A Short-eared Owl Project

 

(This 831st Buffalo Sunday News column was first published on February 25, 2007.)

 

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Short-eared Owl ready for banding

and transmitter attachment

 

Years ago Cornell biologist Bill Hamilton, Jr. gave a talk about predators to the Bergen Swamp Sanctuary Society. In his talk he told how prolific meadow voles (aka field mice) are. He said that in two years a single pair would have enough offspring, if they all lived, to make a row of mice, head to tail, that would reach from Rochester to Albany and back and, he added, with enough left over to reach the moon eleven times.

 

I have never checked out his calculation, but I do know that field mice have a litter size that averages six, they breed in the wild eight or nine times each year and females bear young by the time they are a month old. (In a laboratory a single female bred 13 times in her first year.)

 

Thank goodness for predators. If it were not for them, we would be overrun with these mice. Joseph Merritt summarizes their enemies as snakes, weasels, mink, raccoons, foxes, skunks, opossums, shrews, house cats and humans as well as many birds including hawks, owls, blue jays, crows and shrikes.

 

One of those predators is the short-eared owl, a bird that is on the state endangered species list. Department of Environmental Conservation biologist Chuck Rosenburg is working with University at Buffalo student Sarah Mielke on a study of this rare winter visitor to this area.

 

I love to watch these owls. They are crepuscular, that is they feed at times of dimmed light -- in the evening or early morning. They course over fields with an undulating moth-like flight, much of the time scarcely moving their long wings. Like all owls, and foxes as well, they have remarkable hearing that gives them the ability to detect mice moving deep under the snow. Suddenly they will interrupt their flight to drop to the ground, their talons piercing the snow to reach their prey.

 

Chuck and Sarah, together with Tom Burke, Garner Light, Mike Galas, Tony Wagner and Jim Pawlicki, set out to capture some of these owls in order to mount tracking devices on them to follow their movements.

 

They first tried a trick used by hawk banders. They set out a cage containing a mouse. On the cage they attached monofilament (fish line) loops. In its attempt to get to the mouse, raptors get their legs entangled in the wires and can then be carefully handled and released by their capturer. Chuck also played a recording of a mouse call next to the trap.

 

Unfortunately this approach didn't work. Chuck feels that the recorded mouse squeals may have been too loud. (I prefer to think that the mouse was saying something like, "Stay away I have a gun.") In any case one owl dropped into the snow right next to the trap to take a mouse, paying no attention to the caged one nearby.

 

A new approach was in order. The team knew several locations where short-eared owls roost in small trees. I joined them when they observed one group in a small spruce. At first I couldn't see any owls, but finally Chuck pointed out one, two, three and then four of them in the single six foot tree. One finally came out in the open to give us excellent looks at a most attractive bird.

 

These owls are mottled brown and black, their yellow eyes staring out of a round face below the two tiny feather tufts that give them their name. They are twice the size of screech owls but still much smaller than great horned owls.

 

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Chuck Rosenburg releasing a short-eared owl

from the mist net in which was captured

 

This time the team set up banding nets near one of these roosts and, although one owl bounced off the net, another was captured, its backpack transmitter mounted and the owl quickly released.

 

One objective of this important study is to document short-eared owl wintering locations in western New York and to identify important foraging habitats. The information will be used to establish a long‑term population monitoring program. You can help by reporting observations (locations, numbers of owls, general behavior, etc.) to Chuck Rosenburg (office phone: 716-851-7010, cell: 716-622-3287, e-mail: crosenburg@gw.dec.state.ny.us) or Sarah Mielke (phone: 716-622-9506, e-mail: sarah.mielke@gmail.com).-- Gerry Rising