The annual return of spring is a gradual development marked by innumerable minor events, changes in the behavior of wildlife, and (perhaps more obvious) alterations in the vegetation (greening of the grass, the appearance of the first crocus). Being more of a zoologist than botanist, I'm more attuned to the faunal than the floral changes, and yet invariably I wrestle with identifying which changes to imbue with the greatest significance.
This year, for example, I have long been aware of increasing territoriality and 'breediness' among some of the raptors that I spend time watching. Golden Eagles, Prairie Falcons, and Northern Harriers began back in January the undulating flight displays that serve to both establish their claim on a breeding locale and advertise their readiness to begin the courtship process. But though those January days were clear and blue and beginnning to lengthen, it still most definitely felt like there was a good bit of winter still to be endured.
Not long ago, the grassland birds (especially up in the Columbia Plateau) began to dramatically alter their behavior. The Horned Larks, which had been covorting for long months in large flocks, have begun pairing up, and they will, accordingly, be one of the first songbirds to nest (and some of them will successfully produce 3 broods this year). In Western Meadowlarks, the behavioral change is even more significant. They have also flocked up for the winter, but throughout that season remained almost unobserved, staying on the ground, silent, flying seldom, and not even bothering to post a sentinel. In recent weeks, they've suddenly 'popped up,' with males especially (though you can't tell the gender by looking at them) now spending most of their day perched high and singing lustily.
The medium-sized ground squirrels (Washington, Belding's, Merriam's, and such) have--within the past week or ten days--ended their long period of estivation-followed-by-hibernation that began last July as the shrub-steppe and grassland habitats they occupied dried up and quit producing the grasses and forbs on which they feed. Their reemergence causes movements of hawks and even eagles, and the annual population levels of these squirrels has a significant effect on the productivity of some raptors, notably Ferruginous Hawks and Prairie Falcons.
There are many spring milestones yet to occur--the arrival of the first Osprey (from wintering grounds in southern Mexico, Central America, and northern South America), the first Turkey Vulture, and the first Western Kingbird (to name a few). But yesterday I experienced another notable spring first, one that reminds me of the inevitable progression of the seasons. I saw my first nesting Great-horned Owl of the year, a female in Morrow County sitting on eggs on a stick-nest (originally built by Red-tailed Hawks). As a member of one of the first bird species to nest each year, this female will undoubtedly sit tight through many days of winter-like weather still to come, but by the time her young are beginning to flex their flight muscles, spring will be back in all its cacophanous, riotous glory.