The research, led by Kinga Piórkowska of the University of Szczecin together with Wiktor Strączyński, Łukasz Jankowiak and Michał Polakowski, combines comparative legal analysis with twelve hunting seasons of national bag statistics, from 2012/2013 to 2023/2024, for five transboundary taxa: the common wood pigeon (Columba palumbus), the Eurasian woodcock (Scolopax rusticola) and three goose taxa of the genus Anser, namely greylag goose, the bean goose complex and greater white-fronted goose. These species were chosen because they are regulated in both countries, span contrasting ecological guilds from forest-breeding woodcock to crop-feeding geese, and have publicly available abundance estimates that allow harvest to be placed in context.

Europe’s hunting systems blend two traditions. In a territorial, district-based model, hunting rights attach to legally delimited hunting districts managed by leaseholders, while in a licensing model access flows through individual permits and registries. Poland and Germany are both hybrids, but in different ways. Poland runs a strongly centralised, district-based system embedded in the Polish Hunting Association, which counts more than 130,000 hunters and about 2,800 hunting clubs. Germany retains district-based hunting rights but grants its Länder far greater regulatory competence, and the Deutscher Jagdverband reports 467,682 licensed hunters as of November 2025. The researchers expected the federal structure to generate more within-country heterogeneity and more local adjustment, and the data bear that out.

The contrasts in season design are concrete. In Poland, one national regulation opens the wood pigeon season from 15 August to 30 November, the woodcock season from 1 September to 21 December, and the goose season from 1 September to 21 December, extended to 15 January only in four western voivodeships. Germany’s federal baseline seasons start later, with wood pigeon from 1 November to 31 January and woodcock from 16 October to 15 January, while geese face a shorter two-part window from 1 to 31 August and 1 November to 15 January that states may modify. Within Germany, the resulting mosaic is vivid: Brandenburg permits extra goose hunting on fields with documented crop damage, Sachsen-Anhalt authorises goose hunting when at least fifty geese are feeding on crops, Schleswig-Holstein extends the goose season to 31 January but bans harvest inside Natura 2000 sites, and Hesse has long maintained a moratorium on woodcock hunting. Germany’s catalogue of huntable birds is also broader, including species such as the mute swan, brent goose and several gulls that are not game in Poland.

Reported harvest differed enormously between the neighbours. Germany averaged 73,444 geese per season against Poland’s 11,033, a geometric mean ratio of 6.67. For Eurasian woodcock, Germany reported 9,742 birds a year compared with 367 in Poland, a nearly 27-fold difference. The largest absolute gap concerned wood pigeon: Germany’s average annual bag of 426,654 birds was more than 37 times Poland’s 11,117. Temporal trajectories were taxon-specific. Goose harvest rose in both countries, by 2.91 percent per season in Poland and 1.99 percent in Germany. Woodcock bag declined sharply in Poland at minus 7.34 percent per season, while Germany showed no directional trend. Wood pigeon harvest fell in both countries, but nearly twice as steeply in Germany, at minus 8.38 percent versus minus 3.85 percent per season, with a significant country-by-taxon-by-time interaction in the global model.

Placing harvest against population estimates sharpens the picture, though the authors stress the ratios are indicative, not demographic mortality rates, because autumn and winter bags may include migrants breeding elsewhere. For wood pigeon, Poland’s annual take represents roughly 0.5 to 0.6 percent of its 1.0 to 1.3 million breeding pairs, while Germany’s corresponds to about 6 to 11 percent of 2.9 to 3.5 million pairs. Woodcock harvest corresponds to under 1 percent of Poland’s 20,000 to 100,000 breeding pairs but roughly 13 to 20 percent of Germany’s 20,000 to 39,000 pairs. For geese, where reference estimates align better with the hunting period, the pattern reverses: Poland’s 9,000 to 11,000 birds per year equal about 22 to 27 percent of wintering and migration-period numbers, whereas Germany’s 78,000 to 108,000 represent about 13 to 18 percent, even though Germany’s absolute bag is far larger.

The institutional machinery behind these numbers differs in ways that matter for management. In Poland, migratory game birds are exempt from the statutory pre-season inventory; leaseholders record a planned take per species with a permissible range of 85 to 115 percent of that value, which in practice tends to anchor on the previous season’s reported bag, making planning largely path-dependent rather than abundance-driven. Recent Polish evidence shows realised waterbird harvest often falls far below planned ceilings. Ownership of free-living animals rests with the State Treasury until lawful harvest, and statutory compensation for crop damage covers only large mammals, leaving growing goose damage outside the mandatory scheme. In Germany, the Federal Hunting Act explicitly aims hunting at preventing agricultural losses by holding game populations at non-damaging levels, and although statutory compensation also excludes geese, states such as Lower Saxony and, since May 2025, Schleswig-Holstein run dedicated goose-damage funds financed from nature-conservation budgets.

The authors are careful about what these associations do and do not show. The study compares governance design and reported harvest patterns; it does not measure enforcement, hunter behaviour or population-level effects, and differences in bag statistics may also reflect habitat, hunter density, reporting incentives and taxonomic aggregation, since German categories such as Wildtauben and Wildgänse had to be harmonised using state-level species breakdowns, including correcting pigeon baskets for the near-total wood pigeon share of about 99.5 percent and subtracting non-native Egyptian and Canada geese. The researchers argue the real governance challenge is not to erase regulatory variation, which can legitimately reflect regional migration timing and agricultural conflicts, but to distinguish coordinated, evidence-based differentiation from uncoordinated fragmentation affecting the same flyway populations, a concern sharpened by climate-driven shifts in breeding and migration phenology.

As a practical path forward, the team points to adaptive harvest management, citing the Svalbard pink-footed goose quota system run by Denmark and Norway since 2013/14 under the AEWA framework. Rather than proposing full adaptive management everywhere, they sketch a tiered framework for transboundary populations: harmonised harvest reporting and shared abundance indices as a minimum; predefined trigger rules, such as conservative season or quota reductions when indices fall below thresholds; and full adaptive management only where monitoring and institutional capacity justify the investment, as with goose populations tied to recurrent crop damage. For birds that ignore borders with such indifference, the study suggests, coordinated bookkeeping is the first and most achievable step toward genuinely shared stewardship.

Subject of Research: Transboundary governance and harvest regulation of migratory game birds in Poland and Germany

Article Title: Regulatory Mismatch and Transboundary Governance of Migratory Game Birds: A Comparison of Poland and Germany

Article References: Piórkowska, K., Strączyński, W., Jankowiak, Ł., & Polakowski, M. (2026). Regulatory Mismatch and Transboundary Governance of Migratory Game Birds: A Comparison of Poland and Germany. Environmental Management, 76(10), Article 318. https://doi.org/10.1007/s00267-026-02584-0

Image Credits: AI Generated

DOI: 10.1007/s00267-026-02584-0

Keywords: migratory game birds, hunting governance, Poland, Germany, harvest statistics, wood pigeon, Eurasian woodcock, geese, transboundary management, adaptive harvest management, hunting legislation, Regulatory

The Bahaba genus comprises large sciaenid fishes, relatives of drums and croakers, that can grow to more than two meters and once formed the basis of important coastal fisheries. Their swim bladders commanded extraordinary prices in dried seafood markets, a fact that helped drive the Chinese bahaba, B. taipingensis, to the brink of extinction. All three species examined in the study are listed as threatened on the IUCN Red List, and all depend on coastal and estuarine environments that are simultaneously being transformed by warming waters, altered salinity regimes, hypoxia, and intense fishing pressure. Understanding where their suitable habitats will persist, shrink, or emerge under climate change is therefore not an academic exercise but a matter of survival.

To build their projections, the research team, led by Yixuan Huang and Shihong Xu of the Institute of Oceanology at the Chinese Academy of Sciences and Yongshuang Xiao, compiled occurrence records for the three species and modeled their environmental niches using the maximum entropy approach, a widely applied machine learning technique that estimates the probability of species presence from occurrence points and gridded environmental layers. The models were calibrated on present-day conditions and then forced forward under four representative concentration pathways, from the stringent mitigation scenario RCP2.6 to the high-emissions business-as-usual pathway RCP8.5, for two future time horizons: the 2050s and the 2100s. Key environmental predictors included sea surface and bottom temperature, salinity, and other physicochemical variables known to constrain the physiology and distribution of coastal marine fishes.

The most dramatic result belongs to B. chaptis, a tropical croaker distributed from the Indian Ocean rim into Southeast Asian waters. The models project persistent and substantial expansion of suitable habitat for this species, with a net increase in suitable area of 59.4 percent under the 2100s RCP6.0 scenario. Even more striking is the projected movement of the species’ range centroid: a northwestward displacement exceeding 4,500 kilometers by the end of the century. A centroid shift of that magnitude implies that the geographic center of gravity of B. chaptis habitat could migrate across entire marine realms, from its current tropical strongholds toward higher-latitude waters, suggesting a high potential for climate-driven redistribution that would carry the species across multiple exclusive economic zones and national jurisdictions.

B. polykladiskos, by contrast, exhibited a deeply nonlinear response to warming that the authors characterize as threshold-like. Under intermediate emissions, the species is projected to suffer severe contraction, with a net loss of 54.9 percent of suitable area under the 2100s RCP6.0 scenario. Yet under the highest emissions pathway, RCP8.5, the same species is projected to expand strongly, gaining 58.2 percent of suitable area by the 2100s. This counterintuitive pattern indicates that the species’ habitat suitability does not decline smoothly with warming but instead pivots around critical environmental thresholds. Intermediate warming may push conditions past tolerable limits across much of the current range, while more extreme scenarios may open vast new areas whose climates come to resemble the species’ niche in unexpected ways. For conservation planners, such sensitivity means that the fate of B. polykladiskos is extraordinarily difficult to anticipate without considering the full envelope of emissions outcomes.

The third species tells a very different story. B. taipingensis, the critically endangered Chinese bahaba, is projected to maintain relatively stable suitable habitat through 2100, with centroid displacement generally remaining below 400 kilometers. This stability underscores the persistent conservation importance of the East China Sea and Yellow Sea shelf, the species’ historical heartland, where productive, seasonally variable shelf conditions appear buffered against the kind of wholesale climatic reorganization projected for tropical waters. For a species already reduced to remnant populations by decades of overfishing, the modeling result is a rare piece of good news: the environmental stage on which its recovery must play out is likely to remain, at least in broad terms, where it is today.

Beyond mapping individual ranges, the study examined how the ecological niches of the species relate to one another through time using niche-overlap analysis based on Schoener’s D, a standard metric quantifying the similarity of two species’ environmental niches. The two tropical species, B. chaptis and B. polykladiskos, showed declining niche overlap under future scenarios, with Schoener’s D falling from 0.533 under present conditions to as low as 0.405. Declining overlap signals increasing spatial and environmental differentiation between the two species, meaning that the habitats that will suit one are progressively diverging from those that will suit the other. Such niche divergence has cascading implications: it can alter patterns of interspecific competition, restructure community composition, and complicate any conservation strategy that assumes the two species can be managed as a single ecological unit.

These findings arrive at a moment when marine conservation planning is grappling with a fundamental design problem. Marine protected areas have traditionally been sited around where threatened species live now, on the implicit assumption that those locations will remain suitable. Climate-driven range shifts break that assumption. A reserve network optimized for present-day distributions may find its protected populations migrating out of bounds while unsuitable conditions move in. The study’s species-specific results translate directly into differentiated planning guidance. For expanding species such as B. chaptis, the authors argue for migration corridors, protected pathways that anticipate and accommodate the northwestward march of suitable habitat across national boundaries. For threshold-sensitive species such as B. polykladiskos, they recommend flexible buffer zones that can absorb the uncertainty inherent in a nonlinear, scenario-dependent response. For the regionally stable but critically endangered B. taipingensis, fixed core reserves anchored in the East China Sea and Yellow Sea shelf remain the appropriate instrument, paired with the captive breeding and release programs already underway for the species.

The transboundary dimension of the projections is perhaps the study’s most policy-relevant contribution. A centroid shift exceeding 4,500 kilometers for B. chaptis would traverse waters governed by numerous states with differing fisheries regimes, conservation capacities, and levels of engagement with international agreements. Species do not respect exclusive economic zones, and neither does climate change. The authors emphasize that integrating projected distribution dynamics and niche shifts into climate-adaptive marine conservation planning requires regional cooperation mechanisms capable of coordinating protected area design, harvest regulations, and monitoring across borders. Without such coordination, a species protected in one jurisdiction may simply be harvested in the next as its range shifts, a pattern well documented in fisheries that straddle national boundaries.

The study also carries methodological weight for the broader field of species distribution modeling. Maximum entropy models have become a workhorse of climate-impact biology, but their reliability depends on careful parameterization, adequate occurrence data, and honest treatment of uncertainty. By projecting multiple species across a full ladder of emissions scenarios and two time horizons, and by pairing habitat projections with formal niche-overlap analysis, the work illustrates how distribution models can move beyond single-species maps toward comparative, community-relevant insight. The contrasting fates of three congeners occupying the same region serve as a caution against one-size-fits-all climate adaptation strategies and a demonstration that even closely related fishes can occupy meaningfully different climatic niches with profoundly different futures. As ocean warming accelerates through the coming decades, the Bahaba croakers of the Indo-West Pacific may become a case study in how conservation science anticipates, rather than merely documents, the great redistribution of life in the sea.

Subject of Research: Climate-driven habitat shifts and niche divergence of three endangered Bahaba marine fishes in the Indo-West Pacific

Article Title: Projecting climate-driven biogeographic shifts and niche divergence of three endangered marine fishes in the Indo-West Pacific: implications for regional conservation priorities and transboundary management

Article References: Projecting climate-driven biogeographic shifts and niche divergence of three endangered marine fishes in the Indo-West Pacific: implications for regional conservation priorities and transboundary management. (n.d.). https://doi.org/10.1007/s10113-026-02675-y

Image Credits: AI Generated

DOI: 10.1007/s10113-026-02675-y

Keywords: Bahaba fishes, climate change, species distribution models, MaxEnt, niche divergence, Indo-West Pacific, habitat suitability, RCP scenarios, marine conservation, transboundary management, East China Sea, IUCN Red List