Thursday, November 13, 2008

Slip slidin' away

Biologists who use telemetry to track animal movements have a variety of ways, temporary and permanent, to attach the transmitter, from surgically implanting it in the body cavity of the subject (obviously pretty permanent) to using a light adhesive that will come off in hours, days or weeks, depending on the need.

Most bird researchers use an external harness of some sort, and that's what we've used for the past seven years in our saw-whet study. We create a figure-eight of very thin elastic nylon beading cord that goes around the wings and holds the radio high in the middle of the owl's back, tucked down under the feathers.

Given that the batteries only last about three months, we don't want to saddle the owl with even the relatively light weight of the radio for the rest of its life, so we make the harness with a knot in a fairly accessible location, on the bird's side, where it can preen and pick at it. We zap the knot with a drop of SuperGlu to give it some protection, but eventually the owl will take it off...hopefully only after it's left the study area or the battery has died.

(©Aura Stauffer)

Morticia, it seems, was a determined little girl. Aura Stauffer was tracking Quasi and Morticia on Wednesday, and after finding Quasi in her accustomed haunts in King's Gap Hollow, she followed Tish's signal to a grove of young white pines. Aura had a strong signal from a fairly open part of the trees where there was obviously no owl perched, so she had a hunch what was up. Today, Aura went back and was able to locate Morticia's radio and harness on the ground. Since the battery only has a few weeks' worth of use, we'll probably recycle the transmitter to a new owl quickly.

The netting and banding have been pathetically slow this week, despite what had been pretty good conditions. All stations combined had three owls Sunday, none Monday, two Tuesday and none Wednesday, as the first rain showers moved in.

Hidden Valley crew members Pat Trego, Gene Harris, Randy Lauff and Denise Donmoyer (©Scott Weidensaul)

We have had some interesting visitors, though. Tuesday night at Hidden Valley we were delighted to welcome Randy Lauff, a professor of biology at St. Francis Xavier University in Antigonish, Nova Scotia. I've been corresponding with Randy for years about his nest-box studies of saw-whets and boreal owls up there, and he's now doing migration netting as well. Although we had only one saw-whet to discuss that evening, we had a great time hearing about his work and getting really, really jealous as he showed us photos of his boreal owls.

Our night tracking teams are taking a well-deserved break after four nights of nocturnal work, and Anna Fasoli has worked up some activity maps from the recent tracking. Here's one from Sunday, Nov. 9, showing Quasi's movements. This map does not show the error polygons that indicate how reliable a particular location is, so it's best to consider those red dots as a general indication of where the owl was at various times, not a pinpointed spot. The X's show where our two tracking teams were positioned -- my nephew Connor Callaghan and me on the left, Anna, Jen Smetzer and Kim Mihalek on the right.

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