[obol] Banding chat

[Dennis P. Vroman]

Tail-less bird percent:

Need to correct my mis-calculation on tail-less birds captured.  Tim Janzen pointed out that my math skills needed work.  The reported 0.004% figure for captured tail-less birds for this year was incorrect.  So, here's the corrected figure, including 30 more "tailed" captures, which now makes the percent of tail-less captures 0.38%.  I suspect it will be even less as the year goes on.

Bird Molt:

David Fix mentioned that bander tend to collect molt information, which I do.  Most passerine birds are just starting to go into primary flight feather molt.  However, if your a bird and wish to retain the ability to fly, then your not going to molt all your flight feathers at on time (like Ducks do).  So, what happens is what's called symmetric molt, a few feathers are molted at any one time during the molt.  Today I captured a BUSHTIT adult in symmetric primary flight feather molt, primaries 1 and 2 were molting (1 mostly grown in all ready).  1-2 are near the center of the wing, primaries 9-10 are at the outside of the wing.  As 1-2 grow in, the next feathers in line drop out and start molting (numbers 3 - 4 - 5, etc).  So, at any one time, the bird would have nearly all its wing surface and could continue to fly.  Being symmetric molt the same numbered feathers would be molting on each wing, so the wing surface would be in balance.  Pretty neat!

Besides lost of all feathers at one time for whatever reason, generally, passerines only grow in all their flight feathers once...as juveniles before leaving the nest.  The tail feathers are the last to grow in and if you captured a juvenile bird still growing tail feathers, then you know it has not been out and about for too long.

...if you want to see a molting "mess" look at older Woodpecker molt, pretty scary, for they can have 3 or more different years of flight feathers at one time.  As a results, Woodpeckers (if you know what your doing) can sometimes be aged back 3 years.

Dennis

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