Hi Rose,
You might want to try taking the male out and watch to see what happens. Have you been resting the pair between each clutch? It’s important to take the nest box down as soon as the chicks fledge, and then remove the chicks when they are weaned. Rest the pair for 6 months before giving them the nest box again. They should be limited to two clutches per year. A pair will only breed once a year in the wild, because the season changes. In captivity, we need to limit how often they breed. A pair gets tired if allowed to breed too often and this can result in smaller clutches & weaker chicks, or poor care from the parents. If the nest box isn’t removed as soon as the chicks wean, some males get impatient to mate again and will kill the chicks in order to make the female mate again. Older pairs also get to where they do not breed as well or care for the chicks as well. So if this pair isn’t worn out from breeding too often, maybe they are getting too old. Another possibility is if their health is not good for some reason, so a vet check might be in order.
Thank you for asking Lafeber,
Brenda