Thanks for your kind words, you are very welcome.
1. Australian Black Swans are considered southern hemisphere swans and do very well in hot weather and not so good in very cold weather. It is for this reason that we suggest Australian Black Swans be sheltered during cold winter months. This species of swans is the only species that has two broods of cygnets a year. The cygnets are very difficult to keep during cold temperatures which is why they, the parents and nest need to be sheltered during this time.
2. Now, we understand the dynamics of the male swans. Usually, the female swan incubates (sits) on the eggs until hatching occurs. Male swans usually only sit to protect the nest while the female takes a break (although this can be a species or individual attribute). South American Black-necked male swans do help incubate the eggs).
In your case, the second male (previous mate to the male parent) still has a bond and both now think they are the parents. Yes, swans of the same gender will pair, mate and nest when opposite gendered swans are not available. Obviously, no eggs will be produced by a male/male pairing, but the swans will still build and sit on a nest until the sex hormone levels go back to normal non-breeding levels. In the case of female/female pairings, eggs may be produced, but again for obvious reasons, they will be infertile. Once sex hormones return to normal and the swans realize the eggs are not viable, the females will abandon the eggs and nest.
So, this brings up your specific scenario. The male parent became the alpha male when the previous male parent died, took up residence with the lone female, and the previous mate (male) to the male parent is still bonded, providing you with a 3 parent situation. Yes, a real Peyton Place (if you are old enough to remember the t.v. drama in the 60’s).
Two male swans will usually not raise the cygnets and can unintentionally injure or kill the cygnets by becoming overly defensive and chasing the cygnets so the young swans cannot enter or exit the water, feed, etc. Usually, the cygnets die from stress from being chased and resulting injuries, starvation/dehydration or from predation because the male parents do not protect the cygnets. Protection and care is mainly provided by the male/female swan pairing.
So, in your instance, the only way to ensure that the cygnets will be properly maintained and protected by the male/female parents is to separate the 2nd male. This may bring up another issue. If you have other males which have bonded, this guy will be the odd man out or produce such a situation if he pairs with another male. The odd man out may be chased and can be seriously injured or stressed. It seems like you may have a flock of young swans which are now coming of breeding age which are producing these new relationships and why you are now seeing these issues.
Separation of the family, the odd man out and other male swans if there are others is the only way to get through this situation during breeding/cygnet season. If you plan on keeping the cygnets, there is always the chance the odd man out will pair up with a 2-3 year old juvenile in the future. However, this scenario will usually result in a female swan being chosen as any introduction with another male will not be dealt with favorably by the male and he can seriously injure or kill a new male swan. A 2-3 year old female is the only pairing that can be offered in this situation as an older male can seriously injure a very young female during mating.
Usually, male swans will not re-pair if something happens to his previous mate. However, in your situation, both males can still see each other and know nothing has happened to each other, so the bond is still there, especially for the odd man out. Temporary separation is the most humane way to address this as permanent separation, i.e., new home would not be fair to the odd man out. Having said this, if the odd man out is constantly being chased or harrassed to the point he cannot enter or exit the water, feed, etc., he needs to be placed in a safe secure home so that he can enjoy his life. We hope this information is of benefit. The Regal Swan