Why are there so many geese in Metro Vancouver?

You can't miss them as they strut around Metro Vancouver: hefty birds sporting brown and black feathers with white chin straps as they congregate in noisy gaggles.

Yes, they're Canada geese — but why are they crowding parks, beaches, the seawall and even crossing busy streets?

Urban biodiversity planner Jennifer Rae Pierce told The Early Edition host Stephen Quinn the geese were re-introduced to the area in the 1970s to boost the population for hunting and consumption purposes. 

But, unlike their native cousins, Pierce said these geese don't migrate.

"Their impact on local ecosystems is quite different," said Pierce in a phone interview. The native goose population changes from season to season as they migrate and are affected by predators and hunters while locals stick around the whole year. 

What about all that poop?

Just like the bird itself, their poop seems to cover Metro Vancouver's sidewalks and grassy areas.  

That's because geese don't have a very efficient system for processing food compared to other animals, according to Pierce. 

"They actually produce more poop volume for their size and for the amount of food that they eat than most other species," she said. 

Some people worry that the huge amount of droppings will contaminate water sources and spread diseases, but  Pierece says that's rare and water is more likely to be contaminated with human-derived feces. 

She said there are diseases found in goose feces that have the potential to infect humans, but it's so uncommon there isn't enough data to study the issue. 

"The feces are primarily an esthetic concern," said Pierce.

It can be a concern, however, on smaller ponds or grass patches where children might come into contact with the poop, she added.

Controlling the population

In order to control the population, the City of Vancouver uses a technique called egg addling. It's a process of sterilizing eggs soon after they are laid. Eggs can be shaken, frozen or covered in oil, said Pierce in a 2016 report for the City of Vancouver. Once the eggs are sterilized, they're placed back in nests to reduce the chances of the goose laying more. 

Pierce said in the study the practice is common and approved by organizations like the animal rights group PETA. 

But urban geese have adapted to this process and try to hide their nests from humans. 

"They'll attempt to nest outside of park areas and more on private land to avoid management techniques," she said. 

Click the link below to listen to the full interview: