Why are colliery spoil sites such havens for wildlife?
The are several key features of colliery spoil sites that make them fantastic habitats for wildlife. The first of these is their varied nature. Colliery spoil sites are highly diverse landscapes of varied topography, aspect, substrate composition, hydrology and pH. These diverse factors act to create complex habitat mosaics in close proximity. This means that a single colliery spoil site can support a wide variety of different habitats including bare ground, heathland, flower-rich grassland, ponds, lakes, seasonal pools, ditches, seepages, reed beds, scrub, and secondary woodland (check out the habitat photos below). Such habitat mosaics are particularly beneficial to invertebrates, many of which require two or more habitats to complete their lifecycle.
Another contributory factor to the high biodiversity value of these sites is their thin, nutrient poor soils. This create stressed ground 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 supporting strong assemblages of nectar-rich, stress tolerant annuals. These provide abundant forage for numerous pollinating insects including butterflies, moths, hoverflies, bees, wasps and beetles. With recent reports highlighting growing evidence for declines in pollinating insects, it is clear how important these colliery spoil sites (which are often the most flower-rich locations in the landscape) are to their future well-being of pollinators in the South Wales Valleys.
Finally, colliery spoil sites are relatively undisturbed locations free from human intervention. Here, nature can thrive in an absence of chemical use and unfavourable management techniques.
What wildlife can be found on colliery spoil sites?
The diverse micro-habitats that develop on colliery spoil sites support a wealth of rare and unusual Fungi, with diverse Waxcap, Coral and Earth-tongue communities. The warm, sunny tip faces also support excellent reptile habitat where Common lizard (Zootoca vivipara) and Slow worm (Anguis fragilis) are abundant. Although not as common, some of the best sites for Adders (Vipera berus) in the Valleys are on colliery spoil, while Grass snakes (Natrix natrix) are more associated with colliery spoil wetlands. Ponds, ditches and seasonal pools offer breeding habitat for Common frogs (Rana temporaria), Common toads (Bufo bufo), Palmate newts (Lissotriton helveticus) and dragonflies. Areas of deep grass and heath support complex networks of mice and vole runs, which in turn attract hunting Buzzard (Buteo buteo), Kestrel (Falco tinnunculus), Red kite (Milvus milvus) and Barn owl (Tyto alba). Diverse, flower-rich grasslands and heathlands provide abundant forage for pollinating insects, supporting at least 28 butterfly species and over 90 species of bees, as well as other insects.
The images below showcase just some of the wildlife that can be found on colliery spoil sites in South Wales.