Monday, March 19, 2012

Surprise Numbers of Swainson's Today Migrating

Migration Today:
Swainson's Hawks-584
Turkey Vultures-24

The weather this morning included a mostly cloudy sky, temperatures in the 40's with a breeze from the north. The Swainson's Hawks that were observed yesterday evening spread out to several roost locations. Liftoff began at 7:25A from the Roadrunner Club and the Fun Farm off of Di Giorgio. The hawks streamed to the northwest in several kettles. Swainson's Hawks began to appear as a very high stream from the southeast. They kettled above Di Giogio Rd before departing to the northwest. These birds probably roosted at Bowen Ranch and La Casa Del Zorro. We counted 287 SW's in the early liftoff. We waited on Di Giorgio Rd as a large number of Swainson's were perched in Tamarisks in rows radiating west from Di Giorgio Rd. At 9:15A the SW's left the trees and formed many kettles. During a 45 minute period, kettles formed and streamed northwest. Small kettles began to form to the south with mixed SW's and TV's. The totals in the late departure included 297 Swainson's and 24 TV's.

Perched Swainson's Today at Sunup
What happened to the hawks with transmitters on them?

1.  Information from a week ago. One Swainson's Hawk entered California on March 7 about 12 miles west of Calexico, continued northwest crossing the west portion of Anzo-Borrego SP and then up to Julian and Valley Center.   
2.  The second entered on March 12 about 6 miles east of Calexico, continued to El Centro and travelled northwest from El Centro to Ranchita. This bird was just south of the border at 0900 hrs on March 12th. The next reading was from Ranchita late evening of the 12th. The following day the bird was north of LA near Santa Clarita. This bird may have passed through Borrego Springs up Hell Hole Canyon or Montezuma Valley Road. This bird moved very fast and never spent the night in Borrego Valley. This raises questions as to when it may have passed through our valley. That is, if indeed it did pass through Borrego Valley  

So both of these birds used the same general trajectory, one further east than the other. It does look like they flew through a portion of the Anza- Borrego SP. 

As of March 15th, two hawks are still in South America, one in Central America, and 4 in Mexico. The birds in Mexico may have moved past our region already. More information later.

Evening Watch:
15 Swainson's flew into the area at 6:35P. They apparently landed at Ellis Farm. 11 TV's were observed in the vicinity of the date farm earlier.

Prediction for Tomorrow:
First kettle of the day-3/19/12
Calm wind tomorrow so liftoff around 8:30-9A. The day count site on Di Giorgio Rd might be the best place to be.



No comments:

Post a Comment