According to this article the Peregrine pokes along at only 60 mph in horizontal flight and can only hit top speed while diving; whereas, the Common swift clocks in at 69 mph, still a bit pokey. Like the Peregrine, I believe swifts can dive much faster than they can fly horizontally.
I once had the pleasure of visiting Hoya de las Guaguas on a trip led by Dapper Don B (who wears button down shirts and always seemed unnaturally clean!) While resting at the bottom of the first drop, which I suppose to be around 700 feet down, I became aware what sounded like small sonic booms. At first I couldn't figure out what was causing it, but when I went to the top of the scree slope and looked straight up I could see that Swifts we diving down into the pit so fast that, like a speeding bullet, they could only be seen when they were coming straight toward me. Just before hitting me between the eyes they would suddenly bank, turn, then plunge down into the lower pit. It was the banking and turning that was creating the booms. The birds were traveling so fast that if I looked at their flight path diagonally I couldn't see them. I once observed a similar "sonic boom" phenomenon while watching the mating displays of male nighthawks which plummet straight down from the heavens to within a few feet of the ground to impress the ladies, much as do the "land diving" cannibals of Vanuatu. It is said that the booming sound is purposefully produced by the ruffling of feathers, not because they are breaking the sound barrier. This is an evolved behavior practiced by all male Nighthawks, but can the same be said of the Swifts screaming down into Hoya de las Guaguas? Swifts also have a spectacular aerial mating display, but I don't think it includes flying straight toward the ground to make a mechanical noise. Is it possible that the Swifts are actually breaking the sound barrier as they dive, wheel, and turn, much in the manner of a cracking whip? If so they would be by far the fastest animals on earth! Sleaze Ps: One other thing in regard to bats, whip cracking, and speed. In the suburban Maryland of my youth I would often fly fish at dusk. Even when I couldn't catch fish I would often catch bats on the wing with a tiny fly. Great sport! -----Original Message----- From: Texascavers <texascavers-boun...@texascavers.com> On Behalf Of Lee H. Skinner Sent: Monday, October 29, 2018 1:54 PM To: New Mexico Cavers <swrcav...@googlegroups.com>; Texas Cavers <Texascavers@texascavers.com> Subject: [Texascavers] Bet You Can’t Name the World’s Fastest Mammal It's not the Cheetah! https://blog.nature.org/science/2018/10/10/bet-you-cant-name-the-worlds-fastest-mammal/?src=e.nature.dlapdo.0818.loc_b&lu=4781941&autologin=true&ds=n&sus=n&md=n Lee Skinner _______________________________________________ Texascavers mailing list | http://texascavers.com Texascavers@texascavers.com | Archives: http://www.mail-archive.com/texascavers@texascavers.com/ http://lists.texascavers.com/listinfo/texascavers _______________________________________________ Texascavers mailing list | http://texascavers.com Texascavers@texascavers.com | Archives: http://www.mail-archive.com/texascavers@texascavers.com/ http://lists.texascavers.com/listinfo/texascavers
