Another ID Challenge - 04 Oct 2010

As I left work this afternoon I could hear the loud 'tsip' of what I thought was the season's first American Tree Sparrow.  I grabbed the camera from my backpack and followed the call to the nearby plum tree, where I found this little guy.  Definitely a juvenile, but Tree Sparrow? Chipping Sparrow? or House Sparrow? 

I snapped away at the bird from just a few feet away while trying to figure out what I was looking at.  Luckily I could eliminate House Sparrow since this little guy was perched next to a much larger House Sparrow.  For me that left American Tree Sparrow or Chipping Sparrow. 

This bird showed traits of American Tree Sparrow: oversized, apparent-looking bicolored bill and evidence of streaking on chest and belly.  A juvenile Chipping Sparrow also shows streaking, and 'usually' a prominent dark streak through the eye.  Examination of my images showed evidence for an eyestripe, but really faint.

The field guides were really not useful in this case.  Internet searches failed to generate any decent photos of juvenile birds of either species, so I had no good reference to go by. 

Thanks to Allen Chartier and Cathy Carroll for responding to my ID request.  Allen mentioned that American Tree Sparrows molt their juvenal plumage prior to migration south, so this bird must be a Chipping Sparrow.  I've never seen a juvie Tree Sparrow, and only a few Chippers, so I have to trust common sense on this one.

Chipping Sparrow it is.  Luckily, just a few days later I'd find a small flock of both adults and juvenile Chipping Sparrows frolicking in the very same trees outside the building at work.  So the ID seems to be confirmed.  Still, I continue to be humbled by the shear difficulty that some birds present in their transitional stages, and have a whole new respect for those bird banders who hold these birds in their hands and still have to consult the Pyle guides for confirmation.

BASF Corporation, Wayne, Michigan, US
Oct 4, 2010 3:00 PM - 3:20 PM
Protocol: Stationary
Checklist Comments:     ID Challenge!
1 species

Chipping Sparrow (Spizella passerina)  1     juvenile! Thanks to Allen Chartier and Cathy Carroll for responding to my ID request.  Allen mentioned that American Tree Sparrows molt their juvenal plumage prior to migration south, so this bird must be a Chipping Sparrow.  I've never seen a juvie Tree Sparrow, and only a few Chippers, so I have to trust common sense on this one.

View this checklist online at https://ebird.org/checklist/S42374315

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