Tuesday, March 11, 2008

Blakeman on Brown-tails and Sex Hormones

The stick killing Brown-tail flies perpendicularly.

After reading yesterday's post about the stick killing yearling Red-tail, John Blakeman sent in his thoughts.--


Actually, I think the immature's attacking of a stick is a combination of -- a season's confusion of -- normal hunting behaviors and the effects of lengthening days on breeding behaviors. As with Pale Male in his first breeding attempt, first year birds are affected by spring sex hormones. So, with this bird, it's impelled to do something with a stick. Hormone-induced instinct prompts this, but there is no mate, no nest territory, or other more mature factors to shape this behavior into real nest building.

This bird is an immature, acting immaturely, much like a child playing house or building a shack out behind the barn. It's preparation for the more serious and adult breeding behaviors in years to come.

--John Blakeman

I'd wondered if the young Red-tails behavior might have been a response to a surge of Springtime hormones. He was having a strong urge that was compelling the adolescent to do something but he just couldn't figure out just yet what it might be. John came up with an excellent deduction which makes perfect sense. The use of large sticks to practice hunting behavior in the youngest Red-tails just might be becoming confused with the use of smaller sticks to build nests by mature. Both activities start with sticks after all. And as John suggests, without all the other cues, the poor guy just didn't have the whole thing nailed down yet and reverted to "baby" behavior.

I've also always thought that as all Red-tails don't do things exactly alike that their "wiring" isn't as specific as some birds. Therefore more trial and error behavior must be undertaken to solve what feels right to satisfy the urge of the moment. That way, appropriate solutions can be found for a variety of situations and environments.

One of the things that made me think about hormone surges was the top photograph. The Brown-tail took off at break neck speed and then flipped to the perpendicular and flew quite a long way, sideways. Was he having an urge towards courtship flight? Or was he just so fired up with Spring that he was doing the Red-tail equivalent of a teenaged human with a sports car?

Donegal Browne

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