Distinguishing Males from Females

Lady Gouldian Finches	Cordon Bleu Waxbills, Blue Capped
Chloebia gouldiae	Uraeginthus cyanocephala

Sexually Dimorphic Species

Some finches are sexually dimorphic, meaning that the males can be distinguished from the females visually. Typically, with these species, the male is the more vibrantly colored or more elaborately marked of the two sexes.⁷ Examples of dimorphic species are the Lady Gouldian Finch and the Cordon Bleu Waxbill, both pictured above. Notice how the cocks have more vibrant and/or more extensive coloring than the paler, less well-marked hens.

Mutations of Sexually Dimorphic Species

Sometimes species which are ordinarily sexually dimorphic may appear sexually monomorphic due to a certain coloration or mutation. One example of this phenomenon is the white Zebra Finch. Typically, Zebra Finches are very easy to sex because the male usually has at least one of the following features that the female typically lacks: cheek patches, a breast bar, or spotted side flanking. The white mutation, however, complicates things because in all-white birds, neither sex has any markings to help distinguish the males from the females. In some cases, the male's beak is a darker red than the hen's orange beak, but some variation is possible making the two genders appear nearly identical. To the inexperienced Zebra Finch keeper, mutations such as these can be very confusing and make sexing the birds a challenge.

Seasonal Changes in Plumage

Also complicating matters is that fact that some of the sexually dimorphic species only show differences in markings and/or body coloration during the breeding season. Unfortunately, in these birds the "eclipse" (non breeding) plumage of the cocks looks nearly identical to that of the hens, who do not change colors seasonally. Examples of these types of species are the Strawberry Finch (Red Avadavat) and the Orange Weaver. To the left is a photo of two strawberry finch cocks in differing amounts of "nuptial" (breeding) plumage. When Strawberry (or Orange Weaver) cocks are sporting their eclipse plumage, they are (basically) visually indistinguishable from the hens.

Sexually Monomorphic Species

To confuse things further, many finches are not sexually dimorphic at all. These sexually monomorphic species do not have any obvious or subtle morphological differences between the genders, making visual sexing impractical, even during the breeding season. Examples of these types of finches are Society (Bengalese) Finches, Owl Finches, and Spice Finches, to name a few. Because cocks and hens are so similar in appearance, other factors must be looked at to determine the sex of these birds. Differences in singing, courtship, and nesting behavior may all provide clues as to the gender of the birds.⁷

Of the two sexes, in nearly all of the species, only the cocks will sing. (The exceptions to this are: violet-eared waxbill hens, purple grenadier hens, melba finch hens, and some firefinch hens which may sing, especially when separated from their mate. In these cases, the song of the hen is shorter, less elaborate, and often softer sounding than the cock's.)¹³ Both cocks and hens may make simplistic chirps and calling noises, but typically only the cocks have the more lengthy and elaborate song. Often the cock's song is accompanied by a "dance." During courtship, cocks of some species may sing while hopping and/or holding a feather or a strand of grass, for instance. In a few cases, hens may try to mimic this dance (such as the occasional Lady Gouldian hen which hops up and down while vocalizing), but they chirp instead of sing. If possible, place a group of monomorphic birds of the same species in a community aviary or flight and observe them. Catch the birds which sing and/or display male courtship behaviors and band them to make their identification easier. Males sometimes court other males, so the birds being courted are not necessarily hens. If your bird lays eggs, it is a hen; hens can lay eggs even in the absence of a male.

How to Sex Your Finches

In summary, use the following tips to identify the gender of your bird(s):

• Birds which sing or dance while singing are (almost always) cocks.
• Birds which lay eggs are hens.
• In a sexually dimorphic pair, the cock is the more vibrantly colored and/or elaborately marked of the two birds, especially during the breeding season.
• In many species, the male's seminal glomerulus will push the cloacal wall into a prominent projection (called the cloacal protuberance or cloacal promontory) during the breeding season.⁷ This causes the area surrounding the vent to protrude more in cocks than it does in hens. When the breeding season is over, the vents of the two sexes appear similar.

The Specific Species section of this site provides more specific details on how to sex individuals within a given species.

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