About a third of the bird species inhabiting the British Isles are considered endangered. Among them is the secretive bittern, which was until 2015 on the UK’s Red list of most-threatened species. Today however, the thickset heron is among dozens of other endangered bird species whose population numbers are steadily recovering thanks to conservationists.

One of the most recent and notable conservation efforts is the transformation of a former quarry in the east of England into a vast reserve that’s offering vital sanctuary to endangered birds. One of these birds is the UK bittern, for which the marshy plain of the Fens outside Cambridge has become an attractive habitat in recent years, reports Phys.org.

“It’s really a demonstration of how working with partners—big decisive action at large scale—we can bring species off that Red list,” said Chris Hudson, senior site manager at the Royal Society for the Protection of Birds (RSPB) Ouse Fen Nature Reserve. Researchers estimate that about five percent of the elusive heron’s number now nest at Ouse Fen.

Insect decline

According to experts, the main reason that led to the decline of bird populations in the UK and Europe is a growing change in land use, which deprived birds of food and habitat. “The decline of these birds might tell us something about a huge decline in the biomass of insects, which has been a real concern for conservationists across Europe recently, and it’s probably a much wider phenomenon,” said Richard Gregory, head of monitoring at the RSPB Centre for Conservation Science.

“So we need more research, but that’s a real warning sign about how the environment is changing around us. “But we also know that when you manage the habitats, when you protect the habitats, and you protect the birds, they can bounce right back,” said Gregory, alluding to the rewilding of the Ouse Fen site.

Making the conditions right

The mix of reedbeds, open water, and grassland opened in 2010 and is now visited by 20,000 people annually. Once Europe’s largest sand and gravel quarry, the site is now an important nesting place for the many endangered bird species in the UK. The ongoing project consists of digging out millions of tonnes of aggregate to create small lakes and reeds, which are highly appreciated by the birds.

“Our job here was to recreate the right habitat conditions that would bring the bittern back,” said Hudson. These include lots of feeding opportunities to get their prey sources like fish, and particularly eels. He continued: “Once we’ve put those conditions in place, that effectively brings the birds back. ‘If you build it they will come’ is the phrase that we quite often use.”