I have had a camera nestbox for 3 years and up to now it has been empty. I now have what looks like 2 blue tits fighting over it. Both blue tits are bringing nesting material and exhibiting nesting behaviour. The fighting has been going on for days. Is this likely to continue or will one bird eventually give up? I did wonder whether the second blue tit was the male at first, but why would they be fighting in that case?