[SBB] Pajaro River grosbeak

[michael mammoser <[[email protected]]>]

All,

There has been some discussion between myself, Mike
Rogers, and Steve Rottenborn about the identity of the
alleged Rose-breasted Grosbeak along the Pajaro River
last month. Some questions have been raised and I
thought it might be informative to the members of this
list to see that discussion.

Michael Mammoser


> -----Original Message-----
> From: Mike Rogers
> Sent: Tuesday, July 24, 2007 
> To: Mike Mammoser; Steve Rottenborn
> Subject: Re: [SBB] Pajaro River etc.
>
>
> Based on the photos taken of the "Rose-breasted 
> Grosbeak", it appears to be an HY bird. I doubt RBGR
> are breeding down there, which makes the ID 
> questionable in my mind, given the time of year. The
> fact that the bird was not that different from Tom 
> Grey's first photographed bird suggests to me that
it
> may be a heavily streaked juvenile BHGR, which Steve
> Rottenborn agreed with. Of course, I haven't seen
the
> bird - but it is not encouraging that nobody is 
> getting photos or good looks at the center of 
> the breast. Call notes would be helpful too...


> -----Original Message-----
> From: michael mammoser
> Sent: Monday, July 23, 2007 9:28 PM
> To: Mike Rogers; Steve Rottenborn
> Subject: Re: [SBB] Pajaro River etc.
> 
> 
> I was back and forth on that apparent RBGR, but I
> couldn't find any literature reference that
indicated
> a Black-headed would have streaking that heavy on
the
> underparts. What, in Tom's photo, indicated that the
> bird was a "bird-of-the-year"?


> -----Original Message-----
> From: Steve Rottenborn
> Sent: Tuesday, July 24, 2007 
> To: Mike Rogers; Mike Mammoser
> Subject: Re: [SBB] Pajaro River etc.
>
>
> I've been surprised that there hasn't been more 
> discussion of the identity of the "RBGR" on SBB, 
> especially since so many people have now claimed to 
> have seen one.
>
> I'll be the first to admit that I haven't done any 
> detailed research (e.g., using Pyle) to establish 
> either the age or the identity of this bird using 
> finer points of plumage, so my "analysis" is 
> admittedly superficial. 
>
> I think the bird in Tom Grey's photos is definitely
> a juvenile. The wing feathers appear very fresh, not
> worn at all. I think an adult female would be worn.
> Also, I could swear that bird still has enlarged 
> pinkish rictal flanges. I can't find a photo of an 
> adult RBGR on the web with enlarge pink rictal 
> flanges. If it's a juvenile, the chances of it being
> a RBGR, or a hybrid, are greater than zero but still
> very, very low.
>
> MJM, in your post to SBB you mentioned that Rich 
> said that the center of the breast is streaked. It
> is my understanding that female BHGR can have 
> streaking on the center of the breast, but it is 
> finer than on RBGR 
> (see http://fog.ccsf.cc.ca.us/~jmorlan/grbkid.htm). 

>
> When I saw Peggy Don's photos, I thought that the 
> streaking on that bird looked broader (not as fine)
> as I'd expect on a BHGR. However, if I had to guess,
> I'd bet that the bird is just a heavily streaked 
> BHGR. The photo of a female RBGR on the following 
> web page shows my impressions of a typical female 
> RBGR: 
>
>
http://www.wbu.com/chipperwoods/photos/rbgrosbeak.htm 

>
> The female shown on the following web page shows a 
> bird with much, much less buff (and not nearly as 
> orange) as on the Pajaro River bird. Interestingly, 
> the streaking on this bird is even less extensive 
> than on the Pajaro River bird:
>
> http://www.pbase.com/lilwings/image/60639418
>
> I haven't seen the bird, nor have I done a detailed 
> analysis of age or species using Pyle, so I'm not 
> claiming that the bird is definitely a BHGR.
However,
> someone claiming a RBGR should do such an analysis
to
> age the bird and, if it is a juvenile, rule out
BHGR.


> -----Original Message-----
> From: Mike Rogers
> Sent: Tuesday, July 24, 2007 
> To: Mike Mammoser; Steve Rottenborn
> Subject: Re: [SBB] Pajaro River etc.
>
>
> The AHY (after hatch-year) female RBGR I saw along 
> Stevens Creek on 2 June looked very much like:
>
> http://www.pbase.com/lilwings/image/43569873
>
> http://www.pbase.com/lilwings/image/43669763
>
> Broad streaks with similarly broad streaking across 
> the mid-breast and some buff in the upper 
> breast/flanks, but none of the orange of the Pajaro 
> bird.
>
> I aged the Pajaro birds (Tom Grey's photos are of
two
> different birds) based on their very fresh,
uniformly
> aged plumage. As Steve pointed out, Tom Grey's
photos
> in particular show narrow yellow-green edges to all 
> flight feathers, something I don't think an adult 
> would ever show, especially this early in fall.
>
> It is my understanding that the pink bill (upper 
> mandible) is only a good field mark for RBGR in
AHYs.
>
> I too still have to check Pyle on these birds, but 
> I suspect that juveniles may be more extensively 
> streaked than first-winters, which could explain the

> heavier than expected streaking on the Pajaro bird. 
> It's yellow underwing coverts rule out a male RBGR I

> think (I know these are pink in male RBGRs by Sep 
> anyway).


> -----Original Message-----
> From: michael mammoser
> Sent: Tuesday, July 24, 2007 3:40 PM
> To: Steve Rottenborn; Mike Rogers
> Subject: RE: [SBB] Pajaro River etc.
> 
> 
> I just looked at all the photos (I've dismissed Tom
> Grey's first 3 photos - they're obviously of a
> different bird) and these all seem to show virtually
> the same bird. So, I think everyone is on the same
> page in that regard. 
> 
> I don't think this bird is in "juvenal" plumage.
That
> plumage should show cinnamon wing bars and cinnamon
> edging to upperpart feathers. At a minimum this bird
> would be in 1st basic plumage, which, according to
> Pyle, can be held into the second year. 
> 
> Steve's comment about the rictal flanges is very
> interesting. I think these can be seen most easily
in
> Peggy Don's photo 47171_IMG5Q_RB_Grosbeak_Pajaro...
> This would seem to be indicative of a
> "bird-of-the-year", and unless your willing to 
> believe that Rose-breasted Grosbeaks breed in Santa 
> Clara County, or nearby...? 
> 
> After all, these aren't Swainson's Hawks :-)


> -----Original Message-----
> From: Steve Rottenborn
> Sent: Tuesday, July 24, 2007 
> To: Mike Mammoser; Mike Rogers
> Subject: RE: [SBB] Pajaro River etc.
>
>
> It's obviously an interesting bird.  I'll try to
take
> a closer look at the photos later, but in the 
> meantime, it wouldn't hurt to send them to Joe
Morlan
> (and others? Kimball Garrett?) for an opinion.  
> We'll learn something one way or the other.





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