Canadian researchers discovered that warm temperatures combined with the appearance of thistle flowers create a physiological response in Goldfinches. The flowers seem to be a cue that triggers a response to increase sex hormones and to go into breeding mode. The Goldfinches don’t eat the thistle flowers, but rather the seeds that follow later. The flowers may be a signal of what is about to happen. Read about it at Wired Science Songbird’s Sex Hormone Surges at Sight of Flowers | Wired Science | Wired.com.
Related Articles
- Songbird’s testosterone surges at sight of thistle blooms (sciencenews.org)
Natural History Wanderings 
This could explain why Goldfinches pull the petals off my Zinnias every year here in NC. They always do it in pairs. They are NOT eating the seed but simply pulling the petals off and letting them drop to the ground. Quite often there is some form contact between to male and female finch after they have cleaned a flower head. They will touch beaks then fly away.
LikeLike
By: Leighsa Wilson on July 15, 2011
at 11:08 AM