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| Document Type: | Article |
|---|---|
| All Authors / Contributors: | Richard J Clark |
| ISSN: | 0084-0173 |
| OCLC Number: | 479751899 |
| Language Note: | English |
| Notes: | Adult male short-eared owl over a nest east of Marquette, Manitoba, Canada. (Photo courtesy of Robert R. Taylor, Manitoba Museum of Man and Nature.) Fig. 1. Geographic distribution of the short-eared owl shown in relation to food habits. Circles indicate localities of food habits studies. White indicates percentage of diet that was voles (Microtus spp.), black is other foods. Shaded area indicates the zone of permanent residence. Fig. 3. Nature and location of winter communal roost sites of short-eared owls studied. Roost names appearing in the text: A Niagara, B Cayuga, C Seneca (#1), D Tompkins, E Tioga, and F Seneca (#2). Fig. 4. Nesting sites of short-eared owls in the Manitoba study area where observations of breeding behavior were made. Fig. 5. Reporting regions of the American Bird (formerly Audubon Field Notes). A, B, and C refer to groupings listed in Table 3. Fig. 6. Aggressive and agonistic displays of short-eared owls. (A) The deep wingbeats of the Underwing display. The wings are about 50 degrees above the horizontal plane of the body. (B) Side view showing the exaggerated depth of the wingbeat, which along with the slowness gives the owls flight a moth-like appearance. Note the teardrop shape of the body in flight. (C) Dorsal Wingspread, typical threat of many members of the family Strigidae. (D) Distraction flight. The owl volplanes over the vegetation with wings and feet extended. (E) Low intensity Wingclap of the female. Three different females were observed to start the Wingclap but the wings were not struck together. The result of this display was the creation of a pulsating "whoosh" of air. The male strikes the wings together while performing the courtship Wingclap. (F) Sashay flight is accomplished by an asymmetric wingbeat causing the owl to rock back and forth as it descends. This perhaps serves to display the wing undersurface. Fig. 7. Audiospectrographs of some vocal displays of the short-eared owl. (A) Pssssss-sip (food-begging) display of an owlet (semidiagrammatic). This ventriloquistic call is given by the young as they roam through the grass, or perch, awaiting the arrival of a parent with food. (B) Chitter display of mild aggression. (C) Voo-hoo-hoo-hoo (courtship) display of male. Fig. 8. Feeding behavior of the short-eared owl. (A) The prey is sometimes held in one foot and torn apart. (B) Usually, the prey is held against the perch with both feet while being torn apart. Note how the tail is used to counterbalance the head. (C) The legs are used for increased leverage in pulling on the prey. Note nictitating membrane drawn over the eye. (D) Typical body position during and following the swallowing of prey. (E) Alert feeding position. (F) Defensive position while guarding food; note the crouch. Fig. 9. Maintenance behavior of the short-eared owl. (A) Typical warm weather perching and sleeping position. (B) During cold weather the owls sleep with neck withdrawn, wings pulled in tight, body crouched with one leg pulled up into the abdomen feathers which are fluffed. (C) The very flexible neck allows the bird to preen nearly all parts of the body. (D) Ear and face scratches are direct and the foot is usually held in the zygodactyl position. (E) The two-wing (=double-wing) stretch. The wings sometimes nearly touch over the back and occasionally are directed forward. This same attitude is sometimes assumed during elimination of the mute. Fig. 10. Hunting activities of a marked wintering short-eared owl (Right-two) for the evening of 4 March 1969. (A) Location where Right-two was trapped 23 February 1969. (B) Observation station. (C) Roost site for 4 March 1969. Fig. 13. Hunting territory of Right-two as demarcated by aggressive encounters on the evening of 2 March 1969. (A) Roost site of Right-two for 2 March. (B) Location from which I made observations. Arrows indicate direction that moving encounters followed. Fig. 14. Hunting territories of resident owls compared to that of Right-two (a marked bird). A-E locate points where another marked bird (Left-two) was observed in the period 26 February-17 March 1969. Fig. 15. Breeding territories of the short-eared owl (Manitoba) for 1968 and 1969. Fig. 16. (Upper) Activities of a mated male short-eared owl (during early courtship) for the evening of 13 April 1969. a. Roost site for the female. b. for the male. (Lower) Activities of the male (later courtship) for the evening of 16 April and morning of 17 April 1969. Fig. 17. Nest-sites of the short-eared owl. A scrape (Upper) shows the dark earth where vegetation had been removed. The female (Middle) can be seen just leaving a nest of green vegetation in a stubble field. On a hummock (Lower) was situated a short-eared owl nest, there is an owlet just below the dark spot in the center. Fig. 19. Local shifting of a winter assemblage of short-eared owls (Niagara roost) in 1969-1970. Fig. 20. Some banding recoveries of short-eared owls. The point of banding and recovery are connected with a broken line. The arrows show direction only insofar as they point from banding to recovery. Numbers correspond to birds listed in Table 20. Fig. 21. Location of National Wildlife Refuges providing data tabulated in Table 21. |
| Awards: | |
| Other Titles: | A Field Study of the Short-Eared Owl, Asio flammeus (Pontoppidan), in North America |
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