This information has been gathered from the following experts and others mentioned in the text;
- Norman Smith started studying Snowy Owls more than 30 years ago.
- Tom McDonald from Rochester NY has been banding Snowy owls for 25 years.
- Denver Holt studies Snowy Owls on their breeding grounds in Barrows, Alaska.
Scott Weidensaul has been studying owls for many years and is one of the key researchers involved with Project Snowstorm http://www.projectsnowstorm.org/ . Visit this page to access some excellent information. Some text below is directly quoted from Scott.
Norman banded his first Snowy Owl in Massachusetts in 1977 and has been fascinated with them ever since. In 1981 he started a project at Logan Airport observing, banding and relocating Snowy Owls. He has spent countless days and nights in every imaginable weather condition each winter observing them roosting, hunting and interacting with other Snowy Owls as well as other raptors. He collects pellets, traps, bands, color marks and relocates them.
Birds are not welcome at airports for good reason, especially flocking birds. In 1960 Eastern Airlines flight 375 ingested starlings in the engines causing it to crash into Boston Harbor killing 62 people. Although Snowy Owls are not a high risk species because they do not fly in flocks they can and have caused damage to aircraft. From 1990 through 2012 at least 73 Snowy Owls have been struck and killed by aircraft across the continent (more than have been documented dying from starvation). For the safety of the planes and the owls they are trapped and relocate away from airports. Our own HBMO bander, Phil Roberts, performs this function at the Windsor Airport.
Owls are banded and color marked to aid in determining where they go and to see if they return to the airport. There are no documented records of owls being impacted by stress do to the handling and banding process.
Are most of these owls starving as many claim? There is a prevalent misapprehension that Snowy Owls move from the arctic in search of food, become emaciated and die. Norman’s 32 year database shows that in winters when owls are abundant the vast majority are in very good condition. Tom McDonald’s data shows the same as does that of other banders. Far from being emaciated these owls are generally in excellent physical condition.
Snowy Owls only breed when the lemming population is sufficient to support potential young. In Northern Quebec last summer was a great lemming year with exceptionally good Snowy Owl reproduction. Some nests contained as many as fourteen eggs. As is true of most raptors, when the young of the year leave their parent’s care they need to disperse and find their own space. When local populations are high this dispersal is amplified. They are pushed out by adult birds and need to travel farther south than they normally do. They generally arrive in the south in November and leave in April.
Do some of the owls that come south die? Inevitably yes. Like all raptors many young birds die from a number of causes. They pick up parasites, get fungal infections, they are hit by cars and planes and die of electrocution. They also perish as secondary victims of rodent poisons. Tragically, some are even shot. Undoubtedly a few are not good hunters and do starve. This winter in Massachusetts there have been ten dead Snowy Owls examined at the time of this writing. Four were hit by planes, one electrocuted, two poisoned, one hit by a train, one died from undetermined head trauma and one from internal parasites.
To date this winter 43 Snowy Owls have been banded at Logan Airport. Most are HY birds and all were in good body condition and weight.
Snowy Owls on the breeding grounds are diurnal because it never gets dark during breeding season. However, in winter, using night vision equipment, Norman has found that they do most of their hunting at night (which is also the best time to capture them). He has collected over 6,000 pellets. He has watched these master hunters capture an assortment of mammals and birds including mice and rats, rabbits, cats, passerines, waterfowl including geese, great blue heron, gulls, and even other raptors including American Kestrel, Northern Harrier, Short-eared Owls, Barn Owl, Saw-whet Owls, Barred Owl, Peregrine Falcon and even another Snowy Owl. Distribution trends and tracking during the current invasion seem to indicate that much of the transplanted population is preying on sea birds.
A number of owls have returned to the Logan Airport from 2 to 16 years after they were banded. It was assumed they made it back to the arctic but this had not been documented so a few years ago it was decided to equip some of them with satellite transmitters so they could be tracked. This had never been done with Snowy Owls before. Norman collaborated with Mark Fuller who put transmitters on nesting owls in Barrow, Alaska. Wintering owls in Massachusetts were also outfitted with transmitters. The owls from Barrow went north for the winter and stayed on the pack ice, probably feeding on sea birds, something that had not been documented before. Of the Massachusetts owls three were shot in Massachusetts, but the others made it back to the arctic in the area of Baffin Island. This proved that some owls do make it back to the arctic and come back to Massachusetts in future years. It also suggests that some adult birds may visit the south on a regular basis. Not just during invasion years.
A few words about aging and sexing Snowy Owls: Contrary to the impression given in many field guides aging and sexing these birds in the field is no simple matter. Like most owls you need to have them in hand to take measurements and examine plumage patterns and molt. The assumption that all very white birds are adult males, darker ones are female and very dark ones are immature is often incorrect. While these assumptions are undoubtedly true in a number of cases, and may even be true in the majority, there are enough exceptions to negate them as valuable field identification criteria. Snowy Owls are individuals with unique individual coloration. Researchers have noted, for example, that the last bird hatched in a clutch is invariably darker than the first, regardless of sex. A very dark captive Snowy Owl at one nature center in the U.S. is almost as dark now as the day it was fledged. Many visiting ‘experts’ look at it and proclaim it to be a hatch year bird. This Snowy has reached the venerable age of 18. In Russia, Irina Menyushina, who has been studying Snowy Owls on Wrangell Island for almost 30 years, has photos of birds that are almost completely white and have been sexed in hand as breeding females. Given these and many other variations noted during banding operations we can only conclude that aging and sexing in the field is risky at best.
HBMO Vice President
For more information about aging and sexing Snowy Owls from the Delaware Valley Ornithological Club, click here.