Hawkwatch
Training
Training for field-identification of the hawks is given in a series of evening sessions in July. Nineteen species of raptors are seen from the hill, which comprise the basis of the training. Each program is presented twice in a given week, providing a choice for participants. The training sequence is completed in three weeks, but there are make-up sessions for those who are unable to complete the series. The presentations are well done and invaluable for beginners. Many experienced hawkwatchers also attend these sessions, since refreshing the key points always helps and you always learn something more.
In the field
Each hawkwatch volunteer is assigned to a team which spends one day on the hill every two weeks, beginning in mid-August and continuing until mid-December. A team consists of a day-leader, and ideally at least nine hawkwatchers. The viewing directions are divided into four quadrants, and the team members are divided among them - apprentices are generally teamed with more experienced personnel, which provides learning opportunities. One person is designated to record the observations that are called out by the watchers.
View in the East Quadrant from Hawk Hill.
Team members assemble in the morning at Building 1064, Ft. Cronkhite, in the Marin Headlands at about 8:45. The plans and expectations for the day are reviewed and the group carpools to the hill; operations begin at 9:30. After each hour on site, the observation quadrants are rotated so that everyone gets the opportunity to observe at each post, as well as act as the recorder.
The recorder also measures and documents the temperature, wind speed, wind direction, sky conditions and visibility at the top of each hour.
Observing is completed in the afternoon at 3:30. The team returns to Building 1064, where the day's results are totaled, and the appropriate records are completed. On occasion, the team will have been assigned a housekeeping chore to complete.
The 1998 Tuesday I Hawkwatch Team
The raptor data that are recorded for each hour are the species, and when possible, the sex and whether it is a juvenile or an adult. If the identification is uncertain, the sighting is recorded as an undocumented buteo, accipiter, etc., or undocumented raptor. If there is a disagreement over the identification, the day-leader makes the final decision as to what is recorded.
Correct identification of the hawks is important. However, avoiding misidentification is even more critical. Incorrectly identified hawks can potentially skew the data and lead to misleading conclusions based upon the statistics. Consequently, it is better to report a sighting as undocumented (that is, to say that the identification is uncertain) than to guess. One of the most difficult judgements commonly encountered on the hill is to distinguish between Sharpshinned hawks and Cooper's hawks. There is an on-going effort to quantify the error rate in this identification and to improve the skills of the volunteers. This is called the accipiter ID study, and provides a valuable opportunity for the participants to identify accipiters in a situation where the species is known.
When a hawk flies from one quadrant into another, the observer following the hawk calls out to the appropriate quadrant where the bird is, and whether or not it has been officially counted. Someone in the new quadrant then picks up responsibility for keeping track of the hawk so that it is not recounted.
A frequently-asked-question is how does one avoid repeatedly counting hawks that disappear behind a hill and then reappear? The rule is that if you cannot be certain that it is the same bird, it is counted again. The data are used to track changes in raptor populations and behavior year-to-year. It is therefore most critical that the observations are done consistently by all observers with as little left to individual judgment as possible. The decision was made to monitor raptor activity, rather than absolute numbers of hawks, which would be a more uncertain number.
Another major concern for the observing team is fog or rain. When the hill is fogged in, the team generally waits in Building 1064 until it lifts, or until about 1:00 PM, when the day-leader declares that the day is a washout.
Weather on the hill can be hot, cold, sunny, cloudy, windy or still, so one has to be prepared for all eventualities. There can be times when you get all of these conditions in the same day. The views, except sometimes when heavy fog rolls in, are always spectacular. There are slow times when you are glad to see a turkey vulture, and times when the hawks roll by one after another. For me it's always a thrill to watch a red tail nearby, riding an air current and suspended nearly motionless in space for several minutes.
Adult
red tail hawks (Buteo jamaicensis ): the first hawk was photographed
while front-lit by the sun from my Greenridge Road backyard in Castro Valley;
300-mm lens, 400 speed Kodak Ektachrome film. The second was photographed
while back-lit by the sun in Sunol Regional Wilderness using 200 speed film.
Return to 
main page,
or the Description of the Radiotelemetry program