Migration Monitoring – September 24th, 2007 & Rose-breasted Grosbeak Photo

In a recently discovered map of the Grand River prior to European exploration the area around what is now Ruthven Park is left blank except for the cryptic phrase “Here there be Goldfinch”. Historians are puzzled as to what this may have meant….

The weather forecast called for clear skies and high temperatures and by all indications it was to be a quiet day of banding. This seemed to be the case when the breaking of dawn brought naught but the insistent calls of the Canada Geese resting on the river in front of the mansion.

The first net round was fairly slow, and the surrounding woods were mostly silent. Then, out of seemingly nowhere, for reasons known only to themselves, every goldfinch in the universe descended upon the feeders. At least that’s what it felt like. There were a lot! Happily, they brought some friends too. (For stats freaks, the catch per 100 hours for Net 1 was just under 500).

The first Slate-Coloured Juncos of the season were banded today. It seems early for them, but that could just be due to the unseasonably warm weather making thoughts of winter seem unlikely.

Banded: 87
American Goldfinch 41
Tennessee Warbler 1
Magnolia Warbler 2
Nashville Warbler 2
Chestnut-Sided Warbler 1
Common Yellowthroat 5
Black-Capped Chickadee 6
Chipping Sparrow 3
Slate-Coloured Junco 4
Bay-Breasted Warbler 1
Blackpoll Warbler 1
Purple Finch 1
White-Throated Sparrow 6
Song Sparrow 3
Grey-Cheeked Thrush 2
White-Breasted Nuthatch 3
Swainson’s Thrush 1
Blue Jay 3
Mourning Dove 1

Retrapped: 20
American Goldfinch 7
Blackpoll Warbler 1
Chipping Sparrow 1
Common Yellowthroat 1
White-Breasted Nuthatch 2
White-Throated Sparrow 4
Swainson’s Thrush 1
Grey Catbird 3

From Rick Ludkin, regarding the picture below:

Rose-breasted Grosbeaks have a “Complex Alternate” molt strategy. Young (or hatch year – HY – birds) go though a partial pre-formative or pre-basic moult in the late Summer/early Fall. In Grosbeaks this tends to be some body feathers and some secondary coverts but NOT remiges; i.e., wing feathers. In the Spring they go through a pre-alternate molt replacing some body feathers and secondaries with newer and brighter ones (the “alternate” plumage is synomymous with “breeding” plumage). In a typical HY male grosbeak in the Fall, the body would be brown like in a female (and this one is); most of the secondary coverts would be black; but the wing feathers – primaries, secondaries and tertials – would be a contrasting brown colour. The next Spring it would be easy to tell that it was in its second year by this brown/black contrast between the wing feathers and the secondary coverts.

What is interesting about this bird is that it has the HY body plumage (looks like a female) but has molted all of its wing feathers – coverts and remiges – so its wings looks like and adult’s.

One thought on “Migration Monitoring – September 24th, 2007 & Rose-breasted Grosbeak Photo

  1. So, without looking at the retrap card, if this bird were re-trapped in spring 2008, you might be inclined to call this an ASY bird (assuming you ignored the tail, as we don’t know what is going on with that)?

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