The marbled teal, the most endangered duck in Europe, continues to show a very delicate population status and a high risk of extinction. This is the main conclusion of the second meeting of the working group on the species, declared in a critical situation in Spain by the Ministry for Ecological Transition (MITECO) in 2018. At the meeting, held in Trebujena (Cádiz), representatives of public administrations, experts, researchers and conservation entities have agreed on new actions to monitor the specimens they breed in our country, as well as surveillance tasks in the wetlands they use. Among others, it has been decided to mark specimens with GPS transmitters to detect possible black spots of unnatural mortality.
In 2018, they bred between 68 and 71 pairs of marbled teal in 13 wetlands. The largest number of breeding females was recorded in the lower Guadalquivir, especially in the Doñana Natural Area (Huelva-Seville), where 16 were detected, and in the Trebujena marshes, where 12 were sighted. It was followed by those recorded in the natural parks of El Hondo (Alicante), with six, and S ́Albufera de Mallorca (Balearic Islands) with between four and seven breeding females.
The trend shown in recent years is one of slight increase, although always within the framework of a very worrying population situation and with a high risk of extinction. In 2017, they bred 60 pairs.
At its last meeting, the working group has highlighted the importance of knowing the patterns of movement and causes of mortality of marbled teal, given that to date there is no precise data on the fate of the specimens that are born annually in Spanish wetlands. For this reason, individuals will be marked with GPS transmitters in the two most important areas (Alicante wetlands and Doñana surroundings) throughout 2019, which will contribute to detecting possible black spots of unnatural mortality.
Based on the data obtained, surveillance measures will be undertaken in wetlands considered key not only in the breeding season, but also in autumn and winter, and actions will be facilitated to improve the productivity and survival of the chicks born with the help of nesting boxes and protection against predators. Likewise, work will be done to reduce the negative effects produced on the ecological quality of several wetlands by the presence of invasive exotic species, such as carp.
The participants in the working group, which is coordinated by MITECO, have also considered it necessary to deepen coordination at the state level in the captive breeding of the species to optimize the resources and performance of the centers in which it already breeds. Currently, the El Saler centre managed by the Generalitat Valenciana and the Cañada de los Pájaros in Seville have a large contingent of marbled teals that breed in captivity and that are a valuable reservoir to undertake population reinforcement tasks in different wetlands with appropriate characteristics for this bird. These actions will be enhanced thanks to the incorporation of new possible areas for the release of specimens in Castilla-La Mancha, which complement the work already carried out in Andalusia, the Valencian Community and the Balearic Islands.
HABITAT RESTORATION
Habitat restoration in wetlands is also essential, especially in those enclaves where the species breeds. Thus, for example, an important battery of adaptation measures is being developed to favour the marbled teal both in the marshes of Trebujena (Cádiz) and in wetlands in the south of Alicante in the surroundings of the El Hondo Natural Park.
The actions in this area are varied and range from the acquisition of key wetlands for the reproduction of the species, and currently privately owned, to the improvement of hydrological management to ensure adequate quality and quantity of water in several wetlands, or to the renaturation of flooding processes in different marsh areas by eliminating existing barriers and infrastructures. The degree of execution of these actions is being satisfactory with respect to the needs raised as priorities in 2017 within the framework of the working group.
To develop all these measures, the environmental administrations of the autonomous communities in the species’ distribution area are allocating significant resources, with the support of MITECO and sectoral associations, which are expected to be reinforced by the European Commission through the LIFE+ programme. The role of research centres is equally important in assessing the effectiveness of the measures implemented and in understanding the most important aspects of marbled teal ecology.
AN ABUNDANT SPECIES UNTIL THE MID-TWENTIETH CENTURY
Abundant in Mediterranean coastal wetlands, and especially in Doñana, until the mid-twentieth century, the marbled teal is today the most endangered duck species in Europe. Its distribution in Europe is restricted to several Mediterranean locations concentrated mainly in Spain.
It selects shallow-water wetlands with good quality, with availability of macrophytes (aquatic plants) and aquatic invertebrates on which it feeds, and that maintain water well into summer since it reproduces at relatively late dates.
Different factors associated with the reduction of water quality and the unnatural mortality of the species have caused its populations to decrease drastically, to the point of being declared in a critical situation in 2018 following the criteria established in compliance with Law 42/2007, of 13 December, on Natural Heritage and Biodiversity.
