Eric Vanderduys, CSIRO and April Reside, James Cook University
Australia has a bad record for losing species, and more are likely to follow: more than 1,700 species of animals and plants are listed by the Australian government as being seriously threatened.
The extinction of a species usually comes about from several interacting threats, and the extinction process usually starts with losing a few populations, or a particular subspecies, until eventually there are only a few individuals remaining.
The southern black-throated finch, Poephila cincta cincta, is a bird that has become endangered mostly through land modified by agriculture, resulting in the loss of around 80% of its former range.
Our research, published in PLoS ONE, shows that more than half of the remaining finch habitat is potentially subject to mining development.
Pushed out of home
The other subspecies, the northern black-throated finch Poephila cincta atropygialis, is believed to be secure, as it occupies habitat on the less-developed Cape York Peninsula.
The southern black-throated finch is almost entirely restricted to an area from Rockhampton north to Townsville, and has been declared extinct in New South Wales. The northernmost part of its range is threatened by urban and peri-urban development around the northern Queensland city of Townsville.
The largest remaining stronghold for black-throated finches is within the Galilee Basin, a 500 km-long coal measure running from around Alpha to Hughenden.
Within this area are the proposed Adani (Carmichael), Alpha, Kevin’s Corner, China First, China Stone and South Galilee coal mines. Collectively, these cover nearly 1,700 square km. Much of this area is proposed to be open cut. The Carmichael mine in particular covers the best “hotspot” known for black-throated finches. Were these mines to go ahead, the finches are likely to suffer steep declines.
In our paper we modelled likely black-throated finch distribution, based on what we know about their habitat and climate preferences. Given their historic decline throughout much of their range, we know they are quite sensitive to land modification, so it is unlikely that areas where mining and associated activities occur will be finch-friendly.
Around 60% of the finch’s remaining habitat is potentially threatened by mining activities. Our research also shows that of the very high-quality habitat known in the Galilee Basin, 50% is under threat from mines that have undergone advanced planning.
Offset the damage?
So what does the government do when faced with a threatened species or subspecies in the face of large development proposals? The answer is to offset.
Offsets mainly involve conserving a species’ preferred habitat to account for what has been lost to development, but they could be also be in the form of research funding.
Offsets have been proposed to help reduce the impact on the black-throated finch, but these measures do not stand up to scrutiny.
First, offsets are supposed to result in “no net loss” of that species. In the case of black-throated finches, this means offsets should maintain the population at roughly the same trajectory as they would be on without the mining.
Second, areas proposed as offsets for one mine are potentially subject to development approval for other mines.
However, for a species that has lost 80% of its range (and is therefore demonstrably sensitive), losing any more of its key habitat guarantees an increased loss of finches.
The existing, mine-free finch populations in the Galilee Basin are currently doing well. To truly offset losing this habitat to mining, new high-quality habitat for black-throated finches would have to be created.
This has never been done. Not to mention the difficulty in achieving accurate population estimates in areas of “lost” or “gained” habitat.
Black-throated finches eat grass and herb seeds after they’ve fallen to the ground, so they need particular seeds to be available throughout the year, with just enough bare ground so they can find them. We are still in the process of trying to understand all the factors that make high-quality habitat for black-throated finches, and we’re a long way from having the expertise to recreate it.
Offsets are widely regarded in the scientific literature as failing. They are locking in species declines; far from guaranteeing survival of threatened species, they are guaranteeing their loss.
For the southern black-throated finch, which has already lost 80% of its range, losing 50% of what is known to be prime habitat within the Galilee Basin is likely to lock in its continuing decline.
The most reliable way of avoiding this decline would be to protect and enhance the little suitable habitat that still remains.
Eric Vanderduys, Research Projects Officer, CSIRO and April Reside, Postdoctoral Research Fellow in Spatial Ecology, James Cook University
This article was originally published on The Conversation. Read the original article.