Flight Lines: Birdlife noticeably absent this winter
Take a look around the state at recent bird reports and a person can't help but arrive at a somewhat ho-hum conclusion: There really isn't much out there. Oh sure the usual suspects are around, the chickadees, house sparrows, woodpeckers, etc. But in terms of "good" birds - the ones which stir excitement and motivate some folks to take a drive to see them - there really is a palpable scarcity. And it's not just me. I put this question to grasslands biologist and bird expert, Dan Svingen, of Bismarck. He said, "This is one of the more uninteresting winters that we've had in decades."
Why? For what it's worth, I've given this much thought during the dreary weeks of cold relative darkness and come to a few conclusions - some concrete, some theoretical. First, there is a cyclical mechanism at work with regard to northern birds which infrequently winter here. Take common redpolls, for example. Last winter there were easily tens of thousands in the state. This winter I've seen two and that was in November. Most of these winter travelers flourish by following food sources, whatever that may be. According to Ron Pittman's winter finch forecast released last fall, most of these birds had ample supplies farther north so winter expectations here in the states were low to begin with. He wrote, "The theme this winter is there will be no major finch irruptions outside their normal ranges."
Okay, that pretty much satisfies one part of the equation. But that still leaves the question open for others such as vagrant rarities and overwintering common birds. How come we're not seeing more of them? First, there are always inescapable demographics of North Dakota itself. We have relatively few people, thus few eyes. Of those, a tiny percent consider themselves bird watchers. Then there is the issue of access. Thousands of miles of township roads are currently impassable merely because of snow cover. So it's entirely likely a few birds out there are going unnoticed. But that doesn't explain all of it.
Snow has to be one of the factors in play. What biologists call cover - those places of refuge occupied by critters of all stripes - is being compromised, in my opinion, merely by the depth of snow. Take cover away, and the bitter winds which frequent our little corner of the world become that much more challenging. Not only is that the case, but food is being buried too. Svingen said, "There aren't a lot of areas in the state where you have snow-free places. That's fine if you can still access the food. But in places like Bismarck and along the Sheyenne (river) the snow is deep enough where frankly it's just sealing up a lot of the waste grains that would otherwise be used."
Interestingly, Svingen thinks the root cause may have begun months before the chilly north wind hit the plains or the first snow flake fell last fall. He said, "If you recall, spring of 2009 was characterized by odd weather resulting in delayed phenology; crops went in late, butterflies emerged late, and bird migration was off by up to two weeks. I think that screwed up not only nesting but I think it also screwed up food resources."
He's referring to a weakened link in that classic food chain we all learned about in grade school. In this case it's the lowly but vital herbivore, the bug. Remarkably, we experienced little in the way of pest bugs last year despite the widespread high-water. Svingen said, "Although that made for pleasant living, it certainly wasn't suitable for flycatchers (a fairly large family of birds) for example."
"So many birds rely on insect prey that I think a lot of species didn't do well. And with the lack of reproductive success, there was just far fewer birds to get lost and provide exciting birding or attempt to winter and provide variety," Svingen said. He may very well be on to something.
Take all the factors mentioned above and combine. Add a dash of natural cycles and a pinch of 'we-just-aren't-sure-why,' and I think you end up with a reasonable recipe to fairly accurately explain this winter's bird shortage.