The Pigeon in the Coal Mine

The Côa Valley, Eastern Portugal, is dotted with thousands of pigeon houses. It is impossible not to notice the elegant structures that seem to fit timelessly within the landscape. Though they look like they’ve always been there, this is not true. For a region with a history dating back tens of thousands of years, they are newcomers, only appearing in the beginning of the 20^thcentury. Why they are there, and what their purpose is today, turns out to be a magnificent story of the complicated relationship between humans and their environment.

The Côa Valley is nowadays at the forefront of land abandonment in Europe. Villages are shockingly empty, houses left to crumble. At the beginning of the 20^thcentury, the region was at the opposite end of the demographic pendulum, growing tremendously in population and therefore converting the land into terraces for growing rye, vines, olives, and other crops. People in the area speak of past sand cascades on the steep banks of the Côa, the result of intense agricultural transformations that led to soil erosion on an impressive scale. Without trees to stabilize the loose ground, it simply slid away into the river.

The era of agricultural production in the valley did not only lead to soil erosion, but also to the depletion of nutrients. The extensive and habitual use of fire to clear land for animals and crop plantations exacerbated these problems, leading to increasingly difficult conditions. The pigeon houses first appeared at the height of these agricultural transformations and had two functions: raising pigeons for meat and, more importantly still, producing guano for the depleted fields. The structure of the pigeon house is made with guano production in mind. The imperfectly circular building has pigeon holes on the inner walls and a lifted stone table on the bottom, with space between it and the walls. This allowed for the collection of important quantities of guano that returned some of the nutrients to the overly exploited soils.

As the 20^thcentury moved away from agricultural production in remote areas and towards monocultures on industrial scales, and as urbanization accelerated, the region started being abandoned. Some traditional practices, such as setting fire to the land, still continue today, but a lot of plots are no longer in productive use. The pigeon houses were themselves abandoned during this momentous transition from rural to urban economies. As the 21^stcentury rolled in, the desolation of abandonment gave rise to a preservationist ethic. Pigeon houses were catalogued and restored, for architectural and cultural purposes. They were deemed cultural artefacts worthy of protection, despite their relatively short history. Somehow, in their life-span of barely 100 years, they had managed to insinuate themselves within the landscape.

The restoration and preservation of the pigeon houses spurred for a moment the practice of keeping pigeons, though nowadays most houses are abandoned again. Without the need for pigeon meat or guano, there was no reason to keep them alive. The abandonment of the area also provided opportunities for rewilding projects. The era of intense agricultural use had not only transformed the soil but had also made wildlife habitat a rarity. Through plantations of crops and fire, the land had been made inhospitable to a range of animals that had existed in the area for millennia (and poignantly etched into its rocks). The Transhumance and Nature Foundation (ATN) started buying formerly agricultural land and consolidating it into a natural reserve. When they started the rewilding of parts of the Côa Valley they were primarily interested in the conservation of eagles and vultures through the reconstruction of their habitat. These had become endangered or had entirely disappeared from the area. ATN set off to protect nesting sites as a first line of defence against local extinction.

While restoring suitable habitat for eagles and vultures, activists also co-opted the restoration of pigeon houses. Besides the problem of shrinking habitat, birds of prey had also had to contend with the problem of diminishing prey. The pigeon houses offered an elegant solution to the problem of low prey numbers: grow pigeons (and keep alive a by-now cherished tradition) for the eagles to hunt. In several areas of habitat restoration, ATN is running pigeon houses in order to ensure that the eagles have enough to eat to grow their population. Ideally there would be enough wild prey for both eagles and vultures to survive unassisted. However, the reality of land fragmentation in the area is such that only pockets of land have currently been made suitable for wildlife again.

What used to be production houses for agricultural fertilizers became production houses for the feeding of wild birds of prey. The farmers of the 20^thcentury have left an unintended gift to the conservationists of the 21^st. Perhaps a further hundred years from now the story of the pigeon houses of Eastern Portugal will be told with wildlife at its heart. Besides their architectural beauty, they surely deserve to be celebrated as symbols of a changing relationship to the natural world, away from land depletion and towards restoration. Their meaning as cultural artefacts has only grown deeper.