We were in Holland a couple of year's back and Mark Van den Berg was telling us. They liberated at nightfall and timed doos during the night. His loft had spotlights to illuminate the loft so the birds would trap. Also was told a story with two prominent distance flyers both liberated late at night on the way home they seen the batch go down and land on a roof. On returning home both fanciers had one bird home each. Both these birds went on to score numerous times across the channel. Maybe just coincidence???? The young bird national this year guys were timing in the dark.