Territorial Behavior of the Flammulated Screech Owl

Abstract

I had the good fortune to observe the Flammulated Screech Owl (Otus flammeolus) during the summer of 1938 at two localities, both in the Sequoia National Forest of the Sierra Nevada, in Tulare County, California. The first locality is the vicinity of Whitaker' s Forest (property of The University of California) on the west slope of Redwood Mountain. The life-zone is Transition, consisting of open forest of yellow pine, white fir, incense cedar, and black oak which lies just below the heavy stands of big tree, Sequoia gigantea. The results of observations made here from May 20 to July 9 and from August 6 to 15 are summarized on the accompanying map (fig. 26) and table (p. 73 ) . I found at least eighteen males, of which six were collected. Their territories, shown on the map, fall within an area of about two square miles between the altitudes of 4850 feet and 5800 feet. Females were heard or seen in five of these territories. One juvenal was obtained from campers near Whitaker' s Forest. The dates of observation (both successful and ' attempted) of each individual are listed in the table. The second locality is in the Canadian zone timber (Jeffrey pine, lodgepole pine and red fir) at Big Meadow, 7659 feet altitude, five miles east of Whitaker' s Forest. Four males were collected and one female was heard on July 10. These were found within an area of fifty acres. The female was heard there again on August 15. The eleven specimens from both localities are now numbers 74629-39 in the California Museum of Vertebrate Zoology.Success in locating, collecting, and observing the Flammulated Screech Owls depended on the use of a special method; namely, attracting them by uttering imitations of their hoots. Males readily answered these calls; but their shyness and their habit of concealing themselves in high, dense trees allowed no glimpse of them until their curiosity or antagonism was aroused by a long "conversation." Then they would follow me, uttering their curious "protest calls," and would allow themselves to be led into low trees and watched with the aid of a flashlight.The eye-shine of this species of owl varies in color from pinkish at middle distances to white at long range. At close range, no eye-shine is visible because the bird' s pupil contracts when a bright light falls upon it. I watched one bird at a distance of six feet, and noticed that a full eye-shine was visible for but a moment when the light was first turned on. Almost immediately, the pupils contracted; thereafter only two very small points of light were reflected. When the bird turned toward the darkness, a pinkish glint was reflected through the now widened pupil of the one visible eye.The single hoot of the male Flammulated Screech Owl is uttered at regular intervals, constant in each individual but varying from a little over two seconds to more than eight seconds in different birds. The hoots are short, uninflected vowel sounds like 00 in hoot. Their approach to a staccato effect can be represented by the words poop, poop, poop. Their pitch, fair...

Flammulated, boreal, and great gray owls in the United States: A technical conservation assessment

“…The remarkable crypsis of owl plumage against pine bark may be responsible for the nonrandom use of ponderosa pine as roosting sites in Oregon (Goggans 1986). Marshall (1939) noted that singmg sites were well up in tall trees. used radio-tracking to locate the exact tree s i n p g birds occupied in 22 cases.…”

“…Many field guides and compendia now refer to this owl as "locally common." Most authorities (e.g., , Richmond et al 1980, Marcot and Hill 1980 believe that because of its "secretive" habits the flammulated owl simply went undetected in much of its range until ornithologists and birders, following Marshall (1939, began imitating calls to incite vocal responses by territorial males. This procedure enabled collectors to begin an assessment of the U. S. and Middle American range in the 's and 1960's (Marshall 1967) but contributed little to understanding of densities [although up to 10 birds were sometimes called into one location (e.g., Johnson and Russell 1962)l.…”

“…A hunting bird locates prey from a perch visually, then flies to capture it aerially, to glean from needles (while hovering) or branches, or to pick it up from the ground. Marshall (1939) described hawkers as returning to the same perch while Reynolds and Linkhart (198%) described hawkers as landing on a new perch. Captive fledglings used their feet to capture prey, including moths taken in an upside-down position from a ceiling.…”

North American owls: biology and natural history

“…Evidently there was an initial competition for territories among males and later competition among females for obtaining established territorial males as mates. Marshall (1939) observed distinct territorial behavior among males of this species, judging that the territories were relatively small, usually under 300 yards (275 meters) in diameter. He also (1957) reported that in one year there were 18 territorial males in a distance of about 3.6 kilometers surveyed between Sunnyside and the head of Sylvania Canyon of the Huachuca Mountains, Arizo~a, or one territory about every 200 meters of lmear distance.…”

“…Density estimates are not numerous, but Marshall's (1939) estimates of 24 males in an area of about two square miles suggest an approximate density of about 1.9 males per 40 hectares (4.75 males per square kilometer), and other similar density estimates range from 1 to 5 males per 40 hectares (Reynolds and Linkart, 1987b). Winter (1979) found a density of about 5.3 males per square kilometer in similar California habitat.…”