It’s September. Seize the moment.

gray seals, which can be seen swimming up and down the shoreline and occasionally hauling out in groups on the beach in the early morning. The growing seal population has attracted great white sharks, which in early autumn ply the waters frequented by the seals. On the beach, I came upon seals with gaping wounds – evidence of shark attacks. For the great white, a gray seal is breakfast, lunch and dinner.

Thus, amid all this burgeoning life, the solitary walker witnesses much evidence of nature’s darker side. One encounters the carcasses and bleached bones of seals, the dried-out bodies of gulls, terns and gannets, and along the sound side of the island, hundreds of the whole remains of the primitive-looking horseshoe crabs, which wash up from the shallows – individuals small and large that have died in numbers from some unknown cause (natural mortality?).

These are examples of another form of migration, from the land of the living to the realm of the dead – through an active and violent process, or a passive one. They remind us that life is short, and that life and death are parts of the same whole. I think of the perils faced by the shorebirds during their long flights over the ocean. I think of friends and loved ones who are mortally ill or who have recently died. I think of the safety of my family and friends scattered across the planet. I think of my own mortality as I enter the autumn of my existence. I think of the sandy island I am on – continually changing, reforming, shape-shifting – parts dying and parts being reborn.

Two stark points emerge from all of this lonely contemplation. The first and most obvious is that we should make sure, daily, to reach out to those dear to us and express our love. We never know when these loved ones will migrate from our lives. There’s never enough love in our world.

The second is that we should take note of and cherish the riches offered by nature’s changing seasons – the unusual surprises, as well as the benign predictability of the stately annual process. The transition from summer to autumn has close parallels with the passage of our own human lives. We should seize the moment. Live each day with passion. Savor each season’s natural transitions. Make the ephemeral eternal through the richness of preserved and cherished memory.

Beehler is a naturalist and author of 12 books, including “Birds of Maryland, Delaware, and the District of Columbia” and “North on the Wing.”