Merlins are well known for their aerobatic shenanigans with other raptors during migration. And a lot of Merlin hits are taken by innocent watchsite owls (Bubo plastiptero) at lookouts across the continent. B.plastiptero also suffers antagonism from Sharp-shinned Hawks and occasionally, Cooper's Hawks. During the autumn of 2009, however, observers at New Hampshire's Little RoundTop Migration Observatory were witness to the determined harassment of Bald Eagles by Cooper's Hawks. Passing Merlins seemed intent on zooming toward their migration goals, the occasionally mischievous Sharpie might dive-bomb a Broad-wing or Red-tail, but the Coops seemed particularly intent on needling other birds. We watched them go for Broadies, ravens, Red-tails, and even a Kestrel, but it was their pestering of Baldies that captured our attention. We would wonder, "How long is s/he going to keep that up?" And keep it up they would, sometimes all over the sky.
Always the target bird would seem undeterred and continue on its way with only the slightest discernable twitch of primaries. This sort of drama does present a problem for site leaders, because...
as everyone is watching the show, there's a chance that something really good is flying past behind them!
That's interesting Susan. I see WAY more sharp-shinns harrassing birds than Coopers Hawks.
ReplyDeleteDo you notice mostly juvenile birds doing the harrassing? We have a theory at Pack that it's mostly young birds diving and attacking (a way of life training and practicing), while older accipiters and merlins dont bother as much.