WEST COLUMBIA - The Columbia Bottomlands is an ecological gem.

It is the place in Southeast Texas where the salty coast gives way to a hardwood forest. Monarch butterflies pass through here in the spring and fall and millions of migratory songbirds use it as resting place, after their long journey across the Gulf of Mexico. It is also disappearing as growth from the Houston area pushes outward.

But on Thursday The Nature Conservancy announced it had purchased 1,900 acres in the Columbia Bottomlands in Brazoria County as a result of a $14 million donation from Australia-based BHP Billiton, the world's largest mining company. Of that amount, $8 million will go to establish two nature preserves in Brazoria County, and $6 million will be used to buy land in Arkansas. It is the largest private donation the group ever has received to buy land in Texas.

The Nature Conservancy seized the chance to buy the property, which sits in the heart of the Columbia Bottomlands, right between the Brazos and San Bernard Rivers.

"If you need more evidence that this is a ecologically valuable piece of property, there it is," said Jeff Weigel of The Nature Conservancy of Texas, nodding to a Monarch butterfly perched on a milkweed growing at the group's new Brazos Woods Preserve. "It truly has it all."

Indeed, the whole area is considered a nature lover's paradise. Visitors flock there each year to witness exhausted migrating birds resting in the forest canopy.

The area is of such importance to wildlife that the U.S. Fish and Wildlife Service is seeking to protect 70,000 acres there and has recently joined forces with The Nature Conservancy to accomplish that goal.

It won't be easy. Of the original 700,000 acres of forest, only 147,000 acres remains today. The forest began to vanish when farming took hold in the region decades ago, a trend that has only continued to worsen as Houston's population exploded and began pushing out to the exurbs.

Protecting the land from development will improve water quality for the whole region, save habitat for fish and wildlife and increase opportunities to educate urban children about the value of nature, said Laura Huffman, Texas state director of the Nature Conservancy.

"When the Nature Conservancy sees the opportunity to help protect a fragmented landscape, we swing into action," she said. "But we realize that we can't get the job done by ourselves and need both private and public partners. This is an area that deserves all of our attention."

Connecting the islands

Almost 50 years ago, Congress recognized the importance of the Columbia Bottomlands by establishing the San Bernard National Wildlife Refuge.

The refuge is a birding paradise - migratory songbirds such as warblers and orioles spend their winters there as do ducks and other waterfowl. U.S. Fish and Wildlife Service officials say they realized long ago that protecting the refuge means protecting the land that surrounds it. So the agency began acquiring property in the area with the goal to conserve 70,000 acres in the Columbia Bottomlands, roughly 10 percent of its historical expanse.

"As we start thinking about development in the urban areas, it makes every piece of property even more critical," said Benjamin Tuggle, head of the fish and wildlife agency's regional office that oversees Texas. "That's why we can't think of these as islands that function independently because the impact would be overwhelming. There needs to be connections."

Enter the Nature Conservancy of Texas, an Austin-based nonprofit that focuses on conserving land and water. The group had been approached about four years ago by BHP Billiton about the prospect of making a donation for land conservation.

In some ways, it was an easy choice.

The Brazoria County properties had it all: river access, intact forest or forest that could be restored, and proximity to the company's Houston office, which was a preference of BHP officials. And the land also was relatively close to the Nature Conservancy's Nash Prairie Preserve, one of the last intact pieces of coastal prairie in the Houston area.

"We're trying to get 70,000 acres in this archipelago of land," said Weigel who heads strategic initiatives for the conservancy in Texas. "And we try, because the science tells us to, to lock up the biggest pieces of land for the greatest ecological benefit."

An unlikely ally

At first blush, an Australian mining and oil company might seem like an odd choice to step up to save a swampy plot of forest land in Southeast Texas.

BHP Billiton officials, however, said they wanted to make a donation that would benefit land conservation in a state where they worked. BHP is drilling in two Texas fields - the Permian Basin and the Eagle Ford Shale.

"We went to the Nature Conservancy and asked 'What are the best areas we can conserve?' '' said Ed Mongan, BHP's senior manager for the environment. "They said this is a really special area that has a lot of things that are worth preserving."

Since 2001, the company has donated more than $2 billion to community projects worldwide.

But the company's global philanthropy recently has been overshadowed by a dam collapse that occurred in Brazil in 2015 that killed 19 people, destroyed several villages and polluted a river with waste from its Samarco mine. The event is widely considered one of Brazil's worst environmental disasters.

The catastrophe happened more than two years after the company initially approached the conservancy about the donation to the Texas and Arkansas land preservation projects, a fact company officials pointed to when asked if the gift was an example of corporate "greenwashing."

Nature Conservancy officials don't see it that way, either.

Huffman said given the demand for land in Texas, there's almost no way the group can procure property without the help of corporate partners like BHP.

The money will help pay some forest restoration and for both new preserves. Native trees will be replanted where needed and invasive plant species like Chinese tallow and water hyacinth removed if possible.

At the Brazos Woods Preserve, there are plans to build an outdoor pavilion, which will function as a gathering place and an outdoor classroom of sorts. The conservancy also recently erected a webcam near a nest visited by eagles every year.

"As people become less and less connected to nature, it becomes more important to have opportunities to take classrooms outdoors and show them what it looks like," Huffman said. "Houston was built on a prairie and there are still some places like this you can get a feel for what it used to be like."