Tosefta su Deuteronomio 22:7

A male [bird] is exempt [in the commandment of] "sending away." A male pheasant -- Rabbi Eliezer deems one liable and the Sages deem one exempt. An impure bird is exempt from sending away. A bird that is crouching on top of the eggs of a different species is exempt from sending away. [If the mother bird] was standing among them (i.e., the fledglings), one is exempt from sending away. [If] she was sitting on top of them, one is liable in sending away. [If] she was hovering over them at a time that her wings were touching them, one is liable in sending away. [If] her wings were not touching them, one is exempt from sending away. [If] the fledglings are tereifah, she is exempt from sending away. [If the] eggs [are unfertilized (Hul. 140b:14)], one is exempt from sending away. [If the] fledglings are able to fly and do not need their mother, one is exempt from sending away. [If] he took the mother and he did not have enough time to take the chicks before they died, or before they became tereifot, he is exempt from sending away. [If] he took the mother and afterwards took the chicks, he is liable in sending away. [If] he took the chicks and afterwards took the mother he is exempt from sending away. [If] one person took the mother and another person took the chicks, the one who took the mother is liable. One who finds nests in pits, ditches, or caves, they are permitted as to theft but forbidden as to sending away, and if [their wings were] tied, one is liable for theft and exempt from sending away. As to pigeons of a dovecote and pigeons of an attic (Hul. 139b:6, Steinsaltz tr.), they are liable in sending away and also forbidden with regards to theft, in accordance with the ways of peace.

[With respect to the ritual involving two live birds to purify a metzora, see Lev. 14:4-8,] one who finds a nest shall not [use it to] purify a metzora, as it says "v'lakach" (i.e., "take" or "buy"). One who carries away the mother with her chicks, Rabbi Yehuda says, he is to be flogged, but need not send away the mother (Makkot 3:4), and the Sages say, he sends away [the mother] and is not flogged. This is the general rule: All negative commandments that require one to get up and perform [an act], one who [violates] it is not liable [for lashes]. A person must not take away the mother with her chicks, and even not to purify a metzora, because [the purification ceremony] will be performed through a transgression. § Rabbi Ya'akov says (see Hul. 142a:3-9), there is no commandment in the Torah whose reward is not stated next to it, and [as to which] the resurrection of the dead is [not] written in it, as it says, "Surely send away the mother [... so that it will be good for you]." Someone climbed to the top of a tree [and sent away the mother bird] and fell and died, and [another climbed] to the top of a building [and sent away the mother bird] and fell and died -- where is the goodness in that? [Rather,] it is said (Deut. 22:7), "so that it will be good for you" -- this is in the "good world" (i.e., this world) -- "and your days will be lengthened" -- this is in the "long world" (i.e., the eternity of the world to come).