[texbirds] Ever wondered if two birds can collide during flock maneuvers? Sure they can

  • From: MBB22222@xxxxxxx
  • To: texbirds@xxxxxxxxxxxxx
  • Date: Mon, 8 Apr 2013 12:24:09 -0400 (EDT)

Often when watching a flock of birds flying  I wondered if they ever  
collide. Flocks of small shorebirds, blackbirds etc are like a live swarm that  
seems to move on its own, like one organism powered by some intelligent or  
magical force inside (but every individual is on its own - Birds can resolve  
rapid movements better than humans, for whom flickering at a rate greater 
than  50 Hz appears as continuous movement. Humans cannot therefore 
distinguish  individual flashes of a fluorescent light bulb oscillating at 60 
Hz, but  
Budgerigars and chickens have flicker thresholds of more than 100 Hz. A 
Cooper's  Hawk can pursue agile prey through woodland and avoid branches and 
other objects  at high speed; to humans such a chase would appear as a blur. 
BTW birds can also  detect slow moving objects. The movement of the sun and 
the constellations  across the sky is imperceptible to humans, but detected 
by birds. The ability to  detect these movements allows migrating birds to 
properly orientate themselves).  But I never noticed collisions inside the 
moving flock. Small tern flocks are  different. Birds keep greater distance 
from each other. Maneuvers by individual  birds inside the flock can be 
impressive (e.g. LETE can fly upside down with  head in ‘normal’ position) 
but the 
flock does not make impression of being one  entity. But, evidently, one 
bird can bump into another. Look here (under tail  covert feathers got 
separated from tail feathers allowing a great view):
 
http://www.pbase.com/mbb/image/149582203
 
Example of LETE flying with body upside down with its head up inside the  
flock during quick maneuver (note: To obtain steady images while flying or 
when  perched on a swaying branch, birds hold the head as steady as possible 
with  compensating reflexes).  
 
http://www.pbase.com/mbb/image/149582204
 
I wonder if many observations of colliding birds have been recorded when  
they are flying in formations (did you ever see one?); I couldn't find any  
photos, and found only a few anecdotal notes. And I am not talking about  
aggressive encounters or gulls trying to get thrown piece of bread. BTW long  
time ego I saw two hummers collided when trying to establish who owns the  
feeder. One lost conscious for a few minutes but was OK later. 
 
Mark B Bartosik
Houston, Texas
http://www.pbase.com/mbb/from_the_field
Edit your Freelists account settings for TEXBIRDS at 
//www.freelists.org/list/texbirds

Reposting of traffic from TEXBIRDS is prohibited without seeking permission 
from the List Owner

Other related posts:

  • » [texbirds] Ever wondered if two birds can collide during flock maneuvers? Sure they can - MBB22222
  1. Home
  2. texbirds
  3. Archive
  4. 04-2013