How can birds still fly if they have to constantly eat to have enough energy to fly? Doesn’t eating make them so heavy that they need even more energy to keep flying?

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When I watch the birds at the feeding station in my garden, I notice that individual birds often eat a lot at once. Doesn’t all that food make them so heavy that they need more energy/food to fly than they can carry in flight?

In: Biology

16 Answers

Anonymous 0 Comments

So, there IS a degree of diminishing returns, where extra energy is just mostly lost into moving that extra mass, but most birds are nowhere near that level. It’s like filling the fuel tank of a car, its not enough extra mass to make much difference.

Plus, they never really know when their next meal will be, so generally it’s always a good survival trait to fill up whenever you can.

Anonymous 0 Comments

Some birds like vultures and cormorants can definitely eat so much they struggle to get airborne afterwards. They’re “high flight cost” birds that don’t have a large margin on their normal lift/weight ratio, either because they’re relatively heavy (vultures) or have stumpy wings (cormorants).

The spazzy little songbirds that visit your backyard bird feeders weigh almost nothing and are very strong fliers so they’re “low flight cost” birds that have a lot of extra power if need be. They can pack in as much food as they can fit and still take flight no problem.

They don’t need to eat constantly, but many birds do eat a lot for their size because their metabolisms run so high to make sustained flight possible. You need a lot of energy on demand to do that.

Anonymous 0 Comments

How can an airplane fly if it has to constantly refuel? Because the engines are powerful enough that they can handle the extra weight from the fuel and whatever passengers or cargo might be aboard. Likewise, a bird’s flight muscles are strong enough to handle a little bit of extra food in its belly. Evolution might be blind but it ain’t stupid.

Anonymous 0 Comments

Birds aren’t affected so much though vampire bats which weigh around 35g can drink upto 20g in blood and so start urinating when they feed so they can fly back home.

I’ve no idea how to Google that, and on enough lists already to try but its probably something Attenborough said so its good enough for me.

Anonymous 0 Comments

Birds that glide are excellent at “reading” air currents and thermal updrafts. They use this knowledge to use as little energy as possible. It doesn’t always work but they’ve had millions of years to evolve.

Anonymous 0 Comments

I’ve seen a seagull fly down into a courtyard to eat a load of stuff out of a bin then struggle with an almost vertical takeoff (due to it being a courtyard) so it threw everything up and then managed to get airborne.

Anonymous 0 Comments

The airplane needs fuel to lift off and does the weight of the fuel not make the airplane heavier so it can’t lift off?

Anonymous 0 Comments

Post like these remind me that not everyone’s brain works the same.

This post has caused me to spend like 30 minutes typing out various replies that I kept deleting.

I’ll just say that I’m thoroughly confused about your confusion

Anonymous 0 Comments

How do planes fly? Doesn’t filling them with gas make them so heavy they need even more gas to fly? /s

Anonymous 0 Comments

I remember once reading about how homing pigeons are incredible athletes. They can fly at 100kmh/60mph all day on nothing more than an ounce of birdseed and a sip of water.