Beginning with the Mishna on today’s daf we move from the place of zevaḥim – animal sacrifices – to the place of sacrifices brought from fowl – doves or pigeons.
Sacrifices brought from fowl are not formally zevaḥim, which are limited to animals that are slaughtered in an ordinary fashion. These sacrifices are prepared for sacrifice by means of melika, where the kohen will pierce the neck of the bird with his fingernail (see Vayikra 1:14-17 and 5:8-10). The Mishna on today’s daf describes this preparatory service, and the Gemara quotes a baraita that describes it as the most difficult service that was performed in the Temple.
What was involved in the service of melika?
Rav Zutra bar Toviyya quotes Rav as teaching that the kohen would hold the wings with two fingers and the legs with two fingers stretching out the bird’s neck, and the bird would be killed by means of the kohen‘s thumbnail. According to the baraita, the bird’s body was held in such a way that it was outside the hand of the kohen, and – while holding the wings with two fingers and the legs with two fingers – the kohen would kill the bird with his thumbnail.
According to Rav Ovadya mi-Bartenura, as well as the Rambam, the kohen would hold the bird in his left hand according to one of the two opinions, and would perform melika with the thumb of his right hand. This parallels cases of slaughter in the Temple, where both hands are used. The Shita Mekubbetzet quotes Tosafot as suggesting that the entire melika service was done with the right hand. According to this approach we can easily understand why this service is considered to be the most difficult one, since the bird had to be held and killed with a single hand.