Why is it that differenct breed of birds aren't able to produce offsprings?

Question

Dogs & cats are able to produce young through inter-breeding. Why can't birds or monkeys?

Answer 1

I am not sure if I understand your question? Do you mean two dogs like a Cocker Spaniel and a Collie breeding? Or a Cocker Spaniel and a Siamese Cat breeding?

I will address both, then go to birds and monkeys.

First dogs are all the same species. It does seem incredible, but a Chihuahua is the same species as a Great Dane and would be able to produce puppies, though it wouldn't be easy! Any of the domestic house cats, like Persians, Siamese, etc are also the same species. Because of domestication people have been able to selectively breed these species to get a wide variety of types. They are called breeds, not species.

Birds and monkeys have not had this same manipulation. Even birds that look fairly similar, like a White-throated Sparrow and a Swamp Sparrow are different species. There actually can be some hybridization between similar species, but its rare and normally a bird of one species will choose a mate of its own kind.

Monkeys are the same. They are different species. I am not as familiar with monkeys as I am with birds, and there may be some hybridization, but they are still separate species.

Oh, if you meant cats and dogs breeding with each other, that doesn't happen.

Answer 2

different breeds of dogs (and cats) are NOT different SPECIES! Actually some birds that are in the same genus can inter-breed, because they are very closely related, and they will produce a hybrid, which would than be sterile. If two animals match in number of chromosome and are in the same genus, they can breed.

Answer 3

because birds and monkeys have evolved so much that they are different species, dogs and cats are still the same species. The egg of a blue jay will not let an eagle sperm through, its just because of the chromosomes. - simple biology

Answer 4

Sure what about the turkey vulture or the great northern chickeneagle? I never heard of dogs and cats interbreeding with each other though. That's perverted.