Could a large bird be used as transportation?
Sometimes I reminisce about the giant eagles from The Lord of the Rings and two things come to mind:
Boy, I wish I could have my own giant eagle!
Could a bird even carry something that heavy on its back?
How big would a bird have to be in order to carry an average human being on its back? Are we talking roc-size or something smaller? Would it be able to wear some sort of harness so its passenger(s) weren't merely clinging on for dear life? And won't someone make these hypothetical giant birds real so I can commute to work in style?
EDIT I left this question to bake overnight and I have not been disappointed! Anyway, someone asked me to specify whether the person could be carried on the ground or flying, and I intended for both person and bird to be in the air at regular bird altitudes.
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I decided to try to extrapolate from some known data. I used various sources to find that:
- The Harpy Eagle at 6 to 9 kg can lift a Three-Toed Sloth of 3.5 to 4.5 kg
- A Peregrine Falcon of 0.3 to 1.0 kg can lift a feral Pigeon of 0.25 to 0.4 kg
- An adult Human is typically somewhere around 60 to 100 kg
- The largest (known) bird ever was Argetavis magnificens, which was 70 to 72 kg
- The largest (known) thing ever to fly was Quetzalcoatlus, estimates ranging from 70 to 250 kg.
Using just the harpy eagle and peregrine falcon data, the answer to "How much can a bird lift?" appears to be "About half its own weight." I admit my sample size is very small, but sounds reasonable for a first round estimate.
However, we also have to understand that the carrying capacity of an animal follows a rule of diminishing marginal returns. A 5 mg ant can hoist a 500 mg leaf (10,000%), while a 5000 kg elephant might be able to carry 500 kg of logs (10%). The larger animal can carry more, but at a significantly reduced ratio. Our ever larger birds might be reduced to 30-40% or less.
That means to lift a husky human we need at least a 200+ kg bird. It seems that the known size range of birds falls very short of that. Even a gaunt human is almost equal in weight to its would-be feathered steed. Sorry.
Meanwhile, if we expand to pterosaurs and their ilk, we might just have a chance. It is becoming my go-to example. Assuming the higher-end estimates for its mass and a generous allowance for its lifting capacity, I would love a ride on a Quetzalcoatlus. (Do I have to say it yet again? Modern literature needs more Quetzalcoatlus.)
Update: Since posting this a month ago, we now have this. I am tempted to recant my entire answer in favor of Mr. Munroe's.
This post was sourced from https://worldbuilding.stackexchange.com/a/38554. It is licensed under CC BY-SA 3.0.
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