Saturday, March 29, 2014

Swainson's Hawks Go To Ground-Saturday March 29, 2014

Pam, assisted by Wes, Rose, Joe and Hal

Migration Today:
Swainson's Hawks-160
Turkey Vultures-9

We discovered that most of the SW's went to ground from the Date Farm. They were sitting in the sand and on grape stakes (redwood stakes from the 50's and 60's when grapes were a major crop in Borrego Springs). This is the first observation of Swainson's Hawks on the grape stakes. At 8:50A hawks began to power flight to the northwest one at a time. They did not kettle until they reached the mountains to the west. They moved out of the valley through Henderson Canyon and the ridge behind. The initial count was 129 SW's. After 10A 2 kettles of SW's were spotted along with some stragglers that brought the morning count up to 160. Nine Turkey Vultures appeared to be migrating. Check out the youtube from yesterday evening at: This evening we said goodbye to our "Eyes". Rose Leong has moved on. She has been responsible for finding well over 75% of the distant hawk kettles this season. She will be sorely missed.

Question: How do the hawks choose a roost site? We are not certain of what motivates the hawks to select a specific roost site. Over the years we have seen some trends however. The hawks almost always select the Date Farm February and most of March. By the last few days of March through April 15, the hawks begin to roost at Ellis Farm and east of the potato fields. For instance, this evening we had hawks drop into Tamarisk trees to the east near the potato fields. Different groups of hawks have affinity to certain sites? They probably are hot wired to seek out roost sites from past years.  

Evening Watch:
At 5P we spotted a kettle of 55 SW's and TV's and followed them northwest. Another small kettle (around 20 SW's) was found at 6P. At 6:45P a group of around 30 Swainson's Hawks was found to the east. In total around 100 Swainson's are in the valley.

The wind is predicted to pick up late tonight into tomorrow. If it is windy early tomorrow, the hawks will take off by sun up. The SW's are spread out throughout the valley in probably more than one roost site. It is hard to predict where they will kettle up tomorrow. We will be out early to try and intercept them.

Swainson's Hawks on the ground-3/29/14
Using a grape stake for a perch-3/29/14-taken through a scope
Light Morph SW through a scope-3/29/14

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