What do Welsh Otters eat?

by Ceri Morrison 14. Mar, 2012in animal science, assessment, biotechnology, conservation biology, evaluation, evidence

collection, genetics, interpretation, research, research methods metrics and analysis, skills and competences, species,

statistical analysis

We took our knowledge of poo to another level last month, with an Otter diet workshop as part of

the MISE (Mammals in a Sustainable Environment) project.

A fresh otter spraint.

Last year Coastal otter surveys were carried out by volunteers at a number of locations around

the North Wales coast, organised by Snowdonia Mammal Group, Menter Mn and Flintshire and

Denbighshire County Councils.

The great spraint hunt

Otters leave droppings, known as spraints, in prominent places to mark their territory. These

distinctive droppings are generally black in appearance with lots of fish scales and bones sticking

out. The smell is the real giveaway a strong fishy smell which some say resembles Jasmine tea.

Looking for spraints is therefore an easy way of surveying for Otters, since the likelihood of

spotting the animals themselves is quite slim!

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Some of the volunteers analysing their spraints.

The main aim of the surveys was to establish the presence of Otters across a number of coastal

sites, and collect spraint for DNA analysis. Our project lead partners, the Waterford Institute of

Technology, have developed new DNA techniques to extract genetic information from otter

spraint.

From this we can find out the sex of individual otters, as well as identify individuals so that we

can start to build up a picture of population size, territories and breeding success. It is still early

days for this work, but recent results have been quite promising we have identified a number of

individuals and have seen some evidence of interesting interactions. Ill give an update on this

once we know more

A spraint sample sorted and ready for us to start identifying the bones.

Otter numbers encouraging

In all, the surveys showed that Otters are widespread across the Lleyn and the North Wales

Coast, and making a comeback across much of Anglesey as well. Great news for Welsh otters.

Originally, we hadnt intended to carry out dietary analysis on the spraints but since some of the

volunteers were keen to learn more about their local otters, we thought it would be worth doing.

So I arranged for the Welsh otter spraint, that had already travelled to Waterford for DNA

analysis, to come back to Wales for further analysis. Surely the best travelled Otter poo in the

world?

I was astonished when 45 people signed up to take part in the workshop, some travelling from as

far as Shropshire Mammal group, others local to North Wales. It seems people are more

enthusiastic to dig around in Otter droppings than I had thought!

My colleagues, Irish MISE project officers Denise OMeara and Andrew Harrington also came

over to learn how to run a similar workshop in Ireland, and brought with them some Waterford

Otter spraints to compare with our Welsh samples.

Fragments of Salmon or Trout backbone.

Rob Strachan, Mammal Ecologist and our mentor for the weekend, gave a great presentation on

Otter ecology and let us loose on the spraints. The idea was to take a spraint which had been pre-

soaked in a washing powder solution (guess who had the lovely task of doing that? I get all the

glamorous jobs!), sieve it and pick out the tiny bones that would remain from whatever the Otter

had eaten. Rob would prove invaluable in helping everyone identify the prey remains and verify

their results, as it can be surprisingly tricky to know your Bullrout vertebrae from your Rockling!

The skillful spraint sift

The work demanded a lot of concentration, with volunteers having to carefully pick out individual

bones before inspecting them under a microscope. Then, using an identification key and looking

for characteristic notches and shapes, we could work out which species the bones belonged to. A

total of 17 fish species were found both from marine and freshwater environments, the most

common being Eel, but we found lots of Salmon and Trout as well, easy to identify from the

honeycomb appearance of their bones.

A closer look under the microscope reveals characteristic shapes to help us work out which fish

these bones are from.

There were some surprises in the spraints a few contained lots of bird feathers, and one lucky

volunteer discovered a birds claw in her sample! We think this was from a young Moorhen,

which an Otter would have no problem in making a meal of. Crab shells were prominent in some

spraints some people think that juvenile Otters may favour crabs since theyre easier to

catch.could this be evidence that otters are breeding on the North Wales coast? Frog bones

were easy to find given their resemblance to double-barrelled shotguns, and we even spotted the

remains of Woodmice and a Pygmy shrew, identified by their teeth!

While fish vertebrae and jawbones were quite easy to spot, it was the elusive fish eye lenses that I

was particularly keen to see a tiny, solid glass-like sphere from inside the eye. After two days of

searching, we found one! I now have a rather grisly reference collection of all the best bones and

teeth from the weekend which we can use for future studies.

One of the more grisly finds Woodmouse fur, bones and teeth!

The workshop gave us a valuable insight into what our coastal otters are eating, and I hope to do

some further work on the rest of our samples to complete the picture. Keep an eye out for my

report later in the year. It was also a great lesson in how keen people are to learn more about one

of our favourite Welsh mammals who would have thought that so many people would give up

their weekend to pick through Otter poo!

Important!

Contact me for more information

If you are keen to get involved, we will be running further otter surveys on Anglesey this year.

Please contact me for if youd be interested in lending a hand.

The MISE Project is part funded by the European Regional Development Fund (ERDF) through

the Ireland Wales Programme (INTERREG 4A)

Tags: Denbighshire County Council, dormouse, ERDF, European Regional Development Fund,

Flintshire County Council, harvest mouse, mammals, Mammals in a Sustainable Environment,

Menter Mn, MISE project, otter, pine marten, polecat, pygmy shrew, Realtime PCR, red

squirrel, salmon, Snowdonia Mammal Group, spraints, trout, Waterford Institute of Technology,

weasel, WIT, woodmouse

Its all in the DNA

Pant-y-llyn Turlough an Irish freshwater habitat in Wales

Post Author

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This post was written by Ceri Morris who has written 2 posts on The Welsh View.

Ceri joined CCW in May 2011 as the project officer for the new Mammals in a Sustainable

Environment (MISE) project, the aim of which is to engage volunteers in a range of small

mammal surveys across Wales and Ireland using innovative genetic techniques. With a BSC in

Zoology from the University of Liverpool and an MRes in Marine & Fisheries Science from the

University of Aberdeen, Ceri specialized on Bottlenose dolphins, and also spent three years on

the East coast of Australia with the University of Queensland [watching and listening to singing

Humpback Whales!] However, the Hiraeth eventually pulled her back home to North Wales and

both Ceri and her partner share their time between kayaking, diving, travelling and entertaining

three large dogs!

http://thewelshview.co.uk/what-do-welsh-otters-eat/comment-page-1/#comment-22051

In the meantime, I can recommend the Mammal Society publication A Guide to the Identification of

Prey remains in otter spraint by Conroy et al 1993, which is an excellent key to help you identify

most of the fish species youre likely to encounter.

http://thewelshview.co.uk/author/ceri-morris/http://thewelshview.co.uk/http://thewelshview.co.uk/what-do-welsh-otters-eat/comment-page-1/#comment-22051