More nocturnal otter activity

I have not seen any otters in the day time since early January but the trail camera continues to capture night-time activity.   Last night an otter was scratching its ear by the entrance to the cliff holt at 19.45 pm and again at 02.07 am.   Only a single otter, and I cannot be sure whether it is male or female.   It comes to the holt every two or three days.   The family we had in early January seems to have gone.

 The first signs of spring are everywhere - catkins on hazel, willow in bud and earlier this week the first frog spawn on the pond I made in the garden.   The timing is consistent with previous years, mid February to early March.

An Otter Getting Comfortable!

I got an excellent clip last night from the trail camera (I found out that it works best with batteries that are not flat after 3 days with no pictures!).

This is an otter gathering bedding at the cliff holt.    All the recent otter activity has been at night, often in the early morning.    It seems to rest up in the cliff holt, spending several hours there.

Greater and Lesser Butterfly Orchids: Survey Results

There is very little to comment on at the moment;  the otter family seems to have disappeared and I have picked up nothing on the trail camera.  There are though some spraints by the slipway.   There are a few mergansers and great northern divers about, common seals and the occasional curlew and I saw a couple of bullfinches in the garden last week (new to us), but it is quiet, so much so that I have been photographing mosses, which I know virtually nothing about.

This post is therefore a look back to last summer and beyond.   Over the last 2 months I have brought together and analysed 6 years of data that I have collected on the two butterfly orchid species that grow on the croft.   Lesser butterfly orchid (Platanthera bifolia) and Greater butterfly orchid (P. chlorantha) are at a molecular level almost indistinguishable, yet they are still considered separate species and they certainly look different. The former is whiter and less creamy than the latter but position of the pollinia which carry pollen is the most telling way to discriminate between the two:- wide apart in greater, parallel and close together in lesser.

  

  

                                              Lesser butterfly orchid                      

                Greater butterfly orchid


On the croft the two species grow close together and in some patches they intermingle, which is unusual and gives scope for comparison with some of the environmental variables such as climate, nullified.

There is a degree of introgression, making the pollinia test to discriminate imprecise.

Lesser and Greater butterfly orchid plants growing less than 1 metre apart.









The data that I have gathered show statistically significant differences as follows:

a) Lesser butterfly orchids flower 7 - 9 days earlier than Greater butterfly orchids.
b) Height of the flower spike: Lesser average 17.2 cm, Greater average 25.3 cm
c) Width of the lowest of the 2 basal leaves: Lesser average 2.4 cm, Greater average 3.2 cm
d) Spur length: Lesser average 1.6 cm, Greater average 2.5 cm

Summarising, Greater butterfly orchids are more robust than Lesser butterfly orchids, a finding that is not always recognised in the literature.

The seed set efficiency, the number of flowers developing into a seed pod, appeared to be governed by environmental factors especially climate, and slug damage (a significant problem in 2013) rather than any interspecies difference.  Seed set in lesser butterfly orchids was fairly consistent year on year with on average 26%, whereas for greater butterfly orchids the average was 31%, but there was much more yearly variability. In some years the seed set efficiency was statistically significantly different, but in other years it was not and environmental factors, such as slug damage in 2013 seem to mask any difference.



Lesser butterfly orchid seed pods




                                Greater butterfly orchid seed pods




I found no difference in the number of flowers on the spike (Lesser average 12.3, Greater average 10.6, the average reduced by unusually low numbers in 2013 because of late flowering and slug damage)

I looked at the growing conditions.   Soil pH, ground slope, soil temperature and moisture content were not significantly different though equipment limitations might have masked differences.  There was though a difference in the sward height - the height of surrounding plants.   Greater butterfly orchids were commonly to be found where the sward was higher than the plant, whereas lesser butterfly orchids seem happiest in areas with less competition, though there is overlap.

So are they different species?   Morphology would suggest they are, and my data shows that there are differences in the physical size of the two orchids as well as the pollinia positioning differences.   But I am not so sure, and it may be that one is just a bigger version of the other, adapting to different habitat conditions.

The number of flowering plants has grown year on year.   The orchid areas are either mowed or strimmed once a year in early September, after seed set and dispersal, perhaps with some further strimming in the winter if the weather has been mild.

Year	P. bifolia Lesser butterfly flowering plants	P. chlorantha Greater butterfly flowering plants
2008	6	8
2009	8	25
2010	18	38
2011	20	67
2012	35	105
2013	41	104

A few plants have flowered every year for 6 years; by contrast some flower in one year but do not reappear the next (though occasionally they may flower in a subsequent year).

I looked closely at the plants which flowered for the first time in 2012 comparing those that only flowered in that year with plants that flowered again in 2013.   17 new Lesser butterfly orchids flowered in 2012 of which 11 flowered again in 2013, and 6 either produced only a leaf or nothing at all.   I could find no statistically significant differences between the two groups (height, leaf width, number of flowers, seed pod development) though of the plants that flowered in both years, the leaf width was greater in the second year than in the first.

Similarly with Greater butterfly orchids.    There were 59 new flowering plants in 2012, of which 22 went on to flower again in 2013, and the remaining 37 produced only a leaf or nothing.   There were no statistically significant differences in the average height or number of flowers of the two groups, but the average leaf width in 2012 of the plants that went on to flower again was wider than for those that did not.

If anyone is interested in a more detailed account, please get in touch.

Otter Images on a Trail Camera

I have had the trail camera out next to the landward side of the cliff  holt for over a week now.   It works on infra red so there is no disturbance to the animals.

The images aren't great as the otters are coming down, or going up a slope and the camera was too close.   I have now moved it a few feet back.  Here though are a three pictures.

We had one visual sighting of the otter family during the last week, briefly and at high tide, but the trail camera has picked up the otters on 8 occasions:

30.12 17:28 Saw them near the shore an hour earlier
31.12 14:56
1.1  16:01 and 18:21  Probably resting up in the interval
2.1   05:35 and 07:56  Probably resting up in the interval
2.1   18:02
3.1   6:32
Only 2 daytime occurrences, the other 6 after dark.

Returning Otters

Its quite a while since I last update this blog, but the autumn has been relatively quiet, with wildlife interest restricted mainly to fungi.  Waxcaps are ok but they are not that exciting.

This week has been a little different.   The weather has been challenging; we have had strong winds for over 2 weeks now, with a couple of trees brought down.  But an otter family has turned up. In October and November we had occasional otter sightings, probably a male, but the return of a mother and cubs at this time of year follows the pattern of previous years.

Last Sunday I saw a mother and cub briefly, alerted by the weak piping whistle that cubs make, but on Tuesday we had a 30 minute view of a mother and two cubs.   The cubs were about half the length of the mother and therefore probably less than a couple of months old.   

It was low tide, and quite dark, with the otter family swimming very close to the shore in no more than a metre of water.   Almost a training swim.

The family are using a holt at the cliff - heavy sprainting, a dead dogfish and a well used path - and I have put a trail camera there.

No still pictures of the otters because it was too dark, but I have quite a lot of video to do something with.  

Rain, lots of it

We have had lots of rain recently.   At the weekend, weather from the west meant strong winds and heavy rain.   On one day alone we recorded over 90 mm (over 3 inches) and the a run off stream from the hill behind us became a torrent.  Fortunately it runs steeply and directly into the sea, because otherwise, that ominous forecasters' phrase 'disruptive rain' would be appropriate.  As an aside, forecasters have some intriguing words to describe rainfall; one I heard recently and am puzzling over is 'organised rain', whatever that means.

In fact there have been few dry days recently and the recent poor weather confirms that the best time to visit Skye is either May or October, not in late summer.

There are still a few insects about such as common carder bees and white tailed bumblebees hunkering down on plants against the rain, mainly devil's bit scabious, goldenrod and autumn hawkbit. Fox moth caterpillars are everywhere.

White-tailed Bumblebee

Fox Moth Caterpillar

Besides fox moth caterpillars there are a few other moth caterpillar species such as knot grass and what I think is a ruby tiger moth, (not certain because I have never caught an adult on the croft) which I found during a break in the rain.  

Probably a Ruby Tiger Caterpillar

Knot Grass Caterpillar

A few fungi are also making an appearance.   Needless to say endless work is needed to get anything like an identification of them and maybe I will compile a list in a future note.

The real highlight though has been regular sightings of golden eagles.  A bird perches on the summit of a modest hill, Beinn Reireag Bheag (225m) at the north end of Scalpay, roughly 2.5km away and therefore  a scope is needed to see it.  Typically it sits there almost motionless for 20 to 30 minutes then takes off either to the east side of Scalpay and out of view, or towards Raasay to the north. One day we saw two eagles together in the late afternoon on the thermals.


Incredibly the sun is now shining and so that is all for now and I am off outside.  

Haytime

Over the last couple of weeks it has been 'haytime'.  I have been mowing the grass on half the croft now that the bluebells have set seed.  We are  trying to create a hay meadow replicating I hope, what was done 20 or 30 years ago.  According to the Skye and Lochalsh Haymeadow Report 2003,traditional management of a croft involved a rotation of 2-4 years cropping (potatoes,turnips, oats, oats-undersown) with 7 or more years of grass. The grass was cut annually in late summer to make hay for winter feeding of cattle and horses. The aftermath was grazed in autumn by cattle coming off the hill, then rested in winter before shutting up for the summer hay crop.  Hay meadows are now a rare sight on Skye and indeed elsewhere, having been replaced by year-round sheep grazing or earlier cropping of grass for sileage.  Many crofts have been abandoned to bracken and brambles (and new houses).

Sweet vernal grass

The dominant grasses in our hay meadow are Yorkshire fog, viviparous fescue, common bent and sweet vernal grass with patches of purple moor grass and occasional crested dog's-tail.   Common sedge, oval sedge, starry sedge and green-ribbed sedge are frequent in the damper areas. Soft rush and bracken are the aspirationally dominant plants and have to be kept in check.  More colourful plants include bluebells and pignut in May, and at the moment meadow buttercups (creeping buttercups in the only area that I think was once dug over), and devil's-bit scabious.   This assemblage seems fairly consistent with the 2003 survey.

Rather than gathering the hay up I now leave the grass in place, raking it over a little so it dies down and provides a little nutrient, equivalent to autumn grazing, and it is noticeable that bluebell seeds germinate well under the mown grass.  I disturbed a toad during the cut but surprisingly no field voles.

Areas where the orchids flowered have been left for a later cut in September and October, as they are just at the point of developing seed pods.   I do rake the grass off those areas to keep the level of nutrients low - which is not too difficult - and it seems to benefit the orchids.

There have been no mammals to report, other than a few pipistrelles at dusk.  Reasonably regularly in July and August in the past we have had a sighting of dolphins but not so far this year.   We therefore went up towards Staffin at the north end of Skye where there is a more reliable viewpoint and sure enough we had a twenty minute view of probably 20 or so dolphins (maybe common dolphins but I cannot be certain) in the channel between Skye and Rona.   Too far away to get a photograph - fortunately as I had left my camera at home.   Here is a picture taken four years ago in Loch Ainort of bottle-nosed dolphins

Insects have been the main focus of attention.   Dragonflies are on the wing, a black darter and common dragonfly perched long enough to allow a decent view.

Black darter

Common dragonfly

Common blue

Scotch argus butterflies are everywhere though they do seem to have a preference for the damper areas.   I also found a Common blue butterfly down by the shore.

Scotch argus

Down by the shore there is a little pocket of woodland plants such as wood anemone and I found a few Skullcap plants there.  Feeding on them was what I think is a caterpillar of the Skullcap sawfly.

I nearly forgot; I found another sedge on the croft, pale sedge.   Only a few plants but that brings the number of Carex species up to 8.

Pale sedge