Fall Owl Banding: Week 4

We are officially halfway through our 2022 Fall banding season. Time is flying by so fast and the owls are on the move. Just in the past week, we caught 128 Northern Saw-whet Owls (NSWO) and our first Barred Owl (BDOW)!  Making a total of 242 NSWOs so far this season.

Here is the beautiful Barred Owl caught the evening of 10/12/22. A young hatch-year male.

The night of October 9th into the 10th was our busiest night so far. An MSRW record-breaking night with a total of 65 NSWOs! Needless to say, we had our hands full. But with our experience combined, Hannah and I make an efficient team and the night went very smoothly.

Processing an owl only takes 1 to 3 minutes each and during that time we place a band on their right leg which is marked with 9 digit number, unique to each bird. Then we collect their weight, wing and tail measurements, age, sex, and if they’re in molt.
In all raptor species, females are larger than males. Between their weight and wing length, we can determine if we have a male or female owl. Females weigh between 86 and 105 grams. For comparison, a medium tomato weighs around 100 grams. Our largest female this season weighed 108 grams! Males weigh only 74 to 88 grams which is about the same weight as half a cup of blueberries.

My favorite part of the process is aging an owl. NSWOs, and other owl species, have a chemical known as porphyrin that glows a fluorescent pink color under ultraviolet (UV) light. When the feather is new there are a lot of porphyrins present in the feather. Over time, and when exposed to sunlight, the pigment fades and you only see a white feather. As an owl gets older they go through different molts and replace old feathers. The new feathers coming in will glow pink once again. Based on the pattern of pink in the wing, we can age the owl.

Here is a After-Second Year (ASY) Northern Saw-Whet Owl. The pink feathers can be seen under a UV light due to the chemical porphyrin found in new feathers. This is a ASY owl because it has at least 3 generations of feathers. A owl that hatched this year would have all new feathers and it would be completely pink all the way across it’s wing.

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