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Isfahan Pigeon Towers
Travel

Isfahan Pigeon Towers

Late one summer day, I was seated on a local bus as it rumbled through open fields and orchards on the outskirts of Isfahan. Lurching down the hot, dusty road, while my fellow passengers napped, I looked out the window and saw in the distance what appeared to be four or five ancient mud-brick watchtowers falling to ruin.
But as the bus drew closer, I noticed the towers didn’t have crenellated battlements or loopholes in the upper walls for rifles. Moreover, open farmland seemed an oddly exposed placement for any sort of fortification. Standing 9 to 12 meters high, these plastered, dun-colored towers looked like giant chess pieces.
After reading about the exquisite Persian melons and the elaborate gardens and fortifications of Isfahan in the travels books of the German scholar Adam Olearius in Seventeenth-Century Iran, did I eventually discover that these structures were pigeon towers dating back to at least the Safavid Empire (1502-1736). Especially noteworthy are the towers built during the rule of Shah Abbas the Great (1571-1629), who made Isfahan his capital.
Olearius’ account led me to later observations by the French traveler Jean Chardin. Traveling in Iran from 1673 to 1677, Chardin described how the towers were built to attract huge flocks of wild pigeons, numbering in the thousands. He estimated there were more than 3,000 pigeon towers in and around Isfahan.

  History
Given the number of towers (called kabutar-khane in Persian) and their size and architectural sophistication at the time of Chardin’s observations, it seemed reasonable to assume that the pigeon towers of Isfahan in fact considerably predated the Safavid Empire. Lending support to this theory, Hafiz-i Abru stated, in his 15th-century work Majma’ al-Tawarikh, that Ghazan Khan (1271-1303), the seventh ruler of the Ilkhanid dynasty, “has banned hunting near the towers to protect the pigeons.”
The typical pigeon tower of Isfahan is cylindrical outside, constructed of unfired mud brick, lime plaster and gypsum. Large towers range from 10 to 22 meters in diameter, and stand 18 meters high or more.
The pigeon towers were designed to collect pigeon dung, which has high nitrogen content and is a boon for Isfahan’s nitrogen-deficient soil. Pigeon droppings are also rich in phosphorus, another fertilizing agent. The dung was used to fertilize fruit trees, as well as the legendary cucumber and melon fields of Isfahan.

  Calculations
Chardin wrote that pigeon dung, when mixed with soil and ash, was tehalgous, or “enlivening,” according to the Persians. Applied at the standard rate of 900 grams per fruit tree per year and approximately 1,680 kilos per hectare annually, the dung increased the harvest by as much as 50%.
By rough calculation, a large pigeon tower of that time may have contained 5,000 to 7,000 pigeonholes. On average, one pigeon produces 2,750 grams of dried dung per year, which translates into approximately 16,500 kilos of high-quality fertilizer per large tower per year. Under optimal conditions, such a tower could thus provide enough fertilizer for more than 18,000 fruit trees or nearly 10 hectares of cropland, and was therefore a very valuable source of income for a village or the individuals who built and maintained it.

  Other Usages
Pigeon dung was also used in the legendary leatherworking shops of Isfahan. Mixed with water, it acts as an important softening agent in what is called “bating”—the final step before the actual tanning process.
More importantly, the dung was an essential ingredient in the manufacture of gunpowder, which consists of approximately 75% potassium nitrate (saltpeter), 10% sulfur and 15% carbon. The shah’s army had no natural source of potassium nitrate, but was able to manufacture it using a mixture of pigeon dung, ash, lime and soil.
The wild rock pigeon (Columba livia) was by far the most common pigeon inhabiting the towers. The birds were not captured and trained to occupy the towers—rather, they were instinctively attracted to them because they replicated the rocky ledges and crevices in which pigeons like to nest, mate and rear their young in the wild.
The birds were provided housing, but not food. The flocks of pigeons went out to seek water and to forage during the day. At night they would return to the pigeon towers where they were safe from raptors, mammals, snakes and other predators.
They nested in a checkerboard pattern of closely spaced niches that covered the entire interior surface of the towers, which slanted inward slightly toward the top. The pigeonholes measured approximately 20 by 20 by 28 centimeters, with a short projecting perch made of dried clay set at the opening of each one. The inward-slanting tower walls allowed pigeon dung to fall directly into a central collection pit at the foot of the tower, where it dried. The towers were opened once a year to harvest and sell the dung. A small tax was paid to the shah.
Today, perhaps 250 or 300 towers remain in and around Isfahan. Some 65 of them are now nominally protected by their inclusion on the National Heritage List.
Even in their tumbledown state, the pigeon towers that remain are still impressive to see. Small flocks of wild pigeons occasionally roost in the towers, despite collapsed ceilings and huge cracks in the walls that expose the roosts to the weather. The view upward from the bottom of a tower reveals a sculptural quality and haunting beauty that transcend its utilitarian purpose as a place to collect the dung of wild birds.
Beyond the preindustrial mud-brick engineering that so efficiently solved complex structural problems with a perfect marriage of form and function, the pigeon towers remain as an enduring tribute to the ingenuity of unknown master builders who have left their unique creations for all to see, still standing on the fields of Isfahan.
This article is written by Eric Hansen who is a free-lance writer and photographer based in California.

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