Depiction of a bonnacon in a medieval bestiary.

Do Not Attack the Bonnacon, A Medieval Beast with a Toxic Defense

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The bonnacon is a strange beast believed to have existed in the ancient world. The first attestation to the existence of the bizarre creature is traced to the Roman natural historian, Pliny the Elder. Belief in its existence continued well into the Middle Ages and it was a prominent figure in many medieval bestiaries – perhaps due to the crude and unusual way it defended itself.

The Beast’s Protection

The earliest known reference to the bonnacon (variations include ‘bonachus’, ‘bonacon’, ‘bonaconn’, and ‘bonasus’) is said to be found in Pliny the Elder’s Natural History . According to Pliny, it can be found in the region of Paeonia, which roughly corresponds to what is today the northern part of Greece, the FYROM, and western Bulgaria. Pliny states the creature “has the mane of the horse, but is, in other respects, like the bull, with horns, however, so much bent inwards upon each other, as to be of no use for the purposes of combat.”

The mythical beast cannot use its horns for combat.

The mythical beast cannot use its horns for combat. ( CC BY SA )

As the creature’s horns are practically useless in combat, the bonnacon would, in the face of danger, flee, instead of standing its ground to fight. The most bizarre aspect of the bonnacon is the mechanism which it used to escape from its pursuers. According to Pliny, “while in the act of flying, it (the bonnacon) sends forth its excrements, sometimes to a distance of even three jugera (104 Roman feet, which is roughly 31 meters); the contact of which burns those who pursue the animal, just like a kind of fire.”   

Another reference to the bonnacon can be found in a piece of writing known as On Marvellous Things Heard , which has sometimes been attributed to the philosopher Aristotle, though generally believed by scholars to be a product of the Peripatetic School. The description of the mythical animal in this piece of work agrees with that of Pliny’s, though further details are presented.

According to this work, the bonnacon’s habitat is placed specifically in “the mountain called Hesaenus, which divides Paeonia from Maedice,” Other details furnished by On Marvellous Things Heard about this creature include “each of these (i.e. the horns) holds more than three pints and is pitch black, but they shine as though they were peeled”, “when the hide is skinned it covers the space of eight couches”, and “its flesh is sweet”. This work also states that the excrement of the bonnacon only burns when the creature is disturbed.

Folio 16r from a 13th century Bestiary, The Rochester Bestiary (British Library, Royal MS 12 F XIII), showing the Bonnacon.

Folio 16r from a 13th century Bestiary, The Rochester Bestiary (British Library, Royal MS 12 F XIII), showing the Bonnacon. ( Public Domain )

The Popularity of the Bonnacon Creature

For one reason or another, the bonnacon became a somewhat popular creature and it found its way into many medieval bestiaries. One of these, for example, is the Aberdeen Bestiary, which states that the beast is a native fauna of Asia (and not Paeonia as indicated in Natural History and On Marvellous Things Heard ).

Additionally, this bestiary notes that the heat of the creature’s excrement is so strong that it sets fire to anything it encounters. In these illustrated works, the bonnacon is often seen being hunted by human beings, and therefore, these illustrations show the creature shooting fire from its behind. The pursuers in these scenes are often shown with a look of disgust on their faces.

The creature defends itself.

The creature defends itself. ( cludbdesmonstres)

The bonnacon is also mentioned briefly in the Golden Legend , a medieval collection of saints’ biographies. In the hagiography of St. Martha (a figure mentioned in the Gospels, and the sister of Mary and Lazarus), the saint is said to have left Judaea with her siblings after the resurrection of Christ and eventually arrived in France. In a wood between Arles and Avignon, the saint is recorded to have encountered a dragon-like monster called by the natives as Tarasconus – which is believed to be the offspring of the Leviathan and a bonnacon.

Tarasconus model in a Corpus Christi procession in Valencia.

Tarasconus model in a Corpus Christi procession in Valencia. (Chosovi/ CC BY 3.0 )


A depiction of these animals are often found in Tibetan mandala's...almost of if to show its nature of fire and movement...I always wondered why it was there, I thought it was bull must be this bonnacon though.

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