Can Birds and Greenhouses Co-exist?

The greenhouse industry in southern British Columbia is growing rapidly, and Environment Canada scientists are working with government, industry and environmental groups to ensure that it doesn't threaten the survival of millions of migratory and wintering shorebirds, waterfowl and raptors living in the Fraser River Delta.

An internationally significant habitat for over 300 species of birds, the Delta is unique because it possesses three distinct habitats: vast intertidal mudflats, coastal marshes and open-soil farmland. Unfortunately, the fertile soil, abundant sunlight and moderate temperatures that make the region ideal for wildlife also make it prime for development. As natural habitat has gradually disappeared, many species of birds have come to rely more and more on open-soil agricultural land for food and cover.

But now even the farmland is changing. Twenty-two thousand hectares of land in the Delta-Surrey area designated as an Agricultural Land Reserve because of its high-quality soil have gradually been encroached upon by urban and recreational development. In recent years, industrialized farming practices that don't offer the same benefits to wildlife as traditional open-soil agriculture have also intensified. The highly lucrative greenhouse industry is one of them.

SOURCE: Canadian Wildlife Servcies - Click to enlarge

Although greenhouses currently occupy only one per cent of Fraser River Delta farmland, scientists say the rapid rate at which they are expanding could cause irreversible damage unless steps are taken now to keep things under control. While only 5.3 hectares of this land was under glass prior to 1996, plans have since been approved for another 95 hectares--much of it within two kilometres of the environmentally sensitive foreshores of Roberts Bank and Boundary Bay.

According to scientists, these mammoth structures--some the size of 18 football fields--have numerous potential negative impacts. By shrinking available habitat they force birds onto fewer fields and exacerbate any crop damage they cause. They also fragment the residual landscape, leaving small, disconnected spaces that are useless to birds that require larger, more open habitats. Greenhouses, roads, airports and increases in human traffic disturb flocks, while high-intensity lights used to grow some crops may disorient migrating birds or make them easier prey for predators at night. The burning of waste wood chips for heat and the use of chemical fertilizers threaten to pollute the air and groundwater.

Scientists have advised the municipal council in Delta that the fragmentation issues are not addressed by a draft by-law recommending greenhouse coverage be limited to a maximum of 40-60 per cent of farmland and structures be screened by landscaping. A preferable solution, they say in their report, would be to bank at least an equal and contiguous hectarage of high-quality habitat for traditional, open soil agriculture for each hectare placed under glass.

The Common Barn-Owl is considered rare in Canada; the Fraser River Delta has the highest population of this species in the country. The owl's survival in the delta depends on maintaining barns and old fields as habitat.

Although the issue is still under discussion, the success of land acquisition and stewardship programs elsewhere in the province has Environment Canada scientists optimistic that a solution can be found that enables the greenhouses and birds to co-exist.

  Home |  Air |  Atmospheric Science |  Climate Change |  Environmemental Action |  Habitat |  Pollution |  Species at Risk |  Technology |  Water |  Weather |  Wildlife