The Mourner-in-the-Mist

With severe global cooling causing the gradual decline of the massive towertrees, the final stronghold of the immense and awe-inspiring boomsingers - high-browsing placental birds - is lost in the mid-Ultimocene ice age. The largest land animals that had ever lived upon Serina, the boomsingers had a rare combination of attributes that let them surpass most other vertebrates upon Serina, namely lightening air sacs in their bodies and hollow matrixes in their bones, and not two, not three, but four weight-bearing legs to support their great size. Boomsingers during their peak in the early Ultimocene reached heights of fifty feet, with extremely lanky legs and long upright necks. Lacking a balancing tail, their anatomy more closely resembled large ungulate mammals than more (relatively) close relatives such as sauropod dinosaurs, and they were exceptionally tall for their weight of no more than fifteen tons. With resonating chambers in their nostrils, boomsingers called loudly across the plains with explosively noisy bursts of low, partly infrasonic sound to communicate even over vast differences. Their enormity meant they could afford a gigantic fermenting stomach to break down tough plant material, and their great size allowed them to stay warm primarily just by existing, with little need to actively maintain body heat via special metabolic processes - they were largely gigantothermic.

Boomsingers were specialists, and specialists rarely do well in the face of change. Yet they were not entirely helpless to shifting environmental conditions. As the climate cooled, some boomsingers became smaller and more densely feathered again, adapting for a time to survive a cooling climate within smaller and more reduced patches of forest. A handful of small species followed the forest as it retreated south to the coastline of Serinarcta, until the bitter nightly wind pushed once tall trees down near the ground into stunted, frostbitten shrubs, selecting for shorter and smaller boomsingers over generations. But without the benefit of their immense height, they lost their primary defense against predators as well as their competitive advantage over much more efficient molodont herbivores. They were soon unable to survive on the mainland, their vulnerable calves caught by predators before maturity, with even the adults barely finding enough food to sustain themselves. Today the boomsingers are extinct on Serinarcta.

But one species still clings to life upon a small offshore island in the icebox seaway, a refuge twelve miles offshore from the coast where once the towertree taiga grew. With an area of just 4.5 square miles, the island supports no other terrestrial animals and few plants except short dry grasses and thorny, inedible shrubs. There are no trees, and no food source that would seem able to support a giant browser on this cold, wet rock in the sea, which for most of the day is shrouded in a heavy gray mist. Yet it is here, on this barren waste, that the last boomsingers cling to a precarious life, one made possible only by the fact that no thorngrazers, and no predators, have yet reached it.

They swam here about 500,000 years ago, before the land they left was completely uninhabitable. Perhaps they were chased out to sea by predators, or they were merely juveniles following an instinct to disperse, blindly, to anywhere in hopes of finding their own habitat. The founding population was extremely small, and so upon the island the population very quickly diverged from its ancestors and became genetically distinct. With no trees, they were forced to graze what little vegetation could be picked off the ground, awkwardly splaying their legs and lowering their necks in a posture uncomfortable at best. Sparse food resources led to further and drastic reduction in size as they were subjected to island dwarfism, and a combination of prolonged hunger and a size too small to allow for a strong fermenting stomach led to more adventurous feeding habits. The castaways learned to scavenge easier-to-digest seaside refuse, seaweed and even carrion that washed up on the shore of their island in the tide. They supplemented their diet with the eggs and defenseless nestlings of the few seabirds which nested on the tiny isle, digging up their burrows to access this vital source of protein and trace minerals (not an easy task for an animal that long ago lost all of their claws and nails and was left with feet made up of nothing more than a soft fleshy pad.)

The mourner-in-the-mist is the very last of the boomsinger lineage, a stunted creature that now stands only a few inches taller than a human and weighs less than four hundred pounds - barely larger than the newborns of its early Ultimocene ancestors. Its name comes from its plaintive and melodic voice, akin to a melancholy humming that fills the misty air of the island every dawn and carries far offshore when the ocean is calm, so that the island itself seems to sing its own lament at its fate. The mourner is now almost exclusively dependent on eating seaweed and other debris brought in by the waves, gathering at low tide to graze as much as they can and then retiring to higher ground to rest while the tide comes in. Their diet is low in copper and some other necessary trace minerals, so they are now extremely good at processing what little their diet does include, to the point that a normal diet of land plants would now be toxic to them. To feed, they awkwardly splay or simply kneel down on their knees, a posture that would leave them extremely vulnerable… if only anything lived on the island that could hunt them.

The mourner is, evolutionarily speaking, a desperate last-ditch attempt of a species to survive in a niche it was never supposed to. It is only because they are the only land animal on the island, and so nothing even slightly better adapted is there to stop them or to eat them, that they manage to exist. But even with these things in their favor, their long term odds of survival are still low. There are no more than 150 of them alive at any time upon their isle - a number that could be completely lost in just a single unfortunate event, such as an outbreak of disease, and their population is shrinking. Inbreeding depression has reduced their fitness, and many of their calves are born stillborn. Those that survive show an increasing quantity of accumulated deleterious genes affecting immunity, digestion, and organ functions that result in a low life expectancy.

It won’t be predators or competitors that will be the end of this relict species, but inescapable, destructive changes within themselves. For though they have adapted against all odds to survive at the very fringes of their world, escaping to their isolated refuge, they cannot escape their own genes.

Mercifully, they do not comprehend their circumstances. Their cries, mournful as they may sound to more thinking minds, are not songs of hopelessness at their fate, but merely proclamations of territory. Until the very end, the mourners-in-the-mist will carry on their instinctive lives, doing what every creature does until their last breath: trying to stay alive. Eventually the day will come that they fail, but so too - eventually - will this fate befall every creature upon Serina... and beyond. The mourner will not go into the dark night alone.

Today, they won’t go at all. It is just another morning, and the tide is low. Time for a new mother to take her young offspring - her first to survive birth - down to forage for the gifts brought by the tide, as they have done for thousands of years, and with luck, will still do for thousands more. Extinction occurs over a scale of time far too vast to concern those who just need to live in the moment today.