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December 2010

In This Edition

Northern Harrier

—Nicholas Del Grosso

Photography by Mary Ann Brittain

One of the first signs that winter is on the way is the appearance of the Northern Harriers in the skies over the Tallgrass Prairie. Most of the birds seen on the Tallgrass Prairie are birds that have been pushed south by the gathering winter. In the spring these same birds return to their northern breeding grounds. The Northern Harrier breeds across the northern portion of the continent from Alaska across Canada. It is also a year round resident in the western United States and the mid-latitudes of the eastern United States. The only confirmed breeding in Oklahoma occurs in the panhandle counties. Winter bird counts at the Tallgrass Prairie over the past 10 years have averaged 64 sightings a year. In 2010 the count tallied 105 birds.

Of the thirteen worldwide Harrier species only one can be found in North America. The Latin name for the species, Circus Cyaneus, is an apt description of both behavior and appearance. Circus refers to a literal translation of around and this describes the habit of the Northern Harrier of flying in quartering circles as it searches the prairie for small mammals and birds. Cyaneus references to the blue gray coloration of the male Harrier. The old terminology for this bird was Marsh Hawk and although you will find it occasionally in a marshy area, you are more likely to spot this bird circling on a grassy prairie or meadow. The word harrier can be traced back to the old English word hergian, which means a hostile attack, which describes what happens when this bird launches its aerial assault.

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The female is larger than the male. Females are dark brown above with buff coloration below. The male is blue gray above and white below. As they soar in search of prey a white patch can be seen on the top of their torso between their body and longish tail.

If they are not in the air circling in search of prey you can sometimes find them perching on a rock, log or high point on the ground. Unlike other hawks you rarely find this bird using fence posts, trees or phone lines as perches.

One of the unique things about this hawk is where it nests. It builds a mound of sticks, reeds or grass on the ground. The female lays 4-5 pale blue or white eggs in the nest. Northern Harriers are polygamous and a male will service several females in his territory. The courtship flight is a series of barrel-rolls done by the male. After mating the males role is not over, he will assist the 3-4 females in his territory with the feeding of the chicks and the females on the nest for the first 10-14 days. The young fledge within 33 days.

Photography by David L. Ross

The Cornell Ornithological Survey does not list this bird as one of particular concern region wide, however in Oklahoma it has been estimated to have had a decline of 15.6 per year.

Another behavioral trait of the Northern Harrier, which sets it apart from other hawks, is that it uses both sound and sight when it is hunting. When you study the face of a Harrier you note feather dishes around the eyes which are used to catch and amplify sound much like an owl. This aids the birds as it searches its environment for prey in the tall grass.

In the winter Harriers form communal night roosts on the ground in grassy areas. These roosts can be made up of a few to hundreds of birds. Interestingly enough they can sometimes share their roost in the company of Short-eared Owls. Over the coming months enjoy watching these visitors from the north as they harvest the bounty of the Tallgrass Prairie.

Docent Coverage Of Season Days

—Andrew Donovan-Shead

We slipped a bit a bit more in November, but we are still ahead of last year.

Docent Coverage of Season Days

 

Tallgrass Prairie Preserve Visitor’s Center Latitude & Longitude

Here is the latitude and longitude of the Visitor’s Center that you can give to visitors for entry into their GPS navigation device.

Kiosk Maintenance

The manufacturer’s instructions for cleaning the touch-screen recommend use of a soft dry cloth only. This proved inadequate for smeared fingerprints. Soft-paper kitchen towels work well, slightly damp with a small drop of soft handsoap. Application of a dry kichen towel removes any residual moisture.

Over time, a matter of several weeks continuous operation, I have noticed that calibration of the touch-screen drifts away from the initial set-point. If you notice that the cursor isn’t under your finger when you touch the screen then restart the kiosk by unplugging it from the wall, waiting a few moments and then re-inserting the power plug. It will restart and recalibrate.

This link points to the complete Kiosk Maintenance Manual.

Back Issues

Some printed back issues of the Docent Newsletter, to February 2009, can be found in the two green and one blue-black zip-binders, stored in the Perspex rack by the file cabinet in the office of the Visitor’s Center.

All back issues are available electronically via the links shown below. All newsletters prior to December 2007 are available in Portable Document Format (PDF), which means that you will need Adobe Reader installed on your computer to read these files. All newsletters from December 2007 onwards are in HTML format that is easily read using your web-browser.

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Newsletter Publication

Deadline for submission of articles for inclusion in the newsletter is the 10th of each month. Publication date is on the 15th. All docents, Nature Conservancy staff, university scientists, philosophers, and historians are welcome to submit articles and pictures about the various preserves in Oklahoma, but of course the Tallgrass Prairie Preserve in particular.