It was a little while after sunrise and I was quietly photographing an Otter that was making its way up the river Wharfe. Much later, when reviewing my photographs, I could see marks on its face, potentially consistent with it having been in a fight (see photograph). I am always concerned about the possibility of conflict between Otters and pet dogs, given the number of dogs that run free along the riverbanks. However, in this case, I think these injuries may have been inflicted by another Otter. The previous day, I had seen an Otter feeding along the same stretch of river. I could tell these were two different animals from markings under their chins. Of particular interest, when it was diving for food, what appeared to be an injury towards the base of its tail was just visible. So, perhaps these two Otters had been fighting.

Otters can be very territorial and will sometimes fight very aggressively in defence of a section of river. Obviously, the likelihood of this occurring increases in line with the size of the local Otter population. At the beginning of the year there were cubs along a few-mile stretch of the river Wharfe (two litters, three cubs in total). These will now be grown and looking for their own space, so there must be increased potential for physical aggression. When this does happen, it is apparently quite common for the tail and genital regions, along with the face and feet, to be targets for attack.

I haven’t seen either Otter for a little while now. Shortly after this, following heavy rains, the river level rose sharply. That is often a time when Otters find other places to be. However, I hope they are doing well. Wounds can be an existential threat to Otters. Studies of Otter mortality indicate road traffic accidents (RTAs) as the major cause of death in wild Otters but, of course, there is a reporting bias. Dead Otters are much more likely to be found if they have been hit by a car. One UK postmortem study found bites to account for 10% of deaths. However, a study, of 56 Otters that were reared in captivity (so no RTAs) found untreated bacterial infections following injury to be the major cause of death (62.5%). Of course, for wounded wild Otters, any pollution in the river is likely to contribute to a poor outcome. The dangers of infection, along with RTAs, may go some way towards explaining the relatively short life expectancy of Otters in the wild. In captivity they can live beyond 12 years – in the wild it is typically less than 4 years.