The tarn is a giant birdlike beast. It is one of the two most common mounts of a Gorean warrior: the other is the high tharlarion, a species of saddle-lizard. The tarn is surprisingly light for its size and an extremely powerful bird, powerful even beyond what one would expect from such a monster.

They are bred for their colors, strength, and intelligence. The most common tarn is greenish brown in color, however, black tarns are used for night raids, white tarns in winter campaigns, and multicolored tarns are bred for warriors who wish to ride proudly, without camouflage.

Tarns are huge, vicious beasts and are carnivorous. It is not unknown for a tarn to devour its rider.

Tarl Cabot's First Meeting with His Tarn

He entered my apartment, carrying a metal rod about two feet long, with a leather loop attached. It had a switch in the handle, which could be set in two positions, on and off, like a simple torch. He wore another such instrument slung from his belt. "This is not a weapon, it is not to be used as a weapon." ...A tarn-goad...He snapped the switch in the barrel to the "on" position and struck the table. It showered sparks in a sudden cascade of yellow light, but left the table unmarked...Volume I, Tarnman of Gor, page 50.

We ascended a spiral staircase inside the cylinder and climbed for what must have been dozens of apartment levels. At last we emerged on the flat roof of the cylinder. The wind swept across the flat, circular roof, tugging one toward the edge. There was no protective rail...The Older Tarl took a tarn whistle, or tarn call, from his tunic and blew a peircing blast. I had never seen one of the tarns before, except on the tapestry in my apartment and in illustrations in certain books I had studied devoted to the care, breeding, and equipment of tarns. That I had not been trained for this moment was intentional...The Goreans believe..that the capacity to master a tarn is innate and that some men possess this characteristic and that some do not. One does not learn to master a tarn. It is a matter of blood and spirit, of beast and man, of a relation between two beings which must be immediate, intuitve, spontaneous. It is said that a tarn knows who is a tarnsman and who is not, and that those who are not die in this first meeting. Volume I, Tarnsman of Gor, pages 50 and 51.

The Older Tarl took a tarn whistle, or tarn call, from his tunic and blew a piercing blast...My first impression was that of a rush of wind and a great snapping sound, as if a giant might be snapping an enormous towel or scarf; then I was cowering, awestricken, in a great winged shadow, and an immense tarn, his talons extended like gigantic steel hooks, his wings sputtering fiercely in the air, hung above me, motionless except for the beating of his wings..The tarn dropped to the roof of the cylinder and regarded us with his bright black eyes. Volume I, Tarnsman of Gor, page 51.

The Older Tarl had mounted his tarn, climbing up the five-rung leather mounting ladder which hangs on the left side of the saddle and is pulled up in flight. He fastened himself in the saddle with a broad purple strap. He tossed me a small object which nearly fell from my fumbling hands. It was a tarn whistle, with its own note, which would summon one tarn, and one tarn only, the mount which was intenended for me....I blew on a note on the whistle, and it was shrill and different, of a new pitch from that of the Old Tarl. Almost immediately,,,,rose a fantatic object, another giant tarn, even larger than the first, a glossy sable tarn which circled the cylinder once and then wheeled toward me, landing a few feet away, his talons striking on the roof with a sound like hurled gauntlets. His talons were shod with steel - a war tarn. He raised his curved beak to the sky and screamed, lifting and shaking his wings. His enormous head turned toward me, and his round wicked eyes blazed in my direction...his beak was open: I caught a brief sight of his thin sharp tongue, as long as a man's arm, darting out and back and then snapping at me, he lunged forward striking at me with that monstrous beak, and I heard the Older Tarl cry out in horror, "The goad! The goad!." Volume I, Tarnsman of Gor, pages 52 and 53.