Tuesday, April 8, 2014

Surprise Swainson's Today-Tuesday April 8, 2014

Steve, assisted by Hal and Joe

Swainson's Hawks-79

Very warm today-70's-mid 80's by 10A Wind light from the south with a clear sky. First observation of 9 SW's due south probably coming up from Roadrunner Club. First lift-off at 8:40A. At 9:20A kettles of SW's were observed above the Date Farm and to the southeast. One of the kettles had over 40 SW's. We counted most of the second group of  Swainson's Hawks moving due north along Borrego Valley Road. They exited the valley along Coyote Mountain. We believe that the large kettle probably spent the night further southeast.

Question: What is meant by different morphs? Swainson's Hawks exhibit 3 basic color forms, Dark, Light and Intermediate. There is variety in between these forms. Below are 3 closeup SW's. It is a genetic characteristic and does not change during the hawks lifetime. Data has indicated that western Swainson's Hawks are mostly represented by the dark morph. Our data (Borrego Valley Hawkwatch) has shown a possible departure from the standard of darker western hawks. Using photographs of kettles of SW's we are trying to determine the ratio of each morph type of hawks migrating through Borrego Valley.

Evening Watch:
No apparent migration this evening.

Today we had hawks that roosted much further from our local sites. So perhaps with the calm wind condition the hawks are stopping short of Borrego Valley. If so there could be a late migration around 9:30A tomorrow.

Dark Morph
Light Morph-Iris Kilpatrick
Intermediate (rufous) Morph-Iris Kilpatrick

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