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Eastern Screech Owl Nest-camPlease be patient while it takes a few moments to play. Download Windows Media Player 10.
Eastern Screech Owl Description
DescriptionScreech Owls are small owls that are somewhat variable in coloration. They are about 8 inches tall and generally adhere to one of two basic color schemes. The gray pattern is more common here in Western New York, but a reddish or “rufous” color pattern also is found here. Both color patterns are streaked and spotted on the body with broad bars on the wings and tail. The beak is gray with a hint of green. The most noteworthy characteristic of this owl that distinguishes it from New York’s other small owl, the Saw Whet, are the ear tufts. These tufts of feathers on top of the owl’s head do not in fact correspond to the location of the owl’s ears. They are used for camouflage when the owl is perching. A perched owl will sit almost vertically with its body stretched, eyes closed, and ear tufts extended. In this manner it mimics a broken branch quite effectively. Eyes are large and yellow. The eastern screech owl ranges from the Rocky Mountains in the west to the Atlantic Ocean in the East and from the boreal forests of Canada in the North to Mexico in the south. They prefer open forest areas with nearby meadows and fields where prey can be found. In many ways, the eastern screech owl is the nocturnal equivalent of the kestrel going after similar prey species and having similar habitat and housing requirements.
BreedingPairs of screech owls mate for life after a somewhat elaborate courtship that involves the male swiveling his head, bobbing his body up and down and winking his eyes. If the female appreciates his efforts she moves close, they touch bills, and mutual preening ensues. A Screech Owl will find a new mate if one of the pair dies. It has been reported that male Screech Owls will on occasion form pair bonds with a second female in good habitat with abundant prey. Nesting occurs in natural tree cavities primarily in deciduous trees. Screech Owls will also use tree cavities made by large woodpeckers such as the flicker and pileated woodpecker. As with most owls, no attempt is made to bring in nest materials. Screech Owls will readily accept suitable nest boxes such as those designed for kestrels. With our nest box, visits by the owls started about a month before the owls moved in permanently. Typically, we would see an owl enter the box and stay for about one to five minutes. Visits occurred just after dusk, in the middle of the night, and just before dawn. There was a flurry of activity about 3 weeks prior to the owls moving in, but then they disappeared and did not show up again until just a few days before moving in. Then the male would get in the box and make a long trilling call and the female would then enter the box. Both owls would then be in the box together with the possibility of some mating behavior observed. The female made a number of attempts to scuff the nest material that we had placed to attract a squirrel into a nest shape. She would shuffle her feet as she turned in the nest to flatten and shape the timothy hay in the nest. Note that this is not the ideal substrate for an owl, but the box was set up for squirrels. Wood chips or sawdust would be more suitable. The female did not stay in the box during the day until just a day before laying the first egg.
IncubationThe female Screech Owl does most of incubation with some assistance by the male. After laying the first egg, the female was seen to leave the nest and leave the first egg un-incubated all night long and part of the next day. She did not get down to business of continuous incubation until the second day after laying. Even so, there were long periods when she left the nest until the third egg was laid. We will be interested to see what hatching success there is since temperatures at the time of these absences from the nest were below freezing at times. The time of incubation for Screech Owl eggs is 26 days. We should start looking for the first signs of hatching about April 27. There was no sign of a second egg on the second day after the first. The clutch size is from 2 to 8 eggs with a norm of from 3 to 5. Normally, eggs are laid at a two day interval. On April 8 there were four eggs in the nest and the female continued to leave the nest for short periods to hunt.
BroodingScreech Owls raise only one set of young per season. They may re-nest if the first clutch of eggs is lost through predation or disruption of a nest site.
Division of LaborThe male has on occasion spent the day in the nest box with the female. He would sit either off to the side or sit in the entrance to the box, blocking the view of the female below. The male will supply food to the female while she is incubating.
FledgingTime to fledge after hatching is about 28 days. This is when the young start to leave the nest. The adults coax the young to leave the nest by calling to them and withholding food. Since the eggs were laid over a period of a week or more there is some difference in the stage of development of the young. The older youngsters will leave the nest first. Unable to fly well when the leave the nest, the young Screech Owls are adept at climbing and short hops to work their way up in brush and trees. The parents continue to bring food to the young and the female will roost with them. It takes from 8 to 10 weeks after leaving the nest for the young to learn to fly and hunt well enough to become independent of the parents. Shortly thereafter, the parents will force the young to leave their home territory.
Hunting and TechniqueScreech owls feed on a wide variety of small mammals, birds, and insects. They typically use their cryptic body shape to conceal themselves while perched, and then swoop down to capture their prey. Unlike Kestrels, Screech Owls do not hover when hunting mice. Hunting is done at night with much of the activity just after dark or just before dawn. Other prey items include earthworms, amphibians, and bats. The male does most of the hunting when the female is on the nest. We hope to make observations of prey species as the male brings food to the female, and the pair brings in food to feed the young. Uneaten food is cached for later consumption either in tree cavities or in the nest with the female. We observed an uneaten meadow vole in the nest for a full day before it was consumed.
TerritoriesThis owl is resident in an area and does not migrate. Breeding territories occupy 10 to 15 acres in wooded suburban areas and up to 75 acres in more open rural areas. The home range for screech owls is up to 200 acres. This area will contain one or more suitable nest cavities that the male will patrol and defend prior to nesting. A small area around the selected nest site is defended by the male screech owl but nests can occur within 164 feet of each other where prey and nest sites are abundant.
Threats to Survival and relationship to ManScreech owl populations here in western New York appear to be on the increase based on the increasing number of Screech Owls hit by cars in recent years (rehabilitation observations). Car collision appears to be a major threat to their survival since they fly low and at night. Screech owls are prey to larger owls, and some cannibalism has been reported. Their food source of small, short lived species makes them somewhat immune from chemical contaminants which concentrate in larger, longer lived prey species. Despite the threat posed by automobiles, Screech Owls appear to benefit from human activity since farming and clearing of land creates the mix of habitat types and spilled grain that encourages rodents. Suburban development also provides wooded areas in proximity to open areas with bird feeders and spilled grain that attract rodents. Screech owls help out by keeping the rodent population in check. |