Monday, March 19, 2012
The Importance of Chipmunk Chatter
We credit this information to Roger De Silvestro's article "The Key to Chipmunk Chatter" in National Wildlife Magazine, April/May 2012. Chipmunk chatter is common around Ridgefield. It is usually divided into three calls: The chip, the deeper chuck and the startle call. It is meant for other chipmunks but it sometimes sends messages to other species. An example is to ground nesting birds whose eggs and young chicks are preyed on by chipmunks - no they just don't eat nuts. Two birds common in our woods, the ovenbird and veery, will use these sounds as a warning where not to build their nests. Another interesting fact that has emerged, is that the lack of chipmunk chatter is a climate change warning to humans. Studies done at Fordham University on wild individuals have shown that warmer winters effect the efficiency of chipmunks hibernation periods. Torpor is the method that chipmunks use during this time. They do not "sleep" through the entire winter but have active times where they moving around their burrow, feed and excrete. "A 0.9 - 19-degree F increase in mean air temperature during Nov. and Dec. corresponded with an average 37.5 day delay in the first onset of torpor bouts, a 60% reduction in the number of individuals going into torpor and a 88% decrease in the total amount of time spent in torpor." When chipmunks go into normal torpor 90% survive till spring; when they don't, 80-90% die. Since the winter of 2006-2007, chipmunks in the study area have not gone into regular hibernation. This may be an example of how hibernating mammals could be particularly sensitive to climate change. Thus, the less we hear that familiar chip, the more warning it is that climate change is "closing in".