The Brapgul

The Brapgul is a gastrointestinal wonder of nature, a bird that, despite it's incredibly weak wings and odd shape, is capable of flight at high elevations due to its protruding air sacs and hyper specialized rectal passage. The Brapgul utilizes its balloon body to maneuver itself in flight in a way unique to its species and a sly stealth that allows it to have its pick from a wide variety of food.
The digestive organs within the Brapgul contain a colony of microbes which it has specifically adapted with throughout its evolutionary history, this microbe helps break down the food the Brapgul ingests extremely fast allowing it to benefit from an increase of energy from each meal compared to the average bird however the true highlight of these microbes are the hydrogen byproduct which is fed directly into the air sacs upon its back. The elevation of the Brapgul is controlled through a mixture of controlled flatulence and purposeful dispersion of the hydrogen gas throughout its air sacs and while it's wings cannot maintain flight on their own, they serve as a means to ride the wind and to direct the movement of the Brapgul in midair. The air sacs of the Brapgul are reinforced with ligament muscle tissue and faint bone structural support, even so, the air sacs serve as a major target for other aerial predators.
Brapgul's are omnivores that prefer to forage fruits and nuts from trees or drop down onto small animals to hunt. Brapgul's are extremely patient hunters, known to move slowly and so stealthily that prey isn't aware it's being hunted for hours before its demise. The gas released by the Brapgul also plays a part in its hunting process as the scent of their slain prey can be repurposed and used in order to mask its own and lure more prey into its claws. The controlled mixture and release of scented flatulence aids the Brapgul in avoiding becoming prey as well, in a pinch, the Brapgul can release large amounts of its internal gas mixed with the contents of its bowels to create a foul order known to stun, blind, and fend off predators that could easily overpower the Brapgul with ease, this reaction can sometimes initiate upon death causing the killer of the Brapgul to be soaked in a wretched fluid that's known to stick to animals and clothing for months at a time. In the air, the Brapgul uses its airsacs in order to quickly shift its own position to expose its anus and large claws to any would be birds of prey, though this is never a sure fire method of taking an aerial predator down and its not uncommon for a Brapgul to fall to its death with its blinded assailant. For this reason, most Brapguls prefer dwell in regions with few rivals and especially few birds of prey that might take notice of them.
While Brapgul's enjoy the sky and are optimal when inflated, most Brapguls will experience a deflation more than once in their lives. Deflation isn't fatal and a Brapgul can survive and even recover from a direct wound to one of their air sacs however a Brapgul is the most vulnerable when they're without their primary mode of transportation and death is likely if a Brapgul cannot forage and hunt enough food in order to initiate their hydrogen flight once more. When deflated, the Brapgul prioritizes stealth and will search desperately for worms, termites, or grubs that could help either its healing or reinflation. Typically the reinflation of a Brapgul will occur 3 to 8 hours after deflation if the airsacs are still intact and 4 days to 2 weeks in the case of a rupture.
Reproduction for the Brapgul is signaled through a specific gas that a male uses when they've constructed a nest capable of housing a female mate during the mating season of the Brapgul. The female Brapgul will inspect the nest and should she find it to her liking, proceed in fertilization which is said to produce a unique scent that totally masks the scent trail to and from the nest to anyone but the two parents, making the eggs near invisible to possible predators. If the female does not find the nest to her liking, she will release a scent that makes the nest completely uninhabitable. Brapgul young are raised by their mothers while the father hunts and returns for food, they're expected to fully mature and take flight around 5 weeks after hatching, after which they will be unable to return to their home.