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Should You Feed the Birds? Using the Potato Principle

March 15, 2022

By Jennifer Dick, Manager of Interpretation, Royal Botanical Gardens.

One of my favourite childhood memories was building a bird feeder with my father. We measured and marked, measured and cut, assembled and hung. It was a simple feeder with a flat base connected to a peaked roof by twine. I remember sitting bundled in my snowsuit propped against the Red Pine for what felt like hours waiting to see who would come for the sunflower seeds on offer. Sure enough, the chickadees were the bravest and came first. The nuthatches soon followed. I have no doubt that close encounters with wildlife like this when I was a child nurtured my love of nature and played an important role in my career path.

While reminiscing on those childhood memories, I decided at the beginning this year that I wanted to set up a backyard feeder once again. I found a good feeder, a safe spot, some hearty seed, and waited. I waited and tended and waited some more. Over three weeks later, the first birds found their way to our yard. It’s so joyful to watch them through the windows fluttering about and I like tending to the feeder to make sure it’s clean and well stocked for my feathered friends.

In all honesty, despite the pleasure I knew it would bring me, it took me quite a while to decide to feed the birds at my home. After much research, I’ve had some uncomfortable revelations in the past few years about how much harm feeding can do to the nature we love. RBG Nature Sanctuaries are suffering in so many ways because of the overfeeding in those natural spaces. So why would feeding at home be any different than in the Nature Sanctuaries? Here’s where the Potato Principle comes in.

Naturalist, environmental educator, avid birder, and former RBG staff member, Kyle Horner, wrote a blog post in January 2022 that helped me evaluate my feeding dilemma.1 In his post, he introduces six different factors to assess ethical wildlife feeding and calls it the Potato Principle thanks to the handy acronym MASHED. Here’s how it goes:

  • Malnutrition
  • Alteration of natural behaviour
  • Sensitive species
  • Human habituation causing harm
  • Evidence and experts
  • Danger to humans

Horner’s post already evaluates backyard feeding (I recommend giving it a read) but how does feeding in Hendrie Valley Nature Sanctuary stand up to the Potato Principle?

White Breasted Nut Hatch
Red wing black bird perched on the boardwalk railing above a please don't feed the wildlife sign
Cardinals and woodpecker on bridge railing waiting for food

Malnutrition is something RBG is very concerned about for the animals in Hendrie Valley. In a study conducted by RBG ecologists, researchers found that much of the seed being left behind were poor-quality mixes with fillers like corn that don’t provide proper nutrition. We also often see human food left for animals such as bread, breakfast cereal, and even muffins which are not health foods for wildlife. Malnutrition has even led to Angel Wing in one of our Trumpeter Swans. This wing deformity, caused by improper nutrition, means the bird cannot fly and must spend the rest of its life in captivity.

Alteration of natural behaviour is trickier. Studies have shown that bird populations that were fed for many years are not dependent on supplemental food after the food is no longer available.2 So, while we do see a change in the behaviour of the birds in Hendrie Valley from feeding, fortunately they will do what they should naturally if we stop the overfeeding. However, our ecologists have noted that there is a much higher density of opportunistic mammals like skunks and racoons than we should have in the valley because of the increased amount of food brought in by humans. We are feeding an overpopulation of animals that prey on the eggs and young of birds and turtles.

Sensitive species is a critical issue at RBG. We are stewards of many species at risk and their habitat. While the chickadees and chipmunks being fed aren’t sensitive species, the accumulation of added food in the valley is absolutely impacting endangered species. All the turtle species we find at RBG are now species at risk and are being preyed on by the extra mammals. Yes, a cute chipmunk will eat turtle eggs.

Human habituation causing harm has torn little pieces of our hearts in recent years. In one specific example, when one of our young swans became habituated to people with handouts, it started approaching people for food. Towering over a toddler, swans are intimidating and loud, and can appear aggressive as they demand food. Sadly, this young swan was injured by someone on the narrow trail trying to protect themselves from the approaching swan. We’ve also had incidents of chipmunks being killed by being stepped on by visitors or attacked by their dogs; not the kind of experience people want for their children while out for a walk in the woods.

Evidence and experts: RBG is extremely fortunate to have dedicated, passionate ecologists who love and study our Nature Sanctuaries. They’ve shared their concerns about the overfeeding at RBG and the long-term impacts of this behaviour. If you haven’t had a chance yet, please check out our interviews with RBG’s experts linked below.

Danger to humans is also a concern. With higher densities of animals, there’s a greater chance of negative encounters whether its being chased by a hungry swan, or nipped by a demanding raccoon, squirrel or chipmunk (each of which carry diseases and parasites that can spread to people and pets).

Trumpeter Swan with angel wing
Photo: Barbara Philps
Light brown squirrel standing on the boardwalk railing looking inquisitively towards the camera
raccoon looking up from a log in the hendrie valley marsh

While feeding birds and a few neighbourhood squirrels at an urban home passes the MASHED test, offering food to wildlife in urban nature sanctuaries that has over 550,000 visitors a year does not. We have such a gem right here in our own backyard to be able to enjoy nature, let’s not love it to death. We can all help protect it and all the creatures who call it home. One simple way to do that is to not bring anything new (food or otherwise) on your visits. There’s a wonderful travel quote that suits here: “take only memories, leave only footprints (on the trails only please), and kill nothing but time”.


1 Horner, Kyle (2022). “In Defence of Feeding the Wildlife”

2 Brittingham, Margaret C., and Stanley A. Temple (1992). “Use of Winter Bird Feeders by Black-Capped Chickadees.” Journal of Wildlife Management, vol 56, no 1, pp. 103—110

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