Hi Mattie,firstly let me apologise for my reply which has come almost a year too late for you
For future reference i can answer some of the questions you have asked in this thread.
AS has been said already,cock chaffies are very aggressive when in breeding condition,they can and often will chase the hen mercilessly to the point of her dying from
sheer exhaustion.I believe you noticed the hen was missing feathers from the back of her head only ? This usually happens when a hen is sitting on eggs but the cock is
trying to get her to go again and picks at her relentlessly,more often than not resulting in her abandoning the nest.
While a certain amount of rough type behaviour is normal in breeding chaffies,viciousness/violent behaviour is certainly NOT,and is usually a result of the cock bird
being ahead of the hen in breeding condition.Personally i would split a pair for a week or two to allow the hen catch up with the cocks condition.
Young Chaffinches are fed mainly on a diet of live food,mealworms and frozen pinkies are what we use in this part of the world,so i doubt very much you could foster
them under canaries,unless of course you have canaries that will take the various livefoods ?
Anyway Mattie,how did they work out for you after,did you manage to breed any ?
Nick.