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DVOC Field Trip Report
by Adrian Binns
November 6, 2004
HIDDEN VALLEY SAW-WHET OWL BANDING STATION
In the last 10 years or so over 1000 Saw-whets are caught and banded in major irruption years, which usually occur ever 4 years, at banding sites along the Kittitany ridge. In this short period of time the data collected through this Ned Smith Center initiative, along with data from the other 70 Saw-whet banding stations in the US and Canada, has shown that the central Appalachians are a major flyway for what is turning out to be our most common small forest raptor.
Every other year on average is an irruption year, though these tend to be smaller spikes in numbers compared to larger totals every 4 years. Everything was going true to form until 2003. High numbers were banded in 1995 and 1999 and expectations were high for 2003, but alas it was a disappointing year and it is still undetermined as to why. 2004 has certainly been better, but the one glaring omission in the data is the lack of juveniles. Theories abound and the word from ‘up-north’ is that it has been a record low for rodent populations and this no doubt is responsible for Saw-whets only laying 1 or 2 eggs at best, compared to double digits in a good year. With the lack of food comes another interesting fact; the birds are not getting enough to eat to replace their flight feathers. This of course being noted when in the hand at the banding station as they head south as far as Virginia and Tennessee.
80% of the birds banded are females, as studies have shown males tend to stay on territory throughout the year, and interestingly at the Small Valley site this year 9% of the birds caught had already been banded further north.
On this very calm crystal clear starry evening the first two net checks came up empty. Was it too clear a night, though the moon was not to rise till very late? The third check was a charm as a small female juvenile was caught. With the lights out we were able to see the glowing flight feathers when placed next to an infa-red light, these being the porphyrin pigments associated with juveniles. Deborah Danila, who has been volunteering all season, recorded all measurement and data. On subsequent net checks 2 more individuals were caught, both being after hatch year (ahy) females, bring our total to 3 for the evening before most of us left, very contented, around midnight.
Images by Bert Filemyr