The absence of juvenile sexual dimorphism in birds often impedes sex determination using external morphology. We examined sex ratio variation in Scopoli's Shearwater (Calonectris diomedea) fledglings (n = 135) on a Strofades island (southern Ionian Sea) between 2007 and 2011. We determined sex by using a polymerase chain reaction-based methodology on blood samples. The molecular technique revealed a slightly male-biased sex ratio (52.6% ) during the five consecutive breeding seasons. In addition, morphological analysis using six morphometric variables (bill length, bill width, nalospi, bill-head length, head length, tarsus length) and body weight indicated that males were significantly larger than females for all the tested variables. The combined use of those variables correctly classified 81.2% of known-sex fledglings, and the stepwise discriminant analysis pointed out that bill length was the most discriminating variable followed by bill depth, head length, and body weight.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 36 • No. 2