The Gannetgrouse

Aglirium has always been a home for lineages that couldn't find a place elsewhere. Even before geckos rafted to the Isles, the ancestors of the first seawis had begun to make their nests here. Many species have since come and gone, and in the present day most Pelagapterids live in the Perithalassic, as Thalassaurs have become the dominant aquatic tetrapods in the smaller ocean. Only one remains in its ancestral home: a descendant of seacocks that rode out the Ice Age on small islets exposed by falling sea levels. This island-hopping lifestyle still exists among many seacocks outside the Medithalassic, but those that live on Aglirium have abandoned the waves entirely. 

The Gannetgrouse (Phasianapteryx) is a group of about half a dozen medium-sized kiwi species distributed across the subcontinent. Known for their distinctive brightly-colored plumage, they are Apterra's most colorful birds. They typically reach five to ten kilos in mass, making them ideal prey for Aglirium's top predators. Monitor and vampire geckos are a constant threat, so flocks of gannetgrouse are always vigilant and never stay in one place for long. As they pass through an area, they collectively root through tons of soil and leaf litter in search of bugs, seeds, and fruits. Were they to remain in one spot, they'd quickly decimate all the local flora, but since they're constantly on the move, their actions end up enriching the soil and allowing new growth to sprout.

Gannetgrouse have abandoned a monogamous mating system, with males now controlling harems of up to a dozen hens. At the beginning of the wet season, massive leks form, allowing up to a hundred cocks to display their dazzling shoulder and tail feathers, which come in iridescent hues of blue, green, and purple, as well as their bright red-pigmented head crests. These crests are found in both sexes and possess a bony core, while the two pairs of pouches on the sides of the head are made of soft tissue derived from the salt gland of earlier seawis. They have been repurposed for other excretory functions; the lower pair now houses immune cells that produce antibacterial proteins. These are mixed with oil and secreted onto the surface of the pouch. Herdmates then preen the antibiotic oils into one another's plumage, so their entire bodies are protected from infectious attack. Meanwhile, the smaller pair on the cheeks are packed with salivary glands and digestive enzymes. They open into the back of the mouth and release a slow trickle of pre-digestive fluid as the gannetgrouse bites and pecks at food, softening it significantly before it reaches the crop. Both pairs of sacs house their own microbiomes, with various bacteria and archaea aiding in digestion and the fight against parasites.

The Veiled Gannetgrouse (P. velatus) is the most decked-out of all seawis, growing an additional set of long, trailing feathers from the tips of its tiny wings. Indeed, a young cockerel may find himself tripping over his own feathers. This show of inexperience generally dashes his hopes of breeding that year, but the lack of physical violence in gannetgrouse competition means he'll likely get another chance. 

After a few select males gather their harems, all the females lay their eggs in a single communal nest. The leader of the harem will incubate them all by himself, and his partners won't bother sticking around once their job is complete. After a month or so, ten or more chicks hatch, following their father until they're large enough to fend for themselves. Once his fatherly duties are finished, the male returns to the lek, and the cycle may repeat four or five times until the summer rains end. Females tend to choose a different mate each time they breed, so there is no guarantee that previous victors will see repeated success. However, males with a reputation for raising many chicks with minimal losses are seen as the most desirable. Consequently, the best fathers end up becoming a popular choice year after year.