Readers were puzzled as to where such a tradition could have gotten
started for a bird entirely unknown in centers of Torah scholarship until
colonial American times. The answer is possibly given by Darchei Teshuva,
Yoreh Deah, 82:26 He argues (actually citing Arugas Habosem) that we
only require a tradition for a bird that we don't know too much about. In
such a case, we do not rely on the presence of the kosher signs. On the
other hand, we are permitted to rely on such signs if they are present in
many samples of a species we have observed over a long period of time, and
have overwhelming evidence that it is not a bird of prey.
Yitzchok Adlerstein
Los Angeles