Tuesday, March 3, 2020

Snowy Owls Are Tundra Terminators

Male Snowy Owl by Joe Kostoss of Eye in the ParkThirty thousand years before Harry Potter immortalized the snowy owl in popular culture, our European ancestors were drawing them on cave walls.

Snowy owls breed on the treeless northern tundra of Alaska, Canada and Eurasia, using scrapes on snow free boulders, hummocks or rises as nests. Males select and defend their territory, while females choose the nesting site.

In a typical year, when adult snowies consume an average of 1,600 lemmings each, half of their clutch of four to eight eggs will survive to adulthood. In a banner year, when the constantly fluctuating lemming populations explode, the female may lay a larger clutch, up to 12 eggs.  All the chicks may survive, and many head south in what are called “irruptions,” in search of territory or prey, which is why we may see some in the Adirondacks in winter.

Snowy owls are often seen in the United States in fields, shores, lake sides, sand dunes or even airports, not only for the quantity and variety of prey, but possibly because these features most resemble tundra? In a lean year, when the lemmings are difficult to find, the owls may forego nesting altogether, waiting for a better year.

Great gray owls are physically larger than snowy owls, and they have those larger, crushing assassin talons. These can not only kill animals more than twice their size, but their powerful wings enable the great grays to fly away with their prey. Nevertheless, snowy owls can weigh between four and six pounds, with a five to six foot wingspan,. They are very thickly feathered for insulation, making them the heaviest of North American owls. This is helpful, as nesting on the tundra is not recommended for a long life when arctic fox, wolf and polar bear are prowling around. There are estimated to be about 200,000 snowy owls in the wild.

Camouflage and boldness are the keys to survival. Snowy owls have rounded heads, good for blending in with a white background, as well as those cat-like yellow eyes. The male, with his snowy white look, relentlessly dives at curious wolves and foxes, discouraging them from approaching, or at scurrying rodents, who have difficulty seeing the owl coming. The female more commonly defends the nest, while incubating the eggs and keeping the chicks warm, occasionally joining the male in hunting or skydiving intruders.

The snowy owl has great eyesight, which allows them to spot the lemmings, voles, rabbits, ptarmigan, ducks and even fish in shallows. They also have superior hearing, which helps them locate rodents hiding under snow or plants, while they’re cruising just above the ground. Raised feathers surrounding the eyes deflect sound to the ears. Sometimes hunting snowy owls just sit on a stump or high spot, watching or listening for movement. In successful hunting years, nests may appear to be wreathed with dead lemmings. As with other owls, the females tend to be about a fifth larger than the males, partly to be better able to defend the nest.

Courtship begins in March, with mating in May or June. The males fly in an undulating, showoff manner, or they deliver food to a female they’re trying to impress. As with many birds of prey, snowy owls are monogamous, mating for life. They defend territories of up to three or four square miles, and in rare instances, a presumably exhausted male may be supporting two nesting females, a mile or two apart.

The adults mate in April, as the snow is starting to break up, leaving a checkered patchy look to the tundra, which helps to disguise the female snowy on the nest, with her mottled plumage, dark patches against a white background. She lays her eggs she lays about 30 days later. The eggs start hatching in sequence about 30 days after that, about every other day, so older, larger siblings have a serious advantage when it comes to securing more food. This is particularly true if mom joins dad in the hunting, and the parents are basically continually dropping off prey, and going out again to hunt.

While siblicide is uncommon, infant mortality due to starvation is more common. Chicks may start wandering from the nest at about 30 days old. If the parents are successful in corralling the brood together, the chicks will stay with their parents until they are about two months old. They achieve adult weight within about two years and live an average of ten years in the wild.

Photo of a male snowy owl by Joe Kostoss of Eye in the Park.

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Steve Hall

Steve and Wendy Hall run the Adirondack Wildlife Refuge and Rehab Center in Wilmington. They've been rehabbing and releasing wild animals for over 45 years, specialize in predators, keep wolves as the cornerstone of their educational program, and have lived in the Adirondacks for the past 20 years. The Adirondack Wildlife Refuge became a non-profit about 10 years ago.

Visit www.AdirondackWildlife.org to learn more.

2 Responses

  1. That is a female snowy by Joe Kostoss. Steve

  2. Kameron McCorvey says:

    Absolutely beautiful animal. I have some fantastic shots of this same bird type from the refuge. They are silent, beautiful predators. The look you see in those amber eyes is amazing. It brings on a primal feeling when you lock gazes with this bird. So knowing. Dangerous and yet insightful in some way.

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