Growing number of black stork chicks in Douro Internacional

“This set of 10 pairs of black storks (Ciconia niegra) had a productivity of 2.6 flying offspring per couple, in the Douro International Natural Park (PNDI), which is an above average and may be associated with the large availability of ponds and water, as it was a rainy spring”, specifies the regional head of the North of the Institute for the Conservation of Nature and Forests (ICNF).

According to ICNF, the river canyon of the Douro, steep and inaccessible along its border, has been home to one of the most important breeding centers of black storks in the Iberian Peninsula for a long time. “In this zone, the very shy species has a rupicolours behaviour, that is, it selects exclusively vertical boulders, generally close to the margin, to install its nests,” said Sandra Sarmento.

According to birdlife specialists, the nests are uniformly located on both sides of the border in Portugal, in the Douro International Natural Park and in Spain, in the Arribes del Duero Natural Park. In these two Protected Areas, which total 200,000 hectares, the black stork, as well as other rock dwelling birds, are followed and watched, year after year and during nesting, by a cross-border team with about 20 groups that include Nature Watchers ( ICNF), Agentes Medioambientales (Junta de Castilla y León), and biologists from both organisations.

In addition to the assessment of its situation, its reproductive parameters and threats, the species was the target of conservation actions, including the opening of ponds and the implementation of measures to minimize the risks of collision and electrocution arising from the presence of lines electrical devices. “Within the scope of this cross border follow up, the protocol of regular visits to the nests was maintained, even in the current nesting season, in which there were restrictions on movement between the two countries”, stressed Sandra Sarmento. Thus, it was confirmed that in one of the nests that was being monitored (located on the Portuguese side), two juveniles had died inside.

This situation occurred in the final phase of its development, when the vast majority of offspring from the other nests had already left them. Thus, a trip was organized to collect the corpses and observe all evidence of the cause of death. There was no evidence of the most common causes of mortality, namely predation, plastic cords, or direct human action. The specimens were sent, through the Center for Environmental Interpretation and Animal Recovery (CIARA) in Felgar, to the Pathological Anatomy Laboratory of the University of Trás-os-Montes and Alto Douro, where their necropsy and assessment of the causes of death will be carried out.

ICNF reported that in Portugal the species has the status of "Vulnerable" according to the Red Book of Vertebrates in Portugal, and has a population of about 90 couples. The PNDI is a protected area that covers the area where the Douro river forms the border between Portugal and Spain, as well as the Águeda river, a tributary of the Douro. Includes areas in the municipalities of Mogadouro, Miranda do Douro, Freixo de Espada à Cinta and Figueira de Castelo Rodrigo.