Today for the first time I was hanging around a hive and heard a sound coming from it. It was a low, croaking repeated kind of tapping or rumbling sound. Don't think it was queen piping because it didn't sound high-pitched like the ones I've seen on Youtube. More low like the range of a big bullfrog croak. Any ideas? Not really a chewing sound either which I've heard before - they say that's them making wax and building comb.