Woerdense verlaat, Netherlands


Woerdense verlaat, Netherlands
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Veen J.,Veda Consultancy | Overdijk O.,Natuurmonumenten | Veen T.,University of British Columbia
Ardea | Year: 2012

In the period 1998-2010 the endemic subspecies of the Eurasian Spoonbill Platalea leucorodia balsaci breeding in Mauritania has decreased in numbers considerably. The causes for this decline are unknown. This study aimed to investigate the diet of the species. We analysed faecal material collected in the breeding colonies in 8 different years. The results show that Mauritanian Spoonbills almost exclusively eat shrimp (59.7%) and small fish (35.4%), the latter being dominated by Gobiidae (20.8%), Soleidae (4.8%) and Mugilidae (2.8%). Another 10 fish families were represented in small proportions. Shrimp were quantified on the basis of (parts of) mandibles present in the samples. All prey items eaten by the Spoonbills were extremely small. Diet composition of adult birds and chicks appeared to be similar. There was great variation in diet composition of adults between years, but there was no trend in any of the major diet components over the study period. This indicates that the decline of the Spoonbill population is not correlated with changes in food composition. Our diet study has been of a qualitative nature. Considering the dramatic population decline we plea for a more detailed ecological study of the species, including a quantitative approach of food intake and foraging conditions.

Schouten M.A.,Copernicus Institute for Sustainable Development and Innovation | Barendregt A.,Copernicus Institute for Sustainable Development and Innovation | Verweij P.A.,Copernicus Institute for Sustainable Development and Innovation | Kalkman V.J.,European Invertebrate Survey The Netherlands | And 3 more authors.
Biodiversity and Conservation | Year: 2010

Biogeographical zonation based on single taxa poses major limitations on planning for nature conservation. This paper identifies biogeographical patterns of multiple taxa in the Netherlands, where no endemics are present at species level, on the basis of characteristic species. We used occurrence data on five species groups in order to identify spatially coherent, ecologically important regions. TWINSPAN was used to cluster grid squares according to similarity in species composition for each taxonomic group. Species that are characteristic of each of the clusters were identified using a preference index, and corresponding clusters among the taxonomic groups were identified with Kappa statistics. Regions containing characteristic species for several taxonomic groups were defined as 'hotspots'. Stepwise discriminant analysis was then used to characterize these hotspots according to differences in environmental conditions. The analysis yielded five regions that are clearly distinct in terms of species composition for individual taxonomic groups. Each region is characterized by a set of unique species that occur in the zonation of at least two of the taxonomic groups. Stepwise discriminant analysis revealed significant environmental differences among these regions. The concept of hotspots as operationalized in this study can make nature conservation planning more efficient. In combination, the hotspots defined here comprise the majority of the species occurring in the Netherlands for the studied groups. Therefore, this regionalization should be taken into account when prioritizing nature conservation efforts. © 2010 The Author(s).

Jelena K.,Croatian Academy of science and Arts | Antun Z.,Vere Gucunje 20 | Tibor M.,Croatian Society for Birds and Nature Protection | Otto O.,Natuurmonumenten
Waterbirds | Year: 2012

Data on the movement of immature Eurasian Spoonbills from the southern Pannonian Basin are presented for the first time and differences in migration patterns between the Atlantic and southern Pannonian breeding populations are identified. Movements of spoonbills from Western Europe are well known, but there is uncertainty about the movements of the eastern metapopulation, of which the southern Pannonian population forms part. Analyses were based on 707 resightings in Europe and North Africa of 272 color-ringed birds. The studied birds wintered in North Africa (predominantly Tunisia) or southern Italy (Sicily and Sardinia). Most birds used the central Mediterranean flyway, but crossed the Adriatic Sea at more northern latitudes than had previously been reported. With increase in age, the ratio of birds spending the breeding period at the wintering sites decreased (54.2% for second-year and 13.6% for third-year birds), while the ratio of those returning to the Pannonian breeding grounds increased (37.5% and 66.6% respectively). Older spoonbills arrived back at their natal areas earlier. Immature spoonbills from the southern Pannonian Basin population visited breeding colonies in Germany, confirming at least sporadic contacts between two metapopulations. Identification of migration routes and wintering areas is a major precondition for the conservation of the eastern metapopulation. Illegal hunting, tourism development on staging areas and lack of suitable feeding habitats along flyway have been identified as the most important threats.

van Diggelen J.M.H.,Radboud University Nijmegen | Bense I.H.M.,Wageningen University | Brouwer E.,Radboud University Nijmegen | Limpens J.,Wageningen University | And 3 more authors.
Ecological Engineering | Year: 2015

Rich fens are known for their high botanical diversity encompassing many endangered species. For decades, several management measures, including mowing and burning, have been applied to maintain a high biodiversity by means of slowing down the natural succession from calcareous rich fens to acidic poor fens or woodland. In this study, we assessed the long-term effects of these traditional management measures, and explored the effectiveness of liming as a measure to restore rich fen vegetation. Effects of summer mowing, and of burning after winter mowing, were assessed by comparing current (2013) and historical (1967) vegetation data. Effects of experimental liming, using different levels of lime addition (0, 1000, 2000, and 4000. kg. Dolokal/ha), were monitored in the field during 7.5 years. Summer mowing led to more acidic and nutrient-poor conditions as indicated by a shift from rich to poor fen vegetation, including a well-developed bryophyte cover dominated by Sphagnum with some threatened species. Burning (after winter mowing) counteracted acidification but increased nutrient availability, as indicated by dominance of vascular species characteristic of productive tall-herb grasslands and a sparse bryophyte cover with common species. We conclude that the traditional measures were unable to maintain rich fen composition in the long term. Given the fact that the restoration of hydrological conditions, favouring rich fens, is not always feasible, liming could be an alternative to counteract acidification and improve rich fen conditions in the short term. This measure, however, appeared to be unsustainable as the re-establishment and dominance of Sphagnum spp. seriously complicated the development of rich fen vegetation in the longer term. © 2014 Elsevier B.V.

Van Dijk A.J.,Anserweg 8 | De Haan B.,Natuurmonumenten | Messemaker R.,Anserweg 8 | Verbij P.,Anserweg 8
Limosa | Year: 2012

In de northwest of the province of Overijssel one of the larger Dutch peat bog marshlands is situated. De Wieden (9260 ha) is part of the National Park Weerribben and Wieden, and a designated Natura 2000 site. The landscape consists of shallow lakes and canals, marshland, wet meadows and wet alder-birch forest. Each year in large parts reed is cut for commercial use. Farmland and villages are mainly found along the edges of the study area (Fig. i). In 2004-2011 all breeding birds were censused in most of the area using the Dutch variant of the territory mapping method. 138 breeding species and a total of 34,300 breeding pairs were found (table 1, appendix 1). The most abundant species were Willow Warbler Phylloscopus trochilus (2100-4500 pairs), Eurasian Reed Warbler Acrocephalus scirpaceus (1800-3800), Sedge Warbler A. schoenobaenus (2700-3500) and Common Reed Bunting Emberiza schoeniclus (1500-3000). Marshland birds represent 51% of the avifauna. The colonial BlackTern Chlidoniasniger, Eurasian Spoonbill Platalea leuco-rodia, Great Cormorant Phalocrocorax carbo, Grey Heron Ardea cinerea, Purple Heron A. purpurea and Western Great Egret Casmerodius albus are striking representatives in this group, alongside Bluethroat Luscinia svecica, Common Grasshopper Warbler Locustella naevia, Common Reed Bunting, Eurasian Coot Fulica atra, Eurasian Reed Warbler, Great Crested Grebe Podiceps cristatus, Greylag Goose Anseranser, Mallard Anas platyrhynchos, Savi's Warbler Locustella luscinioides and Sedge Warbler. Large open fields of mown reeds are favored by Common Snipe Gallinago gallinago, Eurasian Curlew Numenius arquata and Northern Lapwing Vanellusvanel-lus. In the newly grown reeds many Eurasian Reed Warblers settle, while remaining stands of uncut reed are favoured by Bluethroat, Eurasian Reed, Savi's and Sedge Warblers. Woodland birds (14,301 pairs of 54 species) account for 42% of the avifauna, while only 13% of De Wieden consist of forest. The relatively young alder-birch forests are predominantly inhabited by Willow Warbler, Common Chiffchaff Phylloscopus collybita, Eurasian Wren Troglodytes troglodytes, Garden Warbler Sylvia borin and Tree Pipit Anthus trivialis. Species of old forest like Short-toed Treecreeper Certhia bra-chydactyla, Eurasian Nuthatch Sitta europaea and Hawfinch Coccothraustes coccothraustes are scarce. Farmland represents 4% of De Wieden. Meadow Pipit Anthus pratensis and Northern Lapwing are the most abundant meadow birds alongside Black-tailed Godwit Limosa limosa, Common Redshank Tringa totanus and Northern Shoveler Anas clypeata. The number of breeding birds in villages and buildings is modest with 3% of the total bird population. Barn Swallow Hirundo rustica, House Sparrow Passer domes-ticus and White Wagtail Motacilla alba are by far the most numerous representatives. The proportion of the national population that breeds in De Wieden is strikingly large (10-20%) for Black Tern, Common Snipe, Purple Heron, Savi's Warbler and Sedge Warbler, making this one of their main breeding areas in The Netherlands. The area is also nationally important for Common Grasshopper Warbler, Eurasian Bittern, Eurasian Curlew, Gad-wall, Garganey, Great Cormorant, Spotted Crake, Water Rail Rallus aquaticus and Western Great Egret.

Navedo J.G.,University of Extremadura | Navedo J.G.,National Autonomous University of Mexico | Masero J.A.,University of Extremadura | Overdijk O.,Natuurmonumenten | And 2 more authors.
Ardea | Year: 2010

Understanding the factors driving departure decisions from stopover sites is critical when predicting the dynamics of bird migration. We investigated the interactive effects of wind, tidal characteristics, and precipitation on the departure decisions of the Eurasian Spoonbill Platalea I. leucorodia from a major coastal stopover locality in northern Iberia. Most departing Spoonbills (>80%) crossed an adjacent mountain range to follow a direct route over inland Iberia, while the remainder made a detour following an indirect coastal route along the coast of the Iberian Peninsula. During four consecutive autumns, we daily monitored departing Spoonbills leaving along these two routes. The birds taking the inland route, crossing unsuitable habitats and needing therefore higher fuel-loads, departed preferentially under favourable tailwind conditions (TWC). This represented a significant increase in distance covered and/or a decrease in energy spent per unit time. Moreover, Spoonbills taking the inland route often departed during spring tides. For the indirect coastal route, TWC did not affect the onset of migration but bird departures increased with neap tides. Precipitation and date were negatively correlated with departures towards both routes, whereas Spoonbill density at the stopover had a positive effect. Our findings provide empirical support for the role that wind assistance may play for Spoonbills to resume migration.

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