Few wild birds have as close a relationship to us humans as the white stork. The sight of their enormous nests on village rooftops, with a pair of storks perched on top, is one of the most charming scenes of rural life.
The white stork has been a constant companion of farmers working the fields. As a savvy opportunist, the bird likes to follow the plough as it furrows the soil, picking out earthworms, snails, and other small invertebrates.
For the farmers, the stork is a respected, beloved ally, because its presence is very beneficial: the bird does not damage the crops in any way but keeps insect and rodent populations, which could be hazardous to the harvest, in check.
A white stork spotted in the fields. Photograph: Ana Mínguez
Easily recognizable by its unmistakable silhouette and distinctive black and white plumage, this large wading bird has long, slim legs the colour of coral, which match the red of its long, sturdy, sharp beak. It has broad, rounded wings with very separate primary feathers, like gigantic fingers combing the air in order to fly.
The white stork lives in rural and urban settings where it builds large platform nests in places that are high enough to allow for good visibility: belfries, abandoned chimneys, electrical towers, aerials, and other elevated spots.
The birds mostly use sticks, branches, and canes to build their nests, but will happily add anything that catches their eye in the fields over the years. As a result, these structures can reach over three metres in height, with a two-metre diameter, and weigh up to two tonnes. In the case of very large nesting colonies, this can become a safety issue.
A pair of white storks in their nest on a sunny day. Photograph: Ana Mínguez
White storks are laying their eggs earlier and earlier, but generally speaking this occurs between March and April, with clutches of four to five white eggs. Five weeks later, the chicks hatch, and they begin to fledge around June (60 days after hatching). What distinguishes young storks from their parents is the black colour of their legs and beaks.
A very curious fact sets storks apart – they are completely mute, because they lack a syrinx, the sound-producing vocal organ of birds. They communicate through bill-clattering: by rapidly opening and closing their long beaks, storks produce a melodic sound similar to that of castanets, which allows individual birds to exchange messages of recognition or warning.
The Spanish white stork underwent a very difficult period in the mid-1980s when the indiscriminate use of pesticides in the fields, the loss of wetlands, and poaching reduced the local population to just 6,000 pairs in the 1984 census.
These days, however, the white stork is no longer an at-risk species. With 50,000 pairs across the entire peninsula, it is becoming an increasingly common rooftop tenant in many Spanish cities and villages.
Contributing to this recovery are the surprising ways in which this intelligent bird has adapted to present conditions. White storks have stopped foraging for amphibians in lagoons and ponds and instead turn to landfills for reliable sustenance, where they have discovered a source of constant and varied food.
Another behavioural pattern that is changing is the stork's condition as a migratory species. Traditionally these birds migrated to their wintering grounds in Africa at the start of summer when the wetlands in Spain ran dry. However, more and more storks are now staying in Spain year round given the slow but constant rise in winter temperatures. This is why scientists who are following the evolution of the climate crisis consider the stork a bioindicator of what is happening.