There is much yet to know about bird migration. Oh sure, we've come a long way since the days of faulty beliefs such as swallows hibernating underground or hummingbirds riding upon the backs of flying geese. Still, many questions of how, why, when and where remain largely unanswered.
Recent technological developments - namely miniaturization of GPS trackers - are aiding biologists in the pursuit of this knowledge. Yet there remains a lot of armchair guessing. I contend that's okay. Without mystery there is no wonder, without wonder there is no chase, without the chase we cease to care.
For bird-watchers, this spring stands as one of the strangest migrations I can recall. Some birds seemed early, others late. Some appeared in decent numbers, others missing entirely. "I thought the shorebirds went through earlier than usual," said Sawyer, N.D. resident and birding expert, Ron Martin. "Warblers were on time but it wasn't very exciting." Another authority - David Lambeth, Grand Forks - weighed in: "It was very spotty. I don't think we had any days that were worth much."
The apparent causes for this have been a subject of some speculation among the state's birders. Weather may have played a big role. An exceptionally warm April covered a large area and likely influenced bird movements. "We had an early spring, so maybe they (birds) didn't have to stay around very long," said Lambeth. This is in reference to the notion that birds must stop intermittently to stock up on fat reserves in order to continue north. It's quite possible some birds didn't even stop. "In May there were a lot of clear nights with south winds, so I think a lot of birds just went over us," said Martin.
The wished-for circumstance among spring bird observers is a cold front arriving during the early morning hours of darkness (most birds migrate at night). This has long been held as the ideal condition for "grounding" birds, allowing for local viewing during the following day.
Most of this discussion is, of course, purely selfish. Birders want to see birds, particularly those which only appear briefly in spring and fall. Obviously, the birds don't cater to such whimsy. Instead, they are driven by forces of nature beyond our complete understanding. It's entirely possible migrants rode the wave of April warmth all the way to nesting grounds far to the north, thus withholding from us observers the pleasure of their visit.
Some think overall populations are one factor. "From my perspective, there has been a continual decline the last 30 years or so, and that's backed up by breeding bird surveys," said Martin. Others disagree. "I don't buy into the declining population models much," said Lambeth. Just another example of what we really don't know for sure.
It's entirely possible this spring's migration wasn't that unusual at all in the big scheme of things. Birders, after all, have been treated to some good years of late. Might we be comparing the common with the unusual? Lambeth thinks so. He said, "To some extent, we are comparing this spring to some recent exceptional ones."
Despite the apparent ho-hum migration, there were some notable "home runs," those uncommon-to-rare finds which make headlines among the birding crowd. Horace had another white-winged dove, two different great-tailed grackles were seen, a Kentucky warbler was one of just a handful of state records, and - a first for Cass County - a Eurasian wigeon was found.
The bottom line is this: Every migration is different. Some are good, some not so good, others are merely middling. To think we fully understand the causal vagaries of this grand and complex phenomenon is laughable. Personally, I like the allure of the mystery. It's what draws me to birding. I'm not alone. Lambeth said, "There are so many things to wonder about."