2012 has been the year of the invasion. An invasion of normally arctic-dwelling bird species has descended upon the northern tier of the United States. There have been upwards of 50-60 separate Snowy Owl observations in the state of Montana. The causes for the invasion are, most likely, due to a couple of synergistic factors: the owls have enjoyed several good breeding seasons in the North and the vole population in Montana has exploded. This event is called an irruption. The summer of 2011 saw massive numbers of lemmings scurrying across the tundra like fleas on the rump of a cur dog, and, therefore, providing the owls with more food than normal for their ravenous young. The 2011 crop of young owlets experienced higher than normal survivability due to the surplus of lemmings. This substantial increase in the population has meant that the available hunting territories in the North are over-capacity this winter, which has force many owls further south than usually seen. The great thing is once these owls made it south, they were treated to tons of voles here as well. The perfect storm of rodent population fluctuations and competitive territory allocation has led to the most enjoyable event for us Montana birders.
Summary of Montana Snowy Owl for 2011-2012
|Big Hole Valley||1|
|First People’s Buffalo Jump||1|
|Fort Benton (Hwy. 223, Milepost 7)||1|
|Freezout Lake WMA||2|
|Joplin (17 miles south)||1|
|McNeil Slough CBC||1|
|North of Dodson||4|
|S. Philips County||3|
|Rudyard (21 miles south/5 miles north)||2|
|South of Turner||1|
|South Valley County||6|
|West of Glasgow||1|
|Wilson Butte Road||1|
The red numbered pins reflect generalized counts for an area. The yellow diamond pins represent precise observation locations.
Download Google Earth version of this map
Another irruptive species that has been seen rather readily this winter has been the Common Redpoll. Common Redpoll irruptions are due to the success of the previous year’s seed crop. With lots of food available, the survivability of the young redpolls are increased. However, the next year these survivors are pressed to find food sources. So, they move farther south, and they end up on the alder trees in my little neighborhood. I see these birds in small flocks of around 20 individuals that have continually worked my neighborhood for the past 3 weeks. Occasionally, they are in mixed-species flocks with Black-capped Chickadees and American Goldfinches.