Geese are not as easy to sex as ducks, where the quack is the instant giveaway. New owners often cannot tell their geese apart and a ‘pair’ of perfectly happy young birds can turn out to be the same sex by spring. We’ve heard tales of the faithful ‘gander’ sitting side by side with the goose – on a nest of infertile eggs belonging to the two females of course. It is useful to buy reliably vent-sexed birds.

Geese can also be sexed by a combination of indicators, including colour, shape, voice, size, and behaviour. Just as humans cue their own sex and gender from appearances, geese are aware of their own differences – and they tend to know best.

Watching goose behaviour, interactions and body language will give a good indication of their sex, but signs can confuse because of the personality of individual birds. Just as with humans, there can be big, confident, bossy females and small submissive males. Atypical behaviour can cloud the issue but, taken together, there are several useful pointers to the sex.

Colour differences

In ‘auto-sexing’ breeds, males and females are distinguished by the colour of their fluff and feathers. This distinction only works if they are pure breeds because colour is determined by their genetics. A grey goose and a white gander are not necessarily ‘Pilgrims’.

Pure Pilgrim geese hatch diluted grey females, which retain grey feathers. The female goslings also have a darker bill than the males. The adult males are almost white, have paler bills and yellowish-grey fluff at hatch. West of England and Shetland also show a diluted grey-back (pied) pattern in the fluff and retain this pattern in the adult female; ganders are almost white.

The reliability of these auto-sexing breeds does depend upon the purity of the breeding pair. So-called ‘Pilgrim’ geese can produce white females, and so-called ‘West of England’ grey and white geese can turn out to be male. Obtain stock from an experienced, reliable breeder; the sex always needs to be checked to ensure that they are breeding true.

‘White’ breeds such as Embden, Czech and Sebastopol are auto-sexing as infants with about 80% reliability. This is in a batch of several birds, to see the colour contrast. Both sexes show a faint grey-back pattern in the fluff at hatch. This fluff is darker in the females which can look even like the Grey Back breed at this stage. These dark markings are replaced by white feathers, but females often retain some grey feathers on the rump. This is not a fault, but a useful auto-sexing characteristic produced by the ‘spot’ (pied) gene acting with the ‘dilution’ gene to make ‘white’ feathers.

In contrast, pure White Chinese goslings should have bright yellow fluff when they hatch, replaced by white feathers as they grow. Their white ‘c’ gene is not sex-linked.

Size, voice and behaviour

Male goslings are generally faster growers and have bigger feet. This is very noticeable if the birds are fitted with closed rings (retained for life) at around four weeks of age. Ganders usually end up larger, the size difference being quite marked in Africans and Chinese where the males are taller by 20 weeks. Eventually, the knob on the head of these breeds will also grow larger and broader in the male. In all breeds, females will develop a heavier undercarriage even by 26 weeks.

From around 16 weeks of age, the gosling voice changes. This difference in tone is an adult characteristic. Brecon females have really low voices, whilst the males have higher, more rapid chatter. Listen to them carefully; it is a useful confirmation of the sex. Chinese and Africans are different from European geese. Chinese females develop a characteristic ‘oink’ by 16 weeks. Africans are more difficult to distinguish by voice until older, when the females too will tend to sound more like their Chinese relatives.

Birds should be handled regularly to check their weight. It also it keeps them tame and allows for observing differences in behaviour. Males tend to be more confident in coming forwards and this also shows when held facing you: they tend to sit more calmly in the hands, whereas females chew clothes and hair.

Vent sexing

Goslings can be vent-sexed at 1-2 weeks, but they are small and delicate. So, I do this at 3-4 weeks of age and close-ring birds at the same time. This is a good age to examine the birds because the wing feathers have not grown and there is no blood in the tiny quills. A well-handled bird is tame, more robust, but small enough to be placed on its back across your knee (in a sitting position) and can be kept comfortable.

Force is not applied when opening the vent to determine the sex. The gosling must be allowed to relax its sphincter muscles before applying slight downwards and outward pressure to open the vent. If the sex of the bird cannot be determined after a couple of tries, leave it until another occasion so as not to cause bruising or undue stress. Some birds are easier to handle than others; females generally have a softer vent which will open more readily. An experienced person should demonstrate this first.

Larger juvenile birds are more difficult to handle and get more distressed by the process than a young gosling. It is also difficult to see the tiny penis in the males at this stage, and it can be confused with the genital eminence in the female. The penis grows to its adult size when the males are sexually mature (26-28 weeks).

Adult birds

Quite often, the sex of young geese seems to remain unknown, to the owner, until the breeding season. Females lay eggs in a cycle of around 36 hours so, an egg a day from two birds, indicates two females. Quite often it is assumed that two such birds are a pair because hens and ducks do lay an egg a day. The ‘pair’ of geese may even appear to mate, in the absence of a male.

Two ganders may also behave as a ‘pair’, especially if they have been brought up together. They may get on well until spring and then begin to fight. One will fail to submit to the other’s advances as they start to go through the mating ritual.

Birds do give themselves away by their general habits too. Ganders are usually more aggressive even if it’s not the breeding season. One test is to bring a dog up close, on a leash. Ganders are far more likely to advance to threaten the dog.

There are exceptions to typical behaviour. Some females are far more ready to see off intruders that others; tame male goslings can chew clothes just as enthusiastically as the females and, occasionally, there is a very large goose. However, experienced goose keepers (and the geese) know the signs as a package. It is very rare for a gander to attack a female, even if she had been thoroughly nasty to him. Males instantly recognise a female and will not go through a display leading to a fight.

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