The Status of Butterflies in the Filey recording area
Small Skipper Thymelicus sylvestris
One of the region’s most diminutive yet attractive species, the Small Skipper is widely distributed and resident across suitable habitat within the Observatory area. Small Skippers are essentially a species of open grassland, nectaring at plants including Clovers Trifolium spp., Birds-foot Trefoils Lotus spp., Tufted Vetch Vicia cracca, Knapweeds Centaurea spp., Thistles Cirsium spp., Brambles Rubus fruticosus agg. and Hawkbits Leontodon spp.
A species dependent on grassland with a Yorkshire Fog Holcus lanatus rich sward, males are much more active while feeding and searching for mates, in contrast to the largely sedentary females. Females can occasionally be seen inverting their abdomen into the sheath along the grass blade and laying 2-5 eggs into what will eventually become the secretive caterpillars foodplant. Small Skippers tend to frequent more open exposed habitats than Large Skippers, occurring further into the centres of fields away from boundary features like hedgerows and on more exposed promontories.
The coastal grassland margins and undercliff, The Tip area, Reighton Gap and Hunmanby Ponds are all particularly productive sites for this colonial species. The Small Skipper’s single generation is best observed on the wing from early/mid-June to the end of August. In common with its relatives, Small Skippers hibernate as a larvae, spun in a cocoon within a Yorkshire Fog sheath.
Large Skipper Ochlodes sylvanus
Currently the only other ‘golden’ skipper within the Observatory area, the Large Skipper is equally well distributed, but has a greater preference for damper, more sheltered areas of grassland. A largely sedentary species occurring in localised colonies (which can exist in surprisingly small areas of suitable habitat), males are the more active of the two sexes, mostly during sunny late mornings.
Activity in the afternoons drops and is replaced by perching; this is where shrubs, hedgerows and similar features become more important for locating females. Large Skippers use grasses as their larval foodplants (usually Cocksfoot Dactylis glomerata) and are as abundant as Smalls locally, but are can be more frequently encountered due to their slightly longer flight period, typically extending from around late May to mid-August.
Most areas of sheltered grassland which support flowering plants such as Clovers, Thistles and Trefoils, interspersed with some tussocky Cocksfoot, support this species locally. Local sites including The Tip, Reighton Gap, Hunmanby Gap and more scrubby sections of the coastal undercliff and grassland support well distributed colonies, and searching along grassy margins sheltered by hedgerows can be especially productive.
Dingy Skipper Erynnis tages
The most localised of the three Skippers to be found within the recording area, this species can be abundant during some years at its favoured sites. Whilst perhaps not as attractive as the two ‘golden’ Skippers, the Dingy Skipper is now rare across most of its former national range, and still declining in many areas, making it an increasingly important local speciality.
This springtime butterfly typically exists in sedentary colonies, usually containing less than 100 individuals in a given season. As a result of its early emergence, this species tends to spend a great deal of its time basking.
Females usually lay their eggs on Birds-foot Trefoil, with a particular preference for plants growing in warm sheltered nooks and crannies, surrounded by areas of bare earth. Dingy Skippers are more frequently found in grazed and disturbed grassland than the other two skippers, making local areas of undercliff ideal, due to regular erosion disturbance, an undulating topography, unimproved soils and an abundance of food plants.
This small, fast flying, moth-like species frequents Reighton Gap, with the main colony having persisted in this area for a considerable time. A smaller, possibly ephemeral colony exists at Primrose Valley, with similar small colonies scattered along the cliffs around the southern end of the recording area. The viability of the smaller populations may be dependent on dispersal from the core Reighton colony (/colonies).
Sporadic records from other sites in the recording area (predominantly along the coastal strip) could be either transient individuals or small ephemeral colonies forming. This species is best seen between mid-May and late June, with individuals occasionally persisting into July. Dingy Skippers are typically single-brooded, with no evidence of a second brood in our area so far.
Clouded Yellow Colias croceus
One of a number of migrant species which graces the Observatory recording area, the Clouded Yellow is an almost annual addition to the year list. Numbers reaching Britain vary considerably from year to year due to volatile population cycles; a species of Southern Europe, mass eruptions occur during some summers, often centred around a ten year cycle.
Clouded Yellows are often very mobile along the coast before quickly moving inland or to localised feeding grounds rich in Clovers and Lucerne Medicago sativa, which both adults and larvae feed on. The caterpillars develop quickly during the summer before emerging as adults around mid-August, when they usually move south. Breeding is unusual within the recording area, and is unlikely to occur except in extreme influx years.
As would be expected from such a sporadic migrant there is no reliable site within our area. The species has the capacity to turn up anywhere, with an increased likelihood of freshly landed migrants along the cliffs and in particular the promontory of Carr Naze. Areas rich in Clover and Trefoils are probably best checked between April and October, with an increased number of records from July onwards.
Brimstone Gonepteryx rhamni
Neither a true migrant nor an established resident, this sulphur-coloured nomad occurs sporadically in our area each year; most records are of males, which are more dispersive when searching for mates. Brimstones are often found in association with their larval food plants, Buckthorn Rhamnus cathartica and Alder Buckthorn Frangula alnus.
More specifically, these food plants need to be growing in sheltered areas, to be relatively young, and to receive sufficient sunshine for breeding to occur (making many trees unsuitable). Nectaring adults are far more frequently observed in the area, notably on purple flowers such as Teasel Dipsacus fullonum, Butterfly Bush Buddleia davidii, Knapweed, Red Clover Trifolium pratense and Thistles, and Primrose Primula vulgaris in spring.
The general paucity of sightings is no doubt linked to the limited distribution of food plants locally; breeding is unlikely to take place within the recording area, but invariably does so a little further afield. These long lived butterflies can be seen in suitable conditions throughout the earlier part of the spring and summer, and as a species which hibernates as an adult (relatively early in the season), springtime is a good time to spot one; males emerge up to two weeks earlier than females, from both hibernation and from metamorphosis later in the year.
Large White Pieris brassicae
To the casual observer this is a rather bland looking butterfly, but to the naturalist it’s a fascinating species with a complex life history. The Large White breeds on Brassica species like Cabbage, Kale and Sprouts, as well as other species like Nasturtium and Wild Mignonette Reseda lutea.
The caterpillars are typically quite gregarious, often occurring in large numbers at particularly good sites. They are stimulated to feed by the oily fumes released by the leaves as they eat, until leaves are eventually stripped to the base. Large White populations are prone to a range of parasitoids throughout their life cycle, with a number of species specialising on parastising the eggs, larvae and chrysalis, most notably small parasitic wasps.
Individuals usually start to emerge from their winter chrysalises around April, and can be seen on the wing until around September in the our area. Numbers typically peak in association with the second brood in August. Chrysalises are relatively easy to find in exposed situations high up on walls, tree trunks and buildings.
Large Whites are both a resident species and a true migrant – grey wing-tipped early residents typically occur in low densities until populations are augmented by continental European migrants and second generation adults later into the summer, when numbers are much higher. Large Whites occurring in Britain predominantly arrive from Southern Europe as well as the Baltic region.
British Large Whites undoubtedly also migrate across the North Sea to the continent. Upon settling in an area migrants quickly adopt a less powerful flight and spread out into the local area to feed and breed.
Small White Pieris rapae
Another very familiar species, the Small White is perhaps the most common White within this region, along with its congenerer the Green-veined White. The Small White occupies a different ecological niche in that it prefers better-drained habitats. Not as migratory as the Large White (but still a migrant from the continent), the Small White is essentially a resident wanderer, with loose populations across most habitats locally.
After mating (often with a number of different males), the female lays her eggs, typically during warm sunny weather; in common with the Large White, Small White breed on Brassica species but with a greater tendency to use other species like garlic mustard Alliaria petiolata and charlock Sinapis arvensis as well as Nasturtiums. Warm depressions are generally favoured for laying sites, with the egg laid on the underside of the leaf.
This species is typical of the family in that it starts to appear on the wing around April in this region after spending the winter as a chrysalis. Numbers begin to peak by May before receding in June. A second generation then emerges towards the end of June and continues to persist well into July and beyond. Like other Pierids, Small Whites typically move north during the spring and then south during the autumn.
Our recording area has probably an almost continual migration one way or the other whilst this species is on the wing, and (taking care to avoid confusion with other Whites) the Small White is a relatively easy species to observe locally.
Green-veined White Pieris napi
Essentially a species of damp habitats and wetland edges (but also prone to wandering into surrounding dryer sheltered habitats), the Green-veined White is a delicate flyer with a much more sedentary existence than its aforementioned migratory relatives. Green-veined Whites can frequently be seen nectaring on a wide range of flowers, more so than most other butterflies species in the region, and males can also be seen ‘drinking’ damp mud, usually around the draw-down zone of ponds and ditches.
This is primarily to replace sodium and other essential minerals lost when producing sperm (with flowers being rich in nectar but low in minerals). As with other Whites, up to 15% of the males bodyweight is transferred to the female as dead sperm when mating as a nuptial gift, which serves as an important energy reserve for the female. Egg laying typically occurs on semi-aquatic species like water-cress Nasturtium officinale and cuckoo-flower Cardamine pratensis.
A species of loose colonies in poorly drained damp areas, the creation and maintenance of habitats with a humid micro-climate (e.g. Filey Dams, The Tip and Top Scrub bird ringing rides) has undoubtedly encouraged this species in the local area. The first individuals begin to emerge from their hibernation chrysalis around April and persist until around June; a second generation then emerges in July and persists until early September.
Orange-tip Anthocharis cardamines
This delightful springtime butterfly is scattered throughout the recording area and is a real highlight of the early season. Orange-tips occur in sparse open populations, in which adults radiate along hedgerows, woodland edges and treelines in search of crucifers like Garlic Mustard and Cuckooflower; Honesty Lunaria annua is also likely to be used in the area, attracting this species into gardens.
Orange-tip populations are heavily influenced by the weather, particularly during ovipositing and the egg stage. Prolonged wet weather can result in a notable loss of eggs and young caterpillars, especially if these conditions occur in June. Orange-tip caterpillars feed largely on the seed pods of the plant. This species has seen a moderate range expansion in Northern England, probably reflected locally.
Orange-tips generally occur within three broad habitat types within the study area: the damp grasslands of The Tip, Filey Dams and Hunmanby Gap (in which colonies are sporadic and ephemeral, occurring primarily on Cuckooflower); woodland edge and hedgerow, particularly where a sheltered south facing element occurs in conjunction with vigorous Garlic Mustard growth; and gardens, where plants including Honesty and Sweet Rockets Hesperis spp. are used for breeding (albeit with a markedly reduced success rate). This species occurs as a single brood from April until early July, with a peak around late May.
Small Copper Lycaena phlaeas
This absolutely stunning little butterfly can be seen throughout the area in and around open rough grassland habitats. Curiously this species occurs in a number of colour forms, several of which have been recorded locally. A species of small, close knit colonies which frequently exist along well drained embankments and topographical undulations, Small Coppers are incredibly active throughout the day, subsequently roosting head-down on grass stems in the evening.
Males are territorial and usually centre this around a promontory like a flower, small shrub or even an item of litter. He actively chases away other insects and rival males as he awaits a receptive female to court. The female is a more sedate animal which slowly searches for Sorrels Rumex spp. growing in warm situations, where she will lay her golf-ball like eggs along the midrib of the leaf.
The first brood is generally seen around May, followed by a second generation around July, with adults frequently persisting into August or longer. This species is fortunately moderately abundant within the area, with colonies occurring along the dry edges of cliffs, arable field edges, coastal paths, road verges and edges of semi-improved grassland containing Sorrels. The North Cliff area, The Tip and Yacht Club areas can be particularly good for observing this species.
Brown Argus Aricia agestis
A contender for the scarcest resident species within the FBOG area (and undoubtedly one of the most frequently overlooked), the Brown Argus is on the northern edge of its British range in our region. This short lived butterfly occurs in small colonies generally consisting of just a few dozen adults.
Brown Argus are myrmecophilous (meaning that their larvae are tended to by ants), and their eggs are laid on the underside of the leaves of Rockrose Helianthemum nummularium, the primary foodplant. Species including Doves-foot Cranesbill Geranium molle and other Geraniums are also used, especially on non-limestone soils, and increasingly further north, which may be of importance to local populations.
Sufficiently deep soils are required to maintain a lush growth of this species foodplants, which suffers high mortality of young in excessively dry years when foodplants may die, wilt or become stunted. The caterpillar regularly exudes droplets of honeydew, which feeds ants; in return, they protect the caterpillar from invertebrate predators and even allow it to pupate within their nests.
A species of short open grassland (moderately widespread along the surrounding Wolds), records of Brown Argus have until recently occurred along the cliffs and at The Tip; however the species now appears to have been lost, or has at least gone unrecorded, within the area in recent years. Brown Argus generally occur in two broods, with three broods occurring during some years at other local sites beyond the Observatory’s boundaries.
First sightings occur in early May with the latest sightings around late September. Peak numbers are often associated with the second brood around August.
Common Blue Polyommatus icarus
Probably the most abundant Lycaenid within the recording area, Common Blues live in small discrete colonies typical of most of their relatives frequenting warm patches of wasteland, unimproved grasslands and coastal-undercliff; unlike similar species however, they are less sedentary, and more prone to wandering small distances (although not to the extent of the following species).
Males are combative, spending a good deal of their time defending territories and searching for females, which tend to lay their eggs on Birds-foot Trefoils, Black Medic Medicago lupulina and occasionally Restharrows Ononis spp. These eggs are laid on luxuriant new growth, which is likely to eventually support flowers, this growth has a higher water and nitrogen content important for developing larvae.
In common with the Brown Argus, Common Blues are myrmecophilous, with caterpillars and pupa being tended to by ants. Curiously Common Blues in this region are at the divergence between the number of annual generations, in that they may have one or two broods per year depending on the season length and weather. In most years we see two generations locally, with an emergence in May persisting into early July and a second in August persisting into early October.
In cold wet years or drought years, only one generation may occur. This species is normally plentiful in any area of suitable habitat, notably along the cliff-edge and associated grassy margin, with the North Cliffs being particularly productive, as with coastal areas at Reighton Gap.
Holly Blue Celastrina argiolus
This distinctive Blue varies considerably in its ecology when compared with the other Lycaenid species within the region, behaving much more like a Hairstreak – often flitting between treetops and shrubs looking for honeydew, which they prefer over nectar. The Holly Blue is another species frequently found drinking mud, especially during drought summers.
In spring the female tends to select Holly Ilex aquifolium on which to lay her eggs, with a shift to Ivy Hedera helix for the second generation in autumn. The larvae are small and inconspicuous as they cling onto the side of the fruit on which they feed. The caterpillar bores a small hole into the fruit, which it then hollows out with its manoeuvrable head and neck, leaving distinctive feeding signs, before moving onto fresh further fruit.
The Holly Blue is notoriously cyclical in its ecology, with numbers fluctuating in 4-6 year cycles, predominantly as a result of parasitic wasps. This species typically shows two clear generations with the first around mid-April and the second in late July. A relatively new colonist to the study area and one which is not particularly abundant, neither of its food plants are particularly common locally, with gardens potentially offering the best habitat; small areas of suitable habitat also occur at Hunmanby Gap and Primrose Valley in more mature areas of woodland. During particularly warm summers, influxes from the south may occur, with local populations being augmented by vagrants.
Red Admiral Vanessa atalanta
One of the most familiar British butterflies, this distinctly migratory species has an interesting but often overlooked life history. Red Admirals seldom survive the British winter, with the only exceptions being moderately frost free, mild winters (as in 2013/14), and typically start to occur around early spring, leading into early summer as immigration increases.
Most of our Red Admirals come from Southern Europe, typically around the Mediterranean region, with numbers varying each year; they breed and usually produce one to two unsynchronised broods during the summer, before individuals migrate back to Southern Europe in the late summer/autumn, when local numbers peak. These numbers are ultimately augmented by butterflies arriving from Scandinavia, Scotland and further north, coasting south.
As would be expected from an abundant species which breeds on Nettles Urtica spp., Red Admirals can be encountered throughout the study area, with numbers fluctuating depending on immigration. This species is particularly notable during the early autumn, gathering at sites to feed on decaying fruit during migration. Nitrogen rich soils, in conjunction with warm sunny sheltered areas adjacent to grazed pasture, woodland and hedgerows, appear to host most breeding activity, as they produce the most extensive nettle beds.
Painted Lady Vanessa cardui
An even longer distance migrant than its congener the Red Admiral, the Painted Lady is one of the world’s most successful butterfly species, although the larvae’s inability to survive below 5oC means that it is unable to persist as a resident species across much of Europe (despite being widespread and common across the region).
Instead, the Painted Ladies which reach the recording area are likely to have come from the main breeding grounds in the desert edges of North Africa, often migrating at high altitudes on fast winds, especially with a southern airflow. This species typically arrives within our area from late May onwards, with a notable second peak later on in the summer owing to a new generation of European-born migrants.
This species occurs across our area, with population density dependent on the size of the influx in that given year. Typically a species of open well drained grasslands, characterised by purple flowers like Thistles and Knapweeds, with the former used as the main larval foodplant (with Spear Thistle Cirsium vulgare and Creeping Thistle Cirsium arvense being favoured in our area).
Painted Ladies are perhaps best observed along Carr Naze and the coastal belt of grassland, The Tip and Hunmanby Gap, which all support an abundance of nectar sources and breeding opportunities. In suitable conditions, migrants can be watched as they arrive from over the sea.
Small Tortoiseshell Aglais urticae
This attractive Nymphalid is one of the most abundant butterflies within the FBOG recording area and is often the first species to be seen on the wing during the springtime. The Small Tortoiseshell’s lifestyle is similar to its close relatives, with freshly emerged adults going into hibernation in late summer, emerging the following spring to mate and lay eggs, which then emerge into butterflies in late summer, after which they return to hibernation.
Another highly mobile species which can occur in thousands along cliff top habitats during good breeding seasons, local populations are often augmented by continental immigrants.
Although this species is often considered to be less migratory than Red Admiral and Painted Lady, falls are often encountered, with many observed arriving in over the sea.
As temperatures, day length and food availability start to decrease in autumn (and body weight increases), the butterflies becomes increasingly immobile, and they begin to search for hibernation sites. Not as well-equipped to deter predators as Peacock and not as well-camouflaged as Comma, premature torpor can lead to increased predation from key predators such as Woodmice Apodemus sylvaticus and Brown-long eared Bats Plecotus auritus inside the hibernacula.
Finding Small Tortoiseshells locally is a relatively straightforward task, as it is across much of the species’ range; open areas with Thistles, Knapweeds and similar flowering plants often yield the best results. This ubiquitous species is found in every habitat within the area, from open coastal grassland to dense scrub and gardens.
Great care is taken over the selection of the ovipositing site, with the female meticulously searching beds of Nettles. Both Stinging Nettle Urtica dioica and Small Nettle Urtica urens are used, with a clear preference for large beds in sunny locations; within the beds, the edges of young leaves are favoured.
Peacock Inachis io
One of the region’s most common, striking and interesting butterflies, the Peacock makes the perfect species when studying insect behavioural ecology. Often the first feature to draw the observer to this stunning butterfly is its striking eye spots, which act as a deterrent to predators, mimicking those of an owl (most notably in hibernation sites, where Woodmice can pose a series threat); in addition, the Peacock is able to ‘hiss’, which can be particularly effective against bats.
Peacocks live for up to eleven months (many of which are spent in hibernation, hence the need for a good defensive strategy), and have one brood per year. Breeding occurs on Stinging Nettles, where large clumps of eggs are laid in sunny situations, on large young stands.
The Peacock is easily observed throughout the spring and summer in the local area, although it typically enters hibernation earlier than other similar species as mentioned above, making autumn slightly less productive. Most areas of coastal grassland, woodland, gardens and road verges will support this species, particularly where purple flowers like Knapweeds, Thistles and Buddleia can be found.
The Peacock is not a regular migrant from Europe, being generally unwilling to undertake sea crossings. Most influxes into the recording area are more likely to involve wanderers from the large forest populations to the North, where the species is found in huge numbers. Peacocks are known to travel up to 95km within Britain and after emergence adults tend to spread and wander into the local area.
Comma Polygonia c-album
This cryptic butterfly has only recently made a return to the butterfly fauna of northern England, and is a species which seems to gain a stronger foothold within the recording area each year. Nothing raises the spirits of the butterfly watcher quite like seeing a Comma basking in the spring sunshine.
Commas never reach the same population levels locally as their relatives Small Tortoiseshell, Red Admiral and Peacock. Two colour forms occur, a regular dark form, and the pale golden form hutchinsonii; these are adults which emerge in mid-summer and breed that same summer without hibernating (unlike the dark form adults which hibernate and breed the following year).
Commas can be found almost anytime between March and October, with notable population spikes in April (emerging adults) and from July to mid-September (second generation adults). Not particularly migratory (although small numbers cross the North Sea), most individuals are wanderers from the wider area.
Spring butterflies can be searched for on Sallow Salix spp. catkins and Blackthorn Prunus spinosa blossom, moving onto purple flowers later into the year. In common with red Admirals, Commas will also visit Apple Malus spp. trees in autumn to feed on decaying fallen fruits.
Dark Green Fritillary Argynnis aglaja
The only species of Fritillary to be recorded within the Observatory area (at least in modern times), the Dark Green Fritillary is a large, striking species, which has a notably powerful flight interspersed with glides. Despite this, it’s still a relatively sedentary species, making any local occurrence very noteworthy (particularly given that the nearest breeding colonies occur approximately 20 miles away from the recording area).
The nearest colonies occur on the southern edge of the North York Moors, and this species is probably Britain’s most abundant and widespread Fritillary. Most activity occurs within a close vicinity to the breeding colony, with some individuals dispersing 2-3km to find nearby meta-populations. Dark Green Fritillary breed on Violets Viola spp., with the female only egg-laying in lush, humid locations where the violet growth penetrates the sward.
Habitat within the local area is unsuitable for breeding Dark Green Fritillaries, with the only records involving migrants; any records are most likely to concern the more dispersive males, since the females are relatively immobile. The last record of this species within our boundaries was in the Rocket Pole Field in summer 2010; since then, further records have been made in other coastal locations (i.e. Bridlington 2014), suggesting further sightings are possible. Areas of Knapweeds and Thistles should be checked from mid-June to early September.
Speckled Wood Pararge aegeria
A real success story both nationally and locally, the Speckled Wood is now one of the most numerous species to be found within the area. This species has a preference for open woodland with a mixture of dappled shade and open sunny clearings and rides. Speckled Wood live in largely self-contained colonies, with females typically ranging more widely than territorial males.
Females are however less often observed in comparison to the highly active males due to their arboreal habits. Both sexes venture into the canopy of trees like Sycamore Acer pseudoplatanus, where honeydew (their principal food source) occurs. Females usually only mate once, often soon after emergence. Eggs quickly develop and within a couple of hours she seeks grasses such as Yorkshire-fog and Cocks-foot on which to lay her eggs.
Isolated tussocks growing in sunny sheltered situations with air temperatures between 24-30C are selected, thus limiting these activities to the woodland edge, glades and rides. The range expansion of the Speckled Wood has coincided with the maturation of the Top Scrub and Parish Wood, which along with Filey Dams, Church Ravine and woodlands in the south of the area, offer prime habitat for this species.
The Speckled Wood has an extremely long flight period due to a number of overlapping broods; they can be seen from April to October, with two notable peaks in numbers, in mid-May and again in early June. The reason for these two population peaks is due to the fact that this species overwinters as both caterpillars or chrysalis, a feature unique to Speckled Wood amongst British butterflies.
Wall Lasiommata megera
Unfortunately the wall has suffered a dramatic population crash across the country over recent years, making it one of Britain’s fastest declining species, perhaps making our relatively stable local and wider coastal population even more important nationally.
A species of self-contained colonies (but with the capacity for wandering and occupying new sites), in the Observatory area this is principally a butterfly of newly disturbed open habitats and pioneer vegetation communities. Walls fly when a body temperature of 25-30oC is achieved, meaning a lot of time is spent basking on open substrata. Egg laying occurs on grasses such as Cocks-foot and Common Bent Agrostis Capillaris and occurs in very dry areas, often where the side of the turf becomes exposed and blades of grass overhang the edge.
As one would expect with these requirements, our local colonies are usually found along the edge of the coastal cliffs, particularly in areas of erosion, and are well scattered. A secondary habitat type is occasionally used along the edges of arable fields, where the sward edge is cut and exposed through ploughing, with sunny sheltered sides of hedgerows more typically used for this. Particularly good areas to look for wall include Carr Naze, behind and around the Yacht Club, the Blue Dolphin caravan site area, Reighton and Hunmanby Gap.
Marbled White Melanargia galathea
A stunning black and cream butterfly associated with unimproved, well-drained grasslands, the Marbled White occurs over both calcareous and circumneutral soils, with fewer found on acidic soils (local colonies, however, are often on soils which are partially slightly acidic).
At first glance this butterfly looks especially vulnerable to predation, with its bright colours and relatively slow, indirect flight style; its bright markings are in fact aposematic, and are used to advertise the butterflies bad taste to would-be predators. Chemicals are consumed and stored by the young larvae as they feed on Red Fescue Festuca rubra; once the caterpillar grows it moves onto more courser grasses like the ubiquitous Cocks-foot.
Over the past thirty years the Marbled White has seen a substantial population range expansion, especially along the edge of its range (e.g. the Yorkshire Wolds), and this species has a patchy coastal distribution locally, with wanderers occurring along the entire coastal grassland strip. Our area is almost certain to host dispersive individuals from the huge Wolds colonies which occur close-by such as at Fordon Chalk Banks, which are seeing apparent population increases.
Within the recording area the best place to see this species remains at the Reighton Gap breeding colonies, with the largest annual counts consistently coming from these sites. Carr Naze, Hunmanby Gap ponds, North Cliff, The Tip and the Blue Dolphin can also be good areas to search for wandering individuals.
Meadow Brown Maniola jurtina
Along with the Ringlet, this species is the most populus butterfly within the recording area, with tussocky grasslands often literally swarming with them during high summer. The Meadow Brown is a butterfly of warm, open grassland with a sward height of 50cm or more, ideally containing a diversity of flowering plants like Umbelifers and Thistles (with Creeping Thistle and Bramble particular favourites), interspersed with finer grasses for breeding.
Meadow Browns also occur in more open parts of woodland and scrub, and as long as the habitat remains the same, these populations typically remain fairly consistent. Meadow Browns occur in a single brood from around early June, peaking in mid-July and persisting until as late as mid-September in some years.
The key colonies within the recording area occur along the coastal belt, with good counts consistently coming from both Reighton and Hunmanby Gap, the Tip, Carr Naze and North Cliff. Meadow Browns are easy to find and observe throughout the recording area, even during periods of overcast weather (although not to the same extent as Ringlet). They are generally quite a sedentary species and seldom travel away from their breeding areas, making them less likely to be encountered in gardens, unless suitable habitat occurs close by.
Gatekeeper Pyronia tithonus
Despite its success nationally and regionally, the Gatekeeper is yet to colonise locally, but may well do so before too long. This arguably more attractive relative of the similar Meadow Brown occurs in similar open grassy environments, the main difference in habitat choice being its preference for more sheltered locations (particularly where rough grassland grows in association with scrub and hedgerows).
Gatekeepers require warm dry springs and summers, with colonisation most likely to occur off the back of a series of good weather events. They show a much more defined annual cycle in comparison to the Meadow Brown, and the flight period is notably shorter with emergence typically occurring around late June/early July and persisting for a shorter period until around late August.
Currently still a very scarce species within the recording area, with only a small handful of records over the past 10 years or so, Gatekeepers could turn up almost anywhere locally; a big population increase in the Vale of York and central East Yorkshire, which is almost certainly where wanderers to the coast originate, may hopefully inspire colonisation in this area.
Ringlet Aphantopus hyperantus
Ringlets are an abundant species in our area, occurring in self-sustaining colonies which can contain huge numbers of butterflies; unlike the consistent Meadow Brown, however, numbers fluctuate greatly year on year. Interestingly, Ringlets appear to benefit from wet summers, with population booms in the following year, and population declines in the year following dry summers; this suggests damp conditions with lush grass growth benefits the grass feeding larvae. Even adults remain quite active and regularly fly during rain, unlike most other butterfly species.
Finding Ringlet in the recording area is a relatively straightforward task, with good numbers in areas of rough tussocky grassland; this species typically occurs in less open areas than the Meadow Brown, with scrub edge, road verges and hedge bases being particularly favoured. In our area, the biggest counts generally occur in rough grassland over heavy soils; searching areas such as The Tip, Hunmanby Ponds, Reighton Gap ponds and structurally suitable areas of coastal grassland yield the best results. A single generation flies from early June, peaking early-mid July, until early September.
Small Heath Coenonympha pamphilus
The Small Heath is a highly successful species which occupies a broad range of habitats across a large geographical range, and like the Ringlet, appear to benefit from wet summers. High rainfall in July often results in a population boom the following year, with draught summers having the opposite effect.
Small Heath are essentially a sedentary species of open grassland, occurring in small, self-sustaining colonies; both sexes are willing to disperse, however, resulting in new areas being quickly colonised. Small Heath tend to occur in open well drained grassland, with an abundance of fine leaved grasses within the sward, and tend to lay their eggs on Meadow Grasses Poa spp. and Fescues Festuca spp. A series of broods occurs from late-May until September, with several peaks reflecting new emergences, typically around mid-June and again in late August.
This species is relatively easy to find in the area, although care must be taken as it is often overlooked due to its small size, weak flight and camouflaged underwings. Particularly reliable sites occur in conjunction with the coastal undercliff/grassland, including The Tip, Carr Naze and the Yacht Club. Numbers are notoriously volatile, with large fluctuations from year to year. Areas which are too heavily grazed or have too much rank tussocky grass are avoided, with lower counts in such areas.
Words and pictures by Dan Lombard