June 18, 2008

Strange Happenings From Spring 2008


Unusual. Odd. Bizarre. All words, all adjectives and all descriptive of the spring that is quickly ebbing away. Now please, do not misunderstand. My choice of modifiers is by no means a criticism of our current season. After all, those same adjectives, along with the phrase "devilishly handsome," are oft employed by others to describe me.

Like many happenings in the natural world, this spring's unusual birding was no doubt strongly influenced by weather patterns. Weather patterns impact birds in a variety of ways, but two are particularly important now. The first relates to movements; the second, to food.

On a broad scale, weather patterns are a big factor affecting bird migration. For example, major northward movements typically coincide with strong flows of warm winds pushing up from the Gulf of Mexico. Conversely, heavy airflows from the north stymie such efforts. On a finer scale, weather patterns, interacting with topography, can determine the distribution of suitable habitat. A dramatic example is the availability of open water. The Bismarck- Mandan area is blessed with early opening water each spring, often occurring here several days before ice-out arrives in large portions of neighboring counties. It is not unusual for ice-out on and north of the Missouri Coteau around Max to be even later. The availability of open water dictates spring arrival dates for a host of wetland- dependent species, particularly waterfowl and blackbirds.

Many of the forces that dictate a bird's life relate to food. Food density, food quality and food availability are all important considerations. These are concepts to which I can readily relate. I, too, am concerned whether or not a fast-food provider offers double- burgers or just those little hors d'oeuvre thingamabobs. I, too, am concerned whether the side dish will be fries or, horror of horrors, spinach salad. And I am certainly fixated on whether the restaurant is even open. The latter point is something that all migrating birds, as well as all pre-Memorial Day birders, must plan for in unpredictable North Dakota.

I spend a lot of time in the field during spring, but as with most folks, my seasonal impressions are determined by where I am and when I am there. Overall, I would say that spring 2008 started out dry and cool in southwestern North Dakota and snowy and cool in the southeast portion of the state. Many of the ponds and creeks out west were dry. Much of the early snowmelt in the southeast occurred after the thaw, and so soaked into the soil, rather than recharging surface wetlands. By late April in the southeast and mid-May in some parts of the southwest, several blessed rain systems began an impressive green-up of the plains. The continuing cool temperatures, however, seemed to be the big story.

The impacts of this unusual spring were widespread and robust. Tree budding, and the onset of my spring allergies, were quite delayed. Grass growth seemed to be particularly retarded by low subsoil moisture and cool temperatures. Insect numbers have been especially low; even today, I have yet to swat more than a pint's worth of mosquitoes. These factors in turn affected bird migration. Northern sparrows tarried long here before moving north into Canada. Thrush migration was tardy by several days. Many other bird species showed up 10 to 14 days later than "normal," and numbers of several, such as the grasshopper sparrow, remain alarmingly low. Similar observations have been reported from birders along a wide swath of the U.S.-Canada border.

Flycatching and foliage-gleaning birds seem to have been the most dramatically impacted by spring 2008. Chimney swifts, swallows and purple martins have all had a hard time finding food on-the-wing. Vireos were not widely reported in North Dakota until the end of May. Less than two weeks ago, relatively large flocks of kingbirds were still moving north across the state. And, as if all this oddity was not enough, a bit of "bizarre" was sprinkled in. One of the best such illustrations was the snowy owl that my colleagues and I found on the Sheyenne National Grassland on June 4. The image of that radiant white bird appearing out of the mist to hunt low over the thick, dark green prairie is one I won't soon forget.

So as we bid farewell to spring 2008, I will close with saying that yes, you were unusual, and odd, and even bizarre. But dang, you sure were interesting, even cathartic. I can now better accept being called unusual, odd and even bizarre, myself. At least, as long as they find me interesting. Oh, and devilishly handsome.

(Dan Svingen is a biologist for Dakota Prairie Grasslands.)

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