"It is not only mono-edged feathers that make a Razorwing."
- — Michel Soppe, First Illuminator of Hive Sibellus
The Razorwing is a large avian creature native to many worlds of the Koronus Expanse. It is the size of a mythical Terran hawk or eagle and is known to be a particularly effective and vicious aerial predator. The creature is known to be an incredibly fast flyer; vid-captures show flocks of Razorwings actually out-pacing Chiropteran Scouts and other low-flying aircraft for short periods of time. While the creatures have tremendous speed, they rarely use it except for the initial dive, as otherwise they would overshoot their target.
A Razorwing can also float in thermal updrafts, its wings locked to create a larger lifting surface as it scans for tempting prey with small but powerful eyes. Once it has such a target, a powerful dive of the Razorwing slams it quickly onto its victim, allowing the many offensive abilities of the creature to come to the fore. The claws and beak of the Razorwing are strong enough to cleave through the mass of its prey to get to the bones inside, but these are not the only weapons the Razorwing employs. The feathers of the avian, from the filoplumes on its head to the rectrice feathers on its tail, are as sharp and as durable as a mono-blade. Imperial scholars think this may be due to the excessive amounts of calcium in the Razorwing's diet, as the beasts are known to especially delight in crushing and eating the bones of their victims as well as the flesh. It is believed that it uses this calcium to strengthen and sharpen the feathers into tough and incredibly sharp tissue, like oceanic coral. This means the entirety of the Razorwing is a weapon, with such speed in its dive that it is akin to firing a bullet at its target, allowing the creature to slice or, in some cases, tear completely through a victim's body.
Whilst Imperial Biologis savants have studied the flock mentality of many avian xenos species across the Koronus Expanse and the Calixis Sector, the group tactics of the Razorwing are still something of a mystery (or at the least subject to much dispute). While many flyers hunt apart from the flock or exist as solitary predators, the Razorwing always seems to prefer hunting in a group. The flock seems to be lead by one primary flyer, similar to the way Fenrisian Wolf packs operate. This leader always pulls ahead of the main group in flight and is the first to try to strike a target when on the hunt. This alpha flyer seems to choose the target and also gets the largest share of the meal should their hunt be successful. Tales once taken as tavern nonsense were later verified in independent reports, showing the avians slick with blood and offal as they carry their calcified meal to some kind of foliage, there to eat and parade their kills.
What is more disturbing than its hunting patterns are reports that the Razorwing may be far more intelligent than any xenos researcher has realised. One such communiqué from a xenologist in Winterscale's Realm told of an unknown xenos giving what appeared to be verbal signals and hand gestures to a flock of Razorwings. Later vid-captures indicated the huntsman had trained the Razorwings to attack on command and bring the skeleton of their target back to him. Many seem to think that such incidents are more in the realm of fancy rather than reliable witnesses' testimony, but if such information can be verified, then these creatures could become quite a commodity, and even more dangerous to attain. It may also mean that those Razorwings displaying such behaviour are either previously-trained creatures that have escaped, or that their masters were nearby but out of sight for reasons unknown.
While a skilled predator, the Razorwing is also eerily beautiful. Its plumage takes on a multitude of colours from deep purple to light grey and is streaked with reddish brown hues. The eyes of a Razorwing are golden in colour and can spot a Teklese mouse from one hundred metres or more. The call of a Razorwing is somewhat melodic, but the xenos is known more for the shriek of its victory call than it is for its mating warble. Extended studies in field conditions are hazardous though; few have been lucky enough to witness a flock of Razorwings for long periods without being attacked themselves.
Razorwings were first reported in the Expanse by the inhabitants of Oradum only some sixty standard years ago. They have been sighted on other worlds since, and most savants believe they have actually existed in the Expanse for a much longer time. It is assumed that they are carried to new planets by those who use them in hunts, and that many of those flocks sighted represent specimens either released or that have successfully turned on their masters and escaped.
Wherever they are, Razorwings become major threats to most of the native fauna, especially slow-moving grazing beasts. They seem to prefer hunting fresh prey instead of scavenging for meals, and as such, when a flock goes on a hunt, the bloodsoaked remains of their dining can soon be found dotting the landscape. On some worlds, small packs of scavenging vermin follow the Razorwing flocks to dine on the scant remains the avians leave behind.
Few planets have other species that can compete with these predatory avians once they establish a foothold in a compatible ecosystem, and Razorwings often become apex predators within a few short generations. Their presence has severely cut into the profits of many merchants who rely on meat-supplying beasts on several worlds, leading to many attempts to cull this xenos species harshly and investigations as to if they are being used as biological weapons by rival traders. Most agree that should this invasive species continue encroaching onto further planetary environments, they could wipe out whole foodstuff species that the Calixis Sector needs to survive.
- Rogue Trader: Koronus Bestiary (RPG), pp. 20-21