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Wednesday, April 22, 2015

Caught by surprise

They caught me by surprise:

It's been a good year for Painted Ladies (Vanessa cardui), but today numbers were noticeably higher.  

While photographing one for the record, I noticed another species nearby:

This Red Admiral (Vanessa atalanta) was also nectaring on Sea Thrift (Armeria maritima) along the Bodega Head bluffs.

Not long after this, I flushed a large dragonfly (a darner) from near the trail.  Interestingly, its wings were shiny, indicating an individual that had emerged from a wetland not too long ago.

And then I saw this butterfly land among the grasses momentarily:

Orange Sulphurs (Colias eurytheme) are common inland, but I only seen them occasionally on Bodega Head.  

I've mentioned before that Bodega Head is not the best place for butterflies and dragonflies it's generally too cold with strong northwest winds coming off the ocean.  However, there are certain conditions that create potential for interesting insect viewing e.g., when the winds are from the south or east and the thermometer rises.

The strange thing about today was that I hadn't really noticed these conditions, and there were lots of butterflies and at least a sign of dragonfly movement along the coast.

Had I just missed it?  I looked back at the weather data for the last few days.   The maximum air temperatures were about 57°F and 58.5°F.  Those temperatures are about average, and in fact it was warmer earlier in the month.
Then I looked at the wind.  I checked for the percentage of winds that came from the south, south-southwest, and south-southeast during the last few days.  Here's what those percentages looked like:

April 22 ~15%
April 21 ~14%
April 20 ~35%

Below is a visual representation of the winds on April 20th:

Did the winds on Monday, April 20, encourage a strong northward push of butterflies and dragonflies?

I don't know, but it's worth keeping an eye out for these events and noting the weather around them.

1 comment:

Alice Chan said...

Love these butterflies and thinking about which winds bring them in. Now I'm wondering about West Coast Ladies. As far as I can remember, we had them in profusion until about six years ago, but now I never see them anymore. Any thoughts?