Illegal hunting, power lines and domestic cats are decimating the gray teal, an iconic duck in the southeast peninsula’s wetlands that is in danger of extinction. A study carried out by a group of researchers from the University of Alicante (UA), the Miguel Hernández University (UMH) in Elche and IMEDEA, a joint center of the CSIC and the University of the Balearic Islands, concluded that, if it will not decrease to at least 40% of the unnatural mortality of this species, the gray teal recovery programs in Spain will fail.As the researchers explain, in Spain a lot of media attention is given to endangered species such as the Iberian lynx, brown bear or imperial eagle. However, the seven species that are in critical danger of extinction, that is, those that have an imminent risk of extinction, are not well known. These species include two birds, two mammals, one plant, and two mollusks.
Among them is a duck, the gray teal. This species, considered the most endangered duck in Europe, almost disappeared a decade ago, when only a few dozen breeding pairs were found in the area around Doñana and in the wetlands south of Alicante. To reverse this situation, the Autonomous Communities and the central government have taken various conservation actions, including a recovery program with the release of specimens bred in captivity. Thanks to this program, more than three thousand individuals have been released in recent years, but despite this, gray teal populations have not improved as expected.
With the purpose of evaluating the effectiveness of the recovery program, researchers from the Ecology Area of UMH, in collaboration with researchers from the UA and IMEDEA-CSIC-UIB, conducted a study that allowed us to find out survival. of individuals released in the Valencian Community, identifying the main causes of mortality and, finally, evaluating the future survival of the species. For this, the data provided by the sightings of ringing individuals has been key, as well as the data collected through GPS devices with which more than 40 specimens have been equipped recently years.The results of the study show that mortality from unnatural causes, such as illegal hunting, collision with power lines or theft of cats, triples the natural mortality. Illegal hunting, either due to errors in recognizing legal hunting days or due to poaching, prevails as the most significant cause of species mortality, as it affects one of the three indicators specimens, both captive and wild specimens. To determine the causes of mortality, the use of GPS devices is essential, as it makes it possible to accurately identify the place and day of death. Unfortunately, 50% of GPS devices stop sending data unexpectedly. Researchers suspect that this may be due to illegal hunting, because 70% of these devices suddenly stop working when the bird is inside a preserve. In addition, the results warn that the presence of domestic cats in wetlands is an emerging threat that needs to be addressed carefully because cases of theft of these cats have been detected, which can cause great losses.
Roberto Rodríguez Caro and Esther Sebastián González are the two researchers from the UA Department of Ecology who participated in the study. Pérez García points out that “there are many specimens released in recovery programs, but they cannot establish themselves because the mortality rate is very high.” Analyzes show that the unnatural mortality of these birds must be reduced by 40% to recover the populations. To achieve this, the authors suggest some urgent measures that include banning the hunting of waterfowl during hours with poor visibility to avoid confusion and accidental deaths of non-gamekeepers. species, increasing poaching prosecution, controlling exotic predators in wetlands, and improving management. in water to reduce outbreaks of diseases such as botulism.
The researchers also indicated that some improvements could be made in recovery programs based on captive breeding and release. They suggest that the strategy of delaying the release of captive birds until the end of the hunting season may have negative long-term effects, by increasing people’s habituation and reliance on predictable sources of food Finally, they make recommendations to reduce captivity and provide anti-predator training to birds released from breeding cages.