Magnolia Warbler has a partial preformative molt, and partial prealternate molts that include some to all greater coverts, and occasionally one inner tertial. Sex can usually be distinguished by plumage from first cycle alternate (second year) onward, but in younger birds many intermediates should be considered sex unknown.
- Look at the primary coverts - on FCF/FCA (HY/SY) birds they are grayish (fall) to brownish (spring) and contrast visibly with the black greater coverts, while on DCB/DCA (AHY/ASY) birds they are blackish and similar in colour and wear with the greater coverts.
- Check the tail - HY/SY birds have relatively narrow and somewhat tapered rectrices, while DCB/DCA (AHY/ASY) birds have broad and fairly rounded rectrices; also, males tend to have blackish to black tail feathers, while on females they are more dusky gray.
- Examine r2 (the second rectrix from the centre) - on DCB/DCA (AHY/ASY) males the white spot is similar in size to that on other rectrices, on DCB/DCA (AHY/ASY) females and most FCF/FCA (HY/SY) males the white spot is slightly to moderately smaller than on other rectrices, and on FCF/FCA (HY/SY) females the white spot may be absent or considerably smaller than on other rectrices, but note that intermediate spot size in first cycle birds are fairly common.
- Look at the uppertail coverts - they are mostly black with bluish edging on DCB/DCA (AHY/ASY) males, with distinct black centres and greenish and/or bluish edging on DCB/DCA (AHY/ASY) females and FCF/FCA (HY/SY) males, and generally with only small dark centres and mostly greenish edging on FCF/FCA (HY/SY) females.
- In alternate plumage look at the face - males have a black mask, while on females the head is more uniformly gray.
Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)