In my flock of four Fischer’s lovebirds, two of them are new birds bought last year. They are both healthy and in good shape. But they both does this weird knocking on surfaces(on their cage bars, floor, wall, etc…) with their beak with tapping rhythm. My other two birds never do this. It mostly happens when they are trying to perform a mating ritual. Also the female becomes aggressive during this and acts weirder as if it’s trying to get out by running around at the bottom of the cage. Is this behavior normal or is it a stereotype of mating performance? The cage didn’t have factors that trigger mating.