The Dayflight Bird

I have no mouth, and I must tweet.

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The ponds, rivers and lakes of Serina teem with myriad life in the Ultimocene.

We return again for a moment to the steppe of Serinaustra - a temperate grassland dotted with numerous shallow water bodies. In the many permanent streams and lakes common to the north of the region one finds an abundance of small fishes, darting and shimmering under the surface in all shapes and sizes, as common as they have ever been. These waterways are perennial, persisting season to season and year to year, and so allow fishes to flourish.

But there are other water bodies which appear for only part of the year - vernal pools, formed from spring melt water or summer rains, which can appear overnight and which last just weeks, sometimes a few months - perhaps until the middle of the summer brings high temperatures and dries the pools up. Few fishes, excluding those which have completely adapted to life on land, can reach these pools. The few that may manage to hitch a ride as eggs attached to the leg of a water bird will not survive when the pool eventually evaporates. This means that there is a temporary abundance of food largely untouched for those small water creatures which can reach this habitat and move on when it dissipates. Triops and insect larvae fill the pools first and graze upon the abundant algae that begins to grow as soon as any amount of water collects in a spot for more than a couple of hours. But not very long thereafter, other creatures appear seemingly from thin air within the water as well. Feeding on both the algae and the small invertebrates in equal measure, they swim in shoals just under the surface or scoot along the sediment, propelled with side to side strokes of a pointed tail fin, just like small minnows.

But fish they are not - though you could not be blamed for mistaking them for such. They are however birds, fully aquatic metamorphs which have over countless generations become exquisitely adapted to such an existence, resembling tadpoles or primitive fishes like the lungfish more than a bird. Their ear canals are adapted into gill slits, absorbing oxygen which is passed over them via sucking momentum through the jaws. The eyes are well-developed and they are lively and active visual foragers which feed on both plant foods, such as algae, and small insects and fishes. But they are not as strictly specialized into this lifestyle as the true aquamorph birds that occur elsewhere on Serina; they have not forgone their metamorphosis into flying adults. They are the efts, still thriving after all this time. In order to reach these temporary habitats, these little water-dwellers must undergo a very dramatic transformation. When the pools begin to dry up, the swimmers' initiate the beginning of a remarkable change. They bury themselves in the mud and cocoon themselves in a silken wrapping of their own saliva which hardens into a semi-permeable bag - effectively a second egg, which will retain moisture as the pool evaporates but allow an exchange of gases through tiny pores in its surface.

Here so protected, the larvae transform into flighted and feathered adults. Their gills close up and their lungs inflate in their place. The long tail, so useful for swimming in their past life, now is absorbed back into the body as a source of nutrition for the building of the new adaptations they will require to finish their life cycles. What were formerly pectoral fins used to steer in the water sprout long quills which then open into elegant wings. Insulating plumage sprouts along the body, and small nubs at the base of the tail lengthen into jointed legs complete with grasping toes. Within a period that varies with species from just a few weeks to several months, they emerge from their buried cocoons and take flight, dispersing to new habitats. Some of them are long-lived, spending just months as aquatic larvae but years as flying adults. Whenever conditions in their local area are most suitable, either in the spring in temperate regions or during the wet season in the tropics, they spawn and deposit their numerous small, soft eggs into the suitable temporary bodies of water where they are unlikely to be eaten by fishes or other metamorph birds which inhabit permanent water sources. Such species have well-developed adult forms and are not superficially distinct from other flying birds.

Another group of efts exists here however which reverse the strategy of their fellows, spending most of their lives as aquatic larvae and living just a matter of days once getting their wings. The most extreme example of this can be observed in a group of tiny efts, scarcely larger than bumblebees and known as the dayflights, which live less than a single day as adults. Their adult lifespan is indeed so brief that they do not need to eat and experience drastic simplifications of their bodies during the metamorphosis process. Unlike most other efts, the larvae when ready to transform, in the spring of their second year, do not bury themselves in the sediment but climb out of the water onto an emergent stalk. To allow for this, their gills close up and their lungs mature while they are still active and feeding in the water so that they are able to climb out and still breathe when the time comes. Once out of the water, they secrete their saliva cocoon around their bodies, anchoring themselves to the stalk, and then transform so protected in their own little tent. Like other efts, they first reabsorb the tissues of their tails, using the energy to sprout wing plumage and to build a more substantial skeleton and muscle system to allow for powered flight.

Because their time in the sky will be so short though the dayflight larvae also experiences the loss of its entire digestive system, the almost total degradation of many normally vital organs including the liver and kidneys, and perhaps most drastically, the fusion together of its jaw bones. When it emerges from its mucous cocoon, it is entirely without a mouth and not only can it not eat, it would have no way of digesting food or processing food even if it could. Instead the bird uses the energy it gains from digesting its own organs to accommodate enormous gonads and lay down thick deposits of fat to sustain it for the rest of its life. Within an hour of emergence, all of the dayflights take to the air synchronously. Their wings are simplified and all of the flight quills originate in a single row from the wrist - the most energy-efficient way to build a wing, at the expense of durability and agility. They also lack tail feathers and so are awkward and bumbling flyers. Almost as many crash or drown as are promptly gobbled up by predators, but so many have emerged at once that they overwhelm the abilities of all their enemies to consume them all. The dayflights hardly try to avoid danger and have only a single goal once they mature - to reproduce, and will spend the rest of their lives trying to so so until they burn up their fat reserves and die of exhaustion or else are captured by some other hungry animal. They gather in noisy swarms - though deaf and largely mute, the humming of their wings, multiplied by the thousands, produces an audible buzz.

There are a number of distinct species of dayflight birds which while similar in their development are extremely diverse in appearance and even within a single species all of them are strikingly sexually dimorphic. As males and females have so little time to locate a suitable partner, time is of the essence in quickly being able to determine who is a suitable partner and so garish displays of color are utilized to make each species, and each sex of each species, unmistakably unique and easy to spot at a distance. Because they rely not on individual safety but sheer numbers to survive, and because their lifespans are already so brief, they have no need to remain cryptic to avoid their enemies and so not just the male but both sexes are frequently beautifully patterned in varied hues and colours, both in the visible and ultraviolet spectrum.

The life stages of a dayflight bird, which has no mouth in adulthood and lives less than 24 hours once sexually mature.

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Once males and females locate one another, they gather into dense swarms and perch in thickets of vegetation at the edges of calm freshwater pools. Here females cling to the reeds and deposit up to a thousand tiny eggs each in gelatinous clumps just under the water's surface; they are trailed by groups of males which immediately fertilize the clumps as the females lay them.

Emerging at dawn and breeding through the day, the dayflights die by dusk. Though each individual lives just ten to sixteen hours they will continue to emerge over a period of seven to fourteen days and so swarms will last several days. But eventually the last of the season's emergents runs out of energy, weakens, and falls into the water for the final time, and the ponds fall silent once more. Their reserves burned away and unable to ingest any new calories, their lives come to an end. Born in the water, they die just as they came into the world. Soon the water is coated in a floating layer of tiny brightly-colored bodies which cover the surface like cherry blossoms in the springtime, but within days scavengers have cleaned up the remains and all but removed any trace of existence of the dayflights has ever been there at all. But while the previous generation has gone, they have fulfilled their life's purpose, and soon the eggs they have produced will hatch out into a new generation of small tadpoles. The majority will fall prey well before they are large enough to leave the water at all - combined with the heavy mortality experienced as they make their first adult flights, it's probable less than one out of every hundred larvae successfully reproduces - but they are so abundant that it is guaranteed enough will survive to carry on their lines. These luckiest individuals will grow over the next year into shoaling fish-like creatures up to three inches in length, which dart through the shallows and snap up food with soft-lipped mouths that retain a beak only on their inner surfaces - two hard keratin plates useful to crush the exoskeletons of insects and ridged to scrape algae from rocks. And in just a year after their birth, the new generation will emerge and continue the cycle.