|1/7/2014 5:08:00 PM|
By Jim Anderson
|American Robin doing its thing: The early bird getting the worm. photo by Jim Anderson|
Last week my wife, Sue, and I conducted our segment of the annual Oregon Eagle Foundation's Mid-winter Eagle Count.
The route begins in Sisters, goes out Wilt Road to Lake Billy Chinook, over to Culver and Redmond and back through Fryrear and home. It took Sue and I, running it in our old Toyota 4Runner, a total of 128 miles to cover it all.
Aside from the three bald eagles (one juvenile and two adults) drooling over the geese at the Pine Meadow Ranch in Sisters, we almost got skunked for eagles. One adult baldy was observed perched in a big snag on the Metolious arm of Lake Billy Chinook, and one more was observed on the Deschutes arm of Billy Chinook. We were thankful and pleased when a pair of golden eagles popped up out of the Crooked River arm of Lake Billy Chinook near Culver.
The big surprise was right near the spot where the golden eagles appeared, on Lasalle west of Juniper Butte. The grass hay field on the north side of the road was "filled" with hawks, while on the south side there were thousands - literally - of robins eating something(s) in the irrigated alfalfa fields.
The hawks in the field were assorted red-tailed and rough-legged, accompanied by a northern harrier, and the most interesting thing was they were walking around, or in most cases, just standing still in the field, as though waiting for something to happen - which at times did.
The red-tailed hawks would suddenly leap into the air, or hop and run through the grass to catch something. The rough-legs - who, incidentally have come to Oregon from the Arctic Circle to spend winter with us eating voles and gophers - would quickly fly up to about 20 feet above the surface, hover in the wind momentarily, then suddenly drop to snatch at prey.
Turned out the field is infested with voles (a small, short-tailed, dark-furred rodent that can reach prodigious numbers). When we walked out the next day with a couple of our kestrel-banding helpers, Maddie and Alex, to see what was going on, we found hundreds of vole holes and runways, and watched with awe as a rough-leg grabbed up a vole close to us.
It is at times like this that the specter of poison enters my mind. If the owner of the hay field decides there are too many voles eating his grass hay and starts applying chemicals or poison pellets, the results could be disastrous. Yes, thousands of voles will die, but hundreds of hawks would also fall victim through secondary poisoning, which would make the situation intolerable.
It was the same fear with the robins. It took us quite a while to be certain what they found so delectable in the irrigated alfalfa hay field, but we kept at it. We were fortunate to get close to about 500 robins who were so intent on eating what we wanted to learn about, they tolerated our non-moving vehicle on the road.
It was plain that they were listening (for their food to make a little noise); the birds demonstrating the well-known listening posture, with head cocked to the side. As we watched, a robin would suddenly dash forward a few inches, probe the ground directly under its feet, and come up with something that resembled a worm.
It happened so fast, it was infuriating; the food was gone before we could identify what it was. Finally we got organized, all four of us watching the same robin at the same time. "Ah, ha! Did you see that!" Alex shouted (the windows were closed on the 4Runner). "That was a worm!" Maddie said, more quietly. The more we watched, the more we were convinced what it was some kind of worm-like invertebrate the robins found so delicious. It was a classic example of the early bird getting the worm - even on a 40-degree day.
At first I was afraid the invertebrates were cutworm larvae. Hay-farmers do not like or put up with cutworms. They're the larval form (caterpillar) of the Large Yellow Underwing Moth (Noctua pronuba) that eat and destroy young tender plants like there's no tomorrow.
Sure, they're good eating, especially for birds and shrews, but if the farmer uses chemicals to kill the moth caterpillars, that's also the end of the trail for robins and shrews - and we estimated there were around 10,000 robins in that small area of the agricultural community between Hwy. 97 and Lake Billy Chinook.
For those interested in what we observed on the mid-winter eagle count, here it is:
Bald eagle - 4 (2 adult, 2 juvenile)
Golden eagle - 2 (1 pair)
Red-tailed hawk - 33
Rough-legged hawk - 3
Northern harrier - 1
American kestrel - 10
If you want to join in next year, give us a call: 541-388-1659, or email: firstname.lastname@example.org.
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