The kerodroni /ˈkɛrədroʊni/ is a long-bodied, black-handed stranger characterized by the prominent radio antenna that extends from its mouth. The kerodroni carries its head in an upright posture, and stands with perfect balance, allowing its antenna to remain vertically aligned at all times. Its skin is smooth and soft, and emits a very slight electrical discharge.^Ʀ Its flesh is black, and its body cavity is filled with wires and cables that connect to the radio antenna's base. These wires have only minimal electric charge, and, like the appearance of the kerodroni's antenna, their arrangement varies between individuals.

The kerodroni's skin and flesh are minimally capable of regeneration. Cuts less than a sixteenth of an inch in either width or depth take ten to fourteen days to close up; otherwise, injuries remain open, though they do eventually dry out.

The kerodroni appears on rooftops, balconies, awnings, and other lofty locations of at least nineteen feet in height, with a strong preference for elevation. It first fades in from static, and takes solid form over a period of time between 36 seconds and three hours long. This generation is accompanied by a crunching, fuzzy sound, which quiets as the stranger reaches maturity.

While the vast majority of kerodroni appear typical, two percent of individuals present with rusted, twisted, or broken antennae. A "defective" kerodroni tends to exhibit erratic, violent behaviour, and lives a drastically shortened life.

The kerodroni's disposition is observant and precise. It spends most of its time perched atop a high vantage point, motionless save for the occasional back-and-forth flick of its tail. When it does move, it walks from place to place in direct paths, and does not wander. The kerodroni is adept at climbing, and its balance allows it to easily walk across any beam or cable strong enough to support its weight.

A social stranger, individuals of a similar appearance tend to form groups, which rest on the tops of buildings, where they twine their bodies together and point their antennae upwards to create tower-like formations.^Ԏ When not at rest, individuals within a group groom each other by removing paper, string, and other debris from each other's antennae. Rarely, groups of kerodroni display some aggression towards individuals of a radically different appearance, and push them off of roofs or ledges, or grab and bend their antennae, but this cannot be thought of as a common occurrence, and lone individuals display no such xenophobia.

The kerodroni's broadcasts are cumulative; radios around two kerodroni broadcast two overlapping voices, while larger numbers of kerodroni emit a cacophonous mess of audio.

The kerodroni displays a methodical intolerance of birds, and rips up, crushes, or otherwise mangles any that it finds roosting. It is incredibly thorough in these acts – in addition to mangling birds themselves, it also pulls apart nests, and smashes any eggs inside. Despite these destructive actions, the kerodroni's demeanor remains detached, and most individuals kill birds with a quick, clinical precision. A "defective" kerodroni, however, displays overt ferocity, and even tortures birds before killing them.^ʕ

In addition, the presence of the strain itself affect bird behaviour in erratic ways. Some flocks of birds fly into windows or walls en masse, while others display extreme aggression towards one another, eat their own eggs, or refuse to roost at all, instead flying in dizzying circles before dropping to the ground from exhaustion.

Over a long enough period of time, a kerodroni infestation can completely eliminate the presence of birds from a region.

The kerodroni avoids contact with sensitives, and retreats^Ⴌ when approached. If a sensitive is able to corner the stranger, however, it stops moving, as though unsure of how to react.

The kerodroni is harmed by physical contact with a sensitive, which causes the cables inside its body to tighten and contract, twisting its body into a shriveled and contorted pose. After twenty to thirty seconds of prolonged touch, even the kerodroni's antennae bends inward, as well.

The kerodroni does not exhibit aging (beyond wear-and-tear) and instead dies suddenly, usually when at rest. It takes less than an hour for the corpse's skin to dry out into a grey and ashy crust, which crumbles apart after two to four days to expose the kerodroni's antennae and wires.

Other kerodroni that stumble across a corpse pull apart and scatter its wires, and plant the antennae firmly into the rooftop of the building on which the corpse rests, before they return to their deadpan patrol.