I've just been advised to start a thread about the breeding of such birds,
I'm just curious to see if there's many people that have bred many mules or hybrids,
The breeding and exhibition scene of high class birds is very big here in England and also Europe,
I'll try to explaine here as easy as I can,
Canary x canary = ( cross breed ) although we still call em hybrids, it's a slang thing

Finch x different specie of finch = hybrid
Canary x finch = mule
However all finch x bullfinch hen are hybrids and even a canary x bullfinch hen is still classified as a hybrid, this bit here seems confusing but the reason why the canary x bullfinch is called a hybrid and not a mule is because of the following:
Basically it's never ever been know in the bird world for a cock bullfinch to tread and fertilise any other type of finch or canary, the courtship behaviour of a cock bullfinch is a lot slower and the timing is wrong compared to other birds,
Cock bullfinches simply can't fertilise anything other than its own type,
Only the hen can be used to produce any hybrids,
Goldfinches, greenfinches, chaffinches, brambles, linnets, twites, siskins and redpolls can all produce mules and hybrids from both sexes.
The mules and hybrids of over a 30 year period that I've personally bred and exhibited are as follows :
Goldie mules, linnet mules, twite mules, Siskin mules, redpoll mules and greenie mules,
The birds used to produce the large type exhibition birds where all quality champion bred Norwich canaries, a few miniature mules where also bred aswell using small Irish fancy and Fife canaries

Hybrids are : Goldie-redpoll, Goldie-Siskin, Goldie-linnet, Goldie-greenfinch, Goldie-bullfinch,
Linnet-redpoll, linnet-Siskin, linnet-greenfinch, linnet-bullfinch,
Redpoll-Siskin, redpoll-greenfinch,
Siskin-greenfinch, greenfinch-bullfinch, canary-bullfinch,
chaffinch-greenfinch, chaffinch-bramble,
The bullfinch and chaffinch hybrids are without a doubt the hardest of all hybrids to breed,
Of all the hybrids that I've bred in this time the only one that I simply could not breed after many close attempts was the redpoll-bullfinch,
A few redpoll-bullies have been bred here in England but are now increasingly very rare and pricey
Average redpoll bullies would fetch £400 - £600 a lot of money for a bird that won't ever breed again,
The majority of quality mules and hybrids are purely bred for colour, song and exhibition purposes,
Most mules are surprisingly very hardy and can withstand very cold conditions providing they are not kept in any drafty and damp areas,
Also a lot of mules can live to a very good age, some have gone well over 15 years or more.
When we exhibit our mules it is often best to use carraphil red colour food which is basically a powder form which is added to the drinking water at the correct dosage when the birds moult,
When a bird moults this colour food is pushed through the quills of the feathers and is how the colour is attained,
However it's not necessary to colour feed any canaries, mules or hybrids if one is not interested in exhibiting as a lot of people enjoy keeping mules just purely for the song and rightly so as the song is often a Loverly sound from the birds,
If anyone is interested I can also write at a later stage about the art of cage breeding mules

I don't really specilise in the mules and hybrids now as my main aim is concentrating on quality zebras along with a few other foreign finches but I'd definitely Be interested to know if others are interested and have bred any such birds
