Friday, July 12, 2013

Snakes feeding at night

After lunch nap at Rattlesnake Bend
It is no longer news that we are in a period of warmer temperatures.  This is good news for for our cold blooded snakes but bad news for some baby birds.  First the good news for snakes.
Speckled kingsnake at Rattlesnake Bend
Snakes are ectotherms, which we think of as being cold blooded.  This really means that they lack the ability to control their own body temperature like mammals.  Instead they seek out places that are within their comfort zone like I head for the swimming hole or crank up the A/C on hot days.  We have a shaded curve in our gravel drive that we call Rattlesnake Bend because we frequently see rattlers as well as a ratsnake or speckled kingsnake laying on the road that was warmed by the early morning sun while escaping the direct sun rays.

Ratsnakes are the number one predator of nesting birds, quite capable of climbing up trees and bluebird poles.  Some people are surprised that snakes can climb, as was our neighbor who found a copperhead at eye level in her tree.  Our resident black rat snake easily climbs up the flat side of our house to its second story entrance as it has demonstrated to us several times.

University of Illinois researcher Patrick Weatherhead described the normal pattern of a hunting ratsnake in this 2010 article. The ratsnake normally hunts in the forest, then heads to the edges and openings to warm up.  With the warming climate of recent years they are hunting more at night and seeking shade in the day.

Rat Snake- Shelly Cox
Weatherhead's 2013 research is described in this article.  He and his colleagues are studying ratsnakes and their response to the warming climate in Canada, Illinois and Texas.  They are finding that nocturnal hunting is still on the increase.  This is bad news for birds.
"Females are often on the nest incubating eggs or brooding the young at night," Weatherhead said. "If they are doing that during the day and a snake approaches, they rarely get caught by the snake, but at night they are much more vulnerable because snakes are very stealthy and the incubating birds don't detect the snake approaching. This is good for the snake because it gets a bigger meal."
"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."
This has implications for humans as well.  University of Missouri biologist John Faaborg studies snake populations and birds such as the Acadian flycatchers and indigo buntings whose numbers are down in warmer years.  They bred in the forests before spreading out to other territories.  They help control mosquitoes which can carry West Nile virus.  In Sciencedaily he describes these implications of changing snake behavior.
"Low survival in the Ozark nests harms bird numbers in other areas," Faaborg said. "Birds hatched in the Ozark forest spread out to colonize the rest of the state and surrounding region. Small fragments of forests in the rest of the state do not support successful bird reproduction, so bird populations in the entire state depend on the Ozarks."
Researchers expect that the warming climate may expand the range and numbers of snakes in the northern states.  The black rat snake's scientific name is Pantherophis obsoletus, the obsoletus being Latin for old, worn out, thrown off.  This might as well refer to it common name of Texas ratsnake, more recently renamed the Western ratsnake.  With the warming climate it may eventually be renamed the Ontario ratsnake.

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