Morphometric and genetic sexing in the Gough MoorhenGallinula comeri

Abstract

To develop an accurate, low-cost method for sexing Gough Moorhens Gallinula comeri using morphometric measurements, twelve measurements were taken from 59 birds and validated against genetic sexing. The classification accuracy of variables was determined and discriminant analysis was used to test whether multiple variables improved accuracy. Males were larger than females in all dimensions. Head length reliably differentiated male and female Gough Moorhens. A threshold of 64 mm correctly classified 92% of the sample birds; adding other variables did not improve accuracy. Gough Moorhens can be sexed with an acceptable level of accuracy using a single morphometric variable, but genetic sexing is needed to confirm the sex of individuals that fall within the overlap zone (62-66 mm).

Diet of the introduced Gough Moorhen Gallinula comeri on Tristan da Cunha

“…In 1956, six Gough Moorhens were introduced to Tristan at Sandy Point on the east coast, and they are now present through Birds were killed accidentally during rodent trapping at Pigbite (n = 2) and Big Point Road (n = 2) at 270-350 m elevation. Birds were sexed either by dissection or using measurements (Parker et al 2012). The complete pro ventriculus and gizzard were dissected out and flushed with tap water.…”