Between west Sligo and north Sligo coasts there is an impressive free-standing Mountain, Knocknarea. West of this is a beak like promontory controlling the seas access to one of several tidal inlets around Sligo. This small area (shown in the map below) has a diverse range of habitats and wildlife.It is also an important amenity/recreation area for people of the area with impressive ocean and mountain vistas. An SAC, it contains many plants typical of a sandy habitat containing different niches within it varying from shoreline to high dunes.It is one of several favourite places along the Sligo coast. Others would include Dunmoran Strand and Mullaghmore which makes this Sligo coast rewarding to naturalists throughout a long season, May to October. Of course, at other times other interests take over with populations of Seals and Geese dominating.We have focussed in this page largely on the rare and unusual flowers of the area, Gentians, Orchids, and salt tolerant species. But its shoreline, at any time and at all stages of the tide, can be rewarding for wildlife with many wintering birds and large numbers of Seals gathering to reproduce.Konocknarea, shown BELOW. is the sole upland area and arises in solitary splendour unattached to any chain and dominating the landscape with dramatic cliffs, cairns and a Burial Site. West of that is the ‘beak’ of Strandhill Special Area of Conservation with an Atlantic beach to the west and a large sheltered sand and mudland behind for seals and visiting birds.
Beach, bay, sand-dunes, machair, estuary, tides, sandbanks… this small area of Co. Sligo has it all.
WildWest records and celebrates Nature, Habitat, Scenery on the western seaboard of Europe bringing you reports on how our wild communities (plants, animals, insects etc) are surviving in Ireland and other western extremes.
24 October 2019
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The Coastal areas…
The area studied is the large squarish bay and the dunes and calcareous grasslands on its north and west sides. A convenient car park can be found on the north-east corner of this bay and all the important botanical sites are within easy walking distance. A you enter Strandhill natural habitat you are struck by the variety of ‘places’ within one small area. The beach to the west can be cool and windy but inside the shallow bordering dunes it can be warm and protected leading to an explosion in orchids over a long Spring/Summer season. Very high dunes occur at the north of the photo (ABOVE) and are largely used for recreational purposes. Stable for a number of years, but not vegetated, they consist of a large area of moving sand (and people) with little undisturbed vegetation apart from the critical marram grass at the dune tops..Another shore is the exposed Atlantic coast on the north side of the huge sand pit that forms this unique ecosystem that can be explored in a day… or over many years. People walk through this for all sorts of reasons… to get from the car-park to the beach, to have a picnic, to slide down the dramatic dunes between the western wilderness and the golf club and town to the east. Many of these photographs were taken on one day. The dramatic waves and ‘storm’ were not as massive as they look and the effect was created by using a big zoom and a fast speed to focus on the waves and blur the lighthouse which is in fact some distance away.The large estuarine area between Strandhill and the dominating mountain and cairn of Knocknarea is beloved of seals, Brent Geese, wading birds, diving ducks, Auks and Great Northern Divers fishing in the deep channels during the Winter period. It is a vast area with regular large ebb and flow of fresh seawater leading to ripples, tidal rips, deep channels and smooth silt pans where the Common Seals like to pull out and sing (or lament) before giving birth. Vegetation of zostera and ulva seems suitable for certain ducks but there is not a large population of grazing ducks though Teal, Wigeon and Mallard are dispersed in small groups all over the vast area of mud that is Ballysadare Bay. Mergansers and Long-tailed Ducks are present in small numbers during Winter around the outer margins of this estuarine and coastal system.A final specialised niche can be the zone of halophytes at the foot of dunes and just above the high tide. These are resourceful plants and help stabilise sand dunes and sandbanks. It seems strange to see them flowering in a ‘desert’ right through into the Autumn. But the tolerance for salt also provides them with a tolerance to drying out in the form of waxy skin and active stomata.[The numbers in the Map refer to the five sub-habitats we have defined and described below.]
1. Marginal Sandy slopes…
After crossing the mudflats and passing the Golf Club there is a small gap in a fence leading over low sand dunes and into an area of many small sandy hills and valleys with a great variety of tracks and hill slopes to explore. Often this area is sheltered from the wind and it can be warm. The whole area is composed of low hillocks and banks of sand and calcareous deposits formed from generations of sea shells washing up to form these hillocks. It is these shells that provide the calcium that so many orchids and other plants enjoy. These marginal slopes, particularly close to the south of the promontory, are abundant with orchids. Most — but not all — orchids like an alkaline substrate!Walking up the path from the bay, the large dunes appear ahead — spectacular but not flower rich! It is the lower banks that are covered with a rich tapestry of flowers from May to October. There are a variety of common (pinkish) orchids, red pyramidal orchids and other rarer orchids with very special needs. Typical sand dune plants like violets and roses and clovers abound along with the grasses and sedges we struggle to identify. However, this area is almost entirely bare of any trees. This, and the hot sun that can be experienced here, lead us to think in American terms of prairies and large open landscapes…
ABOVE: The impressive Knocknarea mountain stands on its own to the north of the habitat. Ballysadare bay seems healthy with good growth of green seaweeds. However it does not attract very large numbers of ducks or geese; the south and inner parts of the bay being more popular. Brent Geese feed among rocks in the sea channel.
BELOW: Some of the many Autumn/Winter visiting waders found busy on the shoreline as the tide recedes. These are Ringed Plovers and Sanderling (INSET) The bay is more useful at high tide in Winter with the many fish eating birds congregating in the fast flowing channels as the waters ebb and flow.
2. Dune bottoms and flood areas…
Within a short distance from the ridge of surrounding sand hills (small to the south, larger to the north) there is an area of more settled and greener grassier habitat. This can be either flat or hilly. The hills may be small (3m.) but can still be noticeably drier and plants will easily wilt there. Most of the species considered here, and there are a couple of rarities, are very moisture dependent either by way of flash flooding or low lying slow-to-drain areas. It is a fascinating area with several specialists here in good numbers each requiring and finding the ideal niche for them to seed, grow and flower.
BELOW: Large and Small dunes.Approaching from the southern entrance to the site via the rippled sands of Culleenamore Strand, the high dunes appear as a backdrop to the lower marginal slopes that hold most of the rare and common dune flowering plants.
Typical species associated with these conditions would include:1.Pyramidal Orchid2.Common Spotted Orchid3.Bee Orchid4.Burnet Moths5.Wild Thyme6.Lady’s BedstrawThe image (RIGHT) shows the typical Burnet Moth of Strandhill. This pair is mating on one of its favourite perches — the Pyramidal Orchid. The Pyramidal Orchid (Anacamptis pyramidalis) is a widespread species dominant in this habitat and a uniform densely flowered plant. It is abundant on these slopes, occurring in peripheral low level dunes at the edge of the study area as well as on hillocks and sandy banks within the area. It grows rapidly but will wilt quickly in hot weather as seen in in the image of the full plant, BELOW.
RIGHT:Bee Orchid Ophrys apiferaAlso widespread in more or less the same niche as the Pyramidal Orchid. It seems to be all about water — but NOT too much of it — warm weather, and nutrition. The Bee Orchid is quick to flower and very quick to wither.They are a successful species due to adaptations in their reproductive systems (Discussed elsewhere). A closely related species (the Fly Orchid) does not occur here as it is very limited in the way it is fertilised.This specimen (it can be enlarged) shows the rostellum, viscidia and the released pollinia now dangling in front of the ovary. Both self fertilisation and fertilisation by visiting insects is thus possible making for a successful species!
BELOW: A typical steep but not high bank rising up from one of the many paths and water channels. It provides the warm southern facing aspect that helps orchids to grow and a degree of shelter from drought and wind. Apart from the numerous Pyramidal Orchids, Hawkweed is abundant along with Lady’s Bedstraw — a grouping of species typical to Strandhill.
ABOVE: An uncommon Common Orchid — this is a spectacular and beautiful cluster of the Common Spotted Orchid(Dactylorhiza fuchsii). It is very rewarding to come across these common species when a fresh healthy vigourous specimen or group is found. All Irish orchids will produce these ‘perfect models’ but they need perfect conditions and they don’t last long!
RIGHT:These plants will thrive in differing areas but a habitat can be defined by the plant associations that are particularly notable in defined sets of circumstances. The Carline Thistle (Carlina vulgaris) and Wild Thyme (Thymus polytrichus) are also widely present on exposed sand hills and in the next section dealing with flatter long-grass conditions.
These specialists can be cited as: 1.Marsh Helleborine (RIGHT2.Marsh Orchid (Far RIGHT)3.Frog Orchid4.Field Gentian5.VioletAll these species seem to occur in low ground either wet or damp or where water regularly flows or stays in pools for long enough to support the species. Several of the species display ‘Spiranthes alignment’, a phenomenon where plants align along a previous water boundary at some time in the past, either recent or long ago!The Marsh Helleborine (RIGHT) is common in marshy areas of most sandunes (viz. Bull Island, Co. Dublin). The density of specimens is greater when the wet area is larger. This group is probably the biggest colony at Strandhill.
Above RIGHTMarsh OrchidDactylorhiza coccineaThis also loves wet zones but can occur on the slopes of nearby drier hills.Dog VioletsViola rivinianaA common Violet but a dominant species at Strandhill. It loves dune bottoms and nearby slopes but not in areas of semi-permanent water. It is of interest as it forms dense ‘bushes’ or colonies set apart from one another. Is this a response to floods and droughts, lack of trees, or is it down to the alkaline substrate?This species flowers over a long period from April to October and always occurs in open areas such as wood margins, shores and calcareous grasslands.It is curious the way that, at this habitat, it is mainly present as large separate clumps. These clumps are universally lush and green with healthy large leaves — even when the orchids and gentians are wilting! Perhaps these clumps are one plant with deep roots that can withstand occasional severe downpours.
Trees and Wildlife.
All of the area is naturally almost devoid of trees. North of the area some native Scots Pine survive with associated Pyrola. In this Study Area there are only two trees! This limits the scope for breeding birds and the common species occurring would be the Meadow Pipit, Skylark (ground nesters) and the Stonechat.LEFT AlderThis stunted Alder seemed to mark the site of a spring or a drain (or both) with visible gullies and boulders under the bush. It also marks the lowest part of the Dune bottoms so, presumably, all rain water flows into these lowlands and eventually runs out through subterranean connections under this bush.LEFT Stonechat.This tree is the highest point in this birds territory. They breed here and spend most of their day flitting from perches in the Marram Grass and this clump of Alder. It seems that the pair breeding here would be the sole territory holders in Zone 2 but there are probably other similarly isolated pairs further south.
ABOVE: Prostrate Juniper.. Juniperus communis ssp nana ?We have walked this area religiously and have never seen another specimen of this species… Prostrate Juniper (but possibly a variant of the normal Juniper). It is frequent in exposed western seashores and cliffs such as Dernish Island in north Sligo not far from this location, also in North Mayo high cliffs at Portacloy. It is a tree but rarely grows taller than the specimen shown. Many expansive specimens occur on the abandoned Dernish Island and perhaps seed has been carried from there. It does seem somewhat out of place on this sandy but alkaline flat. This area of Sligo is based on Glencar limestone but the other two locations are on psammitic rocks of metamorphic sandstones.. acid rocks? However, judging by the wealth of base loving plants present here it is clear that the underlying Limestone Formation and the surface deposit of sand laced with calcareous shells is providing the suitable alkaline and mineral conditions required by the orchids and other lime loving plants.
Colour is less vivid in Autumn and these September/October discoveries were delightful to see as the flowering season was ending. The Frog Orchids are familiar occurring as they do in Kesh Mountain, Co. Sligo fairly close to where we live. But they are an interesting orchid that often may never reach a mature state due to grazing or exposure to harsh weather. The specimens from Strandhill were hard to spot when first observed as their bright green leaves and bud blended well with the damp background they were in, but they quickly developed into more discernible and sturdy specimens.Milkwort… The pictures (LEFT) are of Common Milkwort (Polygala vulgaris) a low growing herb found in grasslands and common at this site. The colour and size of these very small plants varies as shown. These pinkish and blue-ish variants occurred side by side and colour variation was visible to the naked eye. Sun intensity was varying rapidly at the time.b) Field Gentian (BELOW),Recording the Frog Orchids led to a later discovery of Field Gentians in the same area. These were in among similarly coloured commoner plants. Tonally, they seemed in between the Milkworts but all the Gentians were of a pale purple hue very much in harmony with their commoner companions.All these images were taken under bright Autumn sunshine and many different Gentian plants were photographed. It seems that the Gentian flowers were all of the same colour but the Milkwort plants genuinely occurred in slightly darker shades of red/blue which also corresponds with a mental memory of many of the Milkworts looking slightly different!
Two unique and unexpected plants.
We have been investigating this Strandhill Habitat for a number of years and were familiar with the main plant populations and the way weather conditions encouraged or discouraged large scale flowering in each species. The Bee Orchid this year, for example, was well represented but only over a short period as many of the plants growing high up banks and exposed to the sun simply dried up within days.a) Frog Orchid Dactylorhiza viridisAt the end of June we were looking for other interesting species. A few very tiny emerging plants of this species were found in one cluster in the slightly humped water pathway leading into the sump at the Alder bush. This small clump over the next few weeks developed into a record of 40 specimens in the same general area. Some of these plants were the finest example of the species we have come across.The Frog Orchid occurs in many different sites in Ireland either on Limestone (Kesh Mountain, Co. Sligo) or on calcareous grasslands or dunes (Sheskinmore Nature Reserve, Co. Donegal). We know of no previous records for this species here? The niche we have found these in is on lush dune bottoms rather than on the sloping borders of bare dried up flood channels where Field Gentians were later seen.
Field Gentian Gentianella campestrisAfter the excitement of seeing a new successful occurrence of the Frog Orchid it was good, a few months later, to discover a new unfamiliar species of Gentian emerging above the wet fringes of the same habitat. Instantly different from the bright blue Spring Gentian of the Burren it seemed smaller than the Autumn Gentian. Final identification was based on the corolla — the petals and sepals.These specimens were very small when first encountered growing on lower slopes of small dunes, which in mid October were closely cropped. The opening flowers lend 50% to the height of the plant but the flowers themselves rarely fully opened this late in the season.As these photographs show this plant had 4-petal flowers and the Calyx had Sepals of unequal size with a large one either side overlapping the narrower sepals in between. Both features identify these plants as Field Gentians.This is a new species to us and no record of it occurring in the Strandhill dunes has been found yet. October is a time of year when botanists tend to switch off and we would not have come across these Field Gentians had we not made such a close study of the habitat earlier in the season and returned to check it out regularly!
3. Settled Sand Dunes…
At the south-western flank of the Flood Area described above there is a medium height linear sand dune which marks a change of habitat. The flood area has been subject to recent flooding, tidal and wind damage. West of this the dunes are stable and more or less undisturbed over a long period. This reduces the species richness.
Leaving the Dune Bottom and heading north and west, this small valley (LEFT) brings you into an area with almost complete grass cover including large areas of waist high Marram.This is a good valley for invertebrates and the bank on the right particularly attracts butterflies and dragonflies as shown on LEFTVegetatively the change of habitat is reflected in the Harebell showing up prominently in the foreground of this picture. A common species which likes more sheltered areas from mountains, to rock shores, to sand dunes. Slopes are a common niche as this plant does not like flooded or permanent damp areas.
BELOWThese cases are to be seen over much of Strandhill, wherever these 6-spotted Burnet Moths (Zygaena filipendula) occur. The yellow cocoon has a black pupal case from which the adult moth has emerged.
RIGHTHarebell,Campanula rotundifoliaClose-up of some of the Harebells from this warm sheltered valley. Many plants have colour variants but white Harebells are not so frequent. They are graceful abundant flowers with a long flowering period — somewhat under appreciated jewels of mountains and dunes.BELOWA largely flat area, like a prairie, between the two marginal lines of dunes, this zone is overgrown with marram grass and not botanically rich. But it is a good area for snails and insects and the Pipits and Larks which feed on them.
List of Habitats/Zones1. Low Dunes2. Dune Bottoms and Flood areas3. Settled sand dunes/prairie4. Halophytes and Deep dunes5. Beach/shore defence
There is an area at the southern tip of this dune system that is interesting, dramatic and little visited. Just offshore one of the main channels allowing the tides in and out passes close to the beach. Consequently the shore is steep and fast water will run past at peak tidal flow (about half way between high and low water) — making this a popular hunting area for seals and birds.On the inland side of the shore there are steep defences in terms of continuous dunes on the margin of the shore and a pocket of a few very small steep sided sand baby dunes. These are a haven for a variety of specialist plants like Harebells and Roses as the area can be very warm dry and sheltered. Mating snails love this area!
ABOVE: Sherrard’s Downy Rose,Rosa sherrardiiThese Autumn pictures are of a cluster of these Roses found in a very limited area in these deep dunes (Habitat #4) We identify it based on the leaf shape with slight point, toothed edges with glands on the underside and on the stems and hips. Up to about 2m. tall with slightly curved sharp thorns. The red moss like growths on the stems are called Robin’s Pincushion and are a gall that distorts an axillary leaf or a terminal bud. The gall is produced by Gall Wasps, Diplolepsis rosae.
Two episodes of Frog Orchid emergence occurred due to weather conditions.
Galling Roses:Roses can be hard to identify especially when out of flower. Two types are shown here bearing galls resulting from brood parasitism by various species of Gall Wasps..BELOW: Burnet Rose with gall from Diplolepis spinosissimae wasp.This is a prostrate rose creeping along bare or lightly covered sand dunes. (It is from Habitat # 3 above — Settled Sand Dunes). The gall is formed in a similar manner to that of the Downy Rose (RIGHT). An egg from the wasp is laid in a leaf or bud axil. The developing larva releases chemicals which trigger an unusual growth from the parent plant. In the case of the Burnet Rose the growth forms a polished spherical cradle cupped in the leaf from which it is fed. Other common examples of galls are Oak Apples and Witches Brooms found on Birch trees.
Halophytes:Halophytes are salt-tolerant land plants often associated with arid climates but important in Ireland on seashores where these plants are resistant to salt spray, submergence in salt water, or tides on a regular basis. The European SearocketCakile maritima (LEFT) is a typical example found around the sandy back shore of Strandhill promontory. This plant can survive in areas most exposed to both wind and tide.This, and the Frosted OracheAtriplex laciniata (RIGHT), help extend the sand dunes at the tip of this site by forming series of clumps along a current margin leading to a build up of sand along the upper tide mark.
Perennial Sowthistle Sonchus arvensisA secondary coloniser, it is normally associated with other plants on disturbed ground or newly forming vegetation. It is the perennial ‘version’ of the Dandelion. This photograph shows the Sowthistle with Harebells and Lady’s Bedstraw.
Sea Sandwort Honckenya peploidesAnother succulent low growing plant with a large root system, grows at the base of dune systems especially, in this case, in the calmer inner south facing part of Ballysadare bay. The glossy leaves help it retain water
Dune Erosion and Settlement.Here an exposed section near the mouth of the bay has been eroded by wind and water but still shows tufts of marram, Orache, Sowthistle and Searocket on the exposed flat sand.
Finally we have reached the end of the Spit facing the open ocean and controlling, through narrow channels, the ebb and flow of the tides. As the water leaves the large area of bay behind the dunes it passes through 2 major drainage channels with very fast tidal flows particularly when the tide is going out. Further banks occur across the mouth of the bay and these are dry at low water —the breaking waves indicate their position.In the distance Raghley can be seen, looking like an island, but it is joined to Ballyconnell with the low hills rising on the right towards Lissadell. It is impressive that, even over such a short distance (8.25 km), the low lying land between Raghly plateau and the Lissadell hills has disappeared. It seems after all, that the Earth is curved! It took us quite a while to work that our but our dog, Beau, seems to be ahead of us in his search for Australia!
5. Beach & Shore defence…
Coastal Erosion at Strandhill.
If you look at the aerial photograph at the top of this page it would seem that this Strandhill promontory, composed of nothing but sand, is very exposed to the Atlantic. Yet it has not suffered major damage over many years. Other dune systems, and coastal areas, around Ireland have been devastated by apparently rising sea levels and undoubted increase in storms in the Summer/Autumn seasons. We have known this habitat as a place for regular walks with one dog or another over 15 years and the broad overall landscape has not changed materially. Why is this?
Factors protecting this habitat.
As you can see (photo ABOVE RIGHT) the sand on the most exposed part of the shore is deep and fine with no shore defences installed apart from the naturally occurring boulders in the background. Nearer the town itself the big dunes and wash-out was caused by a spectacular breach in the traditional shore defences about 10 years ago. To prevent further damage this area and the shore in front of the town and further north has been extensively protected by rock armour to protect the town and its thriving Surfing Industry — another testament to the size of the waves to be found here!The main photograph (ABOVE) taken looking North does provide some further clues to the limited damage exposure is causing at this point. Despite appearances there is land joining the two higher areas of ground shown, Raghly to the left and Lissadell to the right. This barrier is only 8km away so there is only a short stretch for waves to build up and no means whereby ocean waves can directly approach the beach from the north. Furthermore, this photograph is taken at mid to low tide and the offshore breaking waves indicate bank after bank of sand taming the waves before they ever reach the sand-dunes — apart from very high tide levels!However between Raghly Point and Carrodough Spit (# 5 on Aerial Photo) there is a clear uninterrupted line of site to the NW. The Spit is protected from westerly wind and waves by Sligo’s north coast which stretches further north than Strandhill. Also, along the exposed north westerly line there is a shoal called Turbot Bank which straddles the Sligo Bay entrance and is largely composed of sand. So here is to be found a large reserve of sand that can wash up and rebuild the Strandhill shore and dunes. This may explain how a geographically exposed site in North West Ireland is not suffering the level of erosion and territory loss one might expect.
Stabilising the substrate and protection of rare species.
Substrate is the base in which plants are anchored. It can be sand, rock, soil, etc. These various media erode at different rates, sand being the most mobile where it is not anchored by plant or other material. Unfortunately most of the Strandhill peninsula is largely sand, with shell fragments, on top of underlying limestone bedrock. Great pH for plants but a hard environment for the vast majority of plants to settle in. None of the exotic orchids would be present in Strandhill without the marram and other ‘humbler’ plants to do their basic task of stabilising the landscape.