California Sister migration is underway (in California)

Mark Walker MWalker at
Tue Jun 8 02:36:24 EDT 1999

No, I don't think that I have witnessed this phenomenon.  I've run into them
by the hundreds in the western sierran foothills in July, but haven't ever
noticed them in mass migration.

Mark Walker.

-----Original Message-----
From: Paul Cherubini [mailto:paulcher at CONCENTRIC.NET]
Sent: Monday, June 07, 1999 7:14 PM
To: leps-l at
Subject: California Sister migration is underway (in California)

Here at the 1500-2000 foot elevation zone in the Sierra Nevada foothills
east of 
Sacramento, California, the annual northward migration of the California
Sister butterfly 
is in full swing. Today I could view roughly one butterfly every 3-8
minutes. Stiff head 
or side winds don't seem to blow the butterflies off course - they seem very
determined to 
move in N or NNW directions.

The first numbers of Sisters appeared about a week ago. I have seen them
steadily northward for the past 10 consecutive years in the months of either
May and June 
(except last year when the species was rare). In September or October each
year there is 
also a highly reliable and predictable southward movement.

The strangest thing about our Sister migration is that I have not run into
any other 
lepidopterists who have ever noticed this species migrating! So I don't know
if the highly 
directional movements I'm seeing occur only in my area or only within a
altitudinal zone of the Sierra Nevada mountain range. Have others seen
Sisters in 
migration in other localities?

Paul Cherubini
Placerville, California

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