Restoration Twitchiness

Quarrying land being restored outnumbers that being prepared for excavations by more than 300hectares, according to the QPA’s latest sustainability report, so it is worth taking a look at what minerals extraction has already done for wildlife. The great crested grebe is good example. In the third article of our Restoration Twitchiness series with the RSPB, we look at quarrying’s part in the grebe’s survival as well as how today’s companies can help expand the bird’s numbers further.

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It may not be immediately obvious but the great crested grebe has reason to be grateful to the mineral industry. Now a common sight on the UK’s lakes, reservoirs and rivers, in the 1800s it was hunted to the brink of extinction.

In the Victorian period the fashion hungry were demanding grebes. Its striking head plumage and fine breast feathers, or grebe-fur, were de rigeur for those seeking to be seen as part of the millinery in-crowd.

But in 1860 the RSPB was formed to try to save the grebe from extinction by hat fashions. After much high level campaigning the grebe started to become passé and the fickle world of fashion moved on. Grebe numbers started to recover.

However, it was not until after the second world war that grebes really got stuck into growing their numbers. While reunited families busied themselves with creating the baby boomer generation, the grebes were benefiting from the reconstruction boom.

The war-ravaged country needed new roads and houses and this demanded gravel. Once the pits had been excavated they were often left to flood and provided the kind of shallow, inland lakes loved by grebes.

There are now thought to be about 9,400 adults in the UK and the minerals industry is continuing to help create habitat. A good example of this is at Aggregate Industries’ Paxton Pits nature reserve in Cambridgeshire.

It consists of several flooded pits that were excavated for sand and gravel until the 1960s and which have become famed for their bird life, particularly since they were made part of a Local Nature Reserve in 1989. More recent quarrying continues to provide new wildlife habitat, following a plan agreed as part of the original consent.

How is habitat created?

Along with gravel pits, chalk and clay extraction sites are also suitable for creating open water habitats which can attract a wide range of wading birds and wildfowl throughout the year.

Landforming before flooding takes place is the most important part of open water creation. Try to create as much shallow water as you can – around 1.5m deep or less – using topsoil, overburden and silt.

The shoreline should be gently sloping and its length maximised by making it scalloped or sinuous. Tree planting should be kept to a minimum, as water birds prefer an open landscape.

Low, wet islands should be created at a level where they can be completely immersed to manage vegetation. These will encourage breeding wading birds by providing secure, open nesting areas with surrounding shallow water in which their young can feed.
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Such features should also be sheltered from the wind to reduce wave erosion. In most parts of the UK, the south-west corner of the pit is often the most sheltered.

Any islands should be low in profile with shallow gradients into the water. If possible, they should have small, shallow waterbodies within them. The composition of the island will largely determine which birds are attracted to them.

Ray Matthews, chairman of the Friends of Paxton Pits, says the islands there have proved ideal for the reserve’s grebes.

“They can be as little as a couple of square metres, with a bit of willow sticking out of it. Grebes here tend to nest on small islands, near to the larger ones, which are used by lapwings, redshanks and common terns. They like nest security,” he says.

Great crested grebes eat mainly fish such as roach and rudd, so will need some deeper water in which to dive for food. Fish need both warm, vegetation-filled shallows for spawning and sheltering fry, and deeper water for the adults.

At Paxton the grebes seemed to do particularly well in the years immediately after a pit is allowed to fill with water. The two most recent pits were flooded in 1994 and 2003. The following years saw the number of grebes surge.

The tops of newly submerged willows provided excellent nest sites and it is thought the lack of predators in the newly flooded pits also helped the birds raise more young.

If possible, the area around the open water should be turned into complementary wetland habitats, like reedbed, marsh and wet grassland, complete with ditches and ponds. This will create habitat. A good grass sward close to the water’s edge will provide grazing for wintering wildfowl.

Some of the best wildlife habitat at Paxton is the scrub, which has grown up on former gravel storage areas. This is now home to an impressive population of nightingales, with up to 28 singing males every year, which attract thousands of people to listen to them in April and May.

Dr Ben Vivian, Aggregate Industries’ corporate social responsibility advisor, suggests others thinking of following suit should remember it is important to ensure a wide variety of habitats are developed and managed in order to encourage new and rare species.

“Mineral site restoration, particularly following sand and gravel extraction, offers an excellent opportunity to develop and restore back to species-rich nature reserves for the benefit of local communities, visitors and not least the migratory and indigenous species of birds, animals and plants.”