gander will come towards you and the goose will run away if you give them chance to move without too much stress.
we used to catch them by the neck and
very quickly control the wings with your hands. you can carry them under your arm with one hand on the neck to stop them from pecking your face. beware wings really hurt if they strike you, so be quick. iv ripped nails off my fingers with goose wings - ouch.
herding them into a stable makes life easier. iv seen geese caught in the field with a big fishing net but it did take a long times, a bit of sweat and a few swear words...
try catching them in the evening when they are settling down for the night.
if they are pedigree birds of the same breed, then the younger ones are smaller. they should all be fully feathered by now. the younger ones also wouldnt be the leaders in the flock so watch their behaviour if possible.
im sure a lonely gander would be grateful for any female irrespective of age. they do live a long time.
go for one with bright eyes, clean bum and clean feathers. ill birds dont look after their feathers so well.
good luck. im sure the owner will help you, unless he has a wicked sense of humour
