Pérez‐García, J. M., Sebastián‐González, E., Rodríguez‐Caro, R.,
Sanz‐Aguilar, A., Botella, F. (2023). Blind shots: non‐natural mortality counteracts conservation efforts of a threatened waterbird”. Animal
Conservation. https://doi.org/10.1111/acv.12906
In a shell: The study found that 60% of recorded mortalities of the marbled teal was due to non-natural
causes, including illegal shooting. Hunters might kill marbled teals accidentally while shooting other game species. The study highlights the need to reduce illegal shootings to establish a viable population of marbled teal.
Abstract: Waterbirds are particularly affected by the high hunting pressure they
face in many regions, which in some cases is compromising conservation
actions for threatened species. The marbled teal Marmaronetta angustirostris
is one of the most endangered waterbirds in Europe. In order to restore
its population, several conservation actions have recently been
undertaken, including a population reinforcement programme in Spain
using captive-bred birds. With the aim of assessing the success of the
reinforcement programme to establish a long-term self-sustaining
population, we identified mortality causes of marbled teal, evaluated
the survival of individual birds of the reinforcement programme and
estimated the viability of the population under different management
scenarios.
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Pohto: Wikipedia.com
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We used data from wild and captive-bred individuals tracked
by GPS since 2018 (n = 42) and from a mark–recapture programme initiated in 2015 (n = 297).
We recovered 15 dead birds or transmitters: 20% died of natural causes,
60% of non-natural causes (including all anthropic causes) and 20% of
unknown causes. Furthermore, the GPS tags of 24 birds unexpectedly
stopped transmitting without any indication of malfunction, and for
66.7% of these disappeared birds, the cessation was suspected to be
caused by illegal shooting. Survival during the hunting season was
higher for males (31.3%) than for females (12.5%), and for the wild
(50%) than for the captive-bred birds (9.4%), probably due to
differences in migration patterns to North Africa. Population viability
models revealed that maintaining the breeding population at the current
mortality rates is only possible with a permanent release programme of
captive-bred individuals, and that in order to establish a
self-sustaining population, non-natural mortality would have to be
reduced by at least 40%. We recommend management measures to reduce
marbled teal mortality, such as limiting legal hunting to hours with
clear visibility, prosecuting illegal shootings, controlling exotic
predators and improving water management to reduce disease outbreaks.
Some improvements can be implemented in captive-breeding programmes,
such as earlier release times and incorporating anti-predator training.
A press note (in Spanish) here
