Re: [cobirds] late-nesting goldfinches - Boulder Co

I, too, saw a female type Lesser Goldfinch feeding two fledglings regurgitated Maximillian sunflower seed mash on 11October21 at City Park in Fort Collins.  It seemed a bit late but as Peter points out, goldfinches are, indeed, the latest songbird nesters of our species that are restricted to warm weather nesting.  I have always thought the reason for goldfinches nesting late is their reliance on thistle seed/fluff for nesting material.  The timing of when the dominant native and introduced thistle species go to seed determines the timing of goldfinch nesting.  Because of some extreme weather events last spring, a lot of plants were late getting started this past spring/summer.  The other complications in this attempt to determine what is "normal" is the fact lesser goldfinches have only recently become common breeders in northern CO and also they could be double-brooding more often at present than they did historically.  Breeding Bird Atlas I recorded dependent fledglings as late as 25August.  BBA II found them as late as October 27.   A breeding season extension of two months seems significant even if sampling intensity and other factors make the true story of when fledging last occurs off by a week or two.  Thanks, Peter, for your interesting observation.

Dave Leatherman

Fort Collins

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From: cobirds@googlegroups.com <cobirds@googlegroups.com> on behalf of Peter Ruprecht <pruprecht@gmail.com>
Sent: Sunday, October 24, 2021 2:06 PM
To: Colorado Birds <cobirds@googlegroups.com>
Subject: [cobirds] late-nesting goldfinches - Boulder Co

 

Cobirders,

I was part of a small birding party in SE Boulder Co this morning and we were somewhat surprised to see recently fledged Lesser Goldfinches still being fed by their parents.  It struck us as unusually late in the season.

I'll note that both species of goldfinches seemed late to start nesting in this area.  I personally did not see any nesting behavior until after July 15.  Granted, goldfinches are not the earliest species to start breeding ... but to me this seems like one more little example of how songbirds' status is a bit "off" this year.

Peter Ruprecht

Superior

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