Snakes and Birds

Mrs Ornithologist with Gopher Snake

My wife visited her two horses at the stable where they are kept and found two large gopher snakes in the rafters of the barn. One had a nestling House Sparrow in its jaws. The snakes were transported away and released unharmed.

I used to think that blaming nest failure on snakes was like attributing social ills to communism – when you can’t think of any other reason, it must be snakes. Well, there is some validity to that (snakes, not communism) according to an article in the Journal of Avian Biology 45: 325–333, 2014 which I have excerpted and shortened as follows:

“Predation is the leading cause of nest failure for most birds. Thus, for ornithologists interested in the causes and consequences of variation in nest success, knowing the identity and understanding the behavior of dominant nest predators is likely to be important. Video documentation of nests has shown that snakes are frequent predators. A review of 53 North American studies that used nest cameras showed broad patterns in snake predation. Snakes accounted for 26% of recorded predation events, with values exceeding 35% in a third of studies. Snakes were more frequent nest predators at lower latitudes and less frequent in forested habitat relative to other nest predators. Although 12 species of snakes have been identified as nest predators, ratsnakes, corn snakes, and fox snakes were the most frequent, accounting for 70% of all recorded nest predation by snakes and have been documented preying on nests in 30–65% of studies conducted within their geographic ranges. Predation by only ratsnakes and corn snakes was predominantly nocturnal and only ratsnakes were more likely to prey on nests during the nestling stage. Snakes were not identified to species in over 30% of predation events, underlining the need for more complete reporting of results.”

 I have to confess I find snakes a bit creepy, but I respect their role in the ecosystem and would not harm them. When I directed a field station in the Sierra Nevada during the summer, rattlesnakes would slowly increase in numbers in and around buildings as students left food scraps which attracted mice which in turn attracted snakes. We would collect the reptiles and keep them in cages until the end of the summer and released elsewhere.

Of course, the tables are turned regularly as snakes are eaten by hawks, eagles, falcons, herons and egrets. A snake-eating bird of prey appears in a legend of the Mexican people and it is represented in the Mexican flag: The Mexicas, guided by their god Huitzilopochtli, sought a place where the bird landed on a prickly pear cactus, devouring a snake. They found the sign on an island in Lake Texcoco, where they erected the city of Tenochtitlan (“Place of the Prickly Pear Cactus” – present-day Mexico City) in 1325. (In the coat of arms of Mexico this bird is depicted as a golden eagle, though it is often said to be a northern caracara. It is also possible that the bird was a laughing falcon or snake hawk, a bird of prey which feeds almost exclusively on snakes.)

4 thoughts on “Snakes and Birds

  1. Roger,

    Woke at 3am our time and was delighted to see your last post.

    Snake eats mice, bird eats snake. Very familiar occurrence here Down under.

    Australia’s iconic Kookaburra or “laughing bird” is almost exclusively carnivorous, eating mice, snakes, lizards, fish and even raw meat off our BBQs.

    And they are super fast. One day I disturbed a 20cm baby, red bellied, black snake whilst mowing our property, and I heard “swoosh” but saw nothing. But realizing the snake was gone, I looked up to see a very happy Kookaburra with the snake in its mouth.

    And Australians often report hearing a banging sound in their backyards and, on investigation, find a Kookaburra tenderizing their meal by bashing a snake against their back fence.

    Do snakes eat baby Kookaburras, now that’s an interesting question.

    Cheers,
    Peter

  2. Thank you for this. I’m new to birding, but my experience has been one of amazement at this fascinating and sometimes horrible circle of life.

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