Answer: It is believed that this is most likely to occur three to four weeks after the kitten have been weaned or removed (this includes those kittens who die or who are removed at birth). Certainly, it is usually related to the length of the weaning period, so that the longer the time before weaning, the longer before calling being again. Where weaning occurs at the start of the winter period (anoestrus), calling may not be seen again for twenty weeks or more after the previous birth.
However, in a number of cats calling occurs, and mating is possible, soon after the kittens have been born (from two to ten days afterwards), so that it wise to keep queens segregated from toms even though they are still nursing their kittens.
