December 2017

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English summaries

    • Exposure of Geoffroy’s bats to pesticides
    • R. Janssen, J.A. Guldemond, J.L. Lommen & P.C. Leendertse
    • Insectivorous bats play a crucial role in insect pest control, but are therefore also at risk of exposure to pesticides used to control noxious insect populations. In addition, bats that roost in buildings may be exposed to the chemical preservatives used to treat timber. In this study, we aimed to quantify pesticide and preservative concentrations in three maternity roosts of Geoffroy’s bats (Myotis emarginatus) in southern Netherlands (Limburg). In samples taken from dead bats, bat feces and wood shavings from bat roosts, we found a wide array of old (banned) and new pesticides. Specifically, fourteen pesticides were found in dead bats and/or bat feces, and an additional ten pesticides were only found in wood shavings from bat roosts. The effect of many of these pesticides has never been quantified for bat species. However, there is evidence for some of these substances that they may substantially impact bat behavior and neurological functions. Given these potential risks, we strongly advise these potential influences be thoroughly studied, as it is clear that bats are currently being exposed to these chemicals. Moreover, we recommend that timber used in constructions where bats may roost should not be chemically treated, until the effects of these treatments on bat well-being has been adequately investigated.

    • Geese nuisance, perception and solutions
    • Th.C.P. Melman, R. Buij & K. Koffijberg
    • Growing numbers of geese cause increasing damage to agriculture in the Netherlands. At the same time, the Netherlands is bound by international agreements to ensure a favourable conservation status of geese populations. Policy tries to find a balance between the interests of all stakeholders, aiming to minimize damages by geese as well as maintain their favourable conservation status. The effectiveness of concentrating geese in designated foraging areas has been limited to date, largely due to a lack of consistent effort aimed at providing rest in refuges and insufficient scaring of geese where they do most damage. Population reduction is often put forward as a suitable alternative to limit crop damage but it’s effectiveness has not been proven at the national or regional scale, while the population impact of current derogation shooting for protected goose species is little known at the relevant flyway level. We recommend a renewed and improved implementation of refuge management and scaring focused on the most vulnerable crops, based on well-studied examples in other countries and avoiding the shortcomings of the past. Intensive participation by all stakeholders and a robust scientific embedding will be indispensable for a broad acceptance of the findings.

    • The importance of communication to the public for successful eradication of invasive species
    • L.N.H. Verbrugge, J.J.C.W. van Delft, B.H.J.M Crombaghs, S.J. Bouwens & W. Bosman
    • A lack of public support for eradication measures and citizen participation may cause serious delays or ineffective invasive species control. Communication to the public about eradication campaigns is important, but can be challenging. We use examples of successful eradication projects, i.e. American bullfrog (Lithobates catesbeianus), Pallas’ squirrel (Callosciurus erythraeus) and Pumpkinseed sunfish (Lepomis gibbosus), to illustrate important considerations when establishing an effective communication plan. These include (1) a shared understanding of the goals and execution of communication activities among stakeholders, and (2) investment of time and local resources to develop relationships with community members. Another important issue is to inform the public how to prevent new introductions of invasive species.

    • 25 years of nature restoration in the Nieuwkoopse Plassen
    • B. Hartog, M. van Schie & W. van Steenis
    • In the marsh area Nieuwkoopse Plassen, part of the Natura 2000 network of the Netherlands, many measurements were taken to restore nature. The water quality is improved by deminishing the use for agricultural purposes, by lowering the phosphate concentrations of the inlet water. We could stop burning mown reed marsh and remove all mown vegetation because we received more contributions from the province of Zuid-Holland. We dug new small water bodies to rejuvenate the marsh area with European Life Nature Funding. And around the Nieuwkoopse Plassen we changed arable land into nature for meadow and marsh birds. Dragonflies, many reedland birds and water vegetation have greatly improved. Otter recolonized the Nieuwkoopse Plassen. For many species of butterflies, for quacking bogs and Molinia meadows we hardly see any improvement.

    • pdf downloaden The lingering recovery of terrestrialisation habitats in lowland fens
    • E. Brakkee
    • The terrestrialisation habitats of Dutch fen areas have a large botanical value. Since the 1970s, these habitats have been threatened by an accelerated degradation of quality, combined with a limited formation of new stages. In the past two decades much effort has been made to counter these developments. This article gives an overview of the current state of terrestrialisation habitats in three major protected wetland areas: the Wieden, the Nieuwkoopse plassen and Het Hol, to understand if the measures have led to an actual improvement. This overview is based on vegetation maps of the period 1993-2010, in combination with monitoring reports and interviews about more recent developments. In two of the areas, aquatic vegetation has expanded due to improvements in water quality. New terrestrialisation, however, is still limited in all areas, while existing fen habitats are still ageing quickly, often declining in quality. This forms a threat for rare species that are bound to young vegetation types. Locally, however, these species do expand. These small-scale positive developments depend largely on specific restoration measures, such as the creation of new turf ponds, sod-cutting of fens and, in the Wieden, the use of small ditches. The analysis of vegetation maps has some important limitations, but it clearly shows the continuing necessity to address the large-scale factors behind the decline of terrestrialisation habitats.