Chronic industrial pollution and small spills from oil tankers moving through Burrard Inlet are contributing to declining numbers of birds in Stanley Park, according to the conservation program manager for the Stanley Park Ecology Society.

Robyn Worcester said in the past decade conservation group Bird Studies Canada has found a decline in the number of loons and grebes that rely on small fish in the intertidal areas for their food. Birds also feed on the Pacific blue mussels and barnacles that live close to shore.

Worcester said minor oil spills aren't the only cause of the declines, but they do play a role along with other factors, such as climate change and fluctuating ocean temperatures.

"We're seeing declines of these birds," she said. "Maybe there is stress on their food supply, which is the small fish. Instead of increasing the amount of pollution, I think we have to focus on making things better."

Worcester is one of three panelists at a discussion tonight on the effects of oil spills on Stanley Park.

The ecology society is holding the discussion to raise the public profile of environmental issues in Stanley Park related to Kinder Morgan's proposal to expand its pipeline from Alberta to the Westridge Terminal in Burnaby. The energy company wants to more than double its capacity from 300,000 barrels a day to 750,000. The number of tankers going through Burrard Inlet, the company says, would increase from 96 a year to as many as 300.

Kinder Morgan plans to take its proposal to the National Energy Board next year.

If approved, the company plans to start shipping from its expanded facilities in 2017.

Worcester said a major oil spill would have an effect on Stanley Park's four resident pairs of eagles and its colony of great blue herons.

A spill would also affect the thousands of waterfowl from Alberta and the Northwest Territories that spend the winter in and around the park.

Asked if she was being alarmist by talking about the effects of a major oil spill, Worcester admitted she didn't know anything about the logistics of moving big oil tankers through Burrard Inlet's First and Second Narrows and to the terminal in Burnaby.

"I know the (First) Narrows is a treacherous area that is hugely biodiverse," said Worcester. "It's a highly turbulent and narrow passageway. The Second Narrows is even more treacherous.

"The question is: Is it worth it? To me, it's not. I would prefer to use less oil than take any chance that it could happen to this place. Wildlife are so much more valuable that it's worth making the sacrifice."

Worcester said there was some good news about birds and oil spills. She has not seen any birds nor heard of any reports of birds covered in oil in the area for several years.

The last reported incident of birds found covered in oil occurred in 2000, after canola spilled into a storm sewer that discharged into Burrard Inlet. The Vancouver Sun reported wildlife rescue officials recovered 15 birds; three could not be saved.

Worcester, a biologist, oversees the ecology society's Coexisting with Coyotes and environmental stewardship programs.

The society's executive director Patricia Thomson said tonight's discussion isn't meant to look at the economic effect of the pipeline expansion or the safety record of large oil tankers.

"Our role is to take a leadership role in the stewardship of Stanley Park," she said. "If we didn't share what we know of the ecology of Stanley Park, about the environmentally sensitive areas and the animals and what it is they are sensitive to in relation to this proposal and these risks, then we wouldn't be doing our job.

"We're about Stanley Park, these habitats, these shorelines and the food chains that stretch out from there."

Thomson, a long-term West End resident, has been the society's executive director since 2004. She has an undergraduate degree in biology and has coordinated expeditions for the National Geographic Society, the Wildlife Conservation Society and other organizations.

Lance Barrett-Lennard, a marine mammal researcher for the Vancouver Aquarium, and Ben West of the Western Canada Wilderness Committee will also speak on the panel. Tonight's meeting starts at 6: 45 p.m. at the West End Community Centre.

SPILLS

Reported spills into waterways in the Lower Mainland

2007: 641

2008: 542

2009: 607

2010: 667

2011: 615

Collected by Emergency Management BC and compiled by Ministry of Environment. Data on the annual number of discharges into ditches, creeks, rivers, lakes and salt water are compiled from incidents reported to 1-800-663-3456, the 24-hour spill reporting line. The Lower Mainland covers from Boston Bar to Vancouver and from the Sunshine Coast and Pemberton to the US border.