A simple strategy for improving bird sexing from highly degraded DNA samples

A simple methodology was developed to select new sex-specific primers for bird sexing from degraded and low-quantity DNA sources. The strategy was validated using highly degraded DNA extracted from Giemsa-stained blood smears of common cranes (Grus grus). The new primers allowed the accurate molecular sexing using (i) a classic approach of PCR followed by agarose gel electrophoresis and (ii) an advanced real-time PCR method. The simplicity, speed and low cost make this methodology a versatile molecular tool for selection of novel markers/primers for bird sex differentiation from complex DNA sources, which can be used as basis or complement in several fields of ornithological research.