eli5 why aren’t there any big flying animals


I know other people asked this question before. But they didnt give a clear answer. In what way has our ecosystem changed that something like this has now become impossible?

In: 0

The emergence of mammals and the diversification of bird species led to increased competition for resources. Large flying animals require substantial amounts of food to sustain their energy-demanding flight, and with increased competition, it became harder for them to find enough food to support their size.

Additionally, changes in climate and atmospheric conditions have influenced the ability of animals to fly. The size and structure of an animal’s wings must be adapted to suit the specific environmental conditions. As the climate changed, ecosystems transformed, and atmospheric dynamics shifted, it became less advantageous for animals to evolve and maintain large sizes for efficient flight.

Physics also plays a role in limiting the size of flying animals. The principles of aerodynamics and the physical constraints of materials restrict the maximum size and weight an animal can be while remaining capable of flight. The larger an animal gets, the more difficult it becomes to generate sufficient lift and maneuver in the air. Additionally, the structural integrity of an animal’s bones and wings becomes increasingly challenging to maintain as size increases.

It’s just not beneficial in any way for them to get that big.

Depending on what you mean with big it’s not that’s impossible per se, but it is disadvantageous. Biggest flying bird has about 3 meters wingspan. If you mean big like the Quetzalcoatlus (12 m wingspan) there are a couple reasons. First on average there is less vegetation now than when dinosaur megaphauna roamed the earth. Less oxygen and food for big erbivores favor smaller animals. Smaller prey means only smaller carnivores can hunt enough to sustain themselves so most animals are smaller. Notable exceptions are marine mammals because the abundance of their food. In general in the modern ecosystem most species organize in packs or herds and are individually smaller. This makes them more capable of adapting to environmental changes. that Big birds are either scavengers, birds of prey or far travelling sea birds. Scavengers need to be big enough to scare other terrestrial smaller scavengers away from the carcass. Birds of prey need to be big enough to kill small mammals which they usually hunt and migrating birds can’t be too heavy in relation to their wingspan so that they can travel very long distance with minimal effort

Just like any predator bigger than us, we’d eradicate them around major population centers, farms, etc.