bird call at night

nightbirdaudio.m4a

I hear this bird call regularly at night after about 11 p.m. and sometimes later.  It sounds as though it is walking round on my patio (where there is a bird feeder) as it seems to retreat slowly into the distance unless perhaps it is flying round the house.  I don't think it is a Tawny Owl, - certainly not like their normal calls.  Any ideas?