[order] STRIGIFORMES | [family] Strigidae | [latin] Surnia ulula | [authority] Linnaeus, 1758 | [UK] Hawk Owl | [FR] Chouette eperviere | [DE] Sperbereule | [ES] Lechuza gavilana | [NL] Sperweruil
Subspecies
Monotypic species
Genus
In the genus surnia the form is stout, but larger and more hawk-like than nyctea; the wings and tail are long, and the legs rather short. It is found in the northern regions of both hemispheres, it is common in the fur countries, where it is often seen hunting by day, approaching the camps with great boldness. In summer it feeds on squirrels, mice, and insects, and in winter principally on the ptarmigan and grouse. This bird approximates to the falcons in its bold and diurnal habits, and in the absence of facial disk and ear tufts, smaller size of the head, smaller eyes, and less developed ears; its eyes are adapted for the dim light of snow-clad and arctic regions. The birds of this form inhabiting Northern Europe and the northern parts of America have been regarded as identical, in which case the genus would consist of a single species ; but some have endeavoured to show that the American bird is different from the European.
Physical charateristics
The Hawk Owl derives its name from its behaviour and in appearance, both of which are quite hawk-like. It is a medium sized owl – about 13 inches long (33 cm) and with a wing span of around 30 inches (76 cm). It has a small facial disk which is lowered in the brow region over the bright yellow eyes. The wings are large and, unlike those of most owls, pointed at the ends. The tail is very long for an owl and tapers towards its tip. Below, it is mostly white with narrow black transverse bars. In flight, the short pointed wings, long tail, and the speed in the air combine to give it a very hawk-like appearance. The leading edge fringes that assist silent flight in other owls are not well developed.
Listen to the sound of Hawk Owl
[audio:http://www.planetofbirds.com/MASTER/STRIGIFORMES/Strigidae/sounds/Hawk Owl.mp3]
Copyright remark: Most sounds derived from xeno-canto
| wingspan min.: | 74 | cm | wingspan max.: | 81 | cm |
| size min.: | 36 | cm | size max.: | 39 | cm |
| incubation min.: | 25 | days | incubation max.: | 30 | days |
| fledging min.: | 25 | days | fledging max.: | 30 | days |
| broods: | 1 | eggs min.: | 6 | ||
| eggs max.: | 10 |
Range
North America, Eurasia : North. The Hawk Owl can be found in Alaska, western and central Canada, and the most northerly areas of the US, Europe and Asia.
Habitat
Arboreal, northern limits closely paralleling southern limits of Snowy Owl, occupying fringes of forest tundra and boreal taiga as far as treeline, and ranging south to edge of forest steppe and cultivated lands. Seeks ready access to clearings, burnt areas, open peatlands, dry eminences or ridges and sparse woodland, including birch, aspen, and mixed woods; avoids dense coniferous forest.
Reproduction
Breeding starts in Finland end of March to late June. In Russia laying begins end of March. Male advertises potential nest sites, and the female selects one. The Hawk Owl does not build a nest. It lays its eggs in holes in the tops of rotten trees or in large holes in trees. It has little fear of man and will nest close to human settlements. Although the owls are territorial nests can be found as close together as 150 yards (140 metres) in areas where food supply is plentiful.
3-12 eggs, depending on food supply, are laid at intervals generally of one day, from mid-April to mid-May. Incubation is by the female only; the male hunting and bringing food to her. He will generally perch within 200 yards (180 m) of the nest. The regular presence of a single owl during late April is often a good indication that a nest is nearby. Incubation begins with the first egg and lasts for 28-35 days. If food is scarce, only the oldest and largest nestlings will get food and the smaller young will perish. The young leave the nest and start to branch out at 20-22 days old, well before they can fly. Hawk Owls are very aggressive at their nests and will attack any intruders. This is especially evident just after the young have left the nest. After the young are large enough to hunt for themselves, they disperse extensively within the boreal forest zone in response to food availability.
3-12 eggs, depending on food supply, are laid at intervals generally of one day, from mid-April to mid-May. Incubation is by the female only; the male hunting and bringing food to her. He will generally perch within 200 yards (180 m) of the nest. The regular presence of a single owl during late April is often a good indication that a nest is nearby. Incubation begins with the first egg and lasts for 28-35 days. If food is scarce, only the oldest and largest nestlings will get food and the smaller young will perish. The young leave the nest and start to branch out at 20-22 days old, well before they can fly. Hawk Owls are very aggressive at their nests and will attack any intruders. This is especially evident just after the young have left the nest. After the young are large enough to hunt for themselves, they disperse extensively within the boreal forest zone in response to food availability.
Feeding habits
In breeding season, almost wholly small voles with a few small birds and larger mammals; perhaps more birds in winter. Diurnal, and will hunt in bright sunlight; at least when young in nest, will also hunt at nightthough not then necessarily dark.
Video Hawk Owl
httpv://www.youtube.com/watch?v=M-FoCL2jQFE
copyright: youtube
Conservation
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be fluctuating, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Surnia ulula is a widespread resident in northern Europe, which accounts for less than
a quarter of its global range. Its European breeding population is small (as few as
9,200 pairs), but was broadly stable between 1970-1990. The extent of the fluctuation
in Russia during 1990-2000 was unknown, but the species remained broadly stable
overall. Although the size of the European population could render it susceptible to
the risks affecting small populations, it is marginal to a much larger non-European
population.
Surnia ulula is a widespread resident in northern Europe, which accounts for less than
a quarter of its global range. Its European breeding population is small (as few as
9,200 pairs), but was broadly stable between 1970-1990. The extent of the fluctuation
in Russia during 1990-2000 was unknown, but the species remained broadly stable
overall. Although the size of the European population could render it susceptible to
the risks affecting small populations, it is marginal to a much larger non-European
population.
Migration
Dispersive and eruptive. Like Great Grey Owl, leads an essentially nomadic life, dispersing extensively within coniferous (taiga) zone in response to regional variations in food availability. Population fluctuations follow closely cycles of rodent prey. When voles are at normal levels the birds breed and winter well north, while vole abundances can lead to large though temporary southward extensions to breeding range; but vole populations crash at intervals of 3-5 (usually 4) years, and Hawk Owl eruptions may then occur.
Most recent European eruptions (in 1956-8, 1961-2, 1964-5, 1971-2) have been on reduced scale compared with some earlier ones (this century: notably 1914-15, 1928-9, 1930-1, 1931-2, 1942-3, 1950-1), possibly because of reduced population size since early 1950s, but further large eruptions occurred 1976-7 and 1983-4. Erupting birds only infrequently cross Baltic, apparently a fairly effective water barrier, though during larger invasions vagrants have reached Britain, Denmark, and continental countries south to France, Yugoslavia, and Rumania.
Most recent European eruptions (in 1956-8, 1961-2, 1964-5, 1971-2) have been on reduced scale compared with some earlier ones (this century: notably 1914-15, 1928-9, 1930-1, 1931-2, 1942-3, 1950-1), possibly because of reduced population size since early 1950s, but further large eruptions occurred 1976-7 and 1983-4. Erupting birds only infrequently cross Baltic, apparently a fairly effective water barrier, though during larger invasions vagrants have reached Britain, Denmark, and continental countries south to France, Yugoslavia, and Rumania.
Distribution map
