Small heath (butterfly)

The small heath (Coenonympha pamphilus) is a butterfly species belonging to the family Nymphalidae, classified within the subfamily Satyrinae (commonly known as "the browns"). It is the smallest butterfly in this subfamily. The small heath is diurnal and flies with a noticeable fluttering flight pattern near the ground. It rests with closed wings when not in flight. It is widespread in colonies throughout the grasslands of Eurasia and north-western Africa, preferring drier habitats than other Coenonympha, such as salt marshes, alpine meadows, wetlands, and grasslands near water (i.e. streams). However, habitat loss caused by human activities has led to a decline in populations in some locations.

Taxonomy

The small heath is one of 40 species classified within the genus Coenonympha and placed in the family Nymphalidae. It belongs to the tribe Satyrini and its Coenonymphina subtribe. The small heath was first described in 1758 by Carl Linnaeus, a Swedish botanist and zoologist, in his book Systema Naturae. Originally, the female C. pamphilus butterfly was referred to as the Golden Heath Eye and the male as the Selvedged Heath Eye. Entomologist Moses Harris later described it as the Small Heath or the Gatekeeper. However, the Gatekeeper now describes the Pyronia tithonus.

(MHNT) Coenonympha pamphilus - Foret de Bouconne, France - male dorsal.jpg|Coenonympha pamphilus ♂

(MHNT) Coenonympha pamphilus - Foret de Bouconne, France - male ventral.jpg|Coenonympha pamphilus ♂ △

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Subspecies

Subspecies of the Coenonympha pamphilus include:

C. p. lyllus (Esper, 1806) (southern Europe and Siberia, the Crimea, the Caucasus and Transcaucasia)
C. p. marginata Heyne, [1894] (southern Europe and Siberia, the Crimea, the Caucasus and Transcaucasia)
C. p. fulvolactea Verity (1926) (middle Asia)
C. p. centralasiae Verity (1926) (middle Asia)
C. p. infrarasa Verity (1926) (middle Asia)
C. p. juldusica Verity (1926) (middle Asia)
C. p. ferghana Stauder (1924) (middle Asia)
C. p. nitidissima Verity (1924) (middle Asia)
C. p. asiaemontium Verity (1924) (Altai Mountains)
C. p. rhoumensis Harrison (1948)

(MHNT) Coenonympha pamphilus marginata - Foret de Bouconne, France - female dorsal.jpg|Coenonympha pamphilus marginata ♀

(MHNT) Coenonympha pamphilus marginata - Foret de Bouconne, France - female ventral.jpg|Coenonympha pamphilus marginata ♀ △

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thumb|In [[Poland]]

Similar species

The butterfly loosely resembles a small meadow brown, but the brown of the wings appears noticeably paler in flight. Unlike the meadow brown and other common members of the subfamily Satyrinae, the small heath is a lateral basker, only ever resting with its wings closed and angled at 90° to the sun.

Distribution and habitat

[[File:Breckland Heath-Grassland Ecosystem - geograph.org.uk - 415793.jpg|thumb|222x222px|

A semi-natural grassland in Europe

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The small heath is spread throughout the Western Palearctic, particularly in Europe where it has been reported in at least 40 different countries since 2002. It is commonly found in the United Kingdom, largely in England and Wales. Populations are also found in southwest Siberia, regions of Asia, and north Africa.

As a grasslands species, the small heath prefers open habitats with shorter grass compared to other related species. It is also found in an extensive range of environments including meadows, heaths, mountains (in the subalpine zone), and alongside railways. It has been sighted in calcareous grasslands throughout nineteen countries in Europe. For mating and oviposition, small heath butterflies prefer territories that are close to vegetation over areas that are open and clear.

Food resources

Caterpillars

thumb|[[Festuca rubra, a food resource for small heath larvae|238x238px]]

The primary food resources for small heath larvae are different varieties of grass species. These include the Anthoxanthum odoratum, Poa pratensis, Agrostis stolonifera, and Festuca rubra, which commonly appear on some calcareous grasslands.

Adults

thumb|[[Achillea millefolium|Yarrow, a food resource for adult small heath|233x233px]]

Adult small heath butterflies feed on floral nectar of a variety of flowers such as bramble, yarrow, and ragwort.

Parental care

Oviposition

The small heath is a plurivoltine butterfly, having multiple generations in a year. Oviposition varies throughout the lifespan of a female small heath. The rate of oviposition is high for young females, particularly at the beginning of their reproductive life, while older females eventually lay fewer and yellower eggs.

Host plant selection for egg laying

Small heath females prefer to lay eggs in grassland.

Life cycle

right|thumb|Early stages of the life cycle|370x370px

Eggs

Small heath eggs are round and sometimes laid on blades of grass. The eggs are occasionally in clusters, but usually alone. Initially, the egg is a light green with a slight depression on the top and an overall ridged texture. It later gains a white hue with a brown band wrapped around the middle and irregular brown speckles on the surface.<gallery>

File:Coenonympha pamphilus - Küçük zıpzıp perisi 19.jpg|A brown variation in wing pattern

File:Coenonympha pamphilus (1).jpg|A yellow variation in wing pattern

Small heath (Coenonympha pamphilus) underside Italy.jpg|showing dark spots on rear wing underside

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Mating

Aggression between males

Male small heath butterflies often establish their own territories and become stationary. Males with their own territories are more likely to mate successfully with females. This prompts aggressive male behavior between stationary males and wandering males who may contest territory ownership. The stationary male sometimes engages the wandering male in an attempt to determine its sex, and these interactions remain short to reduce vulnerability to predation. Longer interactions between males are typically territorial disputes. Larger males are typically more successful in territorial disputes with other males, as they have longer wing spans and are superior in size and weight to smaller males. Thus, larger males have a significantly higher chance of successfully mating a female.

Copulation

Copulation between male and female small heath butterflies lasts between 10 minutes and 5 hours, occurring at any time in the day.

Thermoregulation

Small heath butterflies typically live well in dry, open landscapes with higher temperatures, in comparison to other species of satyrine butterflies. When temperatures are significantly high, lifespan is shortened but the small heath will fare better than shade-dwelling species, such as the speckled wood, Pararge aegeria. Like other butterflies, it has a small range of optimum temperatures and can regulate its temperatures in a small variety of ways, such as positioning its body to maximally absorb sunlight. In high temperature habitats, the small heath produces eggs at a relatively high rate, has good fecundity, and survives well as compared to woodland butterflies. Male butterflies will also tend to drift and be vagrant in their search for females rather than perch in their territories and wait, as they would do in optimum or sub-optimum temperatures.

Interactions with humans

As a grassland species, the effects of intense, widespread agriculture is a concern for the welfare of the small heath. Grassland management through periodic ecological disturbances (i.e. mowing) is considered necessary to maintain "semi-natural" grasslands. Negative effects of mowing include the loss of biodiversity, the conversion of natural grasslands into agricultural fields, mortality, and loss of nectar resources. However, a study shows that such disturbances of these habitats may actually lead to an increase in the population of grassland butterflies including the small heath.

Status in England

The small heath, like its cousin the wall brown, has been in serious decline across much of southern England for reasons unclear, and was accordingly designated as a UK Biodiversity Action Plan Priority Species (research only) by DEFRA in 2007.

References

External links

Butterfly Conservation species page
Images of small heath
Small heath, Moths and Butterflies of Europe and North Africa