Bill Crossover Ratios in Canadian Crossbills Loxia spp.
- 31 October 1987
- journal article
- research article
- Published by JSTOR in Ornis Scandinavica
- Vol. 18 (4) , 310-312
- https://doi.org/10.2307/3676900
Abstract
The relative direction of crossing of the upper mandible with respect to the lower was recorded in 383 Crossbills and 322 Two-barred Crossbills collected in Canada. There was no significant difference between the occurrence of right-billed and left-billed Crossbills, but a highly significant excess of left-billed Two-barred Crossbills existed. In both species, the direction of bill crossing was independent of sex, age, and geographic locale. It is suggested that these ratios may be related to those of two distinct seed cone morphologies described in several coniferous tree species.This publication has 1 reference indexed in Scilit:
- THE SEQUENCE OF PLUMAGES AND MOULTS OF THE PASSERINE BIRDS OF NEW YORKAnnals of the New York Academy of Sciences, 1900