New publication on illegal and accidental hunting!

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. 

Pohto: Wikipedia.com

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

New Publication on Woodcock mortality and hunting pressure

Prieto, N., Tavecchia, G., Telletxea, I, Ibañez, R., Ansorregi, F., Galdos, A., Urruzola, A., Iriarte, I. and Ariziaga, J. 2019 Survival probabilities of wintering Eurasian Woodcocks Scolopax rusticola in northern Spain reveal a direct link with hunting regimes. J. Ornithol. doi: 10.1007/s10336-018-1617-1

From en.wikipedia.org

Abstract  The management of game species relies on robust estimates of hunting-related mortality. A relative measure of this mortality can be obtained by comparing survival estimates of animals across similar areas with different hunting pressures. We conducted live recapture-dead recovery analyses on wintering Eurasian Woodcocks Scolopax rusticola (hereinafter “Woodcock”) in provinces of Gipuzkoa (GIP) and Álava (ALA), two neighboring regions of northern Spain. The two regions have a similar number of hunting licences issued on a per day basis, but while hunting is limited to 3days per week in ALA, in GIP it is allowed on a daily basis, resulting in a ca. 50% longer period of  exposure of game species to hunting-related mortality here.We used a model based on monthly survival estimates to test whether the mortality of Woodcock varied between the two regions. Mean (± SE from a time-constant model) annual survival of Woodcocks was estimated to be 0.37 (± 0.04) and 0.56 (± 0.04) in GIP and ALA, respectively. If we assumed that this difference was only due to the longer period of exposure to hunting, mortality was increased by ca. 10% per additional day of hunting per week. Moreover, we also found that survival was positively associated with temperature in one of the study zones (ALA), suggesting that a high hunting pressure can override the effect of climate-dependent fluctuations. However, further research into fecundity and dispersal is necessary to assess the viability and sustainability of the wintering Woodcock populations under the current hunting regimes in these two zones.

 

The VIII edition of the Workshop on CMRR analysis ended!

The VIII edition of the annual workshop on CAPTURE-MARK-RECAPTURE and RECOVERY analysis has ended last friday! Thanks for coming (although we have missed the very big shrimp :-) ! It has been great to have you all here at the IMEDEA and learn about dragon-flies, storks, cranes, swans, houbara bustard, audouin's gulls, penguins norway lobsters, black-tailed godwits, marking methods..etc.. and top of all, new exiting biological questions.  More next year!

 

New publication on tern survival !

Payo-Payo, A., Sanz-Aguilar, A., Gaglio, D., Sherley, R.B.,Cook, T.R., Altwegg, R. and Ryan, P.G. 2018 Survival estimates for the greater crested tern Thalasseus bergii in southern Africa African Journal of Marine Science, 40. 45-50, doi: https://doi.org/10.2989/1814232X.2018.1437470

Abstract: The nominate race of the greater crested tern Thalasseus bergii breeds only along the coast of the Benguela region (west coast) of southern Africa, where its population is increasing, in contrast to other species of breeding seabirds in the region which similarly depend on forage fish. Although this population’s trends are well known, its demographic parameters remain obscure. 
We used multi-event capture–recapture–recovery modelling to provide the first estimates of survival. The survival rate of birds older than two years was 0.93 (0.91–0.95); second-year survival was 0.93 (0.90–0.95) and first-year survival was 0.80 (0.73–0.85). A resighting of a 34-year-old bird is a new longevity record for the species. Population growth rates projected with a Leslie matrix model that included our survival estimates were very similar to estimates from annual counts of the breeding population (7–8% y⁻¹), suggesting that these survival estimates adequately describe the species’ demography. High survival rates have likely contributed to the species’ recent population increase in the region.

The study made the journal cover. Congrats Ana & Ana (& Co.)