It is late June, evening twilight, and I am enjoying a stroll on a trail near my house. It occurs to me that last week we passed our cosmic halfway point: the summer solstice. Even though the day lengths are still nearly as long as they ever get during the year, I can tell that they are getting shorter. No, we’re not even close to summer’s “swan song” but those days will come all too soon and this weighs on my mind just a bit. Put another way, from here out, our daylight will wane until we pass our next solstice in late December. So, we’re at the “glass half-full or half-empty” phase of things.

Supposedly you can tell something about a person’s disposition based on how they answer the question “Is the glass half-empty or half-full?” As with many simplistic analogies, I find this rhetoric silly, even if I do understand the point that is being made. The whole thing reminds me of a personal story that dates back nearly 60 years; back to the time when I was just a lad. I had already endured a couple of years of Elementary School and had quickly come to the conclusion that school was a form of slow torture. I had also figured out that school only lasted part of the year and that my favorite season, summer, was a time when we were free from the horrible demands placed upon us by having to attend school. No, I wasn’t a trouble-maker or a delinquent; I just didn’t like being cooped up in stinky old Hoover Elementary.

I continue my crepuscular walk along the trail. I also continue my musings on the long-ago past: Yes, I am back in school feeling like the summer vacation will never come. But then, suddenly, it IS June, and we are all told that the school year is complete and that we are done until school resumes in September. Three whole months of freedom! I am in ecstasy; total liberty for the foreseeable future other than the meal and bedtime constraints imposed by my parents. The days pass and I fill them with exploring the fields and woods that are near my suburban home. I spend vast amounts of time poking along a creek that runs near to my neighborhood; there I catch frogs and crayfish and the occasional turtle, snake, and minnow.

More time passes and one day, when I return from the creek with a large, predacious diving beetle in a jar of water, my mom casually asks me if I’ve been having fun. I tell her that I have and that I love summer so much that I wish it would never end. Her response stops me in my tracks as she then informs me that “I had better enjoy it while it lasts because tomorrow marks the halfway point before you start back to school.” I am crestfallen, shocked beyond belief. She returns to her chores and I’m left standing there feeling like the ground beneath me has dissolved and that I’m falling into an abyss. The words “halfway point” echo in my young mind.

Later that day my mom notices that I have been moping about all afternoon and asks me what’s wrong. I was too young to really know how to explain the way I felt but I know now that it had something to do with my child’s brain coming to the realization that all things in our puny lives are irrevocably brief and finite. This is obvious to an adult, but to a 7-year-old it was devastating. I sulked about for a few days wondering what was the point of going out to play and having fun, it was only going to come to a crushing end and be replaced by school again.

Fortunately, when we are that young, we don’t stay in a funk for too long. There are too many daily miracles to catch our fancy. Eventually, I snapped out of it as some new species of snake or whatever caught my interest and suddenly I was investing all my time keeping my new pet in a home terrarium and offering it different food options to try and figure out what it would eat.

Well, with my long introductory reminiscence over, let me return to my evening hike -- a jaunt that is filled as much with “remembrances of things past” as it is paying attention to the vibrant world around me. For many creatures, their diel cycle is coming to an end. Most birds are creatures of the light; albeit, with several notable exceptions. But for some animals, the gloaming is their dawn, their reveille, the ringing of their breakfast bell. Many mammals fall into this category. At present, a few of both (diurnal and nocturnal wildlife) are active and during the past hour, I have seen a few statue-like deer watch me as I make my way along the trail. The deer stand stock-still and chart my progress, thinking they are invisible to me – and soon enough, they will be, as the light continues to fade. Deer are out during both day and night, but, in my experience, they seem to have a preference for the dark.

Among the birds, the behavior of being diurnal or nocturnal is more definitive, though many birds seem to be at their peak of activity during the dawn/dusk periods. When the trail comes to a forest clearing, the few bird species that are still active in the dim conditions become visible to me. In the open sky, I can see them, though not easily: they are swallows, but given the poor visibility I can’t be sure as to which of the 6 possible species I am seeing. I tell myself: “turn-off the biologist part of your brain, let them be any species, and enjoy them just for being creatures of Nature.”

As I ponder such thoughts, I can’t help but recall the line from the 1931 version of Dracula, famously uttered by Bela Lugosi, as he tells a late-arriving Renfield “to listen to the creatures of the night; the music they make!” I watch for the emergence of our local bats but here and now, in the sky above this small open field, I see only the swallows. The bats will be out soon though, and many of our local bat species are, in fact, dependent on trees for their solitary daytime roosts, since most are not one of the colonial species that roost en masse in caves or mineshafts.

I re-enter the wooded section of the trail and quicken my pace because I prefer to get back to the dirt road that will lead me home before I am enveloped by total darkness. I manage to avoid stumbling on the surface roots of the oaks or the lichen-encrusted cobble-sized rocks that are embedded into the path. I emerge from the woods and reach the dirt road as the last of the light fades. A wide-open sky is once again visible and I walk the final mile home in the company of fewer and fewer swallows and more and more bats and nighthawks. I have a flashlight in my pocket but refrain from turning it on; so entranced am I by the natural conditions. The night ahead may be one of our shortest, but it is more than sufficient for me.

I return to my earlier ruminations and reflect that today when I hear someone ask the question “Is the glass half full, or half empty” I no longer think in terms of optimism or pessimism. No, over my many years of training in ecology (both academically and in my choice of careers) I now see the query more as an opportunity for framing the notion of proper stewardship of our finite resources (and even “renewable resources” can be finite if they are badly managed). So, if you ask me how I feel about the half-full/half-empty glass my response is slightly complex: “The glass is at its midpoint, so we had better get cracking on conserving what we have left in the glass, especially if what we have in the glass is clean water or any other element of a healthy ecosystem.”

But I also think that such worries need not crowd my mind just now. No, I won’t fret about such things as half of this or none of that and instead, I savor my walk and let the world worry about itself. When I do get home I enter the house and, reluctantly, flip on a light. I walk straight to a bookshelf and open an anthology to read a bit of poetry that has been on my mind and I will close this article with that verse:

“The night never wants to end, to give itself over
to light. So it traps itself in things: obsidian, crows.
Even on summer solstice, the day of light's great
triumph, where fields of sunflowers guzzle in the sun —
we break open the watermelon and spit out
black seeds, bits of night glistening on the grass.”

— Joseph Stroud, "Night in Day," from Of This World (2009)