Virpazar’s Glanville Fritillaries

On the hot afternoon of April 22nd after a long day, I saw my first fritillary butterfly of the year, which settled within spitting distance at the top of an area of long, abandoned terraced fields not far from the village of Kruševica on the Virpazar to Rijeka Crnojevića road. At the time, I was eating a bright red but tasteless apple and, in my undue haste, fumbled with the camera whilst trying to hold on to the apple; when I looked up it was gone and away. Too late, I threw the apple a country mile, then checked the area in too much of a hurry and the strands of bramble, as tenacious as barbed wire, took their toll, all to no avail.

April 26th was also hot and sunny but slow moving cloud cooled the day from time to time. My local patch of quarry and south-east facing, scrub slope outside of Virpazar was quiet, just the usual chequered and small-tailed blues and hawfinches clattering off the edge of the road in a flash of white and tan. A golden oriole, singing its liquid song deep in the poplar and willow accompanying the nightingales, was new and indicated spring was just beginning to turn to summer.

A fritillary has a particular way of flying; a jizz that may be described as ‘straight and gliding’ which probably describes many butterfly species and so is not that much of a guide. Just after listening to the lyrical orioles, I saw a fritillary fly away low up a bank of emerging tall knapweed (Centaurea sp.) and charged up after it. There were two and they constrained themselves to the knapweed patch and were most confiding. These are Glanville fritillaries (Melitaea cinxia), which is a common but declining species across Europe especially where farming has become more intensive.

The Glanville fritillary has been, since the late 1980s, the model species used by Finnish ecologist Ilkka Hanski to build the so-called metapopulation theory: the survival of a population through dispersal and extinction of sub-populations within a number of habitat patches, in this case old meadows containing the larval food plants of plantain Plantago lanceolata and Veronica spicata, across a landscape. The work changed the way we think about the conservation of species; the understanding that species with poor powers of dispersal now occupying a few, small isolated sites are all likely to be doomed to extinction unless corridors or larger areas of suitable habitat are created. This is as relevant to managing meadows for fritillary butterflies as it is for designating national parks, buffer zones and migration corridors for elephants in Africa, tigers in Asia and coral reef fish in Tropical seas.

Hanski’s work built on the original metapopulation models of American ecologist Robert Levins, who worked on the population dynamics of the bay checkerspot butterfly (Euphydra editha bayensis); he formulated the original idea of ‘shifting mosaics’ in 1970. Hanski’s methods may also be traced to the so-called Marlboro Circle- Levins, Edward Wilson, Richard Lewontin and the great Robert MacArthur in the 1960s. These American academics combined mathematics, specifically the development of relatively simple mathematical models that had general predictive value, with exceptional field ecology skills. This provided nature conservation science the scientific approach and the core tools that are deployed today. So it is inspiring to see the fine little Glanville fritillary on a hillside in Montenegro and know that it and its American relative, the bay checkerspot, have perhaps done more than most species to help conserve our world’s natural resources.

Posiljani 438 Glanville fritillary resting on a long-lipped tongue orchid (Serapias vomeracea) amongst knapweed.

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