fertile

I’ve been looking into a pair of grays who are both of age and fertile according to some vet analysis papers. For some reason though they are just having a hard time reproducing. Their owner says they’re around 13 and they’ve been together for a long time, the hen lays one of the eggs are...

This is my female cockatiel's first time having eggs. She's done a great job incubating and rolling them consistently, so I have a lot of hope. However, when I candle her eggs, I can't tell whether they're infertile or not. Her first egg was laid nine days ago. She has four eggs now, and it...