Otters in 2026

When this blog started it was mainly to document the local water voles (more on them in a later post), but within 12 months it became obvious that the return of otters to the Ock would be become a major source of interest, firstly with finding of spraints:

https://viewsoftheock.blogspot.com/2010/02/in-search-of-otters.html

And observing the remains of one of their favourite foods - signal crayfish: 

https://viewsoftheock.blogspot.com/2010/08/crayfish-murders-another-victim.html

But the thought of actually seeing one, let alone getting photographs seemed impossible, but 2011 proved be a year of extraordinary encounters:

https://viewsoftheock.blogspot.com/2011/05/otters.html

https://viewsoftheock.blogspot.com/2011/12/review-of-year-2011.html

Yet 14 years later, the otters are still residing in the Ock and still eating crayfish:

As otters live for at about 3 years, this could be signs of the great great great grandchild glimpsed all those years ago.

Yet more dead crayfish

Regular readers of this blog would be aware of the occasional post featuring dead and half eaten signal crayfish (identified by the red claws). 
Certainly I seem to be building an interesting collection of photographs of these mutilated crustaceans (I wonder if there is a name for this?). The most recent being found during August along the Ock Valley walk:
This one was found earlier in the month, have only lost the end of the tail.
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The other was found on Saturday and suffered a very violent and frenzied death - having a claw torn off, it's lower half removed (probably eaten) and lost part of it's head.
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Whilst the death of the first could have several explanations, this one almost certainly is the result of an otter kill.

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The non native signal crayfish has committed a lot of damage on UK wildlife - eating fish eggs in the thousand, climbing up river banks to eat young kingfishers in their borrow and driving the native crayfish to the brink of extinction.
But maybe  the return of otters to UK rivers (http://www.bbc.co.uk/news/uk-england-14557381) has been assisted by this alien (and obviously tasty) invader.

The crayfish murders - another victim...

Last month, I wrote a post on about a mutilated crayfish corpse on the river.  Having considered several suspects I concluded the most likely culprit was an otter.
In the comments section David suggest that it may be a badger - something I hadn't considered.  Badgers are surprisingly common, with an estimated 250,000 living in the UK and I have seen them near Abingdon last year: http://viewsoftheock.blogspot.com/2009/11/badger.html
Whilst walking to work and pondering the circumstances which a badger and crayfish are likely to meet I came across another dead crayfish:
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This one was found in a different part of the river, the lower ock along the ock valley walk in a place that is popular for people to fish.  It also has different wounds, the first one was ripped in half by what seemed like a frenzied attack, whilst this one has a smaller wound in the tail:
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Having examined the area, there are no obvious spraints, but it does make sense for otters to spend most of their time in the nearby Thames and occasionally coming into the shallower Ock to feed. 
Although if it had been an otter, it is  more likely the entire tail would have been consumed rather than just a small bite, unless it was disturbed.
Later in the day, there was evidence of more crayfish abuse, this time the culprit is obvious:
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Would a moorhen kill a crayfish? I doubt it, I suspect  this bird is just being opportunistic.
So if it wasn't the moorhen, then what was it? Although I still think the first crayfish victim was the result of an otter attack, I doubt this one was.  But to be honest, I'm not sure what did it, maybe it was just the accidental victim of an errant fishing hook.
Needless to say, I will be keeping an eye open for more evidence and as always, suggestions are welcome.

Murder mystery on the Ock...

The river Ock, like most of the rivers of England, have been invaded by Signal Crayfish and last year I found a dead one along the river bank:
http://viewsoftheock.blogspot.com/2009/06/ock-valley-walk.html

Whilst surveying for water voles on the upper Ock I encountered another one near Drayton Road Bridge, but this one has suffered a more violent fate - ripped in half and partially eaten:
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When I returned the following day, the carcass had completely gone.
So far, Wild About Britain and Twitter have drawn blanks, so I am left to carry on the tradition of Oxfordshire detecives and investigate who the culprit might be.  I have several suspects to chose from:


People: At the time I suspected the first corpse was a victim of a fishing incident. Discarded when caught by accident.  But  it is unlikely to have been caught by a fisherman as the bank at this part of the river is steep and the undergrowth is high and restrictive.
Also, catching crayfish is illegal without a permit from the environment agency - as it is known for animals (including otters) to be killed in crayfish cages and why would anyone leave a partially eaten crayfish corpse by the river?
Therefore, I suspect the crayfish was not killed by a person.


Rats: I have seen rats further downstream and there are  almost certainly several in the area.  However  I have not found any evidence of a rat killing a crayfish, but it is not outside the realm of possibility.
Although I suspect a rat would go for an easier target - a moorhen chick or a discarded take-away.


Mink: It is highly likely that a Mink would kill a Crayfish in this manner, given they will attack and kill most creatures they encounter.  But there is no evidence to support the idea of mink on the upper Ock: there are no obvious scats; there are water voles and young moorhens nearby - often the first victims when a mink moves into an area. 


Birds: Several birds are known to catch and kill crayfish - Herons (who would swallow it whole), Owls & Buzzards - but a heron would swallow it whole, whilst the others would eat it on a perch away from the river.


Otter: There are cases of otters killing and eating crayfish and there has definitely been at least one otter on the river, as I found an otter spraint  back in February


http://viewsoftheock.blogspot.com/2010/02/in-search-of-otters.html


But the spraint was found over a mile stream upstream where the river is deeper (and before it splits into the upper and lower ocks) and here the river is flowing under the bridge before it becomes it flows through the ock valley walk - popular with dog walkers and children, something an otter would have previously shied away from. Although otters are now being recorded in urban areas - Reading, Leicester & Birmingham - it is possible that they have ventured this far downstream.


Like the best murder mysteries each of the suspects have their albies, but base purely on circumstantial evidence my chief suspect would be an otter.  Hopefully the planned use of mink rafts later in the year should give further evidence of mustelid activity.


I welcome any readers have any insights or suggestions into the death of the crayfish