In Yasukawa' s month-long study of blackbirds, the percentage of smaller birds that survived the duration of the study exceeded the percentage of larger birds that survived
However, Yasukawa' s conclusion that size is a determinant of a blackbird' s chances of survival over a month-long period is probably mistaken, since smaller blackbirds are generally younger than larger ones
Among the blackbirds that survived the month-long study, there was no relation between size and age.