Friday, 19 April 2013

Otter Spraint Survey and April Moths

The drought which we had for several weeks ended last weekend with 2 inches of rain on two successive days.   So back to normal.

There is no sign of the otter family.   I surveyed otter sprainting sites from a point west of the beach by Loch Ainort, the furthest west that I had seen them, to beyond the Ard Dorch grazings boundary on Loch na Cairidh, a distance of almost 1.6km.   I found 32 spraint sites and 4, maybe 5, holts.  Very few of the spraints were recent (within the last week or so) which seems to suggest that the family has moved on to somewhere perhaps with better availability of food.   Kruuk (Otters: Ecology Behaviour and Conservation, 2006) suggests that the diet of otters changes with the seasons and that they do move from more exposed to more sheltered coasts in the summer, from his observations in Shetland.   I hope this is an explanation rather than that one or more of the otters met with an accident on the road for example.

This is a plot of the spraints noted moving from a point of origin by Loch Ainort into Loch na Cairidh.   The spraints were clustered round holts, and the holts were always amongst prominent rocks, with crevices  under and around where water collected.  The holts were on average 293 metres apart (minimum 168 metres, maximum 458 metres).    I will probably further survey west into Loch Ainort in the coming weeks.   

I put the moth trap out on two nights collecting 14, and 13 moths respectively.   There were only 3 species, whereas Brian Neath in Lochaber caught 10 species and many more moths on the same nights.  Brian confirmed my identifications. I can only attribute the paucity of species to the delayed progress of spring.

Hebrew Character
Clouded Drab
Red Chestnut

Indeed Spring is really late.  Primroses are only just shyly coming into flower; we have records covering the last 7 years which show that this year the primroses are flowering later than during any of the previous 6 years, 18 days later than the average.

There were quite a few hoverflies settled on the lesser celandines, probably an insect for every 20 plants or so, but all the same species which I think is Melanostoma mellinum.   This is very common in damp places and its distribution is widespread.  I cannot find a common name for it.

Thursday, 4 April 2013

British Summer Time

Easter coincided with the start of British Summer Time last weekend.   Skye's recent weather has been remarkable; it has looked summer-like and we have several days of almost ubiquitous sunshine and only very light winds.    But those winds have been easterly and it has been cold with overnight frosts and daytime temperatures not getting much above 6 deg.C despite the sun.   As a result spring in its fullness is much later than last year.

We saw the otter family at low tide on the 28th.   The kelp was exposed and the otters spent almost 3 hours in and amongst it, making regular catches.   They moved slowly up Loch na Cairidh and into Loch Ainort turning round at a point which juts out just beyond the sandy beach. The dive time was quite short - not surprisingly as  the water depth was no more than 1.5m.  Eventually they swam quite quickly, maybe 4 to 5 mph, back beyond Croft #1 and towards the Perlandera guesthouse.

I saw the first butterfly of the year, a peacock, warmed out of hibernation, but despite putting the moth trap out on three successive nights the low temperatures restricted  the number caught to 0,0 and 2 respectively.

The moth on the right above is a Clouded Drab (confirmed by Brian Neath); I originally thought it was a Red Chestnut, but he tells me that the short dashes along the outer cross line are diagnostic although not always present.  (Red Chestnut is a distinct possibility at this time of year but he has not seen one yet  It has several dots along the leading edge of the forewing).  The larvae feed on oak according to but we have only two spindly, stunted oaks, so maybe there is a different food supply.   The moth below is a Hebrew Character.

Birds on the sea included a group of 9 red-throated divers, razorbills, great northern divers, shag, and for the first time a little grebe dabbling amongst the wrack.