Exotic beasts from Africa and Asia were captured ready for slaughter in the Colosseum in Rome by army units and civilian hunters virtually unknown to history, even though they matched gladiators for daring, according to new research.

Groups of men in jungles and deserts on the fringes of the Roman empire snared lions, tigers, elephants and rhinos with hair-raising techniques largely ignored by scholars.

The men were at the sharp end of a network of entrepreneurs, shippers and keepers which transported animals to amphitheatres in Italy and northern Europe, said Roger Wilson, professor of archaeology at the University of Nottingham. "This required a huge support infrastructure and organisational know-how on an empire-wide scale about which surprisingly little is known," Prof Wilson added, in findings presented last week to the British School at Rome.

Following a trail of animal bones, mosaics and fragments of written records, the professor concluded that many tigers came not from India but from Armenia, and were shipped across the Aegean. Africa supplied elephants, giraffes, ostriches, leopards and hippos, while northern Europe supplied bears and boars.

The imperial army found the capture of such beasts a useful way of keeping troops occupied and some units became specialists. In a third-century inscription. A member of the 30th legion stationed on the Rhine, Cessonius Ammausius, describes himself as an "ursarius", which the archaeologist translated as "bear-hunter".

"Such was the ferocity of these beasts that their capture demanded special skills and the creation of a special post. An inscription in Cologne talks of the capture of 50 bears in a six-month period," Prof Wilson added.

Without tranquiliser darts and unable to use spears, which risked killing or wounding, the capture of lions was fraught with danger, according to a second-century account by a Greek observer named Oppian. One method of capture was to surround a pit with a camouflaged wall and insert a stake in the middle with a lamb on top. Once a lion had jumped into the pit the hunters would lower a cage.

Another method was for horseriders to drum shields and drive lions towards hunters holding staked nets. At other times, men dressed up in sheepskins and wore out lions by diverting their attention from one hunter to another, until the animals dropped from exhaustion.

Oppian was impressed: "O greatly daring men. What a feat they achieve, what a deed they do - they bear off that great monster like a tame sheep."

Leopards were hounded with blazing torches and elephants were lured into pits.

An artist called Pasiteles was recorded as being eaten by an escaped leopard while drawing a lion caged at a dockside.

Once in the arena the beasts were put into combat with other beasts, or with human fighters known as venatores, or used to execute criminals tied to carts. More than 5,000 animals were said to have been slaughtered during the Colosseum's inaugural games in AD80.

Prof Wilson said an enduring mystery was what happened to the carcasses. Excavations beside an amphitheatre in Trier suggest that in some cases they were thrown into pits with the corpses of humans killed in the ring.