The Turtle Dove Streptopelia turtur has become a symbol of bird conservation. It is threatened by habitat loss on both its European breeding grounds and its African wintering grounds. Besides this, several million hunters have traditionally exercised their right to shoot Turtle Doves across the Mediterranean region, taking in excess of a million birds annually of an estimated 8 million individuals available (adults and their young). There is increasing evidence that such levels of harvest are unsustainable, and that they will inevitably lead to the species’ demise. However, it is also true that Turtle Doves are generally more abundant and doing less badly in countries such as Spain, France and Italy, where they are shot, than in countries like the UK, the Netherlands and Germany, where they are not. A Spanish hunter once passionately put it this way: ‘Look at the UK, they stopped hunting Turtle Doves and now they haven’t got any!’

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119. Mediterranean open pine Pinus forest, with a ploughed ‘firebreak’ to prevent the spread of wildfires, Toledo, Spain, July 2021. Such areas of disturbed soil benefit Turtle Doves Streptopelia turtur by allowing the growth of ruderal plants and providing easy access to their seeds.

Carles Carboneras

Hunting is always present in any conversation about Turtle Doves, and the issue can soon become very political; but, we argue, there is also an important role for science. Our experience with the development of an adaptive harvest management mechanism to regulate hunting of Turtle Doves has shown that scientific knowledge needs to be at the base of any informed decision-making. European Union law has developed the principle that ‘where a species is declining, hunting cannot by definition be sustainable unless it forms part of a properly running management plan that also involves habitat conservation and other measures that will slow and ultimately reverse the decline’ (European Commission 2008). In our role as scientific advisors for the European Commission, we have had to address a fundamental question: Given the continuous decline in Turtle Dove numbers, is it possible to safely extract a fraction of the population without compromising its future?

Our focus on the conservation of Turtle Doves began with the development of the International Species Action Plan (Fisher et al. 2018), delivered by an RSPB team led by CC and funded by the EU’s LIFE programme. The Species Action Plan brought together the best available knowledge[1] and established the need to take measures to ensure the sustainability of hunting. As a tool for long-term conservation, the Species Action Plan was a game changer; but change did not happen overnight, and the hunting moratorium recommended from 2019 was initially dismissed by hunting nations across Europe. Our role over the past two years has been to jointly lead a consortium of research institutions contracted by the European Commission, with the scientific team being led by the Spanish Institute for Game and Wildlife Research (IREC), to deliver the evidence and management tools that will ensure that any hunting of Turtle Doves, if authorised, is done sustainably and without jeopardising conservation efforts.

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120. A complex landscape of farmland with oak Quercus trees, unpaved tracks with grassy margins and, in the distance, Olive Olea europaea groves, Ciudad Real, Spain, July 2021. This type of environment maintains high densities of Turtle Doves. In summer, many flowering plants have completed their annual cycle, but their seeds remain on the ground.

Carles Carboneras

An important analysis initiated at the time of the Species Action Plan was to assess the sustainability of hunting in the western flyway in the period before 2018, when the total harvest within the EU was estimated at 1.1 million birds per year. Using data for 2013, Lormée et al. (2020) built different demographic scenarios and demonstrated that, in most cases, hunting at those levels was unsustainable. We thus began to investigate the potential role of harvest in the Turtle Dove population decline.

New information obtained from fieldwork in France and Spain allowed us to progress to the more complex but also more informative stage of building demographic models. This work was led by Léo Bacon and colleagues from Office Français de la Biodiversité. They built an integrated population model that provided estimates of key parameters such as fecundity (total number of young that could be produced per female per season), annual survival of adults and young, and an estimate, by age class, of the proportion of birds for which the cause of death was hunting in Europe. The model also allowed them to estimate the annual growth rate of the population using the demographic parameters and the levels of hunting in 2019, and provided a look into the future, in the form of predicted growth rates depending on different options of harvest (i.e. the percentage of the population being shot each year), including zero harvest. Finally, it assessed the uncertainty associated with each of those estimates, which can be seen as a measure of tolerable risk.  

We presented those results at various workshops, organised under the auspices of the European Commission, to an audience of national and regional authorities, hunters and conservation organisations in the framework of the adaptive harvest management mechanism proposed by the Species Action Plan. We made a technical recommendation to the decision makers to suspend hunting for the four seasons 2021 to 2024. We saw that time frame as appropriate to allow for change to take place, in the form of increased survival, and for it to be detected and quantified through the long-term monitoring schemes already in place.

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121. A cereal field surrounded by a belt of flowers and a line of trees, which provide good conditions for foraging and breeding Turtle Doves, Ciudad Real, Spain, April 2021.

Carles Carboneras

Despite opposition from the hunting community, the case for the temporary option of zero harvest in the western flyway was made clear during those meetings. The situation was less straightforward in the central-eastern European flyway (east of a line through central Germany and southwards to include most of Italy and Malta), where declines in the Turtle Dove population seem less severe and less generalised. The patchy demographic information available from those countries did not allow the building of a robust integrated population model, so we had to resort to alternative indicators of population status, such as the trends developed by the Pan-European Common Bird Monitoring Scheme (PECBMS, https://pecbms.info). In those circumstances, our technical recommendation for the central-eastern flyway was to substantially reduce the current harvest rate by 25–50%, and to review the situation as soon as new information becomes available. Authorities in those countries were advised to invest in solid, long-term research programmes that will deliver the necessary data and will allow informed decisions on harvest in the future.

Our technical recommendations, endorsed by the European Commission, were followed in both instances. In the western flyway, national and regional authorities in France, Spain and Portugal, one by one, suspended hunting of Turtle Doves in 2021. Their decrees, in many cases, referred to the ongoing adaptive harvest management process at the European level. They chose to opt for zero harvest and, to our knowledge, this has been widely respected by hunters and monitored by the enforcement agencies in those countries. In the central-eastern flyway, the decision was made to reduce hunting by 50% based on our recommendation and informed by the precautionary principle.

Our work and the decisions of public authorities have probably saved the lives of several hundred thousand Turtle Doves. Lara Moreno Zárate (2021) showed that, in Spain alone, the total harvest had declined in recent years, in line with the population decline, and estimated the 2017 harvest at 810,000 birds, plus 80,000–100,000 birds of ‘crippling loss’ (shot but not retrieved). The adaptive harvest management mechanism foresees annual meetings to update information and to make a decision on harvest for that year’s hunting season. Acting as Scientific Advisory Group, our consortium will review its recommendations on harvesting in the 2022 hunting season based on data provided by the countries on the 2021 hunting season. They will be discussed at key workshops this spring under the auspices of the European Commission.

Our modelling predicts that the removal of hunting should allow significant progress towards the recovery of the Turtle Dove. In the absence of any hunting, the population is predicted to grow steadily by 5% every year, assuming that hunting mortality is completely additive to other sources of mortality. The population could thus recover to levels seen in the 1990s in as little as 10–12 years, and the Turtle Dove could potentially be safely removed from the IUCN Red List of threatened species. In a scenario where some restricted hunting was allowed, as proposed by the hunters, the population is predicted to remain stable but at a much lower level than in previous decades and it would become technically ‘depleted’. In the riskiest scenario, business would continue as usual – that is, the continuation of harvest at the level of 2019, 12.3% of the European population annually. The decline would be exacerbated and the risk of extinction under IUCN criteria would increase enormously.

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122. Adult Turtle Dove released after ringing, in an area of typical Mediterranean forest, Spain, May 2020.

François Mougeot

Our modelling therefore supports the case for a hunting ban, though it would be too simplistic to assume that this action alone can sustain the recovery of the species. The assessment made for the Species Action Plan and our own experience indicate that the long-term conservation of Turtle Doves requires dedicated habitat management across the species’ wide range and applied at a landscape level of areas over 1,000 ha, through the implementation of adequate agriculture and forestry policies; and also at the scale of individual sites, through direct interventions to provide the right breeding, feeding and resting habitat for the species on nature reserves, Natura 2000 sites and hunting estates (Browne & Aebischer 2002; Carboneras et al. 2022).

Conservation organisations in northern Europe often complain that their efforts become diluted by the practice of hunting farther south, while hunters in southern Europe argue that it is in fact their management of habitat that has maintained good Turtle Dove numbers at their latitudes. Now is the time to bring those efforts together, facilitated by the common interest and the framework of adaptive harvest management. We expect to see higher survival following the reduction in hunting pressure. At the same time, improved habitat conditions should translate into increased fecundity. The sustainable future of the species will have to be based on good numbers and a robust demography. Hunting of Turtle Doves in southern Europe may resume in the future, if the conditions are right and the population allows. In preparation for that day, it is crucial to think about which mechanisms could be in place for reliably regulating and implementing any agreed hunting take at different scales. It is essential also to continue and ideally expand the current research and monitoring programmes to detect any relevant changes, and to ensure that the necessary evidence for informed decision-making is available.

Acknowledgements
We thank Kelly Thomas for the idea to write this article and Andy Evans for his continued support. Our work was part of a contract with the European Commission to develop a population model and adaptive harvest management for the Turtle Dove, delivered through an international consortium of research institutions led by IREC in Spain.

References

Browne, S. J., & Aebischer, N. J. 2002. The effect of supplementary feeding on territory size, territory density and breeding success of the Turtle Dove Streptopelia turtur: a field experiment. Aspects of Applied Biology 67: 21–26.

Carboneras, C., Moreno-Zárate, L., & Arroyo, B. 2022. The European Turtle Dove in the ecotone between woodland and farmland: multi-scale habitat associations and implications for the design of management interventions. J. Ornithol. https://doi.org/10.1007/s10336-021-01946-1

European Commission. 2008. Guidance document on hunting under Council Directive 79/409/EEC on the conservation of wild birds “The Birds Directive”. 

Fisher, I., Ashpole, J., Scallan, D., Proud, T., & Carboneras, C. 2018. International Single Species Action Plan for the conservation of the European Turtle-dove Streptopelia turtur (2018 to 2028). European Commission, Luxembourg.

Lormée, H., et al. 2020. Assessing the sustainability of harvest of the European Turtle-dove along the European western flyway. Bird Conservation International 30: 506–521.

Moreno Zárate, L. 2021. The status and hunting of European Turtle-dove (Streptopelia turtur) in Spain. PhD thesis, Universidad de Castilla-La Mancha, Ciudad Real.

 

Carles Carboneras and Beatriz Arroyo, Spain; e-mail [email protected] and [email protected]

 

Carles Carboneras manages the International Migrants Recovery Programme at RSPB in the UK and is associate research scientist at the Institute for Game and Wildlife Research (IREC) in Spain. His work focuses on the development of science-based management tools for threatened species, especially those affected by anthropogenic threats (unsustainable hunting, bycatch, illegal activities) or impacted by invasive alien species.

Beatriz Arroyo is a senior researcher at the Institute for Game and Wildlife Research (IREC) in Spain. Her work focuses on the study of the ecology, management and conservation of wildlife, in the context of changes associated with human exploitation of renewable natural resources, such as hunting or farming. 


[1] The Turtle Dove Species Action Plan received contributions from 300+ experts from the entire flyway and was adopted by the European Union and the Convention on Migratory Species in 2018. The Species Action Plan identified habitat loss on the breeding and wintering grounds, and unsustainable hunting as the key drivers of population decline in western Europe. In other parts of the range, poaching (illegal killing) is another important factor.

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Issue 4
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