Chew’s Ridge Site Monitoring 2013

Speyeria adiaste clemencei 2011-13 transect totals

Chew’s Ridge colony

Weekly standardized surveys of Clemence’s unsilvered fritillary (Speyeria adiaste) at the Chew’s Ridge colony site were conducted from late May to late July, 2013, following protocol established for 2011 surveys.  See results of these 2013 surveys below, combined with 2011-12 data for comparison.

The 2013 adult flight season started a week earlier and peaked in mid-to-late June, much earlier and with lower numbers detected on transect counts than the two previous years.  (The very low count of 4 individuals on 6/20 occurred on a cool, cloudy day when a cold front moved through). 

January-March rainfall this year was scarce, and the rainy season was described by local meteorologists as one of the driest in recorded history for Monterey County.  Results of local butterfly counts suggest that nearly all butterfly species were impacted by these drought conditions.  Nectar sources for S. adiaste, particularly Cirsium (thistle) and Monardella (Coyote Mint) had dried up by late July.

Visits to the other known S. adiaste colonies - on Pine Ridge and Skinner Ridge (1.5 mi. S, and 10 mi. W respectively from Chew’s Ridge) also found fewer flying adults than previous years.

2012 surveys

2011 surveys

2013 surveys