Invasion of Y

Silver Y moth, Autographa gamma

It is about a month since I encountered my first Silver Y moth (Autographa gamma) of the year on the south coast of Ireland. Fluttering with an almost comical gracelessness among the cliff top vegetation, its movements belied the remarkable journey it had just completed. A. gamma is a summer migrant to Ireland, coming from southern Europe, North Africa and even the Middle East to escape the harsh summers there. Offspring produced here will return south in the autumn, a fact made possible by phenotypic variation from their parents. Moths found at higher latitudes (over the range 34- 53°N) have longer pre-reproductive periods, making long migrations back south possible (1).

References:

1. Hill and Gatehouse, 1993. Ecological Entomology 18 pp. 39–46

Irish Lousewort

Irish Lousewort, Pedicularis sylvatica ssp. hibernica

The Louseworts (Pedicularis spp.) make up a large (some 400 representatives) genus of hemiparasitic plants that have been shown to take up secondary metabolites, such as alkaloids from their hosts (1). Their rather unfortunate common name came from the belief in the past that they caused lice and liverworms in cattle (2). Ireland is home to two species, Common Lousewort (Pedicularis sylvatica) found on damp heaths and moors and the taller Marsh Lousewort (P. palustris) which is found on bogs, heaths and wet grasslands (3). P. sylvatica can be further divided into two subspecies based on a number of features, the most obvious being the presence or absence of hairs on the calyx and pedicles. Those lacking hairs are placed in P. sylvatica ssp. sylvatica, while those with are called Irish Lousewort, P. sylvatica ssp. hibernica. A further, hairy subspecies, P. sylvatica ssp. lusitanica, is found in Portugal but the hairs on this taller plant are found only on the angles and not all over (4). The Irish Lousewort was first described by David Webb in 1956 from a samples collected in Co. Kerry, and he noted that the plant was distributed almost entirely around the west coast of Ireland (4). While this is still the case, it has been since reported Scotland(5), Norway (6) and Wales to name a few. The sample pictured was seen on the Beara Peninsula in west Co. Cork.

Irish Lousewort, Pedicularis sylvatica ssp. hibernica

References:

1. Schneider and Stermitz, 1990. Biochemistry 29 pp. 1811-1814
2. Phillips, 1977. Wild Flowers of Britain p. 56
3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 242
4. Webb, 1956. Watsonia 3 pp. 239-241
5. Birks and Madsen, 1979. Journal of Ecology 67 pp. 825-842
6. Skogen, 1966. Blyttia 24 pp. 361-367
7. Rich, 1994. Watsonia 20 pp. 61-71

Mating of the Common Blue Butterfly

Female (left) and male (right) Common Blue butterfly (Polyommatus icarus), mating

The Common Blue butterfly (Polyommatus icarus) generally produces two broods per year in Ireland, May/June and August/September. However this may vary depending on the part of the island. In the north there is evidence for only a partial second brood, whereas on the south coast there are at least three broods, being centered around April, July and September (1). P. icarus favours rough, dry grassy areas, sand dunes and roadside verges where its preferred larval food, Bird's Foot Trefoil (Lotus corniculatus) grows. Adults will also feed on this plant and females have been shown to lay eggs on plants with flowers in preference over those without (2). The mating pair pictured were observed in a patch of rough ground dominated by Kidney Vetch (Anthyllis vulneraria), Thrift (Armeria maritima), Red Clover (Trifolium pratense) and Bird's Foot Trefoil in a coastal area. P. icarus has an almost Palaeartic distribution and a sub-species, P. icarus mariscolore exists in Ireland that is slightly larger and more brightly coloured than the sub-species P. icarus icarus found in Britain (1).

Male Common Blue butterfly, Polyommatus icarus

References:

1. Nash et al., 2012. Ireland's Butterflies A Review pp. 156-158
2. Janz et al., 2005. OIKOS 109 pp. 535-538

Yellow Rattle Promotes Biodiversity

Yellow Rattle, Rhinanthus minor

Loss and fragmentation of semi natural habitats such as unimproved grasslands is a problem, not only in Ireland, but on a European scale, where it has accelerated in the the last 60 years (1). This has been largely attributed to agricultural intensification over this time, but the explosion in building in Ireland from c. 1997-2007 had its part to play. Schemes aimed at maintaining such species rich grasslands such as limiting fertilizer application and reducing grazing pressure and cutting frequency on existing swards have all been shown to have some benefits (2). 

Yellow Rattle, Rhinanthus minor

However, the introduction of the hemiparasite Yellow Rattle (Rhinanthus minor) may provide a more holistic approach to the problem of unimproved grassland loss. R. minor is common throughout Ireland, on undisturbed meadows and dunes. Its yellow flowers are visible now (and will be until September), borne on leafy, black spotted, terminal spikes (3). In a survey of five sites in Britain and Italy it was found that the presence of R. minor (and other Rhinanthus species) reduced the numbers of grasses present and increased the numbers of dicotyledons, resulting in an overall increase in plant biodiversity (2). These changes are due to the parasitic nature of R. minor, which resulted in an overall decrease in the productivity of the swards involved. While this could lead to problems with surrounding communities if R. minor were to invade them, these have been foreseen to be minimal as it has very low tolerance to high fertilizer applications, has limited seed dispersal and does not form a significant seed bank, thus minimizing its potential as an invasive agent. R. minor therefore may have considerable potential as a management tool for grassland restoration programmes (2).

References:

1. Critchley et al., 2003. Biological Conservation 115 pp. 263-278
2. Davies et al., 1997. Biologwal Conservatwn 82 pp. 87-93
3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 242

Here Come the Ladies

Painted Lady, Vanessa cardui

The influx of Painted Ladies has begun. The Painted Lady butterfly (Vanessa cardui) has started arriving in Ireland, an annual migration that brings variable numbers of this large, buff-orange butterfly, not only here but to much of Europe. The butterflies travel from Africa, generally believed to be north of the Sahara in areas around Morocco (1). Recent meteorological trajectory analyses of migrants however have shown that the range may even extend further south into the Sahel zone south of the Sahara (2). By thus migrating, V. cardui avoids the harsh African summers, making use of the plentiful supply of its favoured larval food Creeping and Spear Thistles. A second influx arrives in August and September of second generation migrants from Southern Europe. No life stage of V. cardui can survive the Irish winter and adults will return south, however this is rarely observed as it is believed to occur at very high altitudes (3). Orientation upon such migration is believed to be maintained by the use of a sun compass in flight (3).

References:

1. Nash et al., 2012. Ireland's Butterflies, A Review pp. 165-167
2. Stefanescu et al., 2007. Journal of Animal Ecology 76 pp. 888-898
3. Nesbit et al., 2009. Animal Behaviour 78 pp. 1119-1125

On the Ledge

Northern Fulmar, Fulmarus glacialis

Gliding with a wonderful grace, their blue-grey upper wings held stiffly outright the Northern Fulmar (Fulmarus glacialis) is an imperious flier. While they spend most of their lives far, far out at sea, F. glacialis can be seen in large numbers at the moment at their various nesting colonies (c. 3,500 individuals) along the coast of Ireland (1). They breed monogamously, in colonies that can be quite large on cliff faces. Pairs nest in depressions in the cliff, as can be seen in the photograph above. F. glacialis is widely distributed throughout Britain and Ireland now, but this is quite a recent occurrence – indeed the first record of a breeding pair in Ireland was a recent as 1911 in Co. Mayo (2).

Northern Fulmar, Fulmarus glacialis

Although they are superficially similar to gulls, F. glacialis possesses a suite of features that places them in the order Procellariiformes. These are the tube-nosed seabirds, so called as they have nostril tubes on their bills that channels salt extracted and excreted from sea water they ingest to the end of their bills where it falls off (3).

Northern Fulmar, Fulmarus glacialis

 

References:

1. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 34
2. Beletsky, 2006. Collins Birds of the World pp. 33-35
3. Fisher, 1966. Bird Study 13 pp. 5-76

Orchid Hunter

Early Marsh Orchid, Dactylorhiza incarnata

Wild orchids are a treat to behold, their cascade of flowers boldly proclaiming their uniqueness with only c. 28 species present in the wild in Ireland (1). And yet, as is becoming increasingly the case with many species, their numbers are decreasing, dramatically in the case of some of the rarer species. The reasons for this are manifold and complex but are all due to habitat destruction of one form or another.

Early Marsh Orchid, Dactylorhiza incarnata, with emerging flowers

However they are not so scarce as to require treks deep into uncharted territory to view examples of the commoner species. It is rather embarrassing to admit but I had never before seen a wild orchid in Ireland. A combination of bad timing and lethargy has thwarted me over the years so it was with great joy that I found a number of Early Marsh Orchids (Dactylorhiza incarnata) on Galley Head on the south west coast. Their cascade of purple flowers, held aloft above the surrounding grasses was quite the show. Even here, however, they were confined to areas where the vegetation was at its lowest. A 28 year survey of D. incarnata in northern Germany confirmed this observation with populations on meadows enjoying a resurgence with the reintroduction of mowing of meadows (2). While D. incarnata showed some shade tolerance, in vegetation over 150 cm plants were unable to survive. Introduction of such mowing methods in places with surviving populations of D. incarnata would certainly help increase numbers.

Early Marsh Orchid, Dactylorhiza incarnata

Marsh Orchids, the genus Dactylorhiza, are a taxonomically confusing group with many species readily hybridising to give a plethora of morphological variations (1). D. incarnata is no exception, with five subspecies being recorded in Ireland (3).

Early Marsh Orchid, Dactylorhiza incarnata

References:

1. O'Mahony, 2009. Wildflowers of Cork City and County pp. 296-312
2. Schrautzer et al., 2011. Flora 206 pp. 622-630
3. Stace, 1997. New Flora of the British Isles

The Bluffing Buff

Buff Ermine Moth, Spilosoma lutea

Even though the rain is doing its best to deny us the pleasure of it, it is summer, making the apparel of the Buff Ermine moth (Spilosoma lutea) seem a little incongruous. With what looks like a miniature scarf draped over its wings, maybe it knows the Irish summers better than we do. S. lutea is common throughout Europe and much of the temperate belt of Asia at this time of year in a variety of habitats and will continue to be so until August (1). The brown tufted larvae are polyphagous, feeding on quite a variety of plant species.
 

White Ermine Moth, Spilosoma lubricipeda

Being the colour that it is, S. lutea should be an easy target for predators. Yet it is this very colour that saves it from being so. S. lutea is actually a mimic of its close relative the White Ermine moth (S. lubricipeda) (2), a moth that is unpalatable to predators due to its high levels of pyrrolizidine alkaloids (3).

References:

1. Hammond, 2008. The Wildlife Trusts Handbook of Garden Wildlife p. 49
2. Rothschild, 1963. Proceedings of the Royal Entomological Society of London. Series A, General Entomology 38 pp. 159-164
3. Rothschild et al., 1979. Biological Journal of the Linnean Society 12 pp. 305-326