A safari in the Day-Night steppe
The Day-Night steppe is a very resourceful region in Antarctica: despite its frigid and dark conditions during the polar night, summers are warm and the presence of lots of small endorheic basins creates a mosaic of habitats with plenty of life. A perfect place for an antarctic safari.
Some species migrate to the steppe seasonally during the good season for breeding, like the nearly wingless Day-Nightgrabber (Limnaves phoenicopteromimus).
This medium-sized ducktail is semi-aquatic, feeding in the large marshlands that form in early spring in the ecoregion.
They form large groups of hundreds of individuals with a strongly nomadic behavior: after the hatch, chicks must learn to walk after a few minutes in order to not slow down the herd.
They are without doubt one of the most intelligent species of ducktails, with a very complex social structure, being separated into hierarchies.
They possess a complex language that is used to interact with the rest of the herd: a low-rank individual usually produces more acute calls while "talking" with a high-rank Day-Nightgrabber.
The herd is controlled by a dominant couple, that must conduce their subjects in their never-ending migration. Internal conflicts for power are on the agenda for this very aggressive ducktail, that despite its modest size is an uneasy prey for lone sheardogs and herdstalkers, their main predators.
When facing a threat, female Day-Nightgrabbers group together to protect juveniles while males, slightly larger on average, furiously defend the herd from the enemy.
If a single individual is separated from the herd, it can successfully flee thanks to its strong and long legs.
When temperatures start to become freezing (usually around April), Day-Nightgrabbers start a mass migration to return to their wintering refuge, the Belgrano wetlowland. Despite being potentially tolerant to cold temperatures, Day-Nightgrabbers cannot move and search for food on snowy terrains.
During winter, this ducktail shares its range with a Limnaves relative, the Belgranograbber, which is more specialized in browsing than grazing.
Limnaves (commonly called grabbers) is probably one of the most successful genera of ducktails, being found across all Polarica, with a global population of at least 40 million individuals.
Day-Nightgrabber's chicks can often fall prey to large raptorial birds but also to one species of diurnal bats, adapted to the midnight sun of the steppe: the day hawktule (Elionoctula temperata). It's by far the largest species of bat of Antarctica, with a wingspan of nearly 1.8 meters, like a full-grown man.
Despite being still able to roost downward on large trees, this bat prefers to rest on cliffs crouched like a dog, a unique trait for the Chiroptera order. They mainly hunt large ground tyrants, but their great size allows them to feed also on juvenile ducktails and small geotters.
When polar night approaches, day hawkctule congregate together inside large karstic caves, where they enter into a prolonged state of torpor that can last even four months. This lethargy is highly necessary for this species, which has poor night vision and is incapable of using echolocation.
Despite their scary appearance, day hawktules are very fragile animals compared to other carnivores, often being mobbed by large flying predators, like the magnificent incubos (Vulturaquila timor), the nightmare of skies.
This giant eagle can even bring down an adult day-nightgrabber, which comprises most of its diet. Like their ancestors, these birds possess long legs compared to other raptors, in order to pick up speed before taking off.
Along with the species that reside all year in the Day-Night steppe, the black thronghorn (Bubalornis centralis) will take your breath away.
It is a far relative of the steppe bullduck and it's, without doubt, the largest bird that has ever walked Earth: tower ducktails are nothing compared to this two and a half tons creature, capable of bulldozing anything on its path. The Bubalornis genus is well widespread and can be found not only in this steppe but also in other lowlands, like the Belgrano one.
It's the keystone species of its ecoregion, maintaining the rich vegetation composition of the steppe. They are mainly grazers, with leaves and barks comprising only a marginal part of their diet. They are social animals that live in small herds, with usually no more than 60 individuals.
Due to their size, black thronghorns are practically unassailable after their fourth year of life. Only one carnivorous ducktail species has adapted to regularly hunt this herbivore, which uses its strong legs and the giant horn on its head as a defense.
Eggs are laid inside giant excavated nests and they are brooded by youngs or sub-adults, to reduce the risk of breaking them. Chicks weigh no more than two kg after the hatch, but they can already weigh 150 kg (330 lbs) after one year of life. A female can produce more than 15 chicks per year but 60% of them rarely survive the first winter. To rapidly obtain the digestive efficiency of their parents, young thronghorns often eat adult feces, which contain their bacterial flora.
Like elephants, black thronghorns carrion are essential for many predators of their ecosystem, especially during the polar night, when prey becomes very scarce. Without this species, the Day-Night steppe would look very different from now, with a far lesser biodiverse community and a more woody environment.
