Coastal and nearshore ecosystems: rocky shores, reefs and marine mammals

At the shoreline, Howth’s wave‑exposed rocky coast supports the familiar Irish intertidal pattern of seaweeds, barnacles and limpets, with rock pools acting as small refuge habitats between tides.

Offshore, Howth sits next to a wider “protected seascape” in the National Parks & Wildlife Service (NPWS) network. The nearby Rockabill to Dalkey Island SAC is designated for reefs and harbour porpoise, and its conservation objectives explicitly reference links with adjacent and nearby Natura 2000 sites, including the Howth Head SAC and Howth Head Coast SPA. ³⁶

From a lived experience perspective, this is one of the few places near Dublin where you can sometimes watch marine mammals from land. The Irish Whale and Dolphin Group reports long‑running watch effort from Howth Head (Nose of Howth) focused on harbour porpoises, illustrating how the headland functions as a “platform” for observing marine ecology as well as a habitat in its own right. ³⁷

Further details are provided in the Section Coastal Cliffs and Marine Life.

Neolithic Farmers (c. 4000–2500 BC): First Clearance & Settlement

When farming arrived in Ireland around 4000 BC, Howth Head was still largely wooded, dominated by oak, hazel, elm and birch. Pollen evidence from Irish peat deposits shows a marked decline in elm around 3800 BC, often linked to early farming activity and woodland clearance. ⁴⁰

Howth’s thin soils and exposed slopes would not have supported intensive agriculture, but small clearings were likely created for grazing and cereal cultivation. The surrounding sea provided abundant fish and shellfish, and the sandy tombolo at Sutton connected the peninsula firmly to the mainland.

Inhabitants

Evidence of Neolithic activity on Howth includes a shell midden at Sutton dated ~3300 BC ⁴¹ and the portal tomb known as Aideen’s Grave (built ~2500 BC), on the grounds of Howth Castle. ³⁸

According to legend, Aideen was the wife of Oscar, who was killed at the Battle of Gabhra. When news of his death reached her, she is said to have collapsed and died from grief. Oscar’s father, Oisín, buried her at Howth and raised the tomb in her memory as a mark of loyalty and honour. In Irish tradition, such monumental burials were usually reserved for great warriors or kings.

Neolithic life

These early farmers began clearing the primeval woods for small-scale farming and pasture. Archaeological remains show they hunted wild boar, red deer, and hares – animals of woodland and open country – and gathered marine foods, indicating a landscape of mixed forests and coastal resources.

By this time, Howth was a peninsula: the post-glacial rise in sea level had stabilized, forming a permanent sandy tombolo at Sutton that reattached “island” Howth to mainland Ireland.

Bronze Age to Iron Age (c. 2300 BC–400 AD): Expansion of Farming & Further Woodland Loss

By the Bronze Age, woodland clearance accelerated across Ireland. Pollen records show increasing grass and herb pollen, indicating more open land. ⁴²

By the Iron Age, locals were raising cattle. An ancient fort named Dún Bó (“fort of the cows”) (now called Dunbo Hill, where the Garda Station is) suggests grazing was well-established by the 1^st century AD.

The headland’s original oak forests were diminishing. (Indeed, the old Irish name Binn Éadair – possibly meaning “Hill of the Oak Wood” – hints that thick oak forest once covered Howth, even though such woods largely vanished in later centuries.)

The Annals of the Four Masters (Annála Ríoghachta Éireann), a major 17^th-century compilation of Irish history covering events from legendary origins to 1616 AD, records that a fortress was built on Howth around 1000 BC by the Milesian chieftain Suirge, indicating a tradition of prehistoric habitation.

Early Christian / Early Medieval (300  – 1100 AD): Monastic retreat and coastal stronghold

By the Early Christian era, Howth and its islet Ireland’s Eye hosted monastic retreats

Cill Mac Nessan (Church of the Sons of Nessan) is a 7th-century monastic ruin located on Ireland's Eye. Established around 700 AD by the three sons of Nessan, from which the island's alternative name, Inis Mac Neasáin, originates.

It was here that the Garland of Howth was written. This Latin Gospel book is similar (though in a much smaller way) to the Book of Kells.

Through these centuries, however, ongoing clearance for farming, grazing, and fuel on Howth gradually thinned the woodlands. Viking raids in the 9^th century (Howth was attacked in 819 AD) and the Norman arrival in 1177 likely further disrupted the landscape. By the High Middle Ages, much of Howth Head was more open country than deep forest – though pockets of woodland still survived in valleys and estates, and the memory of “oak-covered” Ben Edair lived on in lore.

20^th Century Changes (1900s–1990s): Decline of Grazing & Habitat Protection

One of Howth Head’s signature habitats is its expansive heathland, dominated by heather and gorse. This heath did not arise by chance – it was historically maintained by grazing and occasional controlled burns when the headland was used as common grazing land. Old photographs from around 1950 even show local farmers milking Irish goats on the hillside, harking back to a time when goats and cattle kept vigorous plants in check.

For centuries, this controlled grazing was a defining ecological force on Howth. Livestock and wild herbivores (notably rabbits) kept the upland heath and grasslands short, which maintained plant diversity and prevented any one species (like gorse or bracken) from dominating². Pollen data show that during the grazed period (15^th–19^th centuries), herbaceous plants (dandelion, plantain, clovers, etc.) were abundant, indicating a species-rich turf².

However, when farming and grazing largely ceased after the 1940s–50s, the heath’s delicate balance was upset³. In the absence of nibbling animals, vigorous bracken ferns (Pteridium aquilinum) and young birch trees spread over the once-open heath, and many wildflowers disappeared as taller plants took over. ⁴ The pollen record shows a sharp decline in herb diversity by the mid/late 20^th century.

This successional change was noted as early as the 1970s–1980s by ecologists and is clearly evidenced by rising birch and bracken pollen in the Bog of the Frogs core for the mid-20^th century.

On the sea cliffs, the decline of grazing had a parallel effect: formerly nibbled “lawn” zones (whether by livestock or wild rabbits) grew rank and bushy. Recent observations confirm that the loss of Oryctolagus cuniculus (European rabbit) to disease has allowed coarse grasses and scrub to spread into cliff meadows that were once rabbit-grazed “golf green” turf⁵.

This change in the nature of the heath brought an unintended consequence: a greatly increased risk of accidental wildfires. The pollen record shows relatively little charcoal prior to the 1800s, then a marked increase in fire frequency in the late 19^th and 20^th centuries⁶ .

Oral histories and newspaper archives confirm that wildfires (often started accidentally by people) became an almost annual occurrence on Howth, especially in dry summers. Fire, combined with no grazing, has pushed the heath into a less ecologically stable state. Gorse and dry heather are oily, highly flammable fuels and resprout, while competitors (bracken, coarse grasses) also rebound quickly after fires, together forming a monoculture that chokes out more sensitive species⁶. Fire also inhibits any tree regeneration on the heath.

Large fires periodically ripped across Howth Head in the late 20^th century⁵. These uncontrolled wildfires scorched the peat and seedbank, damaging the heath habitat and endangering nearby homes¹⁰.

A large fire in 1968 left a charcoal layer in the Bog of the Frogs peat stratigraphy. Heather and gorse, which resprout after fire, became dominant on the plateau, while fire-sensitive species and seedling trees were killed, further locking the heath into a cycle of burning and bracken invasion.

In response, the need to conserve Howth’s ecology gained recognition. Parts of Howth were designated as protected natural areas: by the 1990s, much of the headland was listed as a proposed Natural Heritage Area and later as a Special Area of Conservation (SAC) under the EU Habitats Directive, and its sea cliffs (supporting colonies of breeding kittiwake gulls) were designated a Special Protection Area (SPA) under the Birds Directive.

In 1999, the Irish government also gave legal protection to Howth’s landscape character by confirming a Special Amenity Area Order (SAAO) for the peninsula, which restricts unsympathetic development and calls for the preservation of scenery, habitats and public amenities.

Ecological Challenges

Coastal Cliffs and Marine Life

The coastal cliffs of Howth Head – sweeping from the Baily Lighthouse around the Nose of Howth to Balscadden Bay – are recognized as a habitat of international importance. They are protected under the EU Habitats Directive as “[1230] Vegetated Sea Cliffs of the Atlantic coast”, a primary reason for Howth Head’s designation as a Special Area of Conservation (SAC)¹¹.

These cliffs are composed mostly of hard Cambrian quartzite and slate, forming steep rocky sea faces up to ~170 m high, with a smaller area of softer boulder clay bluffs near Redrock¹³. Despite their harshness, the cliffs support a mixture of coastal plant communities zoned by height and exposure:

• Splash Zone (spray cliffs): the lowermost rocks, washed by sea spray, host black and orange lichens (e.g. tar lichen Verrucaria maura and Xanthoria spp.)¹³.

• Crevice & Ledge Zone: slightly higher ledges and cracks where salt-tolerant succulents and herbs take hold. Notable species include sea thrift (Armeria maritima), sea plantain (Plantago maritima), sea beet and rock samphire (Crithmum maritimum – recorded at Howth’s Baily cliffs as early as 1794 and still present today¹³. The rare sea spleenwort fern (Asplenium marinum) endures in a few shaded crevices, a relict of milder coastal microclimates¹³.

• Maritime Grassland (Ungrazed Grassland on Hard Cliffs): On upper slopes and broader ledges, a carpet of grasses and wildflowers grows where salt influence diminishes. Red fescue (Festuca rubra) and bentgrass (Agrostis stolonifera) create a windswept turf, dotted with blooms like spring squill (Scilla verna, recorded on Howth since 1903¹³), kidney vetch (Anthyllis vulneraria), wild thyme, lady’s bedstraw, and orchids. In the past, rabbit grazing helped keep these slope grasslands short and species-rich. However, with rabbit numbers crashing from recurrent myxomatosis outbreaks, some cliff-top grasslands have grown rank, allowing brambles and bracken to increase¹³.

• Coastal Heath: Along the fringes of the cliffs, where salt spray meets upland, pockets of wind-pruned heath occur. Here dwarf gorse (Ulex gallii) and heather (Calluna vulgaris) mix with grasses and wild thyme, forming a low coastal heath transitional to the extensive dry heath atop Howth. This zone has high conservation value, but also faces threats from encroaching bracken and gorse if not kept in check ¹³.

Howth’s sheer coastal cliffs – some plunging 200 metres into the sea – are not just scenic, they are vital ecological havens.

The cliffs are “bird cities” that provide crucial nesting sites for seabirds (the reason Howth’s cliffs are also an EU Special Protection Area). Kittiwakes, razorbills, guillemots, fulmars, cormorants, and gulls nest on the ledges every spring and summer in raucous breeding colonies.¹⁴ (The kittiwake, a small gull, is of particular concern – it’s a globally vulnerable species, and protecting its nesting sites was a key reason for Howth’s designation as a Special Protection Area¹⁴.)

Below the cliffs, the surrounding waters of the Irish Sea – part of the Dublin Bay Biosphere Reserve – teem with marine life, from grey seals and porpoises to kelp forests and fish, benefiting from the relatively clean, nutrient-rich bay waters. The interface of land and sea also creates unique micro-habitats: splashes of salt spray and wet seepages on the cliffs allow unusual coastal plants to thrive. For example, the sea thrift and rare spring squill can be found flowering on the cliff-top grasslands in spring¹⁴.

Above, in grassland and heath areas by the cliff path, a high diversity of invertebrates (including rare ants noted at Redrock¹⁴) and songbirds find refuge where human access is limited by the terrain.

Despite their resilience, coastal habitats face pressures too. Erosion of cliff-top soils, disturbances to natural freshwater flows (some streams have been diverted or culverted) and encroachment by scrub all threaten the cliff flora¹⁴). One invader, the Hottentot fig (an ornamental succulent), has gained a foothold on Howth’s cliffs and can carpet rocky slopes, out-competing native plants. Conservationists have called for renewed efforts to eradicate Hottentot fig from the peninsula’s coastal areas before it spreads further¹⁴).

Plans also include monitoring cliff vegetation and even restoring wet seeps (tiny freshwater springs) on cliff faces that harbour specialized mosses and ferns¹⁵). By caring for these coastal ecosystems – from ensuring water flows to removing invasives – the NPWS and local partners aim to keep Howth’s marine and cliff environments rich and thriving. (See the NPWS Coastal Habitats Conservation Objectives [2016]¹⁵) for more on Howth’s sea cliffs.)

On a positive note, the sea cliffs survey found that many aspects of the habitat remain intact or “favourable”: the full range of expected plant communities is still present (from lichen-encrusted rocks to coastal heath), overall invasive species cover on the cliffs is still under 5%, and no significant coastal erosion or physical damage was noted beyond natural processes. Thus, with active management, the vegetated cliffs can recover. The goal, now formally adopted in conservation plans, is to restore Howth’s sea cliffs from “unfavourable” to a favourable conservation status in the coming years¹⁶.