Two teams monitored a small island's seabirds on alternating weeks. At first, the departing team left a short message saying that the survey was complete. The arriving team assumed that all nesting areas had been inspected. In fact, one cliff had been inaccessible during high winds, and its count had been estimated from a distant viewpoint. When later counts differed, the teams initially discussed changes in bird numbers. A review of the original notes revealed the difference in access. They introduced a handover form that separated direct observations, estimates, and locations not visited. The form did not require every uncertain number to be replaced immediately. Instead, it preserved the reason for uncertainty so that the next team could choose where a return visit would be most useful. A completed form therefore described the limits of the work as well as its results. On the next visit, a previously inaccessible cliff becomes reachable. A direct count there differs from the earlier distant estimate, although the observers do not know whether the birds moved between visits.