Golden Gate Raptor Observatory

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Raptor Sightings in the Marin Headlands During Autumn 1999 *



	1999 Raptor Rate (Hawks/Hour)			1999 Raptor Sightings				Average 1989-98

*Hours*				*528.9*				*536.3*
Turkey Vulture	17.69			9357				5432
Osprey	0.15			81				72
White-tailed Kite	0.13			69				35
Bald Eagle	trace			7				0
Northern Harrier	2.59			1369				559
Sharp-shinned Hawk	12.00			6348				3876
Cooper's Hawk	5.70			3015				2063
Northern Goshawk	trace			1				2
Red-Shouldered Hawk	0.80			424				210
Broad-winged Hawk	0.44			235				104
Swainson's Hawk	trace			3				3
Red-tailed Hawk	23.67			12520				6940
Ferruginous Hawk	0.04			22				19
Rough-legged Hawk	0.04			19				6
Golden Eagle	0.04			20				17
American Kestrel	1.31			694				557
Merlin	0.28			147				109
Peregrine Falcon	0.18			95				81
Prairie Falcon	trace			5				6
Unidentified Raptor	4.07			2151				1690


Total	69.16			36,573				21,782

*Not to be cited except by permission of the GGRO. 1999 data are preliminary and have not been audited.

From August 16th to December 12th, 1999, one hundred and fifty-six volunteer GGRO hawkwatchers monitored the daily overflights of raptors and a variety of non-raptors from the Marin Headlands, tallying up the largest annual flight in 17 years. The tremendous numbers were caused by large numbers of Sharp-shinned and Red-tailed hawks, which were both not-quite-twice their previous ten-year averages.

The peak count day - September 25th with 206 hawks per hour (1238 sightings) - was the highest one-day count since Carter Faust and friends tallied 2833 on September 21, 1984. Peak number of species occurred strangely early, on September 20th with 15 species. And a mid-October peak day of 156 hawks per hour (1098 sightings) was a complete surprise, though accipiter and Redtail numbers remained strong through Thanksgiving.

If you want to learn more about being a GGRO volunteer, visit our Volunteers link or contact the GGRO.

Contact the GGRO:

Mail:
Golden Gate Raptor Observatory
Building 201, Fort Mason
San Francisco, CA 94123

Phone:
(415) 331-0730

E-mail address:
ggro@parksconservancy.org

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