Why do some hawks fan their tails out when they are soaring and others don’t?
On an overcast day earlier this week, I was watching two hawks soaring through the air together, when I happened to notice that one of them kept his tail fanned out all of the time. His tail was so noticeably striped that I am pretty sure that he is a Red-Shouldered Hawk (Buteo lineatus). The other hawk, however, never fanned out his tail. Looking at the wings of the two hawks, I think they are probably the same kind, although one of them looks to have a somewhat longer body.
So I am left wondering why, under the same conditions, they each chose to us their tails differently.
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Mike Powell 
Do they do it to slow themselves down, like an airplane lowering its flaps? Or for help in steering? i don’t know, but I’ll bet somebody who reads this blog will.
My guess is weight distribution for speed, gliding or for diving. Most likely is a speed thing, flare the tail to slow down, close up to speed up.
Excellent pics..:-)
It would be interesting to know if the position of the tail is related to which bird is in front and which bird is flying in its trail, in terms of wind currents.
I don’t think this is well understood yet, but there are lots of theories for the role of the tail in bird flight: flared (open) tail may reduce the drag that the bird’s body creates as it passes through air, supply lift in addition to the lift supplied by the wings, depending on side to side angle, may be used for steering, or depending on horizontal angle, may be used to increase drag or slow the flight — e.g, for landing. There are probably more theories out there I am not aware of.
By the way, David Attenborough has a wonderful video on bird flight.
It’s also possible these two birds might be different species. The right bird has a longer wing for roughly the same body length — which imparts different wing loading and thus flight characteristics. The left bird has a striped tail and round wing like a Cooper’s Hawk, but the right bird has a dark stripe at the end of its tail, like the Red-shouldered Hawk does, and the wing shape resembles that bird as well. OK, this is probably way too much analysis for your question.
Actually, this is just the kind of response that I was hoping for. There aren’t a whole lot of hawks that have striped tails like the one on the left and that was the one that I thought I had pegged as a Red-Shouldered. The left one seemed to me to have longer wings and maybe a longer tail too. I know that there are Cooper’s Hawks at the marshland park where I took the photos, so that is a possibility. For now I am content that I got the shotss.
very observant of you and its an interesting post.
Obviously, to make you ask questions. Great shots!
Thanks (and I like your answer).
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