Breeding Behavior of Jaegers and Owls near Barrow, Alaska

Pitelka, Frank; Tomich, P; Treichel, George

Noteworthy observations on breeding behavior of the Pomarine Jaeger, Snowy Owl, and Short-eared Owl near Barrow, Alaska, in 1952 and 1953, are reported. The breeding of all three depends here on the availability of brown lemmings, which in 1953 passed through a cyclic high. Breeding pairs of the Pomarine Jaeger establish territories on marshy flats and extensive lowlands characteristic of the arctic coastal plain. Clutches of 1 or 2 eggs are laid; there is no satisfactory evidence that clutches in this species may be larger. Incubation lasts 27 to 28 days. Young are dependent for at least six or seven weeks. The nesting cycle lasts 10 or 11 weeks. Territories subserve functions of reproduction and self-preservation. Territorial behavior, comparable in the two sexes, continues throughout the nesting cycle. In all basic features except vocal announcement, which is lacking, the territorial behavior of this jaeger resembles that of many passerines. A display ritual apparently functioning in pairing and pair-bonding is described. This species of jaeger does not perform a distraction display. Near Barrow, Snowy Owls typically place nests on high ground adjacent to a gently sloping drainage axis. Breeding pairs are spaced out and in this sense truly territorial as might be expected with a large predator, but good evidence on defensive and aggressive behavior is lacking. The nesting cycle is estimated to last three months, probably 3 1/2 months. A courtship display of the male is described. By contrast with the other two avian predators depending on lemmings, Short-eared Owls nested near Barrow in 1953 but not in 1952. Territories were established in early June. First eggs were laid from June 6 to 23. Incubation required 28 to 30 days, the female alone incubating. Young unable to fly left the nest cavity at ages of 17 to 30 days. Early in June aerial display serving in territorial establishment and announcement was frequent, as also aggression among ne

Breeding Behavior of Jaegers and Owls near Barrow, Alaska

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