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Posts tagged “Irruptions

Few Northern Finches This Winter

11-27-13  pine siskin-irruption forecast IMG_8713Every year Ron Pittaway of the Ontario Field Ornithologists (http://www.jeaniron.ca/2013/forecast.htm) forecasts the extent to which birds in the Finch family are expected to inundate northern New England in the coming winter. This year’s forecast is not looking great for birders hoping to see influxes (irruptions) of northern seed-eating species such as pine siskins (pictured), crossbills, redpolls, grosbeaks and finches. The reason for the lack of inundations of feathered northern visitors this winter is that the Canadian crop of seeds that these birds eat is more than ample this year, making it unnecessary for most seed-eating birds to come further south seeking food. With the exception of white pine, there is an abundance of cone crops as well as birch, alder and mountain-ash seeds and fruits this year in the boreal forests of Ontario and southern Quebec. Although there will be some southern movement of these birds, this is not predicted to be an irruptive winter, which bodes well for seed-eating birds, but not so much for bird-seeking humans.

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Snowy Owl Irruption

Your chances of seeing a snowy owl are better this winter than they’ve perhaps ever been.  We are in the middle of an irruption (the migration of large numbers of birds to areas where they aren’t typically found) of snowy owls.  There are several reasons for irruptions, the most common being a lack of food in the birds’ normal wintering grounds.  When there is a seed crop failure (birch, maple, pine, spruce and hemlock) further north, we often are inundated in the winter with seed-eating songbirds that typically overwinter in Canada, including waxwings, redpolls and grosbeaks, among others.  Birds of prey typically irrupt at this time as well, for when the seed crop fails, the (seed-eating) population of rodents also crashes, driving rodent-eating raptors further south to find food.  Snowy owls dine primarily on small rodents called lemmings, so one would expect from the current irruption that the Canadian lemming population must have crashed.  However, the opposite appears to be true this winter.  Arctic researchers report that this year lemmings were at historical population highs allowing for a very successful breeding season for Arctic raptors, including snowy owls. The resulting population boom caused overcrowding and competition at typical wintering grounds, resulting in our current banner snowy owl winter.