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Snowy Owl

Bubo scandiacus

Order:
Strigiformes
Family:
Strigidae
Sections

Priorities for Future Research

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We need more detailed studies on a host of topics concerning Snowy Owl life histories: using DNA and behavior to infer mating systems; behavior and physiology of wintering in the high Arctic; behavioral and time budget studies on breeding and wintering grounds; age of first breeding and age of senescence; lifetime reproductive success; mate and site fidelity; and almost all aspects of behavioral ecology. And we urge the replication of studies to buttress prior results. Below we highlight some of what we see as the most urgently needed topics to be addressed.

Satellite Tracking Studies

While satellite tracking has provided researchers with new information (i.e. summering and wintering locations, movement patterns, time and distance estimates), other data have confirmed much of what we already knew from observation, banding, and distribution records (i.e. migration dates and routes, wintering and summering areas). The future of satellite-tracking programs will benefit from follow-up with ground truth to determine why these birds are at specific locations on breeding and wintering grounds, and why they stay or leave – particularly in relation to changing food supplies.

Predator-Prey Relations

The fact that Snowy Owls depend on lemmings for successful reproduction has been known for centuries. How do Snowy Owls evaluate prey resources, deciding whether to stay or travel on during late April or early May, at the onset of breeding? Do the owls ever miss a population high of lemmings? Is the periodic Snowy Owl irruption migration a result of high lemming populations in a specific geographic area? Or, is there synchrony of the lemming “cycle” over wide geographic areas? What are nest densities in specific areas? How is nesting productivity related to various phases of the lemming “cycle”? Finally, we must commit more than a few years to determine that we have actually monitored individual owls through at least one, but preferably two lemming population “cycles.”

Given that Snowy Owl breeding success is linked to lemming population fluctuations, we must study lemmings in conjunction with Snowy Owl breeding. However, owing to such unpredictable lemming population cycles and amplitude variation through space and time, lemmings must be studied for long periods of time. Given that most lemming populations remain relatively low for years, and only reach high numbers periodically perhaps at 2-6 yr intervals, we need to monitor at least two population highs. We suggest monitoring lemming populations and Snowy Owls for at least 1o yr to provide reliable results.

Do Snowy Owls Occur In Distinct Sub-Populations?

Are there distinct groups of Snowy Owls moving throughout the Arctic tundra? Or, is there one population that travels throughout the Arctic in search of lemmings? Or, are males situated in specific geographic areas, showing loose large-scale site fidelity, waiting for lemmings to reach adequate population size, and for females to pass through these areas, and stop and breed?

Inferences regarding winter distribution south of the breeding range suggest that adult females winter farthest north and satellite-tracking results show that some females do winter at Arctic latitudes. However, satellite data have been skewed to females. We also need to determine if adult males winter at northern latitudes.

Social Signaling During The Breeding Season

Why are Snowy Owls the only owl species with such distinct sexual plumage dimorphism? Does female sexual selection or male-male territorial competition influence male plumage color? Why do male and female Snowy Owls delay plumage maturation for several years? These are interesting behavioral and mating-system questions that need to be tested.

Aging And Sexing In The Field Using Plumage

Aging and sexing from field observations remains difficult, even for experienced researchers. Using plumage alone can confound age and sex assignments, and thus reliability of some field studies. Furthermore, using plumage to age and sex individuals during early autumn when their new plumage has fresh dark marks, and later the same winter when the dark color fades, can confound ageing and sexing, even for the same individuals.

Killing Of Snowy Owls

We need to review policies of “legal” killing of Snowy Owls, e.g., the Alaska Fish and Game Department policy on the legal harvest of Snowy Owls. Is it really relevant in a modern world? Also the policy of shooting Snowy Owl that use airports as wintering sites -- is such killing needed when some airports trap and remove the owls to other locations (See Conservation and Management). We need a national policy to deal with owls (and other birds) at airports.

Population Estimates

We need better estimates of Snowy Owl populations, worldwide. Current estimates based on genetic analysis, and extreme extrapolations, are not adequate. To survey the vast Arctic lands of Canada, Russia, Scandinavia, and Alaska is challenging, but simultaneous surveys in different locations would help to bring more confidence to estimates of this owl's population status.

Snowy Owls As The Avian Icon And Indicator Of Arctic Conservation And Health

It is well known that if lemmings are abundant, Snowy Owls are abundant, as are foxes, weasels, jaegers, shorebirds, waterfowl, etc. By tracking Snowy Owls to breeding locations, we may annually learn of other areas where the tundra is experiencing a productive season. Thus, the Snowy Owl may serve as an indicator of healthy and productive areas of Arctic tundra (see Conservation and Management).

Band Data Review

Ca. 5,000 Snowy Owls have been banded in North America, in all Canadian Provinces and ~ 21 U. S. states. Analysis of these data is needed, comparing results (banding origin, return and recovery locations) to satellite tracking data.

Long-Term Studies

Only two Snowy Owl breeding season studies have lasted > 20 yr, and < 10 wintering studies have > 20 yr of data. Short-term studies provide a limited window onto the ecology of these owls. The most useful winter data have come from long-term winter banding studies in North America by dedicated citizen scientists. Furthermore, we also need breeding studies that focus on one location for many years, in addition to short-term studies that track breeders to new locations where nesting may flourish for a year or two.

Recommended Citation

Holt, Denver W., Matt D. Larson, Norman Smith, Dave L. Evans and David F. Parmelee. 2015. Snowy Owl (Bubo scandiacus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.10