According to the Torah (Sefer Vayikra 1:14), the two types of birds that can be brought as sacrifices are torim and benei yonah – turtledoves and pigeons. The tor that is referred to is identified as Streptopelia turtur, while the yonah is identified as Columba livia domestica. These birds are consistently referred to differently, the former are called torim, while the latter are called benei yonah. This is understood by the Sages to mean that a tor is only qualified to be brought as a sacrifice when it is an adult bird, while the yonah can only be brought when it is young, before it reaches adulthood. According to the Mishnah on today’s daf (=page), these two periods are mutually exclusive, and what would be an appropriate sacrifice in a pigeon would be inappropriate in a dove, and vice versa. The cut-off point between the two is just four or five days after hatching, when the bird’s body becomes covered with plumage – gold in the case of torim and yellow in the case of benei yonah.
The ruling of the Mishnah is that torim that are too small and benei yonah that have already reached adulthood cannot be brought as sacrifices and therefore performing melikah on them (see above, daf, or page 19, for a description of melikah) would not be effective in any way.
In explanation of the difference between the two, the Rambam in his Moreh Nevukhim (3:46) argues that the meat of the turtledove is better when it is more mature, while that of the pigeon is better when the bird is young. The Ramban in hisCommentary to the Torah (Vayikra 1:14) offers another suggestion, pointing to the different nature of each of these birds. Adult turtledoves are loyal to their mate to the extent that if one’s mate dies, the other will not choose another partner. This represents the relationship that exists between the Jewish People and God. In contrast, pigeons are jealous creatures that separate and switch mates, even as they are happy and content in their early stages of development.