Return of the Otter

For many years, otters have been more commonly found as fictional characters in children’s books than in Britain’s canals and rivers.  However, it seems that Eurasian otters (Lutra lutra) are making a comeback, according to a recent report by the Environment Agency. The study involved researchers examining 3,327 river sites across England for signs of otter presence (prints and scats) over a 9 month period.  The results are very promising, with otter populations occurring in all English counties apart from Kent, where it is expected to return over the next decade. The River Wye in the south-west had the greatest number of otters, almost reaching maximum capacity, and it seems only a matter of time until they will be seen along the banks of Westminster once more. Overall, the number of otter locations in England has risen ten-fold since three decades ago, a time when otters were believed to be on the verge of extinction within Britain. Hence, this news is extremely welcome, and experts predict that populations of these aquatic mammals will be fully restored in England within the next 20 years.

The cause for this otter boom has been attributed to the combined effects of the classification of otters as a protected species to prevent them being hunted, and the banning of organo-chlorine pesticides in the 1970’s. The improved health of rivers and canals has also resulted in greater fish populations, which are a main component of an otter’s diet. The return of this top predator to our waterways is prime evidence of theimproved water quality, and gives hope to other rare river species, such as the water vole (Arvicola amphibius).

Otters are notoriously evasive creatures, and therefore researchers are forced to rely on indirect evidence to monitor their abundance. Our research team in Costa Rica have been investigating the presence of Neotropical river otters (Lontra longicaudis), which are listed as Endangered (CITES Appendix I), along the Rio Piro. So far, our volunteers have been collecting scat and track evidence of the otters, and the next stage of the study will involve examining the scats under microscopes to prove their otter origins and determine to main components of the otters’ diet. Plans by a local company to quarry alongside this river pose a serious threat to the populations of this rare otter species. It is hoped that this study will conclusively show that Neotropical otters are not only present, but also abundant in this region of the Osa Peninsula. If so, then it will provide a strong case against the proposed quarry.

By Flora O’Brien

Click for more information on our Costa Rica Big Cats, Primates & Turtle Conservation Project