Large flock of birds seems to fly into ground, many dead and injured

[Spinnor]

From YouTube search, "flock of birds crashed into the ground",



Story that got me to search on YouTube,

https://www.wesh.com/article/birds-drop-from-sky-chihuahua/39091334#

 

[berkeman]

So are there any ideas what happened? Flocks of birds and schools of fish often behave like this, but you would think that birds would have a clue where the ground was...

 

[BillTre]

schools of fish

I've only heard of this with whales/dolphins.

It was a very dense flock of birds.
The article had 2 possible explanations:
toxic cloud or something like that
or scared (as a flock, which moves together due to their flock coordinating instincts) by a predator into a predator avoidance response.
The second option would be somewhat like moths diving toward the ground when they hear bat sonar. When a moving car emits bat-like frequencies, some moths will dive into the front of a car due to an unfortunately triggered reflex.

 

[Spinnor]

I wonder if their density becomes too great and they happen to be descending that the lift of the lower ones significantly drops? Like if a helicopter flew directly over another helicopter wouldn't the lower one loose lift?

Flock videos no crashing,

 

[BillTre]

There are some fun bird flock effects in some shows.
I think during one of the Rome shows (HBO I think) a flock above the horizon formed a skull.
Kind of like The Mummy doing shapes in sand.

 

[256bits]

So are there any ideas what happened? Flocks of birds and schools of fish often behave like this, but you would think that birds would have a clue where the ground was...

I think it just looks as if they lost their way on follow the leader ( there isn't one ) en mass, and some of them hit hard and stunned. A miscalculation like when you stub your tow, or stumble on a crack on the sidewalk.
I wouldn't expect all flocking to be completely perfect all the time.
Toxic gas would have left a lot more on the ground for a lot longer.
A predator from above would have seen them all disperse radially in an expansion and regroup after rather than driving them downwards.

 

[russ_watters]

Another possibility I've heard raised is a downdraft/microburst. There is definitely air movement ahead of the birds hitting (puff of dust in the street, bush in the left foreground), but I can't be sure if the mass of air is moving them or if they are moving it. I also didn't think downdrafts could be quite this localized, so I'm leaning against this explanation. Just putting it out there.