May 11th – Aging and Sexing Problems

Note the red underwing and chest patch (the latter reduced)

Slow down, slow down…..this is not about performance problems due to age (“Aged Ruthven blogger reveals his pain….”). Rather, it’s about the complicated art of trying to determine the age and sex of birds. For some birds it’s pretty easy, depending on the time of year, while for others it’s quite difficult, if not impossible. But sometimes even the birds that you think are “easy” can cause you problems. Here’s two examples that we had to deal with today:

Rectrices are broad and truncate suggesting an older bird.

Red chest patch but much smaller than that of a known male.

If you only saw this Rose-breasted Grosbeak (RBGR) from behind, with its brown, mottled plumage, you would say right away that it was a female. But a female RBGR has lemon yellow under the wings and a spotted breast. This bird was red under the wing and had a (somewhat reduced) red breast patch just like a male. Is it male or female. Pyle’s guide to aging and sexing notes that some older females may have a few red feathers. Note the tail feathers: broad and rounded or truncate, very suggestive of an older bird. While we would need to check its DNA for a definitive answer, our call is that it’s a fairly old female.

Known Third Year (TY) male Orchard Oriole - note primary and seconday covert contrast.

Known TY male Orchard Oriole - note olive rump feather.

As shown yesterday, the male Orchard Oriole (OROR) was showing marked contrast between the primary and secondary coverts. You wouldn’t expect to find this in an older bird (that goes through a complete moult at the end of the breeding season). So what’s going on? A second-year male would be an olive colour with a black bib. We recaptured a known 3rd-year male OROR that we had banded the year before as a SY bird. Note the covert contrast and the olive feather in the rump. Is this pattern of covert contrast and occasional olive feathering indicative of a TY bird? Possibly.

So you see, sometimes even the “easy” birds aren’t that easy……

Christine's birthday today and what a way to celebrate it!

It was Christine’s birthday today. She wouldn’t say exactly which one but I’ll bet it’s at least a quarter century. To celebrate she and Chris got up early in order to help open the nets (for the last 2 weeks they haven’t been arriving until 9:00 or so claiming fatigue due to Tree Swallow nesting box monitoring). They arrived just in time to enjoy the sunrise, right after the nets were all opened – at least they tried.

The Assembly Line: Chris, Nancy, Christine, and David Brewer (l. to r.)

We were also joined this morning but renowned birder and author David Brewer whose world-wide experiences and accrued knowledge are always a treat to hear about. It was good to have this sort of help as we were quite busy banding 68 birds of 27 species and retrapping another 41. There must have been a good movement of migrants during the night: we encountered 70 species on the day; there was an influx of Rose-breasted Grosbeaks (many females) and Eastern White-crowned Sparrows; and we encountered 11 species of warblers including two new arrivals – Chestnut-sided Warbler and Northern Waterthrush.

One of the retraps was quite interesting: a Red-winged Blackbird, banded as an AHY bird on April 29th, 2004 making it at least 8 years old.

Banded 68:
1 Yellow-shafted Flicker
1 Least Flycatcher
2 Blue Jays
1 Ruby-crowned Kinglet
1 Veery
1 Gray Catbird
1 Blue-winged Warbler
2 Nashville Warblers
6 Yellow Warblers
2 Chestnut-sided Warblers
3 Magnolia Warblers
1 Myrtle Warbler
1 Western Palm Warbler
1 Ovenbird
1 Northern Waterthrush
5 Common Yellowthroats
9 Rose-breasted Grosbeaks
4 Chipping Sparrows
1 Song Sparrow
1 Lincoln’s Sparrow
1 Swamp Sparrow
6 White-throated Sparrows
7 Eastern White-crowned Sparrows
3 Baltimore Orioles
2 Orchard Orioles
1 Pine Siskin
3 American Goldfinches

Retrapped 41:
1 Gray Catbird
1 Blue-winged Warbler
1 Common Yellowthroat
1 Northern Cardinal
3 Rose-breasted Grosbeaks
1 Indigo Bunting
3 American Tree Sparrows (what are they still doing here!?)
14 Chipping Sparrows
1 Swamp Sparrow
1 White-throated Sparrow
2 Eastern White-crowned Sparrows
1 Red-winged blackbird
3 Brown-headed Cowbirds
2 Baltimore Orioles
1 Orchard Oriole
4 American Goldfinches

ET’s: 70 spp.

Today’s Photo Gallery:

A very late Pine Siskin - Chris Harris

Male Chestnut-sided Warbler - Christine Madliger


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