Field selection of greylag geese (Anser anser) Implications for management of set-aside fields to alleviate crop damage

Copyright (c) 2022 Malin Teräväinen, Johan Elmberg, Carina Tennfors, Olivier Devineau, Karen-Marie Mathisen, Johan Månsson. This work is licensed under a Creative Commons Attribution 4.0 International License.Greylag geese (Anser anser) have been increasing in numbers in Europe during the last decades. They forage and roost in agricultural landscapes and may cause damage to sensitive crops. We studied field selection of greylag geese around lake Sörfjärden in south central Sweden where geese aggregate during the growing season. In this area a set-aside field was established in 2010, i.e., a field where geese can graze undisturbed, with the aim to reduce damage in surrounding conventional fields. The goal of our study was to investigate the general selection of the different field types as well as the specific set-aside field. We used a point survey count to estimate goose numbers and regression analyses to evaluate the relationship between presence or absence of greylag geese and field characteristics such as crop type, distance to roost site and field size. According to the top-ranked model, the probability of presence of foraging greylag geese was higher in spring and in grass fields, while the probability decreased with distance to roost site. Our results also show that the set-aside field in general was used more than other fields in the area during spring and summer but not during autumn. We conclude that it is important to consider variables affecting the probability of field selection by geese, such as season, crop type and distance to roosts to understand the behaviour of geese when establishing set-aside fields.publishedVersio

Efficient application of a browsing repellent: Can associational effects within and between plants be exploited?

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Prevalence of tick-borne encephalitis virus in questing Ixodes ricinus nymphs in southern Scandinavia and the possible influence of meteorological factors

Ixodes ricinus ticks are Scandinavia's main vector for tick-borne encephalitis virus (TBEV), which infects many people annually. The aims of the present study were (i) to obtain information on the TBEV prevalence in host-seeking I. ricinus collected within the oresund-Kattegat-Skagerrak (oKS) region, which lies in southern Norway, southern Sweden and Denmark; (ii) to analyse whether there are potential spatial patterns in the TBEV prevalence; and (iii) to understand the relationship between TBEV prevalence and meteorological factors in southern Scandinavia. Tick nymphs were collected in 2016, in southern Scandinavia, and screened for TBEV, using pools of 10 nymphs, with RT real-time PCR, and positive samples were confirmed with pyrosequencing. Spatial autocorrelation and cluster analysis was performed with Global Moran's I and SatScan to test for spatial patterns and potential local clusters of the TBEV pool prevalence at each of the 50 sites. A climatic analysis was made to correlate parameters such as minimum, mean and maximum temperature, relative humidity and saturation deficit with TBEV pool prevalence. The climatic data were acquired from the nearest meteorological stations for 2015 and 2016. This study confirms the presence of TBEV in 12 out of 30 locations in Denmark, where six were from Jutland, three from Zealand and two from Bornholm and Falster counties. In total, five out of nine sites were positive from southern Sweden. TBEV prevalence of 0.7%, 0.5% and 0.5%, in nymphs, was found at three sites along the Oslofjord (two sites) and northern Skane region (one site), indicating a potential concern for public health. We report an overall estimated TBEV prevalence of 0.1% in questing I. ricinus nymphs in southern Scandinavia with a region-specific prevalence of 0.1% in Denmark, 0.2% in southern Sweden and 0.1% in southeastern Norway. No evidence of a spatial pattern or local clusters was found in the study region. We found a strong correlation between TBEV prevalence in ticks and relative humidity in Sweden and Norway, which might suggest that humidity has a role in maintaining TBEV prevalence in ticks. TBEV is an emerging tick-borne pathogen in southern Scandinavia, and we recommend further studies to understand the TBEV transmission potential with changing climate in Scandinavia

Prevalence of tick-borne encephalitis virus in questing Ixodes ricinus nymphs in southern Scandinavia and the possible influence of meteorological factors

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Push and pull strategies : behaviour of geese in relation to scaring and set-aside fields

Geese have been increasing in numbers in Europe during the last decades. They forage in agricultural landscapes and may cause damage to sensitive crops. Scaring and set-aside fields are two commonly used methods to alleviate damage by “pushing” geese from sensitive fields and “pulling” them to areas where they don’t cause damage. I investigated field selection and the utilization of a set-aside field, as well as the effect of two scaring measures on behaviour of greylag geese (Anser anser) in two areas in south central Sweden. I concluded that the set-aside field was generally selected more than other fields during spring and summer, but not during fall. In addition, an increased field selection with a decreasing distance to roost was found. GPS data from tagged greylag geese were compared before and after scaring. After one hour scared geese were on average 1146 meters (95% C.I. 843 - 1449) away from the scaring location. The number of positions in close vicinity to the scaring location (“return rate”) decreased significantly during at least 48 hours after scaring. Geese scared by walking had a slightly higher probability of returning than if scared by a drone. Geese also showed a significant shift in habitat use, from cropland to wetland the first four hours after scaring, but then returned to arable land. I conclude that scaring can work as a “push strategy”. However, scaring is not a full solution at the landscape level, as geese continue to forage in other fields soon after a scaring event. A combination of scaring and areas such as set-aside fields, where geese can graze undisturbed without causing damage, are therefore important to avoid just “moving the problem around”

Short term effects of capture on movements in free-ranging wolves (Canis lupus) in Scandinavia

Master i anvendt økologi. Evenstad 2016Remote monitoring of wild animals by radio-tags and bio-sensors is frequently applied in wildlife research, monitoring and management. These methods require capture and often anaesthesia of animals that in turn may affect post-capture behaviour. Assessment of post-capture effects is needed to avoid biases in the research data due to capture-related effect on behaviour, but also to measure unnecessary discomfort and suffering for the animals. The Scandinavian wolf population has since its reappearance in the 1980´s been the subject to many studies, and the first wolves were radio collared in 1999. Between 1998 and 2015 several wolves have been captured in Scandinavia. For this study I used hourly GPS positions during the first 100 hours from 25 wolves chemically immobilized between 2001 and 2015. I examined how the cumulative post-capture movement was related to the intrinsic variables sex, body mass and social status, and to capture-related variables, number of captures, pursuit time and the type and dose of drugs used. Sex was the most important factor explaining patterns of post-capture movement. Males had a higher movement rate than females between the release and 23 hours post capture. Body mass was correlated with sex and was positively related to sex-specific movement rates. Contrary to my initial predictions, medetomidine given as an additional tranquilizer during handling increased the movement rate after capture. I also found weak relationships between movement rate and the time the wolf was chased by helicopter prior the immobilisation, and between movement rate and drug doses. The small sample size however limits the inferences that can be drawn from these models. I conclude that capture-related factors can induce differences in post-capture movements of wolves, and that sex is an important predictor of post-capture movement patterns

Short term effects of capture on movements in free-ranging wolves (Canis lupus) in Scandinavia

Remote monitoring of wild animals by radio-tags and bio-sensors is frequently applied in wildlife research, monitoring and management. These methods require capture and often anaesthesia of animals that in turn may affect post-capture behaviour. Assessment of post-capture effects is needed to avoid biases in the research data due to capture-related effect on behaviour, but also to measure unnecessary discomfort and suffering for the animals. The Scandinavian wolf population has since its reappearance in the 1980´s been the subject to many studies, and the first wolves were radio collared in 1999. Between 1998 and 2015 several wolves have been captured in Scandinavia. For this study I used hourly GPS positions during the first 100 hours from 25 wolves chemically immobilized between 2001 and 2015. I examined how the cumulative post-capture movement was related to the intrinsic variables sex, body mass and social status, and to capture-related variables, number of captures, pursuit time and the type and dose of drugs used. Sex was the most important factor explaining patterns of post-capture movement. Males had a higher movement rate than females between the release and 23 hours post capture. Body mass was correlated with sex and was positively related to sex-specific movement rates. Contrary to my initial predictions, medetomidine given as an additional tranquilizer during handling increased the movement rate after capture. I also found weak relationships between movement rate and the time the wolf was chased by helicopter prior the immobilisation, and between movement rate and drug doses. The small sample size however limits the inferences that can be drawn from these models. I conclude that capture-related factors can induce differences in post-capture movements of wolves, and that sex is an important predictor of post-capture movement patterns