Diomedan

Diomedans are a sapient, non-spacefaring species of flying mammalianoids from the planet Diomedes, known to them as Ikt'hanis.

Biology
Diomedans are mammalian creatures with six limbs in total: one pair of legs, one pair of arms, and one pair of membranous wings. They're slightly smaller than Humans and have a wingspan of 6 meters. They also have a meter-long tail equipped with a fleshy rudder at the end. Their bodies are similar to a bipedal otter, and are covered in soft brown fur, which turns grey when they age.

Their hands are muscular and five-fingered, resembling Human hands, while the feet are four-toed, with talons comparable to those of a bird of prey. They can lift up to 50 kg while flying over short distances. The round head rests atop a neck twice as long as a Human's. They have a high forehead, yellow eyes equipped with nictitating membranes, thick eyebrows, a long mammalian snout with a black nose and whiskers, and no ears. A crest on their heads serves to help stabilize their flight. The mouth is wide, and the dentition is similar to that of a bear. Like bears, Diomedans evolved from originally-carnivorous creatures which shifted to omnivory. Their language is vocal, but their hearing range is different from Humans. They can hear certain subsonic frequencies, and cannot hear certain high frequencies that Humans can.

Despite being based on the same elements as life on Earth (carbon, nitrogen, oxygen, hydrogen and sulfur) the biochemistry of all life on Diomedes is distinct and based on different kinds of proteins. Diomedan biochemistry is poisonous to Humans, and vice-versa. Consuming any food from Diomedes would kill a man in ten minutes due to extreme allergic reactions to the foreign proteins.

Culture and society
Diomedans (barring those living in the equatorial zone) are forced to either hibernate or migrate great distances every year to escape the harsh winters caused by the extreme axial tilt of their homeworld. In latitudes of 45 degrees, this extreme weather lasts for a quarter of a year; and in 30 degrees it lasts for a sixth. The need to migrate was the main reason why they evolved wings in the first place, and the advantages brought upon by a social unit which migrates together and can defend the group collectively triggered the emergence of civilizations on Diomedes.

However, an enormous cultural schism exists regarding the values and psychology of Diomedan groups that migrate and those that don't. The former can only mate annually, since younglings and the females that must care for them are unable to survive the rigors of migration. Any kind of sexual feelings outside the mating season is considered a depraved taboo by them. Equatorial Diomedans, on the other hand, can mate annually, and have no such taboos. An unfortunate result of this difference is that both groups view each other as abominations and worth less than animals: the non-migrating Diomedans are appalled at the lack of romantic love and families among their migrating counterparts, and the latter view the non-migrating ones as sexually depraved.

Technology
The lack of iron and copper in Diomedes limits the technological development of the Diomedans. Their technology is based on stone, glass, ceramics and synthetic resins. They possess telescopes and some notions of astronomy and navigation, although the lack of compasses (which require iron) limits their development in those areas.

Appearances

 * War of the Wing-Men, a.k.a. The Man Who Counts, by Poul Anderson (1958)