Figured several of you would find this interesting.

Edge Wade
Columbia, MO
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Begin forwarded message:

> From: Lee Ekland <[log in to unmask]>
> Date: Thu May 27, 2004  02:56:00 AM US/Central
> To: [log in to unmask]
> Subject: [CALBIRDS] Birds on Radar- A Reply from the National Weather
> Service
> Hi Calbirders,
> Several weeks ago there was a discussion on this list about
> radar detecting bird movement.  I am fascinated by this
> subject and wrote the National Weather Service office
> in Hanford (San Joaquin Valley) to ask how they determined
> some of  the movements they observed on radar were birds.
> I just received their reply today and am posting it with their
> permission.
> Lee Ekland    Mariposa
> Hi Lee
> Jim passed on your question to me since I am the radar focal point and
> usually look for anomalous radar returns. The WSR88D radar is extremely
> sensitivity in clear air mode and many times does detect flocks of
> migrating birds, swarms of insects and dust clouds. You can not be
> absolutely sure what the radar is detecting but you can make a
> reasonable assumption of what it may be unless there is an observer
> near the area of interest. During one of my midnight shifts I observed
> a flock take off from some dry lake beds in Nevada east of Reno, fly sw
> through Fresno county over the Sierra disappearing near the Channel
> Islands off the coast towards morning. This was surprising to me because
> I was not aware flock of birds could find their way at night time. I
> have also seen flocks leave in the morning from Lake Nacimiento and the
> San Luis Wildlife Refuge in the morning and fly across the San Joaquin
> Valley to the foothills of the Sierra. I presumed that they were flocks
> of water fowl birds since they originated from a water source. Most of
> the time the birds will show up on the radar as an area of moving low
> reflectivity values in the 0.5 degree slice since most birds fly at low
> levels. However, flocks flying at higher elevations such as the one
> that flew over the Sierra near 10 thousand feet, will showed up clearly
> in the composite reflectivity product. A good method to detect flocks
> is to use web pages that can loop several radar images at a time. This
> way one may pin point when the birds first leave the roosting area
> after sunrise or sunset and fan out as they move further away. In the
> case of bats, the reflectivity area will start out as small point
> source then turn into an expanding donut shape as the bats fly further
> away from the home caves.
> I hope this helps
> Modesto Vasquez
> [Non-text portions of this message have been removed]
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