One is exempt from sending away a non-kosher bird. [If] a nonkosher bird sits on the eggs of a kosher bird, or [if] a kosher [bird] sits on the eggs of a nonkosher bird, one is exempt from sending [it] away. A male partridge — R’ Eliezer rules that one is obligated [to send it away], but the Sages exempt.

[If] she was flying — as long as her wings touch the nest, he is obligated to send [her] away; [if] her wings do not touch the nest, he is exempt from sending [her] away. [If] there is only one chick or one egg, he is obligated to send away [the mother bird], as it is stated: A nest — a nest in any case. [If] there were fledglings or infertile eggs, he is exempt from sending away [the mother bird], as it is stated: And the mother bird is sitting on the chicks or on the eggs — just as the chicks are viable, so must the eggs be viable, which excludes infertile ones; and just as the eggs need their mother, so do the chickes need their mother, which excludes fledglings. [If] he sent her away and she returned, he sent her away and she returned, even four of five times, he is [still] obligated [to send her away], as it is stated: You shall surely send away. [If] one says, ‘‘I will take the mother bird and send away the young,’’ he is obligated to send away [the mother bird], as it is stated: You shall surely send away the mother bird. [If] he took the young and returned them to the nest, and afterwards the mother bird returned upon them, he is exempt from sending [her] away.

[If] one takes a mother bird while on her young — R’ Yehudah says: He incurs the penalty of lashes, and he need not send [her] away. But the Sages say: He must send [her] away, and he does not incur the penalty of lashes. This is the rule: Any negative commandment that has in it a positive commandment, one does not incur the penalty of lashes for its violation.

A person may not take the mother bird while on the young even to purify a metzora. Now, if concerning an easy commandment that involves a loss of about an issar, the Torah states: In order that it be good for you and you may live long, how much more does this apply to the difficult commandments in the Torah!