Page 53 - UMH Sapiens 38

Science for Sapiens A year in research (2024)

llegal hunting, power lines and cats are killing the
marbled duck, a duck emblematic of the wetlands of
southeast Spain and which is at risk of disappearing.
A study carried out by a team of researchers from
the University Miguel Hernández of Elche (UMH),
the University of Alicante (UA) and IMEDEA – a joint
centre of the CSIC and the University of the Balearic
I Islands – concludes that unless at least 40% of the
unnatural mortality of this species is reduced, the recovery
programmes for the marbled duck in Spain will fail.

According to the researchers, in Spain, a lot of media atten-
tion is paid to endangered species such as the Iberian lynx,
the brown bear or the Spanish imperial eagle. However, the
seven critically endangered species, that is, those with an
imminent risk of disappearance, are much more unknown.
These species include two birds, two mammals, one plant
and two mollusks.

Among them is a duck: the marbled duck. This species,
considered the most endangered duck in Europe, almost Author: O. Aldeguer
disappeared a decade ago, when only a few dozen bree-
ding pairs were detected in the environment of Doñana and
the wetlands of southern Alicante. To reverse this situation, “If the human-related
both the Autonomous Communities and the central gover- mortality is not reduced,
nment undertook various conservation actions, including a
recovery programme with the release of captive-bred birds. it will not be possible to
Thanks to this programme, more than three thousand in-
dividuals have been released in recent years, but despite recover a self-sustainable
this, the populations of marbled ducks are not growing as population, no matter how
expected.
many specimens raised in
To evaluate the effectiveness of the recovery programme, captivity are released”
researchers from the Ecology Area of the UMH, in collabo-
ration with colleagues from the UA and IMEDEA-CSIC-UIB,
have carried out a study that has enabled them to find out
the survival of the individuals released in the Valencian According to Juan Manuel Pérez García, a professor in the
Community, identify the main causes of mortality and fi- ecology area of the UMH, the high rates of unnatural morta-
nally assess the future viability of the species. For this, the lity are compromising the recovery of this critically threate-
data provided by sightings of ringed individuals have been ned species. “If the human-related mortality is not reduced,
key, as well as the data collected through GPS devices with it will not be possible to recover a self-sustainable popula-
which more than 40 birds have been equipped in recent tion, no matter how many specimens raised in captivity are
years. released”, the expert points out. The analyses indicate that
the unnatural mortality of these birds should be reduced
The study results indicate that mortality from unnatural cau- by 40% to recover populations. To achieve this, the authors
ses, such as illegal hunting, power lines collisions or preda- propose several urgent measures that include banning the
tion by cats, triples natural mortality. Illegal hunting, either hunting of waterbirds in hours with poor visibility to avoid
by identification errors in legal hunting days or by poaching, confusion and accidental deaths of non-game species, in-
stood out as the most significant cause of mortality for the creasing the prosecution of poaching, controlling exotic
species since it affected one in three GPS-tagged birds, both predators in wetlands, and improving water management
captive and wild-bred. To determine the causes of mortality, to reduce outbreaks of diseases such as botulism.
the use of GPS devices was crucial, as it enabled to accura-
tely identify the place and day of death. Unfortunately, 50% The researchers also suggest that some improvements
of GPS devices unexpectedly stopped transmitting data. could be made to recovery programmes based on capti-
Researchers suspect that it could largely be due to illegal ve breeding and release. They suggest that delaying the
hunting, as 70% of these devices suddenly stopped wor- release of captive-raised birds until the end of the hunting
king when the bird was inside a hunting reserve. In addition, season could have long-term negative effects, increasing
the results warn that the presence of cats in wetlands (both habituation to humans and reliance on predictable food
domestic and feral) is an emerging threat that needs to be sources. Finally, they propose recommendations to reduce
addressed carefully since cases of cat predation have been the stay in captivity and provide anti-predatory training to
detected, which can lead to significant losses. the birds released in the breeding cages.

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