr. Jinelle Sperry.  “This allowed us to compare the snake’s ability to regulate body temperature through behavior changes.”

In warmer climates like those at Fort Hood, these behavioral changes can have other ecological consequences. “In cooler weather, when the snake hunts during the daytime, it usually only eats the eggs or hatchlings,” said Sperry.  “When the adult birds spot a ratsnake during daylight, they set up a ruckus to attract attention of snake predators, such as hawks.  But at night, a ratsnake can make a stealth attack on the nest, often killing the incubating or brooding female in addition to her young, at even greater loss to the bird population.”

According to UIUC’s Dr. Patrick Weatherhead, “The environmental repercussions could be significant if you start eliminating adult females from a population, particularly an endangered species,” he said.  “The loss of females for native birds will have a big demographic effect on bird populations.”

Thermoregulation data for the ratsnakes came from earlier studies in which 143 snakes were captured in the three geographic regions.  The team surgically implanted tiny temperature-sensitive transmitters into the snakes, released them back into their habitats, and collected the data as pulse rates using hand-held radio-telemetry.

Results showed that the snakes’ behavior was surprisingly similar within all three temperature regions.  Similar seasonal activity patterns across all three sites would suggest that warming temperatures would likely lead to an increase in nocturnal activity, as opposed to alterations in monthly activity.  In collaboration with Fort Hood Natural Resource personnel, CERL researchers are examining habitat manipulation strategies, such as brush pile management, that may reduce the likelihood that snakes will encounter birds’ nests.

CERL fort hood ratsnake