Dead Barn Owl Found at Wulf Test Field

April 26, 2000

by Paul Gipe

We found a dead bird with a severed wing on our ranch in Tehachapi, Sunday, April 23. I hired Jennifer Noone, a biologist, to examine the carcass. Noone worked for several years on bird-wind turbine studies in the Altamont Pass. Here's what we found.

Barn owl (Tyto alba), plentiful around Tehachapi. Found about 50 yards from and at about a right angle to the turbines (Air 303 on 45-foot guyed tower, BWC 850 on 65-foot guyed tower) and prevailing wind direction behind a line of red willows about 35 feet tall. Severed wing about 3 feet away. Shoulder bone "likely broken by impact". The impact split the bone.

There was a pile of feathers nearby and the carcass had been "predated". The feathers indicated that it was likely eaten by a red tail hawk. Red tails pluck their prey says Noone. Coyotes chew the whole carcass. From the pile of feathers and the lack of gnawing marks on the bones she concluded a red tail had eaten the owl after it was down. It's unlikely that a red tail could have broken the wing in the way that the wing was severed.

Dick Anderson, CEC biologist, suggested that if the rotor had severed the wing the carcass and wing would normally be more widely scattered. We didn't find any other evidence near the turbines. Noone agrees though she suggests that it could have hit the guy cables and reached the willows before it died or was killed by the red tail.

Noone dated the carcass to about mid week. Maggots had already left the carcass. Eyes had dried but talons were still flexible.

There was no evidence the owl had been shot.

Zond's wind turbines are downwind about 500 yards.

This is the first bird carcass we've found in the one year that we've had turbines operating continuously. We don't search the area comprehensively. We do occasionally find the remains of coyote prey. I found the owl because it was on a route I walk to a spring.

Conclusion: uncertain. Noone couldn't say with any certainty that the wind turbines or their towers killed the owl. But she couldn't say that they didn't either. I'd give this a 50/50 probability of a small turbine kill.

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