והתניא: חיה שקננה בפרדס צריכה לזמן, וצפור דרור צריך לקשור בכנפיה כדי שלא תתחלף באמה. וזו עדות שהעידו מפי שמעיה ואבטליון.
But it was taught: If an animal made its nest in an orchard [and gave birth] [the newborn] must be designated and a sparrow [dror-bird], one must tie its wings so that it does not become confused with its mother and this is a testimony that they testified in the name of Shemayah and Avtalyon.
@General observations
Everything anyone would wish to use or eat on a festival day has to be designated on the day before. This rule applies even to newborn birds. Furthermore, one has to make sure that one takes precisely the bird that was designated beforehand and does not become confused and take by mistake a similar-looking bird that was not designated in advance.[1] Therefore, the rabbis state that after one designates a baby sparrow (dror-bird) on the eve of a festival, one must tie its wings as an identifying marker.
[1] For a further discussion of this topic see the FCBT V/9 on Massekhet Qinnim.
@Feminist observations
Feeding of sparrows (dror-birds) always takes place in groups, even when parents are feeding their young. Therefore, they could easily be mixed up if one is not careful. The rabbis rule that one must tie the wings of a little dror-bird so that it does not become confused with its mother. But male and female dror-birds can be clearly distinguished from one another as they do not look alike. The rabbis, nevertheless, do not argue (as would be the logical line of reasoning) that the male chick could be confused with its father and the female with its mother. Indeed, the mother-bird does not spend more time with the young than the father-bird, as male and female dror-birds take equal part in feeding their chicks. The idea that the female bird is closer to the little dror-bird is borrowed from the rabbinic concept that a mother has custody of her children until the age of six (see the commentary on Bavli 2/1. bBetsah 16a). Because this kind of bird lives in a lifelong “marriage” with her/his partner and, thus, behaves like humans, the rabbis explained the bird’s zoology anthropologically, in accordance with their concept of idealized human behavior.