by E. Vernon Laux, Photo by Greg Hinson
The entire Northeast, especially the Cape and Islands, experienced an incursion (called an irruption) of snowy owls from the Arctic during the winters of both 2013/2014 and 2014/2015. This was the mother of all snowy owl irruptions to our region, and it seemed no beach parking lot, row of dunes, or marsh was devoid of these charismatic, large and spell-binding, diurnal white owls. The invasion of snowy owls during the winter of 2013/2014 was the largest that had ever occurred in this part of the world.
Snowy owls were much in the news then, with the shocking revelation that at Kennedy Airport in New York the authorities issued a kill order, and a couple of these remarkable birds were shot by “wildlife experts”. This information, once made public, caused general outrage in the birding community. A petition was circulated and within seven hours and some 3300 signatures later, the New York Port Authority announced that snowy owls would no longer be killed, but would be trapped and relocated. This is what has been happening at Logan Airport in Boston since 1981.
Snowy owls are attracted to runways and to wide-open spaces when they come south. That landscape resembles their tundra habitat. They are not familiar with planes, and apparently are not fazed by the noise. They are a problem at major airports when they do irrupt south and collide with jets. But, as has been done at Logan for many years, the owls are fairly easy to trap, where they can be studied, measured, banded, and have transmitters attached. Then they are relocated away from the airport, thus removing the hazard for both the bird and the flying public.
These irruption movements are fascinating and engaging for birders and the general public alike. Snowy owls and other predators have cyclical populations linked to prey abundance. Lemming population cycles likely drive much of the survivorship and breeding success of snowy owls. (Lemmings are small Arctic-dwelling mammals resembling fat mice.) We know snowy owls will skip breeding seasons when prey is scarce and may produce large clutches of up to ten eggs when prey is abundant.
Although lemming scarcity is often implicated in snowy owl invasions, a bigger driving force may be highly productive breeding seasons. Periods of high summer lemming populations may drive these invasions more than lemming scarcity. The high number of first-winter owls provides evidence that high breeding productivity is a major factor in these invasions.
Snowy owls are highly mobile. In addition to winter movements, they may move hundreds of miles across the Arctic in summer searching for areas with abundant lemmings. In areas where prey is abundant, snowy owls may nest in relatively high density. In addition to rodents, snowy owls eat lots of birds, especially water-birds, like ducks and alcids. The role of seabird populations in these invasions is not well understood, but many owls on the Great Lakes and on the Atlantic Coast prey heavily on water-birds, flying out over the water to hunt them, especially at dawn and dusk, which is called crepuscular activity.
Keep your eyes to the sky as the snow starts to fly. You may catch a glimpse of our Snowy Owls over the island this winter!