Territorial Behavior of the Flammulated Screech Owl

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, fairly constant in all males, is about B above middle C. A male begins hooting with very soft notes a little lower than the usual pitch (B-flat or even A) ; he gradually raises the pitch and increases the intensity until the full, mellow tones are reached at B. The hoot, although not loud, is resonant and penetrating; it can be heard up to a distance of two hundred yards.Its baffling ventriloquial quality is noticeable when tbe birds call overhead.The outstanding feature of the call is its almost endless repetition.The first male met with at Whitaker' s Forest (my number 377 in territory E) hooted almost continuously throughout the night of May 20.It maintained an interval of a ' 76 THE CONDOR Vol.XL?