During the past five Christmas Bird Counts, Pepper Trail and Chris Uhtoff have paddled a canoe across the calm Rogue River waters above Gold Ray Dam to witness a ribbon of black with tinges of orange stream over the waters of Kelly Slough.

During the past five Christmas Bird Counts, Pepper Trail and Chris Uhtoff have paddled a canoe across the calm Rogue River waters above Gold Ray Dam to witness a ribbon of black with tinges of orange stream over the waters of Kelly Slough.

Tens of thousands of robins that spent their nights roosting in old cottonwoods over the feather-warming waters headed out for breakfast while Trail and Uhtoff attempted to estimate their numbers.

But the warm waters of Kelly Slough are gone now, drained with this summer's demolition of the 106-year-old dam. So Uhtoff and Trail will abandon their canoe in favor of rubber boots to see whether the robin phenomenon has outlived the slough.

"We'll find out Saturday," Trail says.

Saturday marks the Medford version of the National Audubon Society's Christmas Bird Count, the 111th such annual exercise in "citizen science," in which amateur birders count all the birds in a given area on a given day from sunrise to sunset.

The national event started Tuesday, Dec. 14 and continues through Wednesday, Jan. 5.

The survey takes place within "count circles" that are focused on specific areas and organized by a count compiler.

The circles cover a 7.5-mile radius from a specific centerpoint. In Medford, ground zero is the intersection of Highways 62 and 140 — a point that's been used to center this count since it began in 1953.

The data are compiled and shared nationally for a snapshot of what birds are present and visible on count day. The long-term data set can help show trends in abundance and distribution of species.

In Southern Oregon, this methodically repetitious endeavor will have two new wrinkles this year. For the first time in 70 years, a count circle has been drawn in Ashland, and the new-look Kelly Slough will offer birders an altered habitat from which to measure local bird life.

When the slough drained in August, it exposed swaths of mud and vegetation not exposed since the Teddy Roosevelt administration.

"Within days of the water going away, the animals came out exploring that area, just like people," says Craig Tuss, who is overseeing a massive rehabilitation effort along Kelly Slough and other areas changed by the dam's removal.

"It's amazing the amount of tracks you see — anything from bear to raccoon, muskrat, deer and elk," Tuss says.

But perhaps the most amazing denizens of the slough have been the robins — in part because of the nature of the bird and the natural aspects of the slough.

The Rogue Valley often becomes a winter home for many thousands of robins migrating south from Alaska, usually reaching here around Halloween. They are not true flock birds, but their large aggregations serve two clear purposes, says Trail, an ornithologist at the U.S. Fish and Wildlife Service's National Forensic Laboratory in Ashland.

First, night roosting together in large numbers offers better protection from predators, and the robins share information about places to find food, heading out en masse just before dawn for breakfast.

The flock grows as individual or small groups of birds notice the convoy-like collection of their brethren and simply join in, and no place has been better suited for them than Kelly Slough. Trail and Uthoff have counted as many as 50,000 robins there during previous bird counts.

The area is home to great clusters of old, large cottonwoods that can support plenty of birds. It is isolated enough to prevent evening disturbances and the impounded water beneath the cottonwoods soaked up enough sunlight during the day to act as a night-long radiator during cold winter nights.

While the security blanket remains, the warmth of it is now gone.

Tuss says the slough area remains brimming with bird life, but whether it is still a winter respite for robins remains to be seen.

"I don't expect there to be an immediate response," Trail says.

The relative isolation and the large cottonwoods are still there, and they still can serve most of the nighttime needs the robins seek.

"I still think it can be an attractive place to roost — at least for a time," Trail says.

The long-term marriage between the robins and the slough likely will rest largely on whether the area gets developed and whether the trees remain.

The water table could drop and the trees not survive, he says. And, over time, the robins might take their aerial show elsewhere.

As for now, robin numbers appear down this year valley-wide, and other extraneous variables always impact the counts, Trail says.

"The numbers might not be that impressive for reasons other than the slough being drained, but I'll be very interested to see," Trail says.

"We'll see Saturday."

Reach reporter Mark Freeman at 541-776-4470, or e-mail mfreeman@mailtribune.com.