Ecological Relations of Jaegers and Owls as Lemming Predators Near Barrow, Alaska
Pitelka FA, Tomich PQ, Treichel GW. 1955. Ecological Relations of Jaegers and Owls as Lemming Predators Near Barrow, Alaska. Ecological Monographs. 25(1):85-117
Avian predators common near Barrow, Alaska, at least in some years and preying primarily on lemmings are the pomarine jaeger (Stercorarius pomarinus), snowy owl (Nyctea scandiaca), and short-eared owl (Asio flammeus). Other species preying on lemmings but not on a significant scale are the parasitic jaeger (Stercorarius parasiticus), long-tailed jaeger (Stercorarius longicaudus), and glaucous gull (Larus hyperboreus). Predators were scarce in 1951; but they were present in numbers in the following summers and were censused over 7-9 sq mi near Barrow in June and July. In the three-year period 1951-53, their densities underwent striking increase. This change followed the upswing portion of the cycle in lemming numbers, which were low in 1951, moderate in 1952, and high in 1953. Pomarine jaegers did not breed near Barrow in 1951 and occurred sparsely. In 1952 and 1953, breeding densities were 4 and 18 pairs/sq mi, respectively. In the pomarine jaeger, the nesting cycle lasts 10-11 weeks. The breeding season of 1953 was 10-14 days ahead of that of 1952; also, egg laying occurred over a longer period and breeding activities in general were less synchronized in 1953 than in 1952. Unlike 1952, in 1953 the population included breeding individuals with subadult plumage characteristics. Nesting success was lower in the dense population of 1953 than in the sparse one of 1952. Pomarine jaegers are strongly territorial and remain so throughout the nesting cycle. Each pair occupies an all-purpose territory, as in many passerines. In the densely occupied area of 1953, minimal territory size was estimated at 15-20 ac, where in 1952, territory size on the most densely occupied area was approximately 110 ac. Snowy owls were uncommon in 1951. In 1952 breeding pairs were present on territories 2-4 sq mi; in 1953 the breeding density was not significantly different, but the total number of owls present was higher because of an increase in numbers of nonbreeders.
- Type
- Journal Article
- Authors
- Pitelka, Frank; Tomich, P; Treichel, George
- Units
- ARCN , BELA , CAKR , GAAR , KOVA , NOAT
- Keywords
- Arctic, Barrow, Birds, Breeding Biology, Diet, Foods, Foraging, glaucous gull, Habitat Use, Hunting, Jaegers, Lemmings, Long-tailed Jaeger, Mammals, Microtines, North Slope, Parasitic Jaeger, Pomarine Jaeger, Prey Species, Raptors, Shorebirds, Short-Eared Owl, Small Mammals, Snowy Owl, Tundra