Snowy Owls Migration


Scientists and birders watching the extraordinary and disturbing midwinter migration  of hundreds of snowy owls from the Arctic admit that they don’t know why so many of the birds are departing their natural wintering grounds.
snowy owlOne observer used the word “unbelievable.” Another said that it was the “most significant wildlife event in decades.” Like the word ‘surprise’, the implications are not necessarily good. A heart attack is almost always a surprise.
Another watcher suggested that the mass migrations are the result of a bumper crop of lemmings last year, which led to snowy owls raising large broods – five to seven, as opposed to the usual two. Lemmings are the snowy owl’s primary diet.
Migration is nothing new to these magnificent birds, which stand two feet tall with a five-foot wingspan. In fact, every year a few leave their northern breeding grounds for such remote locations as Missouri, Idaho and Massachusetts.
In a normal season, these abrupt and solitary departures from routine and territory are very much like the anomalous environmental prompts that induce moose to wander far from their habitat (roughly north of 47 degrees north with a thumb extending down into the Rocky Mountains) to explore in solitary splendor the cornfields of Iowa and – even more occasionally – the second growth forests of Oregon.  
snowy owlsWhen moose do it, it is sometimes ascribed to a brain parasite, or brainworm (parelaphostrongylus tenuis) that causes neurologic damage and disorientation. The worm is, in effect, the moose equivalent of Alzheimer’s. Fortunately, moose can’t drive.
But neither the brainworm nor any other parasite is known to cause snowy owls to, literally, lose their place in the world. And certainly never before in recorded history in such numbers as are being documented this winter.
The migrations are even being described as “outbreaks”, as though they were a disease. And they may well be just that, though an illness whose cause is more obscure than a worm, and no doubt hidden in the reams of data surrounding global climate change and its causes.
This migration, amongst a species so remote it is difficult to study – and now deeply in decline thanks to a rapidly changing climate – may be like that fabled last flight of the condor  , whose final member was captured on Easter Sunday, 1987, in the bluer-than-blue skies above the San Mateo range in California.
For those lucky few who have seen snowy owls as far south as Oklahoma this winter, cherish the memory. You likely saw history in the making, and the end of a species.
da qui grazie

Snowy owls are drawing quite a crowd of onlookers across America as an ‘unbelievable’ mass migration continues to grow.
Bird enthusiasts are reporting rising numbers of the Arctic birds flying into the lower 48 states this winter in a mass southern migration.
Some states as far south as Texas have reported sightings of birds that are as white as the driven snow.
Fosters.com reported that one snowy owl has even made it to Hawaii.
Thousands of the snow-white birds have been spotted from coast to coast, feeding in farmlands in Idaho, roosting on rooftops in Montana, gliding over golf courses in Missouri and soaring over shorelines in Massachusetts.
Greater competition this year for food in the Far North by the booming bird population may have then driven  younger male owls farther south than normal. 
A certain number of the iconic owls fly south from their Arctic breeding grounds each winter but rarely do so many venture so far away even amid large-scale, periodic southern migrations known as irruptions.
'What we're seeing now – it's unbelievable,' said Denver Holt, head of the Owl Research Institute in Montana.
'This is the most significant wildlife event in decades,' added Mr Holt, who has studied snowy owls in their Arctic tundra ecosystem for two decades.
Mr Holt and other owl experts say the phenomenon is likely linked to lemmings, a rodent that accounts for 90 per cent of the diet of snowy owls during breeding months that stretch from May into September. 
The largely nocturnal birds also prey on a host of other animals, from moles to geese.
An especially plentiful supply of lemmings last season likely led to a population boom among owls that resulted in each breeding pair hatching as many as seven offspring. 
That compares to a typical clutch size of no more than two, Mr Holt said.
The surge in snowy owl sightings has brought birders flocking from Texas, Arizona and Utah to the Northern Rockies and Pacific Northwest, pouring tourist dollars into local economies and crowding parks and wildlife areas. 
The irruption has triggered widespread public fascination that appears to span ages and interests.
'For the last couple months, every other visitor asks if we've seen a snowy owl today,' said Frances Tanaka, a volunteer for the Nisqually National Wildlife Refuge northeast of Olympia, Washington.
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