Great Horned Owls at Nisqually

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The riparian forest in winter is generally a quiet place. There is the occasional mixed flock of kinglets and chickadees, but it’s possible to walk all the way through without seeing or hearing much of anything. Every now and then, though, there is a rare gem, the type of wildlife sighting opportunity that makes the forest a place never to be missed. The sound of deliberate pecking on wood might indicated a sapsucker or pileated woodpecker. And a cacophonous eruption of crows calling and cawing might indicate a real prize: the presence of owls and owlets. The crows may continue their harassment of owls for hours on end, and it can be a bit alarming to watch – visitors often worry the owlets are in danger.

The crows have good reason to be upset. The owls are their primary predator. In fact, the owls are likely to hunt almost anything that moves, with the exception of large mammals. At Nisqually, most common prey likely include voles, mice, squirrels, rabbits, and the nestlings and juveniles of all the local bird species: in wetland ecosystems including Nisqually, owls have a special appetite for Coot. Mostly, though, they tend to stick to the forests and meadows where short, broad wings are ideal for maneuverability. The owl kills primarily through the crushingly powerful grip of its talons, which are so strong they can be used to sever the spine of larger prey animals. Any animal too large to be swallowed whole can be torn apart by the sharp beak. Owls are, in other words, a formidable predator.

All the macabre violence of their predatory daily life is easy to overlook when the adorable owlets appear. Few things on the Refuge inspire as much excitement during the winter and early Spring. Through January, local birders are on the edge of their seat with anticipation, checking everyplace of potential interest. Just the same, they often will have missed the nest’s actual location; such is the stealth and secrecy of the owls. Sometime around the beginning of February, the fuzzy gray heads of owlets will appear in the opening of a tree. Word spreads fast, and the trails of the forest become noticeably busier as nature enthusiasts flock to the Refuge to watch the show.

It may come as a surprise that the owlets appear so early in the winter, when snow and icy storms are still so common. The owls fledge about six weeks after hatching, and hatch after about thirty-three days of incubation, so at Nisqually the owls are sitting on their eggs around Thanksgiving, when the last autumn leaves are still falling from the trees. Their young have hatched by around New Year’s Day. No other bird lays eggs so early. What advantage is there to laying eggs and raising young so early in the winter? The answer is simply that raising young early means less competition for food from the many other species of raptor who share the same preferences for prey. It is a competitive adaptation.

Another adaptation that may seem a bit counterintuitive involves incubation. Most birds delay incubating their eggs until after laying the entire clutch so that all the eggs will hatch simultaneously. In contrast, Great Horned Owls incubate their eggs as they lay them, causing them to hatch in a staggered way: rather than hatching all at once, they each hatch several days apart. This ensures that at least one owl, the oldest, will have enough food to eat and will survive to adulthood. The next owlet will have to compete with its older sibling for food, and will only survive if abundance of food permits. This is even truer for the third owlet in a clutch, typically a full week younger than the first born. If three owlets all hatched at the same time in a year when food is less abundant, all three might starve or succumb to disease. Staggering the births nearly guarantees successful reproduction. Owl broods at Nisqually typically include two chicks, but last winter there were three and all survived to adulthood, indicating a healthy environment with abundant food.

Great Horned Owls are fairly sedentary creatures, living their entire lives in a small area. The nesting pair so visible around the Twin Barns Loop trail at the Refuge are likely the same pair, year after year. Though they are not as visible during the summer months, they are still here, lurking in the shadows. They continue to feed and raise their young through the spring and summer until the juveniles can hunt on their own, perhaps as late as July or August. And then, somehow, no longer dependent, the juveniles fly away to find their own territories, never to be seen at Nisqually again.