With flocks of Canada geese coming home to roost in Edmonton's urban landscape, city-dwelling humans are getting a stern reminder from bird lovers: Bread is bad for the birds.

While some might be tempted to feed the hissing, honking geese currently occupying garden planters and rooftop patios across the city, resist the urge, says Erin Bayne, a professor in the department of biological sciences at the University of Alberta

White bread is junk food for geese and their cousins in the duck family.

"Bread, just like for us, it's a high calorie type of thing," Bayne said.

"It doesn't really have a lot of nutritional value compared to the things they would naturally eat in their environment like seeds, vegetation and aquatic plants so they don't really get a balanced diet from it.

"They're getting the high calories but they're not getting the nutrition."

Not only will a steady diet of bread fatten up the birds, it can be dangerous for their health, Bayne said in an interview Monday with CBC Radio's Edmonton AM.

Things like wheat, birdseed, lettuce or other greens are far more nutritious options for geese.

Geese consistently fed bread will become malnourished, filling up on junk food and neglecting natural food sources.

Extreme cases can lead to a condition called angel wing, a wing deformity which leaves the birds unable to fly.

Feeding the animals en masse can also increase the risk of disease transmission among the birds, Bayne said.

"Try not to go back to the same place, and try not to draw huge numbers of birds into one place, that's the disease issue," Bayne said.

"A lot of people enjoy the experience of having a lot of birds around them but that creates a lot of stress as they're competing for food."

Bayne isn't keen on people feeding wildlife in general. Well-intentioned feeding can come with a host of other problems, like overcrowding and delayed migration.

If you need another reason to stop feeding waterfowl, think of your own safety, Bayne said.

An aggressive adult goose could easily knock you down as it fights for its next meal.

"You have to be very careful with Canadian geese. They're very protective.

"They have the ability to break an arm if they hit you hard enough so it's not an animal that you want to get super close to."