Andrew,

We know that martens have predated black throated diver nests on the Loch Maree Islands and must have crossed ~150m of water at some point to get to these islands. See SNH commissioned report 379 http://www.snh.org.uk/pdfs/publications/commissioned_reports/379.pdf.

The report suggests that crossing 30m of water (between 2 of the islands) is not a problem. This is standing water of course, so a 30m wide fast-flowing river would be different matter entirely. The report also refers to an American study in which American martens crossed either 30 or 64m of standing water.

Would they utilize road bridges? - of course! Pine martens began to colonize the Isle of Skye soon after the bridge was built.

Hope this helps.

Rob

Under the "other mustelids" banner I can say that badgers can swim small creeks, but I don't know if they'd set off across a major river.

Andrew,

We know that martens have predated black throated diver nests on the Loch Maree Islands and must have crossed ~150m of water at some point to get to these islands. See SNH commissioned report 379 http://www.snh.org.uk/pdfs/publications/commissioned_reports/379.pdf.

The report suggests that crossing 30m of water (between 2 of the islands) is not a problem. This is standing water of course, so a 30m wide fast-flowing river would be different matter entirely. The report also refers to an American study in which American martens crossed either 30 or 64m of standing water.

Would they utilize road bridges? - of course! Pine martens began to colonize the Isle of Skye soon after the bridge was built.

Hope this helps.

Rob

Many thanks both! Very useful indeed.

All the best,

Andrew

Our weasels, fishers, martins, and mink are all adaptable and I would say semi aquatic, and utilize bridges and culverts. They can't resist water bird eggs and ducklings for sure! They are as nimble in the water as their bigger cousins the river otters.

We have proof of pine martens crossing rivers on beaver dams.

During dispersal young martens often cross the river of Daugava in Latvia, ca. 100 m wide rather fast flowing river. 

I observed a stoat swimming across a 5 meters width channel without any trouble despite a strong flow.

Dear Andrew,

I have been working with small carnivores in Portugal and South Africa last years. 

During that years I recorded several carnivores using old and young bridges across rivers and/or dams in Portugal, for instance in one of these bridges I found scats from five species, stone marten, red fox, badger, genet and weasels.

I also get some sights on a polecat crossing a huge concrete bridge above a large dam and I have seen genets and polecats swimming and catching some small fishes and amphibians in small rivers and dams sidelines with shallow waters.   

Finally I saw a pine marten in North Portugal crossing a road bridge in a secondary road a few years ago.

Cheers

Filipe Carvalho

Hi Andrew,

you may also be interested in the recent press release at http://www.scottishpower.com/news/pages/pine_marten_family_settle_in_at_cruachan.asp, which includes anecdotal evidence of pine martens attempting to travel by bus, so they're clearly quite versatile!  More seriously, they don't seem to be necessarily restricted in their movements by human disturbance.

Jeanette