San Diego Natural History Museum--Your Nature Connection[San Diego County Bird Atlas Project]

WRENDERINGS
The quarterly newsletter for Bird Atlas volunteers
Winter 1997

In this Issue
Time to Gear up for the San Diego Bird Atlas' First Winter Season

Notable Discoveries

Reports from the Field
The Learning Curve
Stepping Back in Time

Focus On...
Violet-green and Tree Swallows

Progress Report

News and Updates
Feathering Our Nest Egg
Christmas Bird Counts Count Toward the Bird Atlas
Blockbuster Weekends

Time to Gear up for the San Diego Bird Atlas' First Winter Season

The first of December 1997 marks the beginning of the San Diego County Bird Atlas' first winter season, so please plan some time to get into the field during the new three months. The winter phase of the project is unique to San Diego County's effort, giving us an opportunity to set a precedent for other atlases. All other county atlases in California, and possibly state atlases nationwide, cover breeding birds only. San Diego County's having substantially more wintering than breeding species draws us to give this season equal attention. Winter habitat is as essential to birds as breeding habitat.

Yet the winter phase is simpler to handle in some ways than the breeding season. Most notably, we won't have any breeding behavior to record, just an estimate or count of the number of each species seen in the square on each day afield. It is possible, of course, especially with raptors, owls, and hummingbirds, that you will observe birds breeding during our three-month recording period for the winter season, December-February. If you do see breeding behavior during the winter, please record your observations on an incidental-observation form for the breeding season or in the comments section of the winter-record form.

Because of the greater simplicity of the winter phase, we need only one form for recording data. The form has space for 12 field trips. Just enter the date along the top of the column, then insert your estimate or count of the number of each species seen on that day. Be sure to enter a specific number, even if just an estimate, rather than a range or order-of-abundance level-our computer program is able to handle specific numbers only. As on the block-summary form for the breeding season, enter an abundance level only after you have achieved the threshold criteria for your square.

The threshold criteria for the winter phase are similar to those for the breeding season—at least one visit to every accessible habitat, minimum 25 hours in the field, observing at least 90% of the number of species on the target list. The one criterion that differs materially in the winter phase is the spreading of our effort in each square over at least three years. Because the distribution of birds from winter to winter varies so much more than from summer to summer, we want to spread our field work in each square over several years. This allows us to assess some of this annual variability and to express a qualitative difference—whether the species winters in the square regularly or irregularly. Therefore, you won't be entering an estimate of abundance level on the form for at least 3 years.

The front of the form is similar to the front of the block-summary from for the breeding season. The chart has space for 12 field trips. For each field trip, enter the date, number of hours in the field and total hours from home (including driving time), and mileage (for your records—it's tax-deductible), and check the habitats visited on the field trip. Just continue on another form if you make more than 12 field trips. And please send the form to the Natural History Museum as soon as you've completed your effort for this winter.

With this issue of Wrenderings, in addition to winter-record forms and incidental-observation forms, all participants who have adopted squares are receiving more field maps plus the winter target list(s) for those squares. Remember, the target lists are just an estimate of what may be in your square; it's certain that with any significant effort you will find species not on the target list. These should more than make up for species included on the target list mistakenly. Getting to 90% of the number of species on the winter list should be much easier than confirming breeding of 50% of the number of species on the breeding-season list. As always, if you have any questions, don't hesitate to call Phil or Ann at 619-232-3821 ext. 235.

 -- Philip Unitt

Wrenderings Archive | Bird Atlas Introduction