This spring is the 26th I’ve spent on Martha’s Vineyard. From the very start of that run, Correllus State Forest established itself as my favorite place for spring naturalizing. And the third week of April likewise emerged as one of my favorite points in the season.
These preferences emerged from my relatively narrow interests back in those early days. Mainly, I went out looking for early-season butterflies, such as elfins and duskywing skippers, and my unofficial goal was to keep finding those species earlier and earlier in the year.
But it didn’t take long for me to realize that butterflies were just a small part of what was going on in Correllus in early spring. And likewise, I quickly pinned down mid-April as a strong inflection point in the progress of the season. Most years, quite abruptly, the natural world jumped then from “Not Quite Spring” to “Very Definitely Spring,” with dramatic changes happening literally overnight. And I realized that I loved, absolutely loved, that moment.
So a felicitous weather forecast for Sunday, April 20, impelled me out onto my favorite fire lanes in Edgartown and West Tisbury. Things had changed considerably since my last outing, a few days previously. But while I like to find surprises as much as the next naturalist does, this day did not produce any surprises at all. Indeed, the pleasure came from the certainty, amply confirmed, that I knew exactly what I was going to find.
Certain plant species were poised at interesting moments in their seasonal development. A few flowering tufts of Pennsylvania sedge were evident. The tiny, pinkish flowers of bearberry were starting to open. The basal leaf rosettes of colicroot had greened and grown just enough to represent enticing snacks for rabbits or deer, which had browsed nearly every example I came across.
One by one, the expected insects also materialized, often in very specific places that have reliably produced particular species across many years. On a particular 50-foot stretch of fire lane in Edgartown, for example, I noticed a number of the tiny pygmy grasshopper Nomotettix cristatus. Barely a centimeter long, these surprisingly rugged insects overwinter as adults and turn up along the fire lanes in early spring.
I’ve had little luck finding them the rest of the year, when I presume they clamber about concealed in the leaf litter. But I hypothesize that they use the sharp, linear edge of vegetation along the fire lanes in the spring as a mechanism to make it easier to find each other and mate.
While oblique-lined and purple tiger beetles had been active for weeks, April 20 also produced (right on schedule) my first six-spotted tiger beetle. The two former species are called “spring-fall” species, because in their complicated life cycles, adults take a hiatus and largely disappear during warmer months. Their six-spotted relatives, however, iridescent green marvels, can be thought of as a summer species, becoming active only when ground temperatures have reliably warmed, and then persisting through the early autumn. I like them.
Then there’s Tabuda varia, a “stiletto fly” in the family Therevidae that lacks a standardized common name. Fond of the sandy soils and austere habitats of the State Forest, this bizarre-looking insect has a narrow window of adult activity: All of my records for this species fall between April 9 and May 6, a healthy majority of them packed into a 10-day window in the second half of April.
And yes, the butterflies were out. I was a bit surprised not to find a Juvenal’s duskywing bopping along a fire lane amid the oaks that this butterfly’s caterpillars feed on. But spring azure and brown elfin, two other members of our early spring butterfly suite, put in appearances right on schedule, competing with bees to sip nectar from the first few blueberry blossoms.
And finally, my first field sparrow of the season sang from a branch overhanging a certain intersection of two fire lanes, where this species has nested every year since my arrival on the Vineyard. The song, an accelerating series of sweet, whistled, downward slurs, reliably begins in Correllus during the third week of April, and it’s worth a listen.
A key to the pacing of this part of spring, I am convinced, lies in the temperatures overnight. Diurnal creatures badly lost in a nocturnal environment, human beings prioritize daytime conditions in their thinking. Daytime temperatures surely matter in spring; but what really winds the clock is a string of nights that stay above freezing. The root systems of plants respond as warmth soaks into the soil; insects, sheltered underground, behind bark flakes, or in the leaf litter, rouse to enjoy the lengthening day and stronger sun.
All this would happen, of course, if I stayed home. But I wouldn’t miss it for the world, and on a day like that one, I feel like my purpose in life is simply to watch as nature stretches her wings and takes flight.