The report is a thesis conducted by student Sandie Lohse Sørensen, Aarhus University, Mail: 201705597@post.au.dk, tel.: 40 45 48 10
Madsen, J., Pedersen, J., Cao, L., & Clausen, K. K. (2022). On the search for grasslands: long distance dispersal of spring-staging Barnacle Geese (Branta leucopsis) from a farmland area in Southeast Denmark. Journal of Ornithology.
In early March 2019, twenty barnacle geese wintering in an intensively farmed area in Southeast Denmark were GPS-tagged. Tagged geese selected large open (especially permanent) grasslands above relative availability and close to their roosts, although winter cereals were also used. Surprisingly, during March and April almost all tagged birds left the area and moved to coastal grasslands in other parts of Denmark, the German Wadden Sea or southern Sweden, some up to 210 km diametrically opposite to the main migratory direction towards the Russian Arctic later in spring. The unexpected long distance dispersal may be caused by lack of suitable short-grazed coastal grasslands in the study area and it shows that barnacle geese are highly flexible in their site use.
Read the full article here: https://link.springer.com/article/10.1007/s10336-021-01952-3
Heldbjerg, H., Clausen, K. K., Balsby, T. J. S., Clausen, P., Nielsen, R. D., Skov, F., Nyegaard, T., & Madsen, J. (2022). Barnacle goose Branta leucopsis derogation shooting effort in relation to abundance and vulnerable crops. Agriculture, Ecosystems & Environment, 325, [107746].
The population of barnacle geese wintering in Denmark has shown a steep increase during the last decades to now c. 250,000 geese, prompting a parallel escalation of agricultural conflicts. Barnacle goose is listed in Annex 1 of the Birds Directive and is protected from legal hunting. However, landowners can obtain a permit to undertake so-called derogation shooting (lethal scaring) to reduce local damage to agricultural crops where other means of scaring have been insufficient. Totally close to 20,000 barnacle geese are killed annually by derogation shooting in Denmark now. In this paper, we show that the number of barnacle geese during winter and the derogation efforts of barnacle geese have increased in Denmark in the period 2010/11 – 2018/19 with large variation between different areas of the country. A statistical analysis demonstrates that differences in the number of issued derogations permits across the country are primarily explained by differences in barnacle goose abundance, and secondarily, by prevalence of vulnerable crops and differences in crop productivity. Hence, derogation efforts are highest in areas with many geese, high proportions of crops vulnerable to goose grazing and high crop yields.
Read the full article here: https://www.sciencedirect.com/science/article/pii/S0167880921004503
Clausen, K. K., Damsgaard Thorsted, M., Pedersen, J., & Madsen, J. (2022). Waterfowl grazing on winter wheat: Quantifying yield loss and compensatory growth. Agriculture, Ecosystems & Environment, 332, [107936].
Geese and swans have increasingly adapted to forage on agricultural land, and winter wheat is the most commonly reported crop damaged in northern Europe. This study, carried out in Southeast Denmark in collaboration between Aarhus University and SEGES innovation, apply two parallel approaches (exclosure experiments in undisturbed fields and yield assessments in fields subject to scaring) to quantify the impact of waterfowl grazing on winter wheat yield, crop height and nutrient content. The involved species were mainly barnacle geese, but other species of geese and whooper swans were also present in smaller numbers. Results showed that waterfowl grazing led to a substantial reduction in crop height during winter and early spring, but also that compensatory growth led to no significant effect on crop height at the time of harvest. In terms of grain yield, the effect of waterfowl grazing varied from non-significant to a 6 % loss, and exclosure experiments indicated that plots grazed both winter and spring had a protein content 9 % lower than ungrazed plots. While these figures express an economic loss to the affected farmers, they also indicate that substantial economic impacts from grazing geese and swans on winter wheat was rare in the study area. This may also be the case elsewhere in Northern Europe when most waterfowl abandon crop foraging in due time to allow for compensatory growth in late spring.
Read the full article here: https://www.sciencedirect.com/science/article/pii/S0167880922000858
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In recent decades, there have been increasing problems with geese and swans foraging at agricultural sites and causing damage to crops. The reasons for this are a combination of rising populations, improved foraging conditions in the intensively cultivated fields and degradation of the birds’ natural habitats.
The problem causes tension between different stakeholders: farmers who suffer economic losses, hunters who benefit from the increasing number of geese for hunting and consumption, but are not necessarily included in management, and those interested in birds who appreciate the large flocks of waterfowl and are critical of scaring and regulation.
In Denmark, no financial compensation is paid for damage caused by geese and swans, and no support schemes are used to ensure accommodation areas for the birds to forage. Management therefore focuses on scaring geese and swans away from the vulnerable fields, increasingly by using derogation shooting of geese and swans. Landowners can either ' harvest ' the geese themselves or rent out the hunt as a means of compensation for the damage, but they feel that there is an unequal distribution of the burden as long as the species causing damage do not have a hunting season (barnacle geese and whooper swans).
However, there is only limited knowledge of the consequences of derogation shooting. Does it merely lead to the birds relocating to other farmlands in the neighbouring area, or will the geese find alternative foraging sites, and how does this affect their behaviour – do they get more shy and thus have a smaller ' space ' at their disposal, while their daily food demands increase as a result of frequent scaring?
In the spring of 2019 and autumn/winter 2019/20, we examined the effects of various forms of scaring and regulation of geese and whooper swans in the southern part of Guldborgsund municipality. With the participation of local landowners, we also tried to lay out alternative foraging areas - accommodation areas - in the form of harvested sugar beet fields, which were left without soil treatment or were deep-harrowed (as opposed to ploughed). We observed how the accommodation areas attracted a large number of geese and whooper swans and that this, to a certain extent, mitigated the damage to winter crops. We also tried to mobilise a team of hunters who were trained to efficiently regulate barnacle geese by means of derogation shooting, which is the most abundant species in the area and do not have a hunting season. The regulation was planned to take place in the vicinity of the accommodation fields so that the geese had a ' carrot ' in the form of beet waste and a ' whip ' in the form of derogation shooting, if they shifted to the surrounding winter crops. However, the efforts achieved mixed results, partly because the behaviour and presence of the barnacle geese in the fields were unpredictable. Unfortunately, this led to a number of farmers experiencing a negative effect from geese on their fields. Moreover, we also noted that the geese had very few alternatives to crops in the area. Particularly in the spring, the geese showed great interest in foraging on salt marsh areas along the coast and on the islands in Guldborgsund, but most of the marsh areas were overgrown due to lack of grazing and thus unsuitable as foraging areas for geese (Figure 1). This meant that the barnacle geese exploited the farmer’s fields right up until their departure in the middle of May.
Under the auspices of the European Goose Management Platform (EGMP) under the Waterfowl Agreement (AEWA/UNEP), a number of international, adaptive management plans for geese are currently being implemented, including pink-footed goose, barnacle goose and a greylag goose. See: https://egmp.aewa.info/. A recurring goal of these plans is to find sustainable solutions to conflicts with agricultural interests, ensure sustainable exploitation and a good protection status for the populations. Aarhus University is very much involved in EGMP as an international data centre and supplier of scientific assessments to support political decisions.
A steering committee has been set up for the projects with the aim of coordinating activities and communicating with local participants.
Steering committee consists of:
Project ‘Regulation of barnacle geese as part of a regional goose management’ was financed by the Danish Environmental Protection Agency's extra hunting license funds (January 2019-June 2020); it was carried out by Aarhus University (project manager Jesper Madsen) and reported to the Danish Environmental Protection Agency at the end of 2020. The project was coordinated with the project 'Local management of wintering geese - II', funded by the 15 June Foundation (2019) and carried out by Dansk Landbrug Sydhavsøerne (project manager Christian Clausen); the project was reported to the June 15 Foundation in the spring of 2020. Finally, SEGES in collaboration with VKST performed experiments with field damage on winter wheat caused by barnacle geese; The project was financed by the Danish Environmental Protection Agency's extra hunting license funds and will be reported in the autumn of 2020.
As a 'spin-off' of the project 'Regulation of barnacle geese as part of a regional goose management', the Danish Environmental Protection Agency has under the Wildlife Contract with DCE / Aarhus University) committed to the project 'Mapping seagrass meadows in Guldborgsund Municipality as potential relief areas for barnacle geese', which is carried out in 2020.
The project ‘Integrated adaptive management of geese’ is funded by the 15 June Foundation (September 2020-September 2021); it is led by Aarhus University (project manager Jesper Madsen), with SEGES as a partner to carry out investigations of field damage caused by barnacle geese on winter wheat.
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Figure 1. Examples of different conditions of salt marshes. Both images are from Kalvø in Guldborgsund, June 2020.
In the preliminary project, we have carried out a number of studies and gained important experience regarding instruments for the management of geese and swans in the area. Testing how the combination of accommodation areas and scaring /derogation shooting de facto can be implemented at regional level remains to be done, taking into account the birds' ecological needs and natural behaviour, while to a greater extent including proper management of the salt marshes and thereby contribute to achieving biodiversity targets for, among other things, endangered meadow and shore birds.
The overall purpose of the project, which started in mid-September 2020, is to develop a practice-based, adaptive model for regionally anchored management of crop-damaging geese and swans, carried out in a collaboration between the various stakeholders: landowners/farmers, hunters, birdwatchers and authorities in the southern part of Guldborgsund municipality. The aim is for this management to be sustainable and integrated so that it constitutes both an attractive and self-sustaining ' business model ' for the future management of geese and swans in the area, meets the birds ' ecological and behavioural needs and provides recreational value in the form of bird watching and hunting. Furthermore, the goal is to achieve a synergy effect between the management of geese and initiatives to preserve salt marshes, in consideration of endangered biodiversity associated with these areas.
The project will lead to a scientifically founded, integrated and dynamic management of geese and swans in a regional perspective, which can be used in a regional and national strategy for the management of conflict species of waterfowl and other wildlife. This theme – and the need for knowledge – is of great immediate interest due to increasing problems with geese and swans in particular, but also with deer populations, and good demonstration projects are needed that can provide a pathway for more sustainable solutions in a national and international context[1]. In an international context, the project will contribute with completely new, sought-after knowledge that can form a model for management in other countries, which currently use many social resources to mitigate damage caused by geese. In a Danish context, the project is innovative because it will be attempted to combine alternative foraging areas, scaring and derogation shooting across property boundaries and stakeholder interests. The project cannot guarantee that all problems with field damage can be solved, but it has the potential to present a dynamic business model based on collaboration. Collaboration and dialogue are keys to success because the geese constitute a common resource that society is obliged to protect, but primarily forage and cause damage to privately owned land. There is a strong tendency among landowners for geese and swans to be perceived as pests to be controlled, but our first experience from interviews and meetings is that there is an opening and an interest in finding common solutions if they are not left alone to deal with the challenges.
In May 2020, we asked the landowners and hunters in the area about their interest in continuing a project in which we are testing a common management model. There was considerable support for this, which provides the basis for a project of high quality.
Together with its preliminary project, the project will generate new, application-oriented knowledge on how geese and swans utilize the landscape and the effects of various management measures for integrated management of agricultural areas. Furthermore, the project will provide new knowledge about how a locally anchored management process can be developed, including challenges and practical solutions.
