It is often hard to tell one otter from another. The mother is easy because she is trailed by the pup and the baby is easy because that is the one that pushes my camera into the water. But a lone otter is difficult. I assume that the powerful-looking solo animal that goes through the culvert two or three times a week is the resident male. It (he) is quite used to the cameras and either sniffs them or ignores them as he passes. And then this happens.
Because the camera doesn't start recording until about 400ms (0.4s) after it can "see" its target it is always hard to guess what came before. Here the otter does a complete 360° turn before continuing past the camera. Perhaps he was momentarily startled by the infrared light or perhaps he thought he had forgotten something.
On another night, with two cameras recording, a lone otter startles and retreats. Both before and since then the otter I assume to be the dog has been trotting happily past the cameras taking no notice so I wonder if this was a different animal. It is a pity otters don't have unique markings like humpback whales or zebras.
"unique markings like humpback whales or zebras" or brown trout or sparrowhawks! And presumably lots of other things besides. One of my contacts did an angling MSc where he needed to mark perch individually. He used spines on the dorsal fin as a binary number marker, nipping off the point of the "1s". With 15 spines, you could label 2exp15 ie 32768 individual animals. I thought that was pretty clever!
ReplyDeleteSmall mammal trappers mark mice and voles caught in Longworth traps by clipping small patches of fur so they can identify retraps but it would be tricky with an otter!
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