We have spent several years trying to catch a Nathusius at Harrold Odell. Kel had a possible Nathusius detedtor record but it could just have been a cmmon playing up. Nicky recently did a one woman biobilitz here with 7 detectors
The tedium of analysing was worth it as she got a very definste NA after looking at only 3000 of the 7000 sonograms.