{"id":915906,"date":"2026-09-30T23:48:10","date_gmt":"2026-09-30T23:48:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/915906\/"},"modified":"2026-09-30T23:48:10","modified_gmt":"2026-09-30T23:48:10","slug":"wildlife-arrives-on-time-at-rewilded-chalk-grasslands-built-along-hs2-route-hs2","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/915906\/","title":{"rendered":"Wildlife arrives on time at rewilded chalk grasslands built along HS2 route | HS2"},"content":{"rendered":"

The air is scented with the sweet tang of ladies bedstraw and made musical by skylark and blackcap song. An abundance of marbled white butterflies, small skippers and common blue damselflies dart over the flowering knapweed, yarrow and wild carrot.<\/p>\n

That the largest chalk grassland in the Chilterns is full of wildlife may not surprise you. But the fact that it is completely artificial, only four years old and has been built by the much-maligned HS2<\/a>, may do.<\/p>\n

The Western Slopes<\/a> \u201crewilding\u201d project is due to open to the public next year on land beside the high-speed railway as it dives under the M25 and into a 10-mile tunnel beneath the Chilterns<\/a>. The trains may be running late<\/a>, but the wildlife has already arrived.<\/p>\n

A marbled white butterfly. Photograph: Graeme Robertson\/The Guardian<\/p>\n

A decade ago, this area was a vast wheatfield with precious little biodiversity. Today, as the construction effort winds down, more and more of the 127-hectare site is being turned into wildlife-rich grasslands, wet meadows, ponds and small woods.<\/p>\n

It is now one of the largest wildlife habitat creation projects in south-east England, and has already witnessed the arrival of hedgehog clover<\/a>, which hasn\u2019t been recorded in Hertfordshire since 1878, alongside water voles, lesser emperor dragonflies and pyramidal orchids.<\/p>\n

The transformation began when Matt Hobbs, lead ecologist at Jacobs, was invited to take a look at the huge planned HS2 works around the south entrance to the Chilterns tunnel.<\/p>\n

\u201cI asked the engineer: \u2018What\u2019s coming out of the tunnel?\u2019 When he said \u2018chalk\u2019, it was like a lightbulb moment. I thought, I know what I\u2019d like to do with that chalk,\u201d said Hobbs, who has designed and overseen the Western Slopes project<\/a> for HS2.<\/p>\n

Chalk grassland is one of the most wildlife-rich habitats in southern England<\/a> because a wide range of wildflowers flourish on its thin, nutrient-poor alkaline soils, alongside an array of associated invertebrates, including rare moths and bees.<\/p>\n

Matt Hobbs. Photograph: Graeme Robertson\/The Guardian<\/p>\n

According to Hobbs, the valley slopes could have been expensively restored to arable land by HS2, as much of the land temporarily taken for the huge construction effort will be. \u201cWe saw the opportunity to do something different,\u201d he said. \u201cThis project is unique. The whole landscape was predicated on what\u2019s the best thing to do with the earthworks and soils. We\u2019re not moving any soils or material off site. Any concrete waste from this site is crushed and used as aggregate under the grasslands.\u201d<\/p>\n

Reusing 10m cubic metres of chalk, topsoil and subsoils from the construction effort in the immediate vicinity of the tunnel mouth has also drastically reduced CO2 emissions, and the construction traffic that dumping it elsewhere would have entailed.<\/p>\n

According to HS2\u2019s calculations, the wildlife grasslands here could sequester 7% of the carbon impact of the whole high-speed line\u2019s construction, because grassland is much better at storing carbon than regularly-ploughed arable land, which releases carbon every time it is ploughed.<\/p>\n

Over the past four years, all the chalk excavated from the tunnel has been sculpted into rolling \u201cdowns\u201d on the land above the Colne Valley, creating varying topsoils and a future mosaic of grassland, scrub, woodland and ponds and wet areas.<\/p>\n

Two HS2 workers. Chalk grassland is one of the most wildlife-rich habitats in southern England. Photograph: Graeme Robertson\/The Guardian<\/p>\n

It took the ecologists a bit of effort to retrain the digger drivers who were spreading the chalk over the site. Groundworks teams are trained to leave everything beautifully smooth and neat, whereas the ecologists were seeking topographical variation, with dips, hollows and \u201cuntidy\u201d rough areas.<\/p>\n

The future vision is a \u201cwood pasture\u201d landscape, inspired by rewilding sites such as Knepp in West Sussex, where a mixture of scrub and wildflower glades are grazed by herbivores.<\/p>\n

Four cattle-grids have been installed on roads \u2013 believed to be the first in Hertfordshire \u2013 to enable free-roaming cattle to graze within four separate compartments.<\/p>\n

\u201cThey were really key to the project. We wanted to have that Knepp rewilding technique where you have cattle that can move anywhere they want within the site \u2013 it\u2019s brilliant for soil health, soil carbon and dung beetles,\u201d said Hobbs.<\/p>\n

A damselfly. Photograph: Graeme Robertson\/The Guardian<\/p>\n

Luke Craner, a senior landscape clerk of works for the HS2 contractor Align, said: \u201cI\u2019m really keen to get livestock grazing sooner rather than later so we can kickstart biological processes. We\u2019ve already got a really good grassy sward establishing. We want natural regeneration to occur, because it\u2019s always much more beneficial for wildlife. We\u2019ve already got loads of hawthorn and quite a few oaks coming up. It\u2019s already going out nicely.\u201d<\/p>\n

Later this summer, green hay from other calcareous grassland in the local area will be spread on the Western Slopes to bring in more invertebrates. As ant populations develop, rare butterflies including the Adonis, chalkhill and small blue are likely to arrive, with these species interacting with ant colonies. There is also a mammal shelf built into a culvert beneath the railway, enabling badgers, stoats and other mammals to safely cross the high-speed line.<\/p>\n

Some footpaths through the site are set to be opened up in the next 18 months, although the western portion of the site is likely to remain protected from public access to boost the ground-nesting birds \u2013 from skylarks to little ringed plover \u2013 that have quickly colonised the land.<\/p>\n

While HS2 is still under construction, the forthcoming track-building and electrics phase will require a much smaller construction footprint, enabling the nature areas to be expanded.<\/p>\n

At the bottom of the slopes, beside the River Colne, nearly five hectares of new wetlands have been established. These pretty ponds have been rapidly colonised by club-rush, water mint and sneezewort, as well as breeding reed warbler and lesser emperor dragonfly.<\/p>\n

Luke Craner. Photograph: Graeme Robertson\/The Guardian<\/p>\n

\u201cWe\u2019ve definitely extended the population of kingfishers,\u201d said Craner, who has also recorded new sightings of water vole on a tributary of the Colne. \u201cWater voles are a massively declining species because of habitat loss \u2013 we\u2019ve put in habitat that\u2019s good for water voles. They\u2019ve colonised it immediately.\u201d<\/p>\n

What Craner has noticed is the changing soundscape. While the roar of the M25 and the clank of ongoing construction is never far away, in certain glades the human din is now overwhelmed by birdsong and insect hum.<\/p>\n

\u201cWe didn\u2019t have this harmony last year and all of a sudden it\u2019s never silent,\u201d said Craner. \u201cThis is our hidden gem.\u201d<\/p>\n

This article was amended on 30 September 2026. An earlier version said that the image of the damselfly was a dragonfly.<\/p>\n","protected":false},"excerpt":{"rendered":"The air is scented with the sweet tang of ladies bedstraw and made musical by skylark and blackcap…\n","protected":false},"author":2,"featured_media":915907,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[49,48,66,323],"class_list":["post-915906","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-ca","tag-canada","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/915906","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=915906"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/915906\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/915907"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=915906"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=915906"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=915906"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}