Friday, November 2, 2007

Saw-whet Invasion!

Scores of tiny little owls are passing you by tonight. I bet everyone who reads this has passed within a half-mile of a Northern Saw-whet Owl within the last few weeks, if not closer. Yet few of our smallest eastern owl are detected, so adept are they at hiding during daylight hours.

Northern Saw-whet Owls are irruptives; that is, they fluctuate from winter to winter in terms of the number of birds that move south. This is a boom year. All of the stations that are part of a banding network known as Project Owlnet are reporting capturing huge numbers. I've heard that some stations to our north have caught up to 1,200!!! so far this fall.
Kelly Sieg, Bill Bosstic, and Bob Placier operate a banding station near Chillicothe that focuses on saw-whet banding, and they've had their best year to date. They opened the nets in mid-October, and have already caught about 50 owls. They'll go to December 10 or so, so the total will soar well beyond the current figure. I would not be surprised if they eclipse 100 owls this season.
They were good enough to allow myself and some friends to come down and join them last night, and by the time we left at 10:15, eight owls had been captured. As they typically run the nets until 1 or 2 am, I'm sure they caught more, but I've not yet heard the final tally. Following are some photos from this adventure.
Some of our subjects. The owls are caught in mistnets strung through good habitat, then brought to a nearby building for processing. These two are hatch-year birds, and they display little to no fear of people. They'll occasionally snap their bills, but for the most part are as docile as can be. In fact, they seem to enjoy being stroked behind the head, and when pleasured in this way will often appear to virtually fall asleep. When we release them outside after keeping them in a dark room until their eyes re-acclimate to the dark, we'll sometimes set an owl on someone's arm or shoulder. It will often sit there for a minute or more, looking around and riding along with the person, before flying off into the black woods for points unknown.
Aaron Boone, coordinator of the Ohio Breeding Bird Atlas, was along last night. Here Aaron processes an owl. This involves taking a number of measurements, gauging feather molt, body fat, coloration, and of course carefully placing a band on the owl's leg. The funnel to Aaron's left is part of the scale used to weigh birds. Most of these Northern Saw-whets tip in at a whopping 92 grams or so. The return rates of saw-whets are far higher than most groups of banded birds. A dozen or so of the owls caught in Chillicothe have been recaptured elsewhere, or they've caught other banded owls. A few nights before this, they captured an owl that had been banded at Whitefish Point, Michigan.


An interesting way of aging birds is to hold them under a black light. This causes certain feathers to glow pink, and with experience banders can use the reflected colors to see how old the individual is. It also creates a groovy atmosphere in the banding station.



This is what a Northern Saw-whet Owl's ear looks like. They are sizeable apertures, and enable incredible powers of hearing. In many owl species, the ears are offset; they do not occur directly opposite of each other. This better allows the owl to triangulate on an object in very dark conditions, and pinpoint its location. If you are a mouse, this means big trouble. You'll probably never know what hit you.

Keep your eyes peeled when around conifers, grapevine tangles, or dense shrubbery. We know that huge numbers of owls are moving through, but they are very easy to miss. But, you just might get lucky and spot one.

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4 comments:

Anonymous said...

Jim,

you're sure right about the invasion. It took me almost 7 years of birding to see one, then I find 2 in less than a month . What magnificent little beasts.

-Phil Chaon

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Anonymous said...

I am a volunteer with a saw-whet banding team in eastern Massachusetts, now in its fifth fall season. Our banding site is on an elevation above a river valley. So far this season, we have banded 228 saw-whet owls and 1 barred owl. Also, we've recaptured 6 owls banded elsewhere, including one from as far away as Michigan (a rare occurrence).

Numbers of saw-whets moving to find food show cyclical variations. This is a very good year in the East, while last year brought perhaps a third the usual number of saw-whets to most eastern banding stations.

You've done a very nice job showing and explaining the saw-whet project in a nutshell. Thanks.

Anonymous said...

Thanks for your comments about the saw-whets, and it's amazing to hear of the numbers being caught this year. I found out that they caught four more birds after we left. Then, a few nights ago they caught an amazing 20 birds in one night! So far, the Chillicothe banding station is up to 78 birds since mid-October.

Jim McCormac