Please read our briefing paper for a concise overview of the biodiversity value of old re-vegetated coal tips: colliery-spoil-biodiversity-briefing-paper-2017.

What makes colliery spoil tips biologically-interesting?  


The are several key features of colliery spoil tips that make them fantastic habitats for invertebrates and other wildlife. The first of these is the free-draining nature of the spoil substrate, which acts to create dry grassland and heathland habitats that support many specialist insect species. The importance of this free-draining nature is clearly emphasised by the incredible solitary bee diversity recorded on colliery spoil tips. Survey’s of just 5 colliery spoil tips in Rhondda Cynon Taf have so far revealed an astonishing 85 different bee species. Of these 85 different bee species, 69 are solitary bees – solitary in the sense that they do not form social hives typical of bumblebees and honeybees. At least 40 of these species are ground nesting, where they reportedly nest in ‘light’ or ‘sandy’ soils. Together with an abundance of bare ground habitat, the dry spoil provides ideal nesting opportunities for ground-dwelling bee genera, as well as a host of other burrowing and ground nesting invertebrates (e.g. Green tiger beetle Cicindela campestris). As is evident from the plant flora on many coal tips, such as the presence of Round-Leaved Wintergreen (Pyrola rotundifolia spp. maritima), it is apparent that many coal tips are replicating sand dune habitats.


Bilberry Mining Bee (Andrena lapponica) at Clydach Vale Country Park (©Liam Olds)

The second key feature of colliery spoil tips is their thin, nutrient poor soils. These create stressed conditions that prevent dominant plant species from taking over, slowing vegetation succession and leading to the formation of largely open, sunny habitats. These open conditions favour the formation of flower-rich grasslands which support strong  assemblages of nectar-rich, stress tolerant annuals. These provide abundant forage for  numerous pollinators including butterflies, moths, hoverflies, bees, wasps and beetles. With reports highlighting growing evidence for declines in pollinator species, it is clear how important these sites are to their future well-being of pollinators in the south Wales valleys.

Small Blue Twitter

The rare and rather localised Small Blue butterfly (Cupido minimus) at Cwm Colliery, Beddau (©Liam Olds). This species has experienced declines in recent decades and is listed as a Priority Species on the UK Biodiversity Action Plan.  

The slow rates of vegetation succession also often result in substantial bare ground coverage. Areas of open, bare ground warm-up rapidly in the sun to create warm microclimates in which thermophilic (warmth-loving) invertebrates can bask. The presence of bare ground is a key habitat requirement of many species, including the Grayling butterfly (Hipparchia semele). Bare ground also provides invertebrates with burrowing and ground nesting opportunities (e.g. solitary bees), and provides foraging areas for visual predators such as spiders and ground beetles. Evidence also indicates that these warm microclimates aid the incubation of eggs (Key, 2000).

Grayling Coal

Grayling (Hipparchia semele) is a common butterfly on colliery spoil tips, but is currently experiencing declines across the UK, particularly inland. It favours sites with dry and well-drained soil, sparse vegetation and plentiful of bare ground – the perfect conditions provided by colliery spoil tips  (©Liam Olds)

The third key feature of colliery spoil tips is their varied nature. Colliery spoil tips are highly complex habitats of varied topography, aspect, substrate matter, substrate composition, water availability, pH, and levels of disturbance. These diverse factors act to create complex habitat mosaics in close proximity. As such, a single spoil tip can support a wide variety of different habitats including: bare ground, dry heathland, flower-rich grasslands (acidic, neutral or calcareous), ponds, lakes, seasonal pools, ditches, seepages, reed beds, scrub, and secondary woodland. This provides ideal habitats for invertebrates, many of which require two or more habitats to complete their lifecycle. Examples of just some of these habitats can be seen below.


Colliery spoil tips support a mosaic of habitats in close proximity. Some of these habitats can be seen in the photographs below. 

Image 2

Dry heathland habitat at Gelli tips, Rhondda Fawr (©Liam Olds)


Flower-rich calcareous grassland at Cwm Colliery, Beddau (©Liam Olds)


Flower-rich acid/neutral dry grasslands at Clydach Vale Country Park (©Liam Olds)


Marshy grassland at Clydach Vale Country Park (©Liam Olds)


Secondary woodland at Cwm Colliery, Beddau (©Liam Olds)


Bare ground and scrub at Craig-Evan-Leyshon Common, Cilfynydd (©Liam Olds)


Reed bed at Cwm Colliery, Beddau (©Liam Olds)

Invertebrate species

Aculeata (bees) 

With an abundance of nectar-rich plants, and plentiful bare ground providing nesting opportunities, colliery spoil tips are fantastic habitats for bees. The importance of these habitats for bees (and other pollinating insects) is evident in the astonishing diversity of bee species that have so far been recorded on coal tips. An incredible 85 different bee species have so far been identified on just 5 coal tips in Rhondda Cynon Taf. Of these, 54 species (≈ 64%) are uncommon – being localised, scarce, rare, red data book listed, or UK BAP species. The diverse bee fauna of colliery spoil tips is visible in the pictures below.  


Here is a list of the 85 bee species that have so far been identified:


Andrena angusitor Groove-faced Mining Bee (Andrenidae)
Andrena barbilabris Sandpit Mining Bee (Andrenidae)
Andrena bicolor Gwynne’s Mining Bee (Andrenidae)
Andrena chrysosceles Hawthorn Mining Bee (Andrenidae)
Andrena cineraria Ashy Mining Bee (Andrenidae)
Andrena clarkella Clarke’s Mining Bee (Andrenidae)
Andrena coitana Small Flecked Mining Bee (Andrenidae)
Andrena denticulata Grey-banded Mining Bee (Andrenidae)
Andrena dorsata Short-fringed Mining Bee (Andrenidae)
Andrena flavipes Yellow-legged Mining Bee (Andrenidae)
Andrena fulva Tawny Mining Bee (Andrenidae)
Andrena fucata Painted Mining Bee (Andrenidae)
Andrena fuscipes Heather Mining Bee (Andrenidae)
Andrena haemorrhoa Orange-tailed Mining Bee (Andrenidae)
Andrena humilis Buff-tailed Mining Bee (Andrenidae)
Andrena lapponica Bilberry Mining Bee (Andrenidae)
Andrena minutula Common Mini-mining Bee (Andrenidae)
Andrena nigroaenea Buffish Mining Bee (Andrenidae)
Andrena nitida Grey-patched Mining Bee (Andrenidae)
Andrena ovatula Small Gorse Mining Bee (Andrenidae)
Andrena scotica Chocolate Mining Bee (Andrenidae)
Andrena semilaevis Shiny-margined Mini-mining Bee (Andrenidae)
Andrena similis Red-backed Mining Bee (Andrenidae)
Andrena subopaca Impunctate Mini-mining Bee (Andrenidae)
Andrena tarsata Tormentil Mining Bee (Andrenidae)
Andrena wilkella Wilke’s Mining Bee (Andrenidae)
Anthidium manicatum Wool Carder Bee (Megachilidae)
Anthophora furcata Fork-tailed Flower Bee (Apidae)
Apis mellifera Western Honey Bee (Apidae)
Bombus barbutellus Barbut’s Cuckoo Bee (Apidae)
Bombus campestris Field Cuckoo Bee (Apidae)
Bombus hortorum Garden bumblebee (Apidae)
Bombus humilis Brown-banded bumblebee (Apidae)
Bombus hypnorum Tree bumblebee (Apidae)
Bombus jonellus Heath bumblebee (Apidae)
Bombus lapidarius Red-tailed bumblebee (Apidae)
Bombus lucorum agg. White-tailed bumblebee (Apidae)
Bombus monticola Bilberry Bumblebee (Apidae)
Bombus pascuorum Common carder-bee (Apidae)
Bombus pratorum Early bumblebee (Apidae)
Bombus rupestris Red-tailed cuckoo bee (Apidae)
Bombus sylvestris Forest cuckoo bee (Apidae)
Bombus terrestris Buff-tailed bumblebee (Apidae)
Bombus vestalis Vestal cuckoo bee (Apidae)
Coelioxys elongata Dull-vented Sharp-tail Bee
Colletes daviesanus Davies’ Colletes (Colletidae)
Colletes similis Bare-saddled Colletes (Colletidae)
Colletes succinctus Heather Colletes (Colletidae)
Epeolus cruciger Red-thighed Epeolus (Apidae)
Halictus rubicundus Orange-legged Furrow Bee (Halictidae)
Halictus tumulorum Bronze Furrow Bee (Halictidae)
Hylaeus brevicornis Short-horned Yellow-face Bee (Colletidae)
Hylaeus confusus White-jawed Yellow-face Bee (Colletidae)
Hylaeus hyalinatus Hairy Yellow-face Bee (Colletidae)
Lasioglossum albipes Bloomed Furrow Bee (Halictidae)
Lasioglossum calceatum Common Furrow Bee (Halictidae)
Lasioglossum cupromicans Turquoise Furrow Bee (Halictidae)
Lasioglossum fratellum Smooth-faced Furrow Bee (Halictidae)
Lasioglossum leucopus White-footed Furrow Bee (Halictidae)
Lasioglossum leucozonium White-zoned Furrow Bee (Halictidae)
Lasioglossum morio Green Furrow Bee (Halictidae)
Lasioglossum rufitarse Rufous-footed Furrow Bee (Halictidae)
Lasioglossum villosulum Shaggy Furrow Bee (Halictidae)
Lasioglossum zonulum Bull-headed Furrow Bee (Halictidae)
Megachile centuncularis Patchwork Leafcutter Bee (Megachilidae)
Megachile ligniseca Wood-carving Leafcutter Bee (Megachilidae)
Megachile versicolor Brown-footed Leafcutter Bee (Megachilidae)
Megachile willughbiella Willughby’s Leafcutter Bee (Megachilidae)
Nomada fabriciana Fabricius’ Nomad Bee (Apidae)
Nomada flava Flavous Nomad Bee (Apidae)
Nomada flavoguttata Little Nomad Bee (Apidae)
Nomada goodeniana Gooden’s Mining Bee (Apidae)
Nomada lathburiana Lathbury’s Nomad Bee (Apidae)
Nomada leucophthalma Early Nomad Bee (Apidae)
Nomada marshamella Marsham’s Nomad Bee (Apidae)
Nomada panzeri Panzer’s Nomad Bee (Apidae)
Nomada ruficornis Folk-jawed Nomad Bee (Apidae)
Nomada rufipes Black-horned Nomad Bee (Apidae)
Osmia bicornis Red Mason Bee (Megachilidae)
Osmia caerulescens Blue Mason Bee (Megachilidae)
Osmia leaiana Orange-vented Mason Bee (Megachilidae)
Sphecodes ephippius Bare-saddled Blood Bee (Halictidae)
Sphecodes geoffrellus Geoffroy’s Blood Bee (Halictidae)
Sphecodes gibbus Dark-winged Blood Bee (Halictidae)
Sphecodes hyalinatus Furry-bellied Blood Bee (Halictidae)
Sphecodes monilicornis Box-headed Blood Bee (Halictidae)

Note: common names refer to those in ‘Field Guide to the Bees of Great Britain and Ireland’ by Steven Falk (2015).

Lepidoptera (butterflies) 

Colliery spoil tips also support several Lepidoptera species of conservation interest including Grayling (Hipparchia Semele), Small Pearl-bordered Fritillary (Boloria selene), Dark Green Fritillary (Argynnis aglaja), Dingy skipper (Erynnis tages), Small Blue (Cupido minimus) and Six-belted clearwing moth (Bembecia ichneumoniformis).


Dingy skipper (Erynnis tages) – an iconic coal spoil species – at Gelli Tips (©Liam Olds)

Image 5

Six-belted clearwing (Bembecia ichneumoniformis) at Coedely Colliery (©Liam Olds)

Hemiptera (‘true bugs’)

The grassland and heathland habitats of colliery spoil tips also support many Heteroptera (‘true bug’) species. So far, 70 different species have been recorded – of which 11 are considered uncommon. These species include representatives from a wide variety of different families including Tingidae (Lacebugs), Nabidae (Damsel Bugs), Miridae (Plant Bugs), Berytidae (Stiltbugs), Lygaeidae (Groundbugs), Pentatomidae (Shieldbugs), Phopalidae (Rhopalid bugs), Anthocoridae (Flower bugs) and Saldidae (Shorebugs).

Pictures of some of these species can be found below. These include:

  • Adelphocoris quadripuncatus – new to Britain
  • Aelia acuminata (Bishop’s Mitre Shieldbug) – localised
  • Agramma laetum – uncommon
  • Berytinus crassipes – local
  • Chartoscirta cocksii – scarce
  • Himacerus boops – local
  • Hoplomachus thunbergii – local
  • Orthocephalus saltator – local
  • Plinthisus brevipennis – local
  • Rhacognathus punctatus (Heather shieldbug) – local
  • Stygnocoris rusticus – local

Some of the Heteroptera identified on colliery spoil tips in 2015/16

Likewise, approximately 60 species of Auchenorrhyncha (leafhoppers & planthoppers) were identified, at least 7 of which are uncommon species. Key species include:

  • Anaceratagallia ribauti – Local
  • Dicranotropis divergens – Nationally Scarce
  • Idiodonus cruentatus – Local
  • Kosswigianella exigua – Local
  • Mocydiopsis parvicauda – Local
  • Muellerianella extrusa – Local
  • Rhopalopyx adumbrata – Local

More information regarding the other invertebrate groups recorded on coal tips will be added shortly.

The surveys undertaken by the Colliery Spoil Biodiversity Initiative are continuing to improve our understanding of the importance of colliery spoil tips for invertebrates. It is with this knowledge that we can begin to protect these sites for wildlife and for future generations to enjoy.