[SBB] Falcons in Alviso and ID Question

[Andy Pedler <[[email protected]]>]

Hi all,

Falcons were the specialty at Alviso today at lunch time.  There was a standard issue adult Peregrine (Anatum race) sitting on one of the power towers at the bend in the road leading to the EEC.  Also a few Kestrels around.

Better yet, I had a juvenile "Peale's" race Peregrine fly by as I was looking at the gull flock from Spreckles St.  This bird flew past from south-to-north, about 5 feet off the ground, just west of the railroad tracks, barely reaching the altitude of the railroad embankment.  It headed north and was not seen again.  This was a striking bird in how dark it was.  It looked like a Merlin on steroids.  The face was basically all dark, and the entire body was a chocolate brown with the back being slightly darker overall than the rest of the body and underwings.

Finally, out on Disk Dr. driving past the Jubilee Center, I saw a falcon flying over the field west of the road.  I stopped the car
 and got good looks at this bird as it flew over me, catching a thermal and going up and up, eventually out of sight.  I've seen this individual bird three times in the last couple of weeks, and I'm really confused as to whether it is a Prairie Falcon (probably juvenile) or a juvenile Tundra race Peregrine.  This bird is brownish overall, with a distinctive moustache mark on the face.  When it flies, the underwings are darker near the body but do not have the distinct black "wingpit" patches that an adult Prairie Falcon would have.  The tail and outer wings have a translucent look when it soars against a bright sky (as it was today).  The wingbeats are quick and shallow when it takes off.

A couple of weeks ago I watched this bird sitting on the field across from the Jubilee Center.  It would run around on foot chasing ground squirrels.  Remarkably, it caught something (not a squirrel) using this method, then flew up to the top of a
 nearby power pylon to eat.  That day I assumed that this was a Prairie Falcon based on its behavior; typically the Peregrines at Alviso are either in the air or sitting on pylons, and not on the ground.  However, after studying some guides, I'm not real sure how to distinguish between a juvenile Prairie and a juvenile Tundra race Peregrine.  Any advice is greatly appreciated.  

So color me confused...if anyone else sees this bird and can make a positive ID, or offer suggestions about what to look for the next time I'm out there, I'd very much appreciate it.

Andy Pedler - Newark, CA

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