* Other birds: Larger birds, such as crows and jays, can also eat bird seed and prevent smaller birds from getting a chance to eat.
* Cats: Cats can be a major threat to birds, and they may even climb up bird feeders to try to catch the birds.
* Bears: Bears can also eat bird seed, especially if they're hungry or if there's a lack of other food sources available.
* Weather conditions: Heavy rain or snow can keep birds from getting to the bird feeder, and they may also be wary of feeding when the weather is stormy.
* Insects: Insects, such as ants and wasps, can be a nuisance to birds and may even contaminate the bird seed.