Age and sexual differences of measurements in Rustic and Reed Buntings, Emberiza rustica and E, schocniclus

Abstract

1. In the Autumn of 1974, Rustic Buntings Emberiza rustica and Reed Buntings Emberiza schoeniclus were captured and measured at Lake Fukushima, Niigata Prefecture. The measurements taken were divided into juvenile males, adult males, juvenile females and adult females, and analysed.
2. In Rustic Buntings, significant differences were found between the mean weights of the adult male and of the adult female, and of the adult male and juvenile male, between the mean wing lengths of the adult male and adult female, of the juvenile male and juvenile female, of the adult male and juvenile male, and of the adult female and juvenile female, between the mean tail lengths of the adult male and adult female, and also between the mean culmen lengths of the adult female and juvenile female.
3. In Reed Buntings, significant differences were found between the mean weights of the male and female, between the mean wing lengths of the male and female, and of the abult male and juvenile male, between the mean tail lengths of the male and female, and of the adult male and juvenile male, between the mean tarsus lengths of the adult male and juvenile male, and also between the mean culmen lengths of the juvenile male and juvenile female.
4. Generally, the mean measurements of the adult were bigger than the juvenile in any sex, and the mean values of the male were bigger than the female in any age. The causes of these differences are discussed in the text.