Habitat management favouring duck hunting seems to prevent shifting distribution due to climate warming: Another avenue for hunting ‘greenwashing’?

Abstract

Habitat management favouring target species has long been proposed as a potential tool to buffer the consequences of natural habitat loss for such species. Furthermore, during the last two decades, several authors have proposed artificial wetland management as a critical tool to mitigate the ongoing effects of climate change on natural habitats for the conservation of waterbirds (wildfowl, shorebirds, herons, etc.) (e.g. Masero, 2003; Green et al., 2017). Among them, highly mobile taxa such as migratory waterbird species are declining globally, although with contrasting current trends depending on their geography and phylogeny. For example, duck species are overall experiencing population increases in North America (Rosenberg et al., 2019), while they are declining in Europe (Birdlife International, 2015).

In the face of climate change, Gaget et al. (2023) recently found that most migratory waterbird populations in Europe (from a total of 110 species evaluated over 28 years at 851 sites) had shifted their non-breeding distribution towards northern areas following ambient temperature increases during this period, with the notable exception of hunted duck populations. Gaget et al. (2023) propose that habitat management targeting hunted ducks in southern Europe by providing attractive feeding grounds, which mainly occur in anthropogenic coastal wetlands surrounding the Mediterranean in France and Italy, as the main explanation for this absence of geographical shifting to track improved environmental suitability towards the northern latitudes. They further suggest that ‘habitat management for hunting purposes may hence have counter-balanced the effect of climate warming and ‘retain’ hunting ducks to these wintering grounds, which they would otherwise abandon for more northern areas’ (Gaget et al., 2023).

While habitat management for hunting at such specific sites could have partially driven this absence of non-breeding distribution shifting in ducks, regional land-use changes that occur especially in the southern limit of their distribution range in southwestern Europe could have a role. In this light, the creation of several small-scale reservoirs (<1,500 ha) close to rice fields in the mid-Guadiana basin, Extremadura, Spain, during the late 1990s, improved habitat conditions for duck populations that may have resulted in a partial non-breeding redistribution within the Flyway (Navedo et al., 2012). Therefore, if such reservoir creation in nearby rice fields overall improved habitat conditions for duck populations, this could alternatively explain the lack of distribution shifting reported by Gaget et al. (2023) but would support their broader point: habitat management can influence winter distributions of waterbirds.

Among specific long-term consequences of this potential effect of habitat management for hunting on target populations, one crucial ecological issue immediately arises: could such absence of response of migratory duck populations to current environmental changes be maladaptive? Gaget et al. (2023) already recognized that ‘more studies … are needed to understand whether hunted ducks are more persistent against climate change because of habitat management, or trapped there despite ongoing climate warming’. Indeed, hunting management (as well as reservoir creation) could provide attractive habitats for duck populations in the southern range of their distribution in the short term. However, if climate warming continues its current trend, these populations will be trapped in southern Europe in a non-optimal ambient temperature environment with regards to the upper limit of their thermoneutral zone. Even if temperatures in mid-March, when most migratory duck populations start migration, would hardly reach a lethal limit, ongoing climate warming and especially heatwaves that have been increasing in frequency and intensity during the last decades (Perkins-Kirkpatrick & Lewis, 2020) might finally force migratory ducks to displace northwards in the mid-term. Hence, one key unanswered question is how long such potential effects of habitat management on migratory ducks will persist.

Moreover, hunting bags tend to be biased towards non-adult individuals (Cox, Afton, & Pace, 1998), and thereby the chances of non-experienced juveniles of hunted duck species being removed from natural populations are high. Indeed, a species-specific case study reported a long-lasting decline in the proportion of juvenile individuals of the migratory species Mareca penelope in hunting bags from Finland, that is, from ca. 85–95% during mid-80s to below 70% in mid-2010s, indicating a decline in species productivity (Pöysä & Väänänen, 2018). While climate change, interannual variations in breeding habitat quality and phenology shifts are discussed as potential causes of this decline in juveniles, interestingly, no mention of the potential effects of hunting-bias towards juveniles throughout the Flyway can be found. Therefore, hunting-bias towards juveniles in these habitats managed for duck hunting could further obstruct natural distribution shifting by both indirectly hampering recruitment and directly reducing population size.

A final argument against the potential benefits of habitat management for hunting on target migratory populations arises from the ethics and justice of conservation. On the one hand, there is a double-standard in ‘western’ countries, such as those in southwest Europe, where habitat management for hunting is generally seen as beneficial for duck populations and game hunters are socially exonerated as sportsmen engaged in habitat improvement, while traditional ‘indiscriminate’ harvesting methods of local people in countries in the global south within the same Flyway are often condemned (Tan, 2021). On the other hand, game hunting entails an overall injustice for wildlife populations, due to the presumptive superiority of humans with respect to animal resources and environmental management (Tan, 2021). In the end, other than removing targeted, disease-carrying or conflict individuals from a population, hunting itself can hardly be beneficial for biodiversity conservation. Causal conservation evidence, rather than any conservation potential based on correlations that could even be maladaptive, seems to be necessary within the times of accelerated biodiversity crisis and pro-hunting lobbies operating at high political levels trying to influence animal conservation policies (e.g. removing the hunting ban of Iberian Wolf Canis lupus signatus, a crucial taxa included in ‘List of wild species under special protection regime’ in Spain that provides a number of ecosystem services; Beschta & Ripple, 2019). Therefore, considering the ethics and justice of conservation, such presumed benefits of a recreational human activity that essentially removes millions of animals each year from declining natural populations (e.g. 5.5 million ducks shot annually in 24 European countries, Guillemain et al., 2016) can conversely be considered as another avenue of hunting ‘greenwashing’.

To sum up, potential indirect effects of habitat management for hunting through mismatching natural distribution shifting of migratory duck populations in response to climate warming (Gaget et al., 2023), seems to be a real signal of yet another anthropogenic impact of climate change on migratory waterbird populations, with unknown consequences for mid- and long-term population dynamics and fitness, rather than any net benefit for animal conservation, and in this case, for hunted duck populations in Europe.