On a sunny day in the spring, I walked across a field south of Forest Grove and looked west toward the Tualatin River, then east toward the tree line of Chehalem Ridge Natural Area.
Standing on the edge of one of Metro’s newest natural areas in the Wapato Lake basin, my eyes explored the opportunities to help wildlife move west to the Coast Range or east toward the Willamette River.
This story appears in the Summer 2015 issue of Our Big Backyard, a quarterly magazine about parks and nature. Read more stories, plan an outing with a detailed field guide, and find out more about fun nature events and classes.
Movement is essential to life. Corridors connecting wild places help wildlife move between habitats. Scruffy-appearing natural spaces are the highways of biodiversity movement that facilitate exchanges of genetic diversity between populations, a fundamental process for keeping our landscapes wild with native species.
To conservation scientists, biodiversity corridors simply refer to areas where an animal feels safe enough to move through a landscape.
Landscape permeability – science-speak for how easy it is for wildlife to move through corridors and across a landscape – is a factor I think about when designing restoration projects.
Pollinators such as beetles, bees, butterflies and birds move from one flower to another in search of nectar, incidentally pollinating our farm fields, prairies and forests. Natural areas, hedgerows and uncultivated field edges allow pollinators to feed, breed and move to new refuges.
Larger animals such as coyotes, squirrels and black-tailed deer also use biodiversity corridors. And animals not often seen, such as the usually nocturnal bobcat, move through habitat connections to reach new territory.
Bobcats are solitary and generally do not share ranges. Young bobcats must move to new territory or try to push out older cats. This year’s young, born in the spring, will disperse in the fall, searching for habitats rich in rabbits and rodents, their primary prey.
The bobcats I’ve seen at Chehalem Ridge likely use corridors to move to new areas. They may travel west from Chehalem Ridge through headwater streams, natural areas and rough edges of cultivated fields until connecting to Metro’s natural areas along the Tualatin River. Keeping this native cat and other wildlife in our region requires maintaining and adding connections.
Restoration work is done in the context of the health of native plants and animals at an individual site and their interactions with the larger landscape. Biodiversity connections are the social networks of the wild world, essential paths through which wildlife moves, finds mates for breeding, communicates its presence and establishes new home ranges. Effective restoration means thinking about connections at multiple scales, and between and among habitats.
How does that type of restoration thinking get applied in the real world? In the natural areas connecting Chehalem Ridge to the Tualatin River floodplain, we are increasing the amount of native habitat available by planting trees and shrubs to expand the width of riparian areas.
At natural areas where farming continues, we soften the abrupt edge between cultivated and wild spaces with more native plants. We take down or create breaks in fences not needed for public safety or other management needs.
Failing or undersized culverts are removed or replaced with larger ones that allow small animals to safely migrate back and forth under roads. We add in down dead wood, creating the small-scale corridors that rodents, reptiles and amphibians use as pathways across the forest floor.
You can help wildlife move through your neighborhood, too. Wildlife lives in all of our communities, including urban landscapes. Do you know where the biodiversity connections are across and through your neighborhood