It is well known that islands hold the most threatened wildlife on the planet. Isolation first provides the wellspring of new species and then the seeds of their destruction, in the form of habitat loss, introduced predators, and diseases. Any island of habitat can be affected this way. Little pockets of biodiversity are first created, as animals converge when adjacent lands are cleared, and then lost, as species slowly die out.
For this reason, ecologists urge the conservation not just of protected areas but of connected networks of habitat—green fingers of life reaching through the landscape, providing places for wildlife movement and dispersal. Vegetated, protected corridors can prevent the isolation of habitat islands. Such greenways are strongly advocated in Metro Vancouver’s and B.C.’s biodiversity strategies.
The South Fraser Perimeter Road (SFPR) is having a severe impact on habitat connectivity. This infamous highway is turning important local ecosystems, namely Burns Bog and five North Delta ravines, into habitat islands.
The SFPR will complete the encirclement of the Burns Bog Ecological Conservancy lands by covering the vital edge habitat along its western and northern borders. The east side has already been carved up by Highway 91 and the south side by Highway 99. The bog is being sealed off from its surroundings, making it virtually impossible for wildlife, large or small, to move between the bog and the Fraser River foreshore, Crescent Slough fields, or the Delta-Surrey escarpment. As recently as 1999, it was estimated five bears were living in the bog, yet despite its “protected” status, developments and roads now encircle it to such an extent that bear movement from the escarpment has been choked off. Even birds find traversing highways a challenge, judging by the number of dead and injured birds found along roads. These include daytime fliers like barn swallows and nocturnal species like barn owls.
Heading east of the Alex Fraser Bridge, the super highway will chew into the North Delta escarpment, forested bluffs lining the south shore of the Fraser River. Here, along the tidal flats and above Gunderson Slough, the bluffs are intersected by a series of deeply incised ravines, through which freshwater streams run down to the river. The bluffs stretch into Surrey, where more streams make their way down to the Fraser. The SFPR will be a four-lane, split-level highway all along the river here, with high viaducts spanning each of the five North Delta ravines. The upper level will roll along the top of the bluff; the other level will be lower down. At the foot of the slope, on the narrow border between woodland and river shore, lie the Burlington Northern Santa Fe railway tracks, due to be twinned.
The ravines are oases of damp woodland, full of bird song, remnants of the lush forests that once covered these uplands. Deep black soil supports a rich mix of coniferous and deciduous trees, shrubs, and herbs, together with their associated wildlife. The SFPR environmental assessment reported the presence of endangered species such as Pacific water shrew and western screech-owl. Even a casual observer can see common yet beautiful birds, like Swainson’s thrush, red-tailed hawk, and Wilson’s warbler, and the species list in the environmental assessment technical report is incomplete. The streams are fish-bearing, with coho, chum, cutthroat trout, and sculpin.
The ravines are linked by the wooded bluff along the shore of the Fraser, and by the river itself, through stream culverts. The SFPR roadbeds, viaducts, retaining walls, and bridge supports will eliminate the trees on the bluff, and this east-west connection between ravines will be lost. Bluffs along the escarpment are essential wildlife-movement corridors. Black-tailed deer wander through, and coyotes raise their young. Belted kingfishers nest in the muddy cliffs, bald eagles roost in the Douglas fir, and great blue herons move between the river and the alders. Less noticeable are small mammals, songbirds, and amphibians that also need these habitats. Without the connection of the bluff, wildlife diversity in the area will quickly decline.
Parts of the ravines have not been treated well: there are illegal landfills and trash dumps, and streams have been blocked by narrow culverts that fill with debris, where salmon struggle to get upstream. There is scope for restoration work. Some parts are publicly owned; many are private. Regardless, they all face a future of trucks thundering overhead, increased lighting (another known ecological disruptor), isolation from adjacent habitats, and increased culverting as they approach the river. So in addition to dozens of houses being demolished and people’s lives uprooted, these few natural areas are due for terminal degradation.
We need a change of plan, based on respect for the natural world. Fragmenting habitat to this extent is tantamount to complete destruction of scarce wildlife populations. The provincial and federal governments that blindly support this $800-million highway must enforce their laws on species at risk and their strategies on habitat connectivity. Merely bridging the ravines will not save east-west connectivity or the ecological and cultural role of the North Delta bluffs. Making islands out of habitat means no habitat at all for the future.
Anne Murray is a naturalist and the author of two books about the Fraser delta, A Nature Guide to Boundary Bay and Tracing Our Past: A Heritage Guide to Boundary Bay.