Mink vs Otter

[minkhunter]

In one or two commentaries on wildlife, I have seen people state that otters predate or drive out mink from an area. Does any one have the source of proof for this? Where I live mink are endemic and there is a vigorous population of otters. I have once seen an otter chase a mink along a rocky shore line, but didn't se it catch it.

[RKB]

It's mainly based upon the work of Bonesi et al. at Oxford, including David MacDonald:

Impact of released Eurasian otters on a population of American mink: a test using an experimental approach

Competition between Eurasian otter Lutra lutra and American mink Mustela vison probed by niche shift - Bonesi - 2004 - Oikos - Wiley Online Library

[nigel_b]

My basic and rather unscientific understanding of the interaction is that the mink as a species is more tolerant to man than the otter (who also seems to be upset rather more by man's dog than man himself).

Thus they can exist on two separate shifts (daytime/nightime) and therefore not come too much into conflict with each other.

This is borne out by my experience on the river Stour where we have consistently seen mink during daylight hours but the otters only come out to play after dusk.

As for otters predating on mink, I understood that the meat of one carnivore is not very palatable to another and thus would not be a primary food source (although I'm sure this will ensure an avalanche of posts to the contrary).

A major part of the territorial behaviour of otters would seem to be related to the interaction of males and females, subordinate males, etc rather than the protection of food supply.

The chasing behaviour that you saw might have been related to protection of young.

[vole-woman]

Sure I've read a report that says the idea of mink being driven out by otters is only wishful thinking. Though it did add that mink living alongside otters tended to weigh less. If I can find that report, I'll post a link.

My own field work tells me that mink and otters can often live on the same stretches - spraint and scat can be near each other under bridges, for instance.

I wish otters did kill mink!

[RKB]

Originally Posted by RKB

It's mainly based upon the work of Bonesi et al. at Oxford, including David MacDonald:

Impact of released Eurasian otters on a population of American mink: a test using an experimental approach

Competition between Eurasian otter Lutra lutra and American mink Mustela vison probed by niche shift - Bonesi - 2004 - Oikos - Wiley Online Library

"The results showed that otters were associated with a significant and rapid reduction in the densities of mink, while mink occupancy remained approximately the same in an area of 2464 km2 that was used as a control. We observed that the spatial distribution of the mink population throughout its decline was influenced by the yearly cycle of mink activities, with areas being temporarily re-colonized during the dispersal season. Mink is an invasive species in the UK threatening the survival of some native species. Our findings suggest that the reestablishment of otter populations is likely to lead to a decline of mink that may, in turn, be beneficial to native species threatened by this invasive."

[camo]

Whilst not scientific my thoughts are that Otters will live in same areas, i also get both scats and spraints althought the moajority of Mink are young transient and looking to establish new territories. I think Otters naturally bully Mink as they compete for food. Otters are more robust and therefore will encourage Mink to prefer other areas. Otters will cover fairly large areas however I think spend a lot of their time in the heart of their territory. It is therefore logical to think Otters will will push Mink into outer part of their territory.
I have not picked up dead Mink even in the most populated ares for Otters so believe Otters killing Mink is quite rare. I would like to think Otters are guardians of our water vole population but i tend to think they see Mink as unnesescary competition.

Roy

[vole-woman]

Round here the biggest killer of mink is the car, judging by the bodies I see on the bypass.

[camo]

unfortunately the Car also kills Otters and typically in Bedfordshire we will have 5 killed each year. However i guess the road kills indicate a growing population.

[RKB]

Originally Posted by camo

I have not picked up dead Mink even in the most populated ares for Otters so believe Otters killing Mink is quite rare.

Not a good indication. I have not picked up dead field voles, even in the most populated areas for Barn Owls and Kestrels, but that wouldn't suggest they don't kill them.

[minkhunter]

Thanks for the contributions of all before. Its a really interesting subject. In my area we have several off shore islands which used to have terrific nesting populations of shags, cormorants, gulls, terns, duck... all sorts. The closer these havens are to the mainland the more susceptible they have been to mink predation to a point where birds have simply ceased breeding on these islands. All the while, otters have had an established presence on them too.