Monday 7 January 2019

A very unscientific view of Orkney's land mammals

For 2018, I resolved to record all the land mammals I saw in Orkney through the year. It would have been really great if I had made this resolution on January 1st 2018, but it wasn't until February, when I was proof reading the previous year's Mammal Report for the Orkney Field Club journal, that I noticed the words 'very under-recorded' for many of the species.

To be honest, I have been reading those words for several years, but this time I thought, hmmm, I could do something about that. So I set myself the challenge of helping the mammal recorder by making a list of all the land mammals I saw as I went about the archipelago during 2018. Sightings could be from the lounge window, from work journeys or weekend walks. I didn't include cetaceans (dolphins and whales) or pinnipeds (seals), nor any of the few species of bat that reside here, but did include any roadkill which was recent and identifiable at approximately 60mph. By 'recent', I don't mean that I ran it over, and by '60mph' I mean 55mph maximum, officer.

Orkney has an odd mammalian distribution when compared to mainland UK. For instance, we don't have Foxes, Badgers, Moles, squirrels or any wild deer. We have one species of vole, one species of shrew and two species of mouse. No Weasels, and prior to 2010, no Stoats. However, that one vole, the Orkney Vole, is a unique sub-species endemic to Orkney, although unfortunately for it, it is very tasty, especially if you're a Short-eared Owl or a Hen Harrier, or indeed a Stoat. We have two species of Hare (Brown and Mountain), as well as Otter, Hedgehog and wild Cattle (a feral herd on the island of Swona).

Interestingly, Orkney had a visit from a Walrus in March 2018, but I didn't go to see it (and it's a pinniped, anyway).

The most observed mammal was the Brown Hare (helped enormously by the fact that they frequent the fields around Tense Towers). I recorded 98 separate sightings of 135 animals, only one of which was dead (roadkill). All sightings were from either East or West Mainland. 

The next most populous creature was the Rabbit, with 46 records of 88 individuals, two of which were dead from disease or old age. Nine of the records were from islands (South Ronaldsay, Rousay, Sanday, Hoy, Flotta and Papa Westray).

Then we come to the Hedgehog, with 22 records of 22 individuals. 21 of these were roadkill (in fact, I began calling them dedgehogs), with only one seen alive (by Our Lass, quite near to home). Several of the sightings were from islands (South Walls and Burray).

As popular in my data as all the mice, voles and Otters put together, were the Stoats, which is a very scary thought. Would you see a Stoat every year? More frequently than that, or less so? Well, I recorded 10, nine of which were very much alive, with only one a roadkill. The species' proliferation across mainland Orkney in the last eight years is a real and present danger to the native wildlife, principally small mammals and ground-nesting birds. The one positive note was that all these sightings were on mainland Orkney, not any of the islands, although occasional reports come in of suspected sightings, which instigates an incursion response from a dedicated team.

Next comes the Brown Rat and the House Mouse, both with three sightings each. One of the rats was a roadkill, though of the two live ones, a huge specimen was seen wandering along our dry stone wall! The mice were all trap kills in my storeroom, as Autumn turned to Winter.

Sadly, both of my Otter sightings were of roadkill individuals, between mid November and mid December. I guess this is when juvenile individuals are beginning to venture further afield to look for a territory, just at the time when the shortening day length brings them into contact with rush hour traffic (that's a relative term in Orkney, but you get the idea). I am just relieved that I saw a live one in Shetland, and that I didn't run it over!

I considered myself very fortunate to spot a live Orkney Vole skittering across a road in front of me during May. My only other vole sighting being a dead one killed by a predator on Mull Head in July.

Similarly, the only Pygmy Shrew sighting was a dead one, presumably as a result of the teeth or claws of a predator (presumably a cat, feral or otherwise).

Not seen at all during the year were Mountain Hare (only found on Hoy), Wood Mouse or the feral cattle from Swona.

And now that I've got the hang of it, it's all systems go for 2019, too.


Mark said...

Are there many Otters on Orkney? I think they're quite prolific on Yell, Shetland.

Imperfect and Tense said...

There are many more Otters in Shetland than in Orkney. I'm not sure of the estimated population for Orkney, that's a question for the mammal recorder when I next bump into him.