Most birds cannot be reliably sexed on appearance. We determine sex molecularly by targeting the CHD-Z and CHD-W genes on the avian sex chromosomes: females (ZW) and males (ZZ) produce distinguishable fragment patterns. Works from a freshly plucked feather with pulp, or a small blood sample, and returns a clear male or female result for breeding, husbandry and ringing work.
How we determine sex
In birds, the sex chromosomes are reversed relative to mammals: females are the heterogametic sex. We target the CHD gene on both chromosomes and the result is a clean molecular readout, independent of plumage or behaviour.
Female
ZW
CHD-Z and CHD-W differ in length, giving two distinguishable fragments.
Male
ZZ
Two copies of CHD-Z, giving a single fragment pattern.
Sample requirements
One freshly plucked body/contour feather with the pulp (quill base) intact, or a small blood spot on an FTA card. Plucked, not moulted, feathers.
Frequently asked questions
- What sample do you need to sex a bird?
- A single freshly plucked feather with the pulp at the base of the quill, or a small blood sample. Moulted feathers found on the ground rarely retain usable DNA.
- How does molecular sexing work?
- We amplify the CHD-Z and CHD-W genes on the sex chromosomes. Females carry ZW and males ZZ, which produce distinguishable fragment patterns — giving an unambiguous sex call independent of plumage.
- Does this identify the species too?
- Avian sexing returns sex, not species. If you need a species identification from a specimen, use our DNA barcoding test instead.