dgraham@kean.ucs.mun.ca (David Graham) (10/23/90)
Added two birds to my TV list last night (thanks to David Mark for suggesting armchair listing!) by idly turning on PBS and happening on some nature programme whose name I didn't get. First segment I saw had a lot of very interesting footage of nesting Hoatzins in Cuyabeno, Ecuador, including the young birds using their wing claws to clamber around in the branches, and showing a young bird swimming away to hide after jumping out of a tree to escape a native egg collector. The second segment was truly amazing. It concerned footage of Harpy Eagles shot in Guyana. Again, a nesting pair was shown feeding their chick over a period of about 5 months, but the best shots were of flying Harpies sailing over the canopy, including one of a female plucking a 3-kilo sloth from a treetop and flying off to the nest with it. The sloth was apparently about 1/2 her body weight, which seems incredible to me, and I was moved to wonder what bird can lift the greatest percentage of its own body weight, and whether any bird can out-lift a Harpy Eagle. Monkey-eating Eagle comes to mind, but I believe they're slightly smaller than a Harpy. I was struck by the wing shape of the Harpies shown in the show: their wings are extraordinarily broad (i.e. from front to back) in addition to being very long (> 2m wingspan) and I presume this is what allows them to carry such large payloads. Their wingbeats are quite slow, and they don't look very manoeuverable, but slow-motion showed the female Harpy turning completely on one side to snatch the sloth off its tree-trunk, so they aren't clumsy either. Magnificent-looking creatures, anyway... anyone here actually seen one? *************************************************************************** David Graham dgraham@kean.ucs.mun.ca ***************************************************************************
andrewt@cs.su.oz (Andrew Taylor) (10/25/90)
In article <147956@kean.ucs.mun.ca> dgraham@kean.ucs.mun.ca (David Graham) writes: > The sloth was apparently about 1/2 her body weight, which seems > incredible to me, and I was moved to wonder what bird can lift the > greatest percentage of its own body weight, and whether any bird can > out-lift a Harpy Eagle. There are records of Harpys lifting sloths about their own weight. There are records of similar achievements for other eagles. I know peregrines kill prey up to twice their body weight. I don't know if they can carry such prey. Some owls have serious lifting capability too, I've heard of an (Australian) Powerful Owls taking (and lifting) a Lyrebird which I think would outweigh the owl. Eagle-Owls may be even more formidable. > Magnificent-looking creatures, anyway... anyone here actually seen one? I've seen the South American Crowned Eagle (similar habits and appearance) which was exciting, finding Harpys is non-trivial. Andrew
mjm@oliven.olivetti.com (Michael Mammoser) (10/26/90)
In article <1310@cluster.cs.su.oz.au>, andrewt@cs.su.oz (Andrew Taylor) writes: > In article <147956@kean.ucs.mun.ca> dgraham@kean.ucs.mun.ca (David Graham) > writes: > > The sloth was apparently about 1/2 her body weight, which seems > > incredible to me, and I was moved to wonder what bird can lift the > > greatest percentage of its own body weight, and whether any bird can > > out-lift a Harpy Eagle. > > There are records of Harpys lifting sloths about their own weight. > There are records of similar achievements for other eagles. I know > peregrines kill prey up to twice their body weight. I don't know if they can > carry such prey. Some owls have serious lifting capability too, > I've heard of an (Australian) Powerful Owls taking (and lifting) a Lyrebird > which I think would outweigh the owl. Eagle-Owls may be even more > formidable. I've heard of shrikes (Loggerhead, I believe) carrying their own weight. Of course, they can only manage to do this a couple of feet above the ground. I observed a Loggerhead Shrike carrying a House Finch in this manner (just above the ground); a bird which is a fair percentage of the weight of the shrike. Mike