[image id="9227" title="immature red tail hawk" class="size-medium wp-image-19389" width="300" height="198" ] Raptor migration numbers are important indicators of an ecosystem's health. Corpus Christi Hawk Watchers look for immature red tail hawks such as this one during their annual counts to compare to the previous and next years' numbers.

HAWK COUNT SEASON ENDING IN COASTAL BEND — Corpus Christi's hawk watchers are known worldwide for their annual raptor counts, taken each year August 15-Nov. 15 from the Hawk Watch Platform at Hazel Bazemore Park. An average of 700,000 raptors pass over the Coastal Bend area each fall on their way to warmer southern climes. The count has reached as high as 1 million birds, the most counted anywhere in the world. The platform where most of the counts occur is located near Calallen, just 17 miles from downtown Corpus Christi.

Volunteer members of the Corpus Christi Hawk Watchers point their binoculars to the sky "gridding kettles" every day during the fall migration season. Anyone is welcome to come help. A seasoned birder is always on hand at the platform each day to teach and record. Numbers are sent to the Hawk Migration Association of North America.

Raptors fly in groups called kettles. Counting the number of birds in a kettle is called gridding and requires practice and a flexible neck. Patty Waits Beasley of Hazel Bazemore Hawk Watch explains the process on the Texas Hawk Watches' website. http://www.ccbirding.com/thw/id/kettlecount.htm

Get a rough count based on the density and the depth of field of the group (in real life, the hawks are three dimensional, of course, and so are their flight paths. Watching them a second or two before starting to "grid" the kettle will allow you to get a feel for the "thickness" of the kettle; how many layers of raptors are in the kettle, and the depth of the hawks within the layers. Once you get a feel for the layers, so to speak, and the motion and density, you factor that into your equations and voila! You now have a "snapshot" of your cross-section of the kettle.

Now, before those raptors get out of sight, move your binos across the sky, tracking the movement of the kettle, and count the number of fields that are covered by your field of view. Take into account the changes in the densities and depths of field, and multiply the numbers out ("x" number of fields by 400 raptors; "x" number of fields by 200 raptors, etc.) and add them all up. Congratulations! You have now counted your first kettle!

Sound complicated? That's why experienced birders are always on hand to help! Birders have tallied more than 25,000 birds a day from the platform, which sits atop a hill overlooking coastal prairie.

To keep track of the hawk watchers, who are keeping track of the hawks, visit the group's Facebook page.