Friday, November 3, 2017


Yep, that's how many owls we have banded since our first night of owls on October 12, with an opening night of 13 owls! Now on November 3rd, we still have a couple of weeks of migration (October 15-November 15, with sampling on either end). It is our highest number of migrating owls since we have run the station annually in 2005. VERY exciting! The majority >80% have been Hatch Year (HY) owls, hatched sometime this summer in 2017. All these youngsters are easy to age. Here's how. We look at the dorsal side of their wings to see what their molt pattern looks like. And we use descriptions like chocolate to describe the color differences between new and old feathers. We look at the remiges; the primaries (10) and secondaries (13).
Hatch Year, all feathers one age (uniform molt pattern)

Second Year, outer primaries and inner (closest to body) secondaries have been replaced,the new feathers are darker(dark chocolate) and of higher quality then the old,
retained (milk chocolate) feathers. 

After Second Year, (over 2 years old) has three generations of feathers
fresh (dark chocolate), old (milk chocolate) and very old (old milk chocolate!)
And then, there is the magic trick to confirm our age determination. We look at the ventral wing and turn on a black light and like a black light poster, the feathers glow! It's actually a pigment called porphyrin. If you like chemistry, go here to learn more about porphyrins.

Notice the difference in porphyrin glow? As the feather ages, the pigment ages too;
the older feathers don't glow as brightly as the fresh feathers. How old is this bird?