If somebody finds a non-kosher (not fit to eat) bird sitting on a nest, they do not have to send it away. The mitzvah (commandment) of sending away the mother bird applies only to kosher (fit to eat) birds. The pasuk (verse) tells us, “If the nest of a tzipor, a bird, is going to be before you.” We use the word tzipor here to talk about a bird. We only use the word tzipor when talking about a kosher bird. A general word, “of,” is used when talking about all birds, kosher and non-kosher. So we learn from here, from the word tzipor, that it applies only to a kosher bird. So you are allowed to take the mother bird for your own use, even though it is sitting on its eggs or chicks.
In addition to that, if you have a non-kosher bird sitting on the birds of a kosher bird, or a kosher bird sitting on the eggs of a non-kosher bird, you do not have to send it away. The mitzvah of sending away the bird applies only to the bird and the chicks, if they are one and the same, if they are kosher. The fact over here is that if just the chicks or the eggs are kosher, it would not be enough to create the obligation to send the mother bird away.
We also say, “Take the young for yourself.” We learn from here that they have to be edible for you; you have to be able to eat them, not just feed them to your dog. So we learn from here that the mitzvah of Shiluach HaKen (sending away the bird) can't apply is only if the eggs and the chicks are kosher, so that you have the ability to eat it. But if you cannot eat them because they are not kosher, there is no mitzvah to send away the bird sitting on them, even though it is a kosher bird.
Koreh zachar. If a person finds a male partridge sitting on a nest, the partridge is a kosher bird, and it sits on eggs just like the female would. Rabbi Eliezer mechayev. Rabbi Eliezer obligates you to send it away. A male bird of this species sits on the nest just like the mother does, and therefore we can look at it as if it is the mother bird, even though it is actually male. Vachachamim potrin. But the rabbis exempt it from being sent away. According to them, if Shiluach HaKen applies only to a female bird, it can never apply to a male bird regardless of the situation.