European Otters in West Scotland (1 Viewer)

[Troubador]

In west Scotland these Otters forage in the sea, but since they don't have blubber to keep them warm like seals, they have to keep their fur free of salt so that it retains its insulating properties and doesn't stick together. To do this the Otters climb out of the sea regularly to warm up and often wash themselves in freshwater pools near the sea and since they forage among seaweed beds they accumulate on their fur the same elements that make seaweed a decent fertiliser. When Otters finishing dousing themselves in freshwater they rub themselves on nearby vegetation and these fertilisers rub off and encourage the vegetation to flourish. The intense green patches at the far end of the pool and also close to the camera show this effect nicely.

 

[YuShan]

Nice! I will pay attention to this next time I visit Scotland.

 

[Farnboro John]

Very interesting account. Every time these extra-green patches have been shown on TV the presenter has accounted for them as sprainting sites. This subtle rubbing of seaweed mucus is a new twist. I wonder why the patch on the left is not attractive for rolling/rubbing whereas the slight prominences that do show bright green are?

John

 

[Troubador]

Very interesting account. Every time these extra-green patches have been shown on TV the presenter has accounted for them as sprainting sites. This subtle rubbing of seaweed mucus is a new twist.

I wonder why the patch on the left is not attractive for rolling/rubbing whereas the slight prominences that do show bright green are?

John

I think the answer to why the left-hand bank has not been used by the Otter is in the Otter's single-minded use of travelling in a straight line from the inlet almost out of sight beyond the furthest green patch, and a small bay behind the photographer. From the trackway worn in the vegetation, one can see the Otter comes out of the inlet, goes through the pool, and then gallumphs behind the photographer along a visibly worn track through some shallow but long puddles, and about 25 yards later disappears into rocks in the next bay.

We have often seen spraint deposited on rocks next to where streams emerge from underground (e.g. after passing under a farm track) or near a stream's outlet onto the shore. We have rarely seen spraint in grass and when we have the area of enhanced green around it has been minimal.

Lee

 

[Troubador]

In the past we have spent many back-breaking hours gently pulling seaweeds up out of inter-tidal rock pools and carefully searching them for the creatures that live there. See pics for examples of these.
We soon discovered that kelps have a kind of exudation on them. Somewhere between 'sticky' and 'slimy', this must surely end up on Otters' fur and along with the saltiness would need washing off to maintain the fur's insulation properties. I am convinced this exudation contains some of the elements that make seaweeds decent fertilisers and is the source of these green patches.
I think you would need an awful lot of spraint, spread intensively over a quite large area (compared with the size of individual spraints) to cause these green patches.

Lee

 

[Farnboro John]

In the past we have spent many back-breaking hours gently pulling seaweeds up out of inter-tidal rock pools and carefully searching them for the creatures that live there. See pics for examples of these.
We soon discovered that kelps have a kind of exudation on them. Somewhere between 'sticky' and 'slimy', this must surely end up on Otters' fur and along with the saltiness would need washing off to maintain the fur's insulation properties. I am convinced this exudation contains some of the elements that make seaweeds decent fertilisers and is the source of these green patches.
I think you would need an awful lot of spraint, spread intensively over a quite large area (compared with the size of individual spraints) to cause these green patches.

Lee

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The mucous exudation on the surface of seaweeds, especially those in the inter-tidal zone that are regularly exposed to the air, is there to keep the seaweeds from drying out. I would expect that the plants limit the make-up of the mucus to its primary purpose and retain the majority of the chemicals that make them useful fertilisers within themselves. However, the very permeability that makes them need the mucous exudation probably means that some of the fertilising chemicals do escape with it and transfer to the ground where Otters rub themselves clean and dry.

The use of traditional sprainting sites as territorial markers (and presumably "Tarka woz ere" adverts between individuals making use of the same territory but not rivals, e.g. male and female) means that quite a lot of spraint will be deposited in particular places, presumably at fairly short intervals, over many years. That will result in disproportionate fertilising.

I have no idea which source is involved in which places but whereas your well-argued explanation was new to me, the sprainting one seems to be trotted out routinely and treated as authoritative. It is interesting. As with most things I expect one size does not fit all.

Cheers

John

 

[Troubador]

The mucous exudation on the surface of seaweeds, especially those in the inter-tidal zone that are regularly exposed to the air, is there to keep the seaweeds from drying out. I would expect that the plants limit the make-up of the mucus to its primary purpose and retain the majority of the chemicals that make them useful fertilisers within themselves. However, the very permeability that makes them need the mucous exudation probably means that some of the fertilising chemicals do escape with it and transfer to the ground where Otters rub themselves clean and dry.

The use of traditional sprainting sites as territorial markers (and presumably "Tarka woz ere" adverts between individuals making use of the same territory but not rivals, e.g. male and female) means that quite a lot of spraint will be deposited in particular places, presumably at fairly short intervals, over many years. That will result in disproportionate fertilising.

I have no idea which source is involved in which places but whereas your well-argued explanation was new to me, the sprainting one seems to be trotted out routinely and treated as authoritative. It is interesting. As with most things I expect one size does not fit all.

Cheers

John

Next time we visit these sites I will look carefully for spraint. I think these two explanations are not mutually exclusive.
Best wishes

Lee

 

[Troubador]

The use of traditional sprainting sites as territorial markers (and presumably "Tarka woz ere" adverts between individuals making use of the same territory but not rivals, e.g. male and female) means that quite a lot of spraint will be deposited in particular places, presumably at fairly short intervals, over many years. That will result in disproportionate fertilising.

Cheers

John

Had an interesting sighting on the Western Isles a few years ago.

A male Otter (broad 'Churchillian' face) swam into a bay and made its way to three small rocky points in turn. All of them were covered in seaweed and after briefly sniffing at the seaweed the Otter furiously dug at the weed with its front paws on each of the points, scattering the weed.

After finishing doing this on the third point, it returned to the sea and swam leisurely on the surface across the bay and climbed out next to another Otter (which we hadn't noticed) and circled around it, head held low, while the second Otter rotated to keep facing it. This face-off lasted several minutes and then the male swam slowly away.

Our guess (which is all it is) is that the second Otter was the female which had left scent on the three points indicating she was getting near to being inclined to mate and the male disrupted these scent markers to reduce the possibility of other males being attracted by them. On approaching the female with a view to mating it must have been clear that she wasn't 'available' yet.

Lee

 

[Troubador]

Very interesting account. Every time these extra-green patches have been shown on TV the presenter has accounted for them as sprainting sites. This subtle rubbing of seaweed mucus is a new twist. I wonder why the patch on the left is not attractive for rolling/rubbing whereas the slight prominences that do show bright green are?

John

Here is a pic showing the well-worn track made by the otters as they moved away from the pool and through a shallow puddle on their way to the bay nearby.

Lee