Despite the sometimes less than clement summer weather and mild winters (which are not ideal for many species), because of our diversity of semi-natural habitats RCT has 33 species of butterfly which breed or occur as frequent visitors, plus High Brown Fritillary which is a target for recolonisation from the nearby Alun Valley in Vale of Glamorgan.

In habitat terms, our butterfly fauna can be considered in broad habitat types. Because of our diversity of species rich grasslands, we have strong grassland species populations. There are three grassland skippers, the small and large skipper, and in recent years Essex (which has moved into RCT), and the three common ‘browns’, meadow brown, ringlet and gatekeeper, and if are lucky you can also find the beautiful ‘back and white’ marbled white. Jewel like common blues live up to their name (although there are good and less good years), and the magnificent small copper is often the last grassland butterfly of the autumn. These grassland butterflies also occur in our marshy grassland/rhos pastures, but here we also have orange tips (true harbingers of spring which in warm springs emerge at end of March) that depend on the cuckooflowers that are dotted through wet rushy fields, and the spectacular small pearl-bordered and marsh fritillary butterflies real rhos pasture specialists. The ffridd, heaths and acidic pastures support many of the above species but include their own special additional species including our only ‘green’ butterfly the green hairstreak, dark green fritillary, grayling and small heath. Where colliery spoil habitat mingles with the ffridd, grayling and fritillary numbers can be spectacular and these sites are also the strongholds for dingy skipper, small blue and wall brown butterflies, all species that need the warm micro-climates of colliery spoil.

Of our woodland butterflies most thrive in sunny glades or woodland edges (dark thicketty woodland isn’t much use as butterfly habitat). Purple hairstreak are perhaps the most ‘woodland’ species the adults spending their lives in the canopies of oak trees. Speckled woods are woodland, scrub, hedgerows and garden species, while white-letter hairstreaks can be found (with a bit of effort) using wych elm trees virtually anywhere. Brimstones, which can be seen anywhere in RCT even as early as February lay their eggs on alder buckthorn, and therefore although both the bright yellow male and the much whiter female roam widely, they need wet woodlands to breed. The beautifully marked green veined white breeds in damp, open woodland while the magnificent silver-washed fritillary, a soaring beauty of woodland glades, is sadly uncommon in RCT.

The rest of our butterfly fauna is, perhaps, a little more generalist in its habitat use. The nettle feeding beauties, small tortoiseshell and peacock are classic garden butterflies, but both are less common than they used to be, and in some years can be hard to find. The incredible ragged, leaf silhouetted comma, with its orange and black forewings is another garden/hedgerow/woodland edge species and is thankfully a familiar butterfly, while the red admiral is now a much more common and frequent species than it used to be, able these days to survive an RCT winter. The closely related painted lady is a summer migrant with an amazing trans-global life story. A rarer summer migrant that can (in good year) turn up anywhere is the clouded yellow, while small white and large white populations are topped up every by migrants.

In 2008, Ben Williams produced Butterflies of Rhondda Cynon Taf in which he photographed and described our butterfly fauna. Ben distributed this ‘gem of a guide’ widely and, as the first RCT centric wildlife book, it encouraged and gave confidence to local people who wanted to know the butterflies of their area.