Only let them have the nestbox when you actually want them to breed. Cockatiels are opportunistic breeders who will want to make babies whenever conditions seem favorable. The "weather" and the food supply are always great indoors, and if they have a nest area too it's baby-making time.
Their hormones seem to run higher in the spring so that tends to be the best time. But they can produce fertile eggs at any time of year, so it's odd that your pair has produced infertile eggs. How old is this pair? If they're too young they may not be as fertile or as ready to incubate eggs properly as an older pair would be. If they're old enough to be good parents, there may be some fertility issues, or maybe they're not "doing it" exactly right.
I'd separate them from the parakeets. They may be getting along well now, but if the budgies start getting hormonal there could be problems. Budgies are generally more aggressive than cockatiels, and will try to stage a hostile takeover of the nest if they decide they want it. Eggs can get broken and chicks can be injured or killed.
Their hormones seem to run higher in the spring so that tends to be the best time. But they can produce fertile eggs at any time of year, so it's odd that your pair has produced infertile eggs. How old is this pair? If they're too young they may not be as fertile or as ready to incubate eggs properly as an older pair would be. If they're old enough to be good parents, there may be some fertility issues, or maybe they're not "doing it" exactly right.
I'd separate them from the parakeets. They may be getting along well now, but if the budgies start getting hormonal there could be problems. Budgies are generally more aggressive than cockatiels, and will try to stage a hostile takeover of the nest if they decide they want it. Eggs can get broken and chicks can be injured or killed.
