[EBB Sightings] Crockett Hills Raptors: March Census Summary

All;

Here is a listing of the total raptors observed at Crockett Hills during the
March census:

Turkey Vulture  553
Red-Tailed Hawk  2228
Sharp-shinned Hawk 7
Cooper's Hawk  38
Northern Harrier  168
American Kestrel  8
Peregrine Falcon  2
White-Tailed Kite  35
Golden Eagle  3
Red-shouldered Hawk  3
Ferruginous Hawk  1
Osprey  8
Unidentified Buteo  19
Unidentified Accipiter  5
Unidentified Raptor  348

Total Raptors  3419
Total Hours  34.2
Raptors per Hour 100.1

The census was conducted on 9 days from March 20 thru March 30. Different
locations along Cummings Skyway were used. The best site was found to be the
Sky View Trail site (directions to site below). Different watch lengths and
different watch times were also tried. The peak activity period was found to
occur 10:30--3:30. The best watch length was found to be 10:30--2:30.

There were two frontal passages during the census. When the sky cleared in
mid-afternoon after the first frontal passage on 3/20, 413 raptors were
sighted in 1.67 hrs (raptors per hour = 249). After the second frontal
passage 361 raptors were sighted in 4 hrs for an RPH of 90.25. 

A few words on data quality. On two watches I was joined by a second
observer, Bob Battagin and Ted Robertson. I conducted the remaining watches
alone. Single-observer hawk-watch data suffers from several data quality
issues: 1)under-counting when the RPH is high, 2)double-counting when the
RPH is high, 3) observer fatigue. The data above is no exception. For
example, I do not know to what extent under-counting and double-counting may
have cancelled each other out. For these reasons, the data should be viewed
as a basic indicator of raptor activity at this site rather than a count of
raptors migrating through the site. 

Having Bob and Ted on site greatly improved the quality of the data. Much
thanks to them for their help. It was a real pleasure to meet and work with
them. 

I do not have the 2006 Spring migration statistics from the Hawk Migration
Association of North America. However, I do have their 2005 Spring
statistics. 

On the Eastern Flyway, Hawk Mountain Pennsylvania is typical and logged 4.1
raptors per hour during 245 hours of observation in the Spring of 2005. 

On the Central Flyway, ten sites logged an average of 39 raptors per hour
during an average of 400 hrs. 

On the Mountain Flyway, two sites logged 5.1 raptors per hour during 612
hrs, and 2.6 raptors per hour during 1238 hrs. 

On the Pacific flyway, one site logged 19 raptors per hour during 90.5
hours. 

While we should be very cautious about comparing these numbers to Crockett
Hills (RPH 100.1 during 34.2 hours), I nevertheless think this first Spring
survey is very encouraging.

On 4/12, I will begin a second two-week census. For this census, I plan to
divide the site into sectors and record the number of sightings in each
sector. This will provide information on how raptors pass through the site,
how much of the raptor activity is outside the park boundary, and how the
species mix changes from mid-March to mid-April. 

If you have an interest in participating in the census, I need and welcome
your help. Email me at harvmon at comcast.net.

During the second census I will post the daily results here and forward them
to EBRPD and to Golden Gate Raptor Observatory. After the census is
complete, I will write up both censuses and send them to EBRPD and GGRO.

Thanks everyone for your interest and encouragement. Am having a great time
doing this. If you can find the time, I recommend you come and see this
site. It's pretty amazing. 



DIRECTIONS to the SITE (from Ted Robertson, with a little more info from me)

The site is located near Crockett and the Carquinez Bridge. 

Take Highway 4 toward Crockett.  Take the Crockett exit and turn toward
Crockett. You are now on the Cummings Skyway(There is no Cummings Skyway
street sign).  In approx. 2 miles, you will pass a stop light (Crockett
Blvd.).  Don't turn but continue on Cummings Skyway about 1/2 mile until you
see the first large gravel pullout on your right. Park here. There is room
for at least 20 cars.

If you are coming from I-80, take the Cummings Skyway exit (near the
Carquinez Bridge.) Turn right onto Cummings Skyway and go about 1 mile. 
Turn left into the large, gravel pull-out. (If you come to a stop light at
Crockett Blvd, you have gone too far).

Walk across the highway.  BE VERY CAREFUL OF TRAFFIC. On your right, you
will see an old dirt road--head to this dirt road.  At the gate, you will be
able to pass under the barbed wire fence through a hole on your left. When
you get on the other side, you are in Crockett Hills Regional Park. This is
public land; you are not trespassing.  

Once through the fence, you'll encounter a dirt road that parallels the
fence.  Turn left on the dirt road and head up the hill.  About halfway up
the hill (about a 4 to 5 minute walk), you will pass a lone oak tree on your
right.  Exit the trail to your right once you pass this oak tree and head
down the ridge a few hundred yards.  You will see a fence in the near
distance with several long piles of wood stacked parallel against the fence.
Hike about half way toward this fence from the dirt road you just left and
find a comfortable place to sit.  It is about an 8 to 10 minute walk from
where you park.

There are cows and bulls grazing in this area sometimes. If they are in your
path, stay about 50 feet away. Avoid getting between a cow and her calf. 
Once you are settled, the cows sometimes come over to investigate.
Typically, they stay about 10 feet away. I recommend gently shooing them
away; they will sneak up behind you and slobber on you if you don't keep an
eye on them. That said, they are not dangerous or a nuisance.  

(Ted): I recommend bringing a light-weight chair.  I brought my scope along
with my binoculars and used both about equally.  I brought a lunch--make
sure you pack something you can eat with one hand since your other hand will
be used to look at raptors that never stop appearing.

Map:  http://www.ebparks.org/resources/pdf/trails/carq_crockett_map.pdf


Harv Wilson