Johan Elmberg’s research while affiliated with Kristianstad University and other places

Geese and swans are focal species in conservation and in management aimed at reducing crop damage. In the former disturbance should be minimized, and in the latter it is important to know how different species react to scaring activities. Previous research about trade‐off between predation risk and foraging in birds often uses ‘flight initiation distance' (FID) as a proxy to compare fearfulness under different circumstances and among species. We studied variation in FID in geese and swans by species, flock size and composition, time of day, and body size (408 scaring trials on agricultural land in the winters 2018–2021). In single‐species flocks mean FID decreased in the order: bean goose (171 m) > greylag goose (104 m) > whooper swan (102 m) > Canada goose (92 m) > barnacle goose (77 m). In line with predictions based on body mass, the lightest species (barnacle goose) was the least fearful, but contrary to prediction neither of the two heaviest species (whooper swan, Canada goose) was the most fearful. FID was negatively correlated with flock size in bean goose. Flock size and FID did not correlate in greylag, Canada, and barnacle geese. FID did not differ between morning and afternoon in the four species with a sample of > 20 single‐species trials. When in multi‐species flocks, FID differed less among species, converging in the 108–138 m range. Accordingly, bean goose FID decreased significantly whereas it increased significantly in barnacle and greylag geese. Barnacle goose (protected from hunting by the EU Birds Directive) was less fearful than species with an open hunting season in the EU, implying that exposure to hunting affects species‐specific FID. We show that the level of fearfulness varied among swan and goose species, making it necessary to adopt diverse strategies in conservation as well as crop protection.

Goose populations across Europe have been subjected to long‐standing harvest practices, which include shotgun hunting. In addition to immediate mortality, hunting can affect an animal's fitness by inflicting non‐lethal injuries, often referred to as ‘crippling' or ‘wounding'. This could subsequently have negative effects on the population level and causes ethical concerns, ultimately challenging the legitimacy of hunting as a management tool. Understanding spatial variation in crippling rate can assist management to prioritize regions for enhancing awareness and implementing measures aimed at reducing crippling. We examined greylag geese from three subpopulations (Nyköping, Örebro, and Hudiksvall) breeding in three regions in Sweden (Södermanland, Örebro, and Gävleborg) to record prevalence of imbedded shotgun pellets and to quantify crippling impact. Our approach excludes birds that were wounded and subsequently died without being retrieved. We found that across the three subpopulations, 21% of the 176 x‐rayed greylag geese were carrying imbedded pellets (average 2.33 pellets, range 1–16). Crippling rate varied among the subpopulations, being twice as high in Örebro and Nyköping (26.4 and 25.0%, respectively) compared to Hudiksvall (11.7%). However, the probability of being crippled differed significantly only between Nyköping and Hudiksvall (p = 0.04), but not between Örebro and Hudiksvall (p>0.05) or between Nyköping and Örebro (p > 0.05). This study could not elucidate the mechanisms underlying the observed regional variations in crippling rate. Nevertheless, the regional disparities in these rates, and the potential links between crippling rate, levels of crop damage, attitudes, and hunting behaviors, present intriguing avenues for future exploration.

Understanding wildlife stakeholders is vital in mitigating the risk for inertia in the implementation of management and illegal activities, e.g., poaching. We used a unique set of questionnaire data of stakeholders in Sweden (n = 8728) comprising birdwatchers, hunters, farmers, and the general public, to analyze evaluations of geese, beliefs about goose management at multiple levels, and acceptance of management tools. Also, a hierarchical model incorporating prior wildlife experience and integrating cognitions and emotions for acceptance was tested. The overall attitude towards geese was positive, but ecosystem disservices caused by large populations were acknowledged. The general public and birdwatchers displayed trust in the national, regional, and local levels. In contrast, farmers and hunters trusted mainly the local level. Broad stakeholder acceptance was found for several non-lethal tools for damage reduction and more generally a goose conservation approach including e.g., hunting free zones, but also for hunting during open hunting season. We found support for the proposed model in relation to acceptance of both the conservation and the lethal approach, thereby advancing theory integration. Results suggest that while goose conservation is widely accepted, problems caused by geese and distrust in the higher management levels among some stakeholder groups need to be addressed. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-024-80661-2.

Scaring of wildlife is commonly used in attempts to reduce crop damage in agricultural landscapes, but relatively few studies exist on its actual effect. We tracked GPS‐tagged greylag geese (Anser anser) in south‐central Sweden, before and after scaring by approaching them either by walking or by drone. On the field level, we studied the scaring effect by estimating return rate to the field where scared. On the landscape level, we tested if geese were less prone to use agricultural fields after being scared. Geese immediately left the field when scared and 5 min later they were on average 990 m (±56 SE) from the scaring position. The proportion of GPS positions near the scaring position decreased significantly for at least 4 h after scaring. Geese showed a significant shift from agricultural fields to wetland habitats the first 4 h after scaring. However, the effect of scaring soon levelled off; after 24 h the field where scaring had occurred was used to the same extent as any other field in the landscape, and agricultural fields were used to the same extent by scared and undisturbed geese. We did not find any differences in response depending on scaring technique. The probability to return and use agricultural fields after scaring was higher for geese scared in the morning compared to in the afternoon. Moreover, the probability to return and use of agricultural fields were higher in spring than in other seasons. Practical implication. We found that scared geese tend to visit agricultural fields soon after scaring and that scaring alone tends ‘to move the problem around’. This suggests that scaring needs to be repeated across the landscape, but also that accommodation fields where geese do not cause damage may be needed to keep geese off conventional fields. However, our study presents a glimpse of promise as the rather simple drone used covers large areas quickly and minimizes walking in growing crops. With technological advancement and possible autonomous techniques, drones may be capable of providing repeated scaring over large areas in the future.

In recent decades, interest has grown in how increasing populations of herbivorous geese and swans (Anseriformes: Anatidae: Anserinae) affect macrophyte communities in wetlands, especially because many waterbodies are simultaneously subjected to stressors like eutrophication and biodiversity declines. Here, we review the literature on methods applied in grazing experiments that have been conducted in aquatic ecosystems. We also investigate and how different macrophyte characteristics may respond to waterfowl herbivory. Results indicate that both research methodology and responses of macrophytes differ widely among studies. While most experimental studies on grazing pressure employ a ‘paired plot design’ with exclosures and open control plots, the structure, size, and placement of plots vary among studies. Commonly sampled macrophyte variables are biomass (of either above- or below-ground plant parts), density, height, plant cover, and community composition. The literature provides support that geese and swans significantly affect several of these variables, but the outcome depends on additional factors, e.g., waterfowl density, water depth, and timing (within or between seasons/years). Because of the persisting conservation threats to aquatic ecosystems, more knowledge is needed about potential direct and indirect consequences of waterfowl herbivory in these environments.

Geese and swans are focal species in conservation and in management aimed at reducing crop damage. In the former disturbance should be minimized, and in the latter it is important to know how different species react to scaring activities. Previous research about trade-offs between predation risk and foraging in birds often use ‘Flight Initiation Distance’ (FID) as a proxy to compare fearfulness under different circumstances and among species. We studied variation in FID in geese and swans by species, flock size and composition, time of day, and body size (408 scaring trials on agricultural land in the winters 2018—2021). In single-species flocks mean FID decreased in the order: bean goose (171 m) > greylag goose (104 m) > whooper swan (102 m) > Canada goose (92 m) > barnacle goose (77 m). In line with predictions based on body mass, the lightest species (barnacle goose) was the least fearful, but contrary to prediction neither of the two heaviest species (whooper swan, Canada goose) was the most fearful. FID was negatively correlated with flock size in bean goose. Flock size and FID did not correlate in greylag, Canada, and barnacle geese. FID did not differ between morning and afternoon in the 4 species with a sample of >20 single-species trials. When in multi-species flocks, FID differed less among species, converging in the 108—138 m range. Accordingly, bean goose FID decreased significantly whereas it increased significantly in barnacle and greylag geese. Barnacle goose (protected from hunting by the EU bird directive) was less fearful than species with an open hunting season in the EU, implying that exposure to hunting affect species-specific FID. We show that the level of fearfulness varied among swan and goose species, making it necessary to adopt diverse strategies in conservation as well as crop protection.

Because of their dependence on ambient temperature ectothermic animals can serve as sentinels of conservation problems related to global warming. Reptiles in temperate areas are especially well suited to study such effects, as their annual and daily activity patterns directly depend on ambient temperature. This study is based on annual data spanning 68 years from a fringe population of Grass Snakes (Natrix natrix), which is the world’s northernmost oviparous (egg-laying) reptile, and known to be constrained by temperature for reproduction, morphology, and behavior. Mark-recapture analyses showed that survival probability was generally higher in males than in females, and that it increased with body length. Body condition (scaled mass index) and body length increased over time, indicative of a longer annual activity period. Monthly survival was generally higher during winter (i.e., hibernation) than over the summer season. Summer survival increased over time, whilst winter survival decreased, especially during recent decades. Winter survival was lower when annual maximum snow depth was less than 15 cm, implying a negative effect of milder winters with less insulating snow cover. Our study demonstrates long-term shifts in body length, body condition and seasonal survival associated with a warming climate. Although the seasonal changes in survival ran in opposite directions and though changes were small in absolute terms, the trends did not cancel out, but total annual survival decreased. We conclude that effects of a warming climate can be diverse and pose a threat for thermophilic species in temperate regions, and that future studies should consider survival change by season, preferably in a long-term approach.

Releasing farmed mallards into the wild is a common practice in wildlife management worldwide, involving millions of birds annually, and is mainly carried out to increase hunting opportunities. Ringing and previous research show that released mallards have low survival also outside the hunting season, and that survivors may compromise migration habits, morphology, and adaptations of the wild population. Detailed local movements of released mallards have not been studied before, despite the importance of spatiotemporal patterns for understanding the impact of releases and their utility for hunting. We studied local movements in August–October of 11 wild and 44 released mallards caught in the same wetland in southern Sweden and provided with GPS tags. Wild mallards moved longer distances than farmed, over the whole diel cycle, as well as during three out of four separate periods of the day (dawn, day, and dusk). Mallards of both origins moved the longest distances during dusk and dawn, and the shortest during the night. Males and females did not differ significantly in distance moved, regardless of origin (wild versus farmed). Our study demonstrates large differences in spatiotemporal movement patterns between wild and farmed mallards. The typical day of wild mallards included movements between wetlands in the landscape, likely to foraging sites known from previous experience. However, wild mallards frequently returned to the study wetland, probably attracted by supplementary bait. On the other hand, farmed mallards seldom left the study wetland, despite the possibility of accompanying wild birds to other sites. The sedentary behavior of farmed mallards and the fact that wild birds come to join them are both beneficial for hunting purposes. Limited movements of farmed mallards, together with their low survival, could also be positive as they limit hybridization between wild and farmed mallards, as well as dispersal of nutrients.

Several populations of cranes, geese, and swans are thriving and increasing in modern agricultural landscapes. Abundant populations are causing conservation conflicts, as they may affect agricultural production and biodiversity negatively. Management strategies involving provisioning of attractive diversionary fields where birds are tolerated can be used to reduce negative impact to growing crops. To improve such strategies, knowledge of how the birds interact with the landscape and respond to current management interventions is key. We used GPS locations from tagged common cranes ( Grus grus ) and greylag geese ( Anser anser ) to assess how they use and select differentially managed habitats, such as diversionary fields to decrease impact on agriculture and wetlands protected for biodiversity conservation. Our findings show a high probability of presence of common cranes and greylag geese in the protected area and in the diversionary field, but also on arable fields, potentially causing negative impact on agricultural production and wetland biodiversity. We outline recommendations for how to improve the practice of diversionary fields and complementary management to reduce risk of negative impact of large grazing birds in landscapes tailored for both conservation and conventional agriculture.