Using the Alexander Orthoptera Collection to measure the effects of climate change on of Rocky Mountain grasshoppers

Background/Question/Methods: The current study utilizes the recently curated and databased Alexander Collection coupled with a new resurvey program to measure the effects of climate change on grasshoppers found along an elevational gradient in the southern Rocky Mountains of Colorado (http://alexander.colorado.edu/). The Alexander Collection is composed of approximately 19,000 pinned grasshoppers and a series of field data notebooks from a three year 1958-1960 survey project.  During these survey years, Alexander processed over 65,000 grasshoppers from repeatedly sampled sites along an elevational gradient from Boulder (1530 m elev.) to Mt Evans (3900m elev.) in the Rocky Mountains of Colorado.  Using Alexander's sampling methodology, during the 2006 and 2007 field seasons, we sampled the grasshoppers at several sites on a weekly basis.

Results/Conclusions: Data from 2006-2007 show that at mid-elevation sites grasshoppers are becoming adults 15-28 days earlier than they did nearly a half century ago.  We found no changes in the time to reach adulthood at the highest and lowest elevation sites, consistent with the weather station data that suggests little climate change at these sites. Using the collection specimens as a reference point, we did not find significant changes in the body sizes of several grasshopper species. There have been several changes in the distributions of grasshoppers at numerous sites, but the reasons behind this are not yet clear.