Why Don’t All Birds Fly in V Shapes?


[ ♪INTRO ] Think of a flock of birds and you probably
imagine that classic V shape — a leader with sets of trailing birds on either side. But not all flocks fly this way. Starlings,
for example, travel in large, three-dimensional clusters that seem to move like a wave. So why do some species fly in Vs and others
in clumps? It turns out to have a lot to do with the individual birds themselves. Some, like geese heading south for the winter,
are making long treks. The V formation helps them stay in visual contact, avoid collisions,
and conserve energy. It’s the structure of their wings that lets
them take advantage of the V. As the wing flaps, each wing tip creates a
vortex that spirals up from the bottom of the wing and over the top. This vortex trails
off behind each bird as it moves forward and is encountered by the next one in line. The trailing bird positions itself to catch
just the upwash of that vortex, or upward force, and that requires being behind and
just to the side of the leading bird. Lots of birds behind and to the side of one
another creates the V shape. Studies have estimated that birds flying this
way can save around 15% of their energy. So, why don’t all birds fly this way? We talked to Professor Erick Greene from the
University of Montana Bird Ecology Lab and he explained that this has to do with the
size of the bird. You may have noticed that birds that fly in
a V — like geese, pelicans, swans, and ibises — are typically larger creatures with a
long wingspan. These species move their wings only a few
degrees up and down with each flap. This motion creates vortices that lie pretty neatly behind
the bird. Small birds, on the other hand, tend to flap
their wings all the way up and down. The vortices created by these motions are all over the
place — not consistent enough for their flock mates to actually use. And the small birds that do flap their wings
like larger ones just don’t generate a big enough vortex because of their size. For small birds, flying in groups sometimes
even uses more energy, not less. But these species have another need that’s even more
important: protection. In 1971, evolutionary biologist William David
Hamilton proposed a theory called the selfish herd. It suggests that the risk to an individual
is reduced if that animal places another between itself and a possible predator. Repeat this
across enough individuals and you end up with a herd — or in the case, a flock. Other theories offer similar explanations,
but, whether you’re talking schools of fish or swarms of insects, it’s clear that this
is a pretty common survival strategy. So, the next time you see a group of birds
flying by, you’ll know it might be to save energy. Or it could just be to stay alive. Thanks for asking. If you can’t get enough
of SciShow in your eyeballs, it’s also available for your ears — in the form of our podcast,
SciShow Tangents! Join me and our other hosts as we do stuff
like try to stump one another with weird trivia and write science poems. Download it wherever
you download podcasts! [ ♪OUTRO ]

100 thoughts on “Why Don’t All Birds Fly in V Shapes?

  1. So, how does a flock of geese decide which bird takes point? Is it the strongest flier? Is it the one with the best sense of direction? Is it random?

  2. Cyclists draft eachother in a similar way. Two lines moveing in a circular motion. Two people leading two lines, one going slighter faster than the other.

  3. Do you know why when geese fly in a V pattern, one side of the V is longer than the other? Because there's more geese on that side…

  4. Dear Sci-Show,

    Can you answer a question I have?

    I am a long time viewer and subscriber (from the start of your channel), and LOVE your show.

    I find that I am tired often, which I know is an obvious side affect of my depression related to a recent break up. This got me wondering,… do our bodies produce extra melatonin when we are depressed? OR if not melatonin, at least some type of chemical equivalent, that makes us extra sleepy? AND If so, WHY?

    What would justify this evolutionary behavior?

    What is the selective advantage for this trait?

  5. Large migrating birds in V-formations may expend up to 15% less energy? That's NOTHING compared to the almost 100% reduction experienced by certain Ruby Throated Hummingbirds during migration, thanks to a newly discovered, truly astonishing avian behavior, reported in a "Winged Wonders," (Oct.) article: "Hapless Herons Host Hitchhiking Hummers – Who Knew?" Fascinating read and the photos are too cute!

  6. and then trump is planning a May Day trip to view Putin's army?????? after leveraging military aide to Ukraine, who is being attacked by Putin. smh

  7. So this is basically a SCHOOL OF FISH… oops I mean School of Birds.

    Its dizzying
    Its protection in numbers.
    Confusing flight path.

  8. Ever notice ducks flying overhead? Ever notice the V-shape of their flight pattern? Ever notice how one line of the "V" is longer than the other? Ever wondered why? More ducks in that line.

  9. Little known fact: If you look closely, you'll notice that one side of the V is often longer than the other. Do you know why?
    .
    .
    .
    Because there's more birds on that side.

  10. In your scientific wisdom, can you tell us why, in a flock of geese, one arm of the V is longer than the other? Wait for it. Wait for it….because there are more birds in it. I love birds, don't you?

  11. Hey yall i got a question can you exsplain how Peregrine falcons can dive at the insain speed they do i xant remember what it is off the top of my head but i would love to know the science behind them

  12. Hank when you pull a scientific source with the last name Green we immediately assume you have another brother who specializes in birds.

  13. I HAVE A QUESTION, HOW MANY SPECIES OF CAECILIANS. ARE VIVIPAROUS AND HOW MANY SPECIES OF CAECILIANS. ARE OVIPAROUS. I. DON'T WANNA KNOW THE PERCENTAGE. I WANNA KNOWN THE. EXACT NUMBER AND THEIR LIST..

  14. ? ???? ? ????????, ??? ???? ??????? ?? C????????? ??? ?????????? ??? ??? ???? ??????? ?? ?????????? ??? ?????????. ? ???'? ????? ???? ??? ??????????. ? ????? ????? ??? ????? ?????? ??? ????? ????..

  15. ? ???? ? ????????, ??? ???? ??????? ?? ?????????? ??????? ??? ?????????? ??? ??? ???? ??????? ?? ?????????? ??? ?????????. ? ???'? ????? ???? ??? ??????????. ? ????? ????? ??? ????? ?????? ??? ????? ????..

  16. I find this episode lacking. You didnt really answer the question… or rather, you did, but you didn't because you expanded on the answer, and then left the audience with a non answer.

  17. But why, when birds fly in the V formation, is one arm of the V sometimes longer than the other?

    It's because there are more birds on that side. 😀

  18. "They're, uh, they're flocking this way…"

    Also, holy heck that was some awesome footage of the little warbler flying around. Can we get some more in depth look at wing beats?? He looked almost like he was dancing in the air!

  19. I would have ALSO made a distinction between migratory fights and local flights … birds like starlings simply enjoy flying together…. like human dancing in a club.

  20. 2:39 …or gangs of Emo teens…
    Sorry. Had to throw this in there. Everyone knows the "buddy system" rule.
    Gives the foe someone else to pick on. There's nothing new here.

  21. It's simple, birds who did their flight training with the military fly in a "V"
    (Discipline)
    Where as civilian trained birds fly as they please (no discipline)

  22. thanks, the vortex phenomenon provides explanation why large birds stay diagonally beneath one another. but what about the upper side of the V, composed of birds that stay diagonally above one another?

  23. You missed what I consider to be the most interesting aspect of a flock of small birds. The reason they look more like a swarm or insects (the undulations and sharp changes in direction and density) is because of how they instinctively orient themselves within the flock. If a bird next to you moves closer or further to you, you try to keep an even space between yourself and all of the others beside, above and below you. As you correct, the others around will start to move as well, pulling or pushing the entire flock in that direction. This is thought to be a means of moving the majority of the flock away from danger if one of the individuals on the outside sees or encounters a threat. It can also bring an entire flock down upon a food source if an individual spots something like a grasshopper or patch of wild rye.
    You can see this need to keep an equal distance when a flock splits. all it takes is 2 individuals on opposite sides of the flock to move in outward. a few birds in the middle will struggle to keep centered until they are all alone and finally break formation and choose to join the closest group. (Which will, in turn, influence the direction of that group, initially driving it further away from the other).

  24. Have you ever noticed that when geese fly this way, one leg of the "V" is always longer than the other one?

    This is because there are more geese on that side.

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