"The birds above" are everywhere in lstanbul. Swallows hawk across the parks along the Golden Horn at sunset, and jackdaws tumble in the updrafts against the Byzantine city walls. Every fall there is the spectacular, towering gyre of thousands of white storks that forms over the Bosporus as the birds slowly spiral upward to begin their migration to the south. And there are the pigeons strutting and cooing in front of the Yeni Cami - the New Mosque - waiting for handouts of grain from pious passers-by.
Feeding birds, or freeing caged ones, is a meritorious act, the Turks believe. According to the Qur'an, the righteous "feed, for the love of God, the indigent, the orphan and the captive," and some interpret that verse as calling for charity to animals as well as to humans.
Thus the birds that share Istanbul with its human population - as they have for more than 2500 years - are rarely harmed and, in times past, were often helped to find food or shelter in the city. And out of this cherishing attitude grew an extraordinary architectural form: the stone birdhouses, dovecotes and "bird castles" that grace several of Turkey's older cities, Istanbul in particular.
The birdhouses were built on walls that sheltered them from the worst of the sun and from the cutting winter winds that sometimes scour the city. High up under cornices or eaves, well out of reach of meddling hands - or claws - they are often built, delightfully, in the architectural style of the building, or the period, they are part of.
Constructing such birdhouses at various points around homes and other buildings probably came into vogue in the 16th century, with the flowering of classical Ottoman architecture. The practice continued into the latter part of the 19th century, with all the shifts of style and the trends and vagaries of fashion that characterize a true art form.
A pair of birdhouses flanks the entrance of the Ayazma mosque in Üsküdar, in the Asian part of Istanbul. One resembles a little köşk, or garden pavilion, of the kind found in many a park and palace courtyard in the city; the other has similar dimensions but a more mosque-like shape, and both are delicately carved and adorned at each roofpeak with the crescent finials visible all over the city.
On the walls of the nearby Selimiye mosque are tiered birdhouses. With their pronounced eaves, corbelled bay windows and what appear to be the remains of grand staircases, they deserve to be called "bird castles." Elsewhere - on the Yeni Valide mosque, for example, or on the Turkology Institute building - the birdhouses indisputably resemble miniature mosques, complete with arabesque carving, minarets and domes.
The quality of the workmanship varies from one birdhouse to another. At the Selimiye mosque, far example, the holes in the exterior walls where the scaffolding once was anchored were covered with perforated brick or stone to provide a shelter for the birds. At the Seyit Hasan Paşa madrasa, or religious school, on the other hand, the stone of the wall has been carefully plastered to make a smooth, distinct setting far a palatial, mosque-like dovecote.
Such elaborate constructions, even for a good cause, seem whimsical at best. But the true-to-life architecture of the birdhouses, and their locations in relation to other buildings that stand - or stood - nearby, may point to another reason far their existence.
We know from historical records that Ottoman architects - like their Byzantine predecessors in this same city - constructed scale models of the buildings they were designing to show to their patrons for approval. Only a very few such models have survived to our day, and even for those we know neither the dates of construction nor the names of the builders. We would love to know more, of course - and perhaps these wonderful birdhouses, which document such an attractive aspect of Islam, also document some lost aspects of the architectural profession of the past.
Saffet Dagdeviren is on the staff of the Industrial Training Development Center of Turkey's Ministry of Industry and Commerce. His guidebook Central Anatolia is shortly to be published.