A quick question about whether a certain type of evidence is admissable or not as a sign that the species is present.
At the lowest tides of the month, the local bay dries out to reveal the flat bottom. The empty shells of shellfish and crustaceans are scattered across the sea bed, apparently discarded by the local predators, such as otters and eiders. For example, there are shells from cockles, razorfish and green shore crabs.
Are photos of the empty shells admissible as evidence that the species is present? In plain language, do empty shells "count"?