Roaring Fork Valley Phenology | September 25, 2013

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Well it’s happening. The clear days and cold nights that are a hallmark of September in the Aspen area have finally appeared following a rainy/snowy start to the month. The cold nights are a cue for the aspen leaves to change from green to yellow. Typically we can count on this change during the last half of September. In 2012 the main color change was around the fifteenth of September and in 2013 it is looking like peak will be the last few days of the month. The comparison photo above shows Red Mountain last year and this year on September 25. Quite a different story. Last year’s drought and early onset of cool clear nights led to an earlier leaf change. This year’s wet and mild end of summer kept things green longer. 

Other photos from my Rio Grande phenology walks on September 25th, 26th, and 29th 2012 show bears in multiple locations in Aspen‘s West End ravaging crabapple trees. That activity is not happening much this year. Plentiful berries and acorns have been keeping bears out of town so far.  

Hummingbirds and Yellow Warblers were both spotted this week at Hallam Lake. They will be packing up and heading south in the the next week or so. Garter snakes and least chipmunks will be heading into their winter burrows soon as well. If you see any of them, wish them a good winter.

~ Jim Kravitz, Director of Naturalist Programs