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Emperor Swiftlet Variation

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The Emperor Swiftlet, though not the only member of its genus and certainly not its order, is nonetheless easily the most intra-specifically variable swiftlet, with wild populations ranging at one point in height from only eight feet tall - a little bigger than a human - to, at extreme, more than twenty-three - taller than a giraffe, with weights from three hundred to over 1,300 pounds - all despite being a species only 4 million years old! The species undoubtedly owes this great variation to the unusually elastic genome endemic to swiftlets which combined with this species' extremely adaptable diet and the wide-ranging abilities that an ancestrally great size introduced have allowed it to colonize almost all of the southern hemisphere - they are absent only upon Wumbus - and adapt rapidly to localized conditions.

Roughly a dozen subspecies of Grallatacheiropteryx xenosteorynchus, give or take, are described today across the southern hemisphere, with a radiation from polar Aenvarna northwards to the equator. Among the most common and wide-spread of these are the five highly varied species illustrated above; not included are an additional few very similar to those depicted and several more abberant which exist on more isolated eastern lands, some of which are potentially worthy of their own specific status.


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The Greater Aenvarnan Circumpolar Swiftlet is the archetypical member of the species as well as the tallest, with exceptional males reaching up to 24 feet in height. It is this swiftlet which is most typically referred to when the species is mentioned, for by numbers it is by far the most numerous. They are wide-spread across all of Aenvarna, from the polar tropics to the far northern coastal savannah, and are not naturally migratory, spending their entire lives on the continent without large seasonal movements. Though they may cover several hundred miles in a day feeding, this is generally restricted to personal territories and except in very poor seasons, this subspecies does not travel the enormous distances covered by other subspecies as a matter of course, largely because for their height and weight Circumpolar swiftlets have the smallest wings of all their species and experience difficulty taking off without strong headwinds; their wings span on average only 40 - 45 feet across, slightly less than that of some populations that may be only two-thirds their weight. Subsequently, the Circumpolar swiftlets are the most adapted of all their kind to a terrestrial habit, with the longest necks, bills, and legs proportionate to their size of all Emperor swiftlets, and feed largely on smaller prey than others which they can chase, capture, and consume - whole - on the ground, limiting their need to fly. As a result of this, Circumpolar swiftlets exhibit the least prevalent hook on their bills of all the species, sometimes lacking anything notable altogether, reflecting an adaptation to gulping prey whole rather than tearing larger meals apart. This subspecies nests in solitary pairs almost year-round with no set season, depending on their locale, and is the only swiftlet subspecies to frequently nest directly upon the ground rather than upon cliff faces, due to the lack of significant mountain ranges on mainland Aenvarna. The Greater Aenvarnan Circumpolar Swiftlet is the only subspecies which as an adult is entirely without predators or competitors in its environment, existing itself as one of the apex land carnivores of Aenvarna.

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The Transcontinental Migratory Swiftlet is the second heaviest of all the swiftlets, but is considerably shorter than the aforementioned mainland subspecies, averaging 14 - 18 feet in height. This subspecies is, as its name implies highly migratory, moving annually at maturity from the high north of Servallia's temperate zone down as far south as the southern pole seasonally, breeding in the rich north during summer and retreating south during winter when the snow begins to fall (remember, though Sheatheria does not tilt on its rotation, its orbit is elliptical, and winter comes to the equator - and to a lesser extent the pole - during the half of the year when the planet is furthest from the sun.)

Despite their smaller stature, the Transcontinental subspecies carries the largest wingspan - up to 54 feet in males - and is the most adapted variety to prolonged flight and to feeding from the air. The bill is sharply hooked and adapted to tear flesh from carcasses too large to swallow whole and the long, narrow wings give this subspecies the great aerial maneuverability of any of the species, frequently allowing them to swoop and capture prey directly from the air in the manner of birds of prey without having to land. Proportionately they have the longest hind limbs, reduced necks, and shortest and deepest bills of any Emperor swiftlets, further adaptations to this niche where stockiness is beneficial; this variation only very rarely feeds directly upon the ground as most other species do at least occasionally, and subsequently it does not directly compete with the Circumpolar swiftlet, even though for much of the year both animals may share identical habitats. Cross-breeding between Circumpolar and Transcontinental swiftlets is still very possible but occurs relatively rarely as a result of this subspecies' far northern breeding grounds; though vagrants may join other populations and hybridize with one subspecies or the other outside normal breeding ranges, the populations as a whole rarely share genes with this other population, perhaps being well on their way to true speciation. Transcontinental swiftlets frequently breed in solitary pairs similarly to Circumpolar swiftlets but may breed in small colonies around especially rich habitats, which does not occur in the Circumpolar.

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Several Emperor Swiftlet subspecies are endemic entirely to the central sub-continent of Servallia, Sheatheria's largest southern-equatorial land mass, normally never migrating south to Aenvarna as does the aforementioned species. In the west can be found a fairly large population of the species which exhibit more vibrant markings, including dark bands on the neck and tail and a more brown-to-red coloration in contrast to the tans and olive greens of most others. Known as the Resident Eastern Servallian Plains Swiftlet, this subspecies is roughly equivalent in height to the Transcontinental but far lighter, being of much more lithe build. As its name implies, this species migrates little and then only northwards or southwards across Servallia to follow season food booms or to avoid seasonal scarcities, and they nest colonially in the early spring. Resident Eastern Servallian swiftlets feed largely terrestrially, similarly to Circumpolar swiftlets, but retain their sharply hooked bills and are efficient scavengers as a result, able to tear meat from even very large carcasses. They do however lack the crushing jaw strength of both larger varieties and subsequently, unlike these, do not regularly feed on bones. Breeding almost never occurs with the Transcontinental subspecies, but the reasons for this are not entirely known as their sizes are not overly dissimilar and their diets converge. It is possible the two subspecies do not readily speak the same language of calls and struggle to overcome this barrier sufficiently to forge a strong enough pair bond to raise the offspring together - which requires both parents - even if successful mating takes place. These two subspecies diverged almost 3 million years ago from one another, with the Resident Eastern actually sharing a much closer relation to the Circumpolar Swiftlet; though in nature the two races very rarely meet, they diverged from one another as little as 25,000 years ago and this species represents closely an animal similar to the giants' recent ancestors.

Historically, Resident Eastern swiftlets occurred across Servallia, but within the last million years have been pushed increasingly far east as the large, super-predatory flighted Ranamonarchids known as 'dragons', having stumbled upon extremely successful evolutionary innovation in the form of their spear-tongues, have speciated into their niches and locally out-competed them within very little time. Within only 80,000 years this subspecies has split into three, evolving into two distinct far smaller varieties in the east which do not directly compete with larger dragons. Derived from primitive Eastern swiftlets today exist the two youngest Emperor subspecies, the relatively large West Servallian Nomadic Swiftlet and the far smaller Green-throated swiftlet, today extinct in its natural form and survived only in domestication (performed by the Servallian Zucchini Bear). Both of these varieties are by nature colonial and highly social flocking animals - a trait which allowed the domestication of the green-throated - but they differ in their feeding behaviors. Green-throated swiftlets evolved to feed on very small animals and to do so on the ground in the manner of cranes or secretary birds, and have convergently lost their bill hook as has the much larger Circumpolar. However, this species remained small and has wings very large for its size, allowing it to escape larger predators and travel wide distances in search of food. The domesticated form of the subspecies alive today is thought to be smaller still than its ancestors, for this leaves it more easily provided for and suited to its exceptionally small caretakers, and it has lost any natural migratory behavior. West Servallian Nomadic swiftlets, still wild, retain this tendency and are aerial feeders similar to transcontinental swiftlets, though being proportionally smaller they take smaller prey. Their wings are also proportionately very large for their size - the longest of any subspecies - allowing rapid flight, necessary to avoid predators and to find prey over a temperate environment relatively poor in food compared to more southern environments. It is possible green-throated and Servallian Nomadic swiftlets would have interbred historically but this is almost unheard of in the modern day due to the rather large size differential brought about by the former's domestication and its stark change in breeding behavior, reproducing directly within its captor's villages and requiring their assistance to rear their own chicks, having lost a great deal of parental instinct. Indeed, it is much more common for the larger wild swiftlets to attack and eat the much smaller domestics, which they no longer seem to readily identify as being of their own kind, possibly due to their very wide range of abnormal colors and patterns, in particular piebald, which does not readily occur in wild populations.
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