Composed of interconnected hollow stone vessels, Huacarina are slow-moving Rock-types that perch at the peaks of mountains, under natural bridges, and in canyons. They congregate in the windiest areas they can find and let the breeze pass through the holes in their bodies. Their shape lets them sing. The peculiar muscular structures just under their stone shells allow them to open and close the holes individually to make different notes, and it is also assumed that these muscles allow them to walk on rocky legs. The vast majority of their organs seem to be situated at the base of their central bodies.
Huacarina are peaceful herbivores, feeding on the hardy scrubs and berries of the rocky badlands and lumbering around in large groups. When food runs out in an area, they have been observed huddling together and hibernating in caves for months or even years until the fast-growing plants grow back in their home region. They may also migrate in herds dozens strong in order to find new food sources. Some deliberately begin to hibernate or migrate before the plant life is depleted in order to allow the vegetation to grow back in their absence. Huacarina eat slowly and burn very little energy. Their mouths are positioned near the top of their central vessel and the esophagus runs along the back, where a ridge makes room for the spinal cord as well. The passage is narrow, requiring a hungry Huacarina to grind its meal into a fine paste with its rocky, toothless jaws before swallowing, lest it choke. The odd structure of Huacarina's muscles is incredibly energy efficient, making as much use out of its small meals as they possibly can. Their slow movements and efficient use of energy allow them to go without eating for weeks, even when not hibernating.
The rest of its main body is dedicated to the hollow space that catches the wind. The lungs are highly specialized and weave through almost all of the available space under Huacarina's shell. They breathe slowly through four spiracles or nostrils on the backs of their heads, and the air travels into lungs that wrap around their sides and extend down their shoulders. A fifth orifice inside the central vessel is rarely used to inhale. When there is no wind, Huacarina will exhale through this hole, blowing into its vessel to create a soft, constant note. It will continue to sing when doing this, opening and closing its various holes to weave a tune. It can also use this spiracle to make much louder vocalizations, ranging from booming rumbles to high-pitched whistles.
Huacarina's singing is its most iconic trait. UB Whistle is almost never alone, and it loves to harmonize with its herd mates. The song of the Huacarina serves a social function, alerting other individuals to its presence and allowing them to gather for protection. Certain melodies seem to have certain meanings, signaling whether to hibernate, where and when to migrate, and where to find food, among other things. When they are not communicating key survival information, they hum gentle tunes to each other with no apparent pattern. This social function is incredibly important to their psychology; specimens captured for lab study go silent in the testing areas without proper stimulation, and the earliest captive specimens had tragically short lifespans due loneliness and isolation. Protocol for maintaining a captive population has been amended to require companionship for all specimens. Each specimen must be bonded to a minimum one other specimen, and additional resources are now allocated to teaching researchers how to play woodwind instruments, especially vessel flutes, to allow them to bond with their subjects and provide additional enrichment.
On rare occasions, smaller Pokémon have been seen inhabiting the hollow portions of Huacarina's body. These creatures are undocumented and appear to be native to other portions of the planet. So far, it has been impossible to capture or observe these unknown Ultra Beasts up close, as the Huacarina providing them shelter will swing its arms and scream to drive off any potential threats. This behavior is much more common when they are carrying a tenant than when not, implying that they are actively protecting those who take shelter in their vessels. When they have nothing else in tow, they are rather gentle towards researchers. Researchers have obtained photographs of these hitchhikers peeking out of Huacarina's holes, and the promise of new biodiversity in the furthest regions of Ultra Desert has invigorated the passion of scientists assigned to the planet.