Unlikely Partnership: How Snakes Help Birds

Wednesday, March 11, 2020
With the emergence of spring, so too, comes the emergence of Ontario's wildlife species who spent the winter months tucked away from the bitter cold. As I type this, chipmunks are invading my feeders and running off with their cheeks about to burst, and American Robins are singing their hearts out in the treetops. We have also seen reports from across the province of snakes poking out of their cozy hibernaculum to soak up some UV rays for the first time in months. To many, seeing the first robins of the season parading around the yard is a surefire way to bring a smile to their face. Snakes.. not so much. Over centuries, snakes have acquired an unwarranted reputation for being sneaky, vicious, and downright evil. But snakes and birds have more in common than you may think, and believe it or not, snakes actually benefit birds in many unsuspecting ways.

Eastern Gartersnake (Thamnophis sirtalis)
Snakes as protectors
The main component in the diet of most of our native snake species is mice, rats, and other small mammals. Both mice and rats are opportunistic when it comes to feeding, and though they prefer to forage for seeds, they will feed on bird eggs and sometimes nestlings if given the chance. Because snakes eat a large number of rodents, they help to keep populations under control, and in turn, help birds survive to adulthood. In addition to keeping rodents in check, snakes also help to reduce the spread of ticks and Lyme Disease. How? By eating the rodents that carry them. A recent study by a scientist at the University of Maryland found that a single Timber Rattlesnake can consume nearly five thousand ticks per summer!

Snakes as gardeners
Snakes are avid gardeners, spreading seeds wherever they may go. They don't eat plants, but their food does. When a snake eats a rodent such as a chipmunk, the seeds within the chipmunk's cheek pouches are transferred to the snake's digestive system. Because snakes are equipped to digest animal matter, they cannot break down cellulose and other plant material, leaving the seeds intact. Thanks to their lengthy digestive process and vast home range, by the time a snake excretes droppings containing the seeds, they have been given a longer period for germination and will be dispersed quite a distance away from the originating plant. Through this process, snakes become secondary seed dispersers, and gain the title of ecosystem engineers.

Barred Owl (Strix varia) feeding on an Eastern Gartersnake (Thamnophis sirtalis)
Photo by Brenda Hartley-Foubert
Snakes as food
While it is true that some snake species have birds on their list of prey items, the roles are often reversed, with birds acting as predators and snakes as prey. This type of specialized feeding is referred to as ophiophagy and is commonly found in birds of prey like the Barred Owl pictured above. As neonates (newborns), snakes are especially vulnerable not only to birds of prey or larger birds, but to bird species you often see at your feeders such as Blue Jays and even American Robins. Many birds are opportunistic when it comes to their diet, meaning that they might have a juicy little Eastern Milksnake for breakfast, and for dinner, they could choose to dine on seed at your bird feeders. Snakes are an important source of protein for many animals, and unfortunately, 75% of Ontario's snake species are listed as Species at Risk largely due to negative human impacts such as habitat loss and vehicular death. When we diminish a food source, it inevitably puts pressure on other food sources such as insects. This can be especially dangerous in already struggling populations and can lead to population collapses, causing a domino effect across the food chain from producers to apex predators.

Circle of life
Even in death snakes are beneficial to birds & the ecosystem. After death, the carcass of a snake is fed upon by numerous animals including birds, rodents, and insects. The decomposition of the body is carried out by bacteria and fungi, and all the nutrients from the body leach back into the earth. These nutrients help feed plant life, which then feeds animals at all levels of the food chain.

Eastern Milksnake (Lampropeltis triangulum)

Whether you love them or hate them, there is no denying the vital role snakes play in every ecosystem in which they are present. They act as gardeners, protectors, and even food. If you can't learn to appreciate them for their unique beauty, fascinating behaviour, or sheer necessity in the environment, appreciate them because they - like you - help the birds. Click here to learn more about our native snake species and how you can help them thrive in your yard.

Happy trails!
- Shayna

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