Glass half empty

These days press releases on nature and the environment are expected to come with gloomy headlines. So to be told that “Half of British butterfly species on new Red List” was not a surprise. The Red List in this instance is a list of endangered species. The list is split between different categories:

  • Regionally Extinct
  • Critically Endangered
  • Endangered
  • Vulnerable
  • Near Threatened

The reason for the press release was the release of a 2021 assessment of the conservation status of British butterflies. Scientists from Butterfly Conservation put together the new Red List and compared it with the last list from 2011. The new Red List is published today (25 May) in the journal Insect Conservation and Diversity.

Clearly there is a lot to be concerned about. No-one can be complacent about the numbers and distribution of butterflies around the country. But a closer look at the new Red List shows that the headline message is grossly misleading.

The first thing that leaps out is that the number of regionally extinct species hasn’t changed. Four species are identified: Large Copper, Large Tortoiseshell, Black Veined White and Mazarine Blue. The truth is the Large Copper, Mazarine Blue and Black Veined White haven’t been seen on these shores for a century. The Large Tortoiseshell has been extinct for fifty years at least. So there’s no surprises here and no changes either. Actually there is much to be grateful for that no species have become permanently extinct in the last 50 years.

The next category down is “Critically Endangered”. The two butterflies in this bracket in 2011 were the High Brown Fritillary and the Large Blue. The status of both has significantly improved. The Large Blue has benefited from a successful breeding program, largely in Somerset. Reserves such as Collards Hill and Green Down have played a leading role in bringing the Large Blue back from the brink.

The High Brown Fritillary has been moved to “Endangered” also an improvement on a decade ago.

Then there is the small matter of the number of species that are not categorised on the Red List. There are actually more (29) species not endangered than there were 10 years ago (28).

Other species have seen their lot improve too. The Pearl Bordered Fritillary, White Letter Hairstreak and Duke of Burgundy Fritillary (pictured below) have all moved from Endangered to Vulnerable. An improvement in their conservation status.

Of course it is not all roses. There are plenty of butterflies that have become rarer and more threatened. For instance all four British butterflies with northerly distributions, adapted to cooler or damper climates, are now listed as threatened (Large Heath, Scotch Argus, Northern Brown Argus) or Near Threatened (Mountain Ringlet). But overall it is a mixed picture. And although alarmist headlines are attention grabbing, they rarely paint the whole picture. Take a look at the table below and you’ll see what we mean.

Comparison with previous Red List

Red List threat categoryNumber of species qualifying in new Red List 2021Number of species qualifying in 2011 Red List
Regionally Extinct44
Critically Endangered02
Near Threatened511
Least Concern2928

It is perhaps appropriate to pay tribute to some of the excellent conservation work that has kept British butterflies going. There may be some that are struggling, but overall the picture is not as bad as the headlines would have us believe.

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