Last week's Otter ecology training in Trawsfynydd with ecologists Grace Crabb and Geoff Liles was a great success. It was an honour to be given a presentation about otter surveying by otter specialist Geoff Liles who has been conducting surveys for forty years of his career and has recently completed a survey of the whole of Wales. The well attended event was part of North Wales Rivers Trust Freshwater pearl mussel project, funded by Local Nature Partnerships.

Why are we learning about otters?
During the 1950’s Otters nearly became extinct in the Uk due to the introduction of chemicals such as DDT and dieldrin in the 1950’s. These chemicals were used in high doses in agricultural seed dressings and sheep dips. 

Otter populations have made a remarkable recovery since the 1980’s, thanks to conservation efforts and water quality improvements and today otters are found across much of the UK.

Although, the most recent survey completed by Geoff in Wales shows another decline which he explained could be down to habitat loss, pollution and declining fish populations. This means that the importance of surveying for otters is at an all time high and thanks to Geoff we now have a group of the local community trained up in spotting field signs of otters. 

Surveying

A large section of the otter ecology training was focused on Otter spraints. These are a great indicator of otter activity as otters use spraints as a means of communication and to mark out their territory. These will always be left in a prominent place where it will be noticed by other otters. By depositing spraint in prominent places along a river informs all other otters that a patch is taken. Spraints include more than 100 different scent components providing a complex messaging service between otters. Exposed rocks in a river, low overhanging branches and prominent roots all make ideal sprainting places. 

Next steps for volunteers

With the classroom based session of the otter ecology training done the next session will consist of heading out to put our newly taught survey techniques to the test and do a bit of “detective work” (as Geoff put it). Otter surveying is about getting out there and thinking like an otter. Looking for field signs and mapping the area out is a great way to get an idea of the number of otters in the area.

Otters are extremely territorial with a dog otter covering a territory of around 40 km. The female will often cover a lot less area of approximately 20 km but will need to find somewhere safe which is close to a food source to rear her pups. This must be somewhere which is unlikely to be disturbed but also out of the reaches of flood water which due to the ever changing weather patterns is becoming increasingly difficult. 

The next round of training will involve building an otter holt on the Afon Eden. The dog otter can have as many as 30 resting sites that it uses within its territory but these are often sites that are disturbed whilst the otter is sleeping during the day. Building an otter holt will increase its amount of safe resting sites and could potentially be a great location for a wildlife camera trap in the future. Camera traps are a great way to get more information about the amount of otters in an area, for example a mother with pups. These details can’t be discovered through spraint alone.

You can find out about our future events by signing up to our newsletter. Or to express your interest in otter holt building and surveying please email poppy@northwalesriverstrust.org

Written by Simone Williams