Pesticide risk assessment for birds and mammals
Yellow wagtail Motacilla flava
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- Country Population size
- Agricultural association
- Body weight
- Risk assessment
5.1.6 Yellow wagtail Motacilla flavaGeneral information The yellow wagtail occurs in open country, especially meadows and pastures, across most of the Zone. Most populations have declined in recent decades, and in Denmark – and maybe also in other parts of the Zone – occurrence is now rather scarce and local (Table 5.). Table 5.. Population size and trends of yellow wagtail (breeding population) in the Nordic and Baltic countries. Sources: BirdLife International/European Bird Census Council (2000), BirdLife International (2004), Ottosson et al. (2012).
The birds mostly arrive at their breeding grounds during May, with laying occurring mainly in late May and June. Yellow wagtails are usually single-brooded within the Zone, but two broods have been reported from Denmark and may also occur elsewhere in the southern part of the Zone. Autumn migration may begin as early as late July but the bulk of migration occurs from mid-August until late September. European birds winter in sub-Saharan Africa. Agricultural association In the breeding season, yellow wagtails mostly prefer riversides, lakesides, pastures and similar habitats with low, dense and moist herbage or turf (Cramp 1988). In the northern part of the range, the species (subspecies thunbergi) is also found in peat bogs (mires) and grazed fens. Locally, especially in Central Europe, yellow wagtails seem to have adapted to intensive agriculture and occur in arable fields, particularly in row crops such as potato and beet but also in cereals (Glutz von Blotzheim & Bauer 1985). In North European farmland the species is mainly found in permanent grassland, although before the decline it was common in spring-sown fields in, e.g., southern Finland (Piiroinen et al. 1985, Tiainen et al. 1985). Population densities in farmland may generally reach 2–4 breeding pairs per 10 ha under optimum conditions, i.e. in extensively managed grassland. In arable fields, maximum densities of 0.5 – 0.7 pairs per 10 ha have been reported from Central Europe (Glutz von Blotzheim & Bauer 1985). Body weight Body weight of both sexes mostly 14-21 g (Snow & Perrins 1998). Mean body weight (17.5 g) may be used for risk assessment. Energy expenditure The energy expenditure may be calculated allo metrically using the equation for passerine birds in accordance with the formula in Appendix G of the EFSA Guidance Document (EFSA 2009). Diet Yellow wagtails feed almost exclusively on arthropods, mainly Diptera. They prefer small food items (2-7 mm) but may also take larger insects such as dragonflies Odonata. Three main foraging techniques are used: (1) picking from ground or water surface while walking; (2) run-picking, where the prey is picked from the surface (ground, plant or water) or when it takes off; (3) flycatching after short flight from ground or perch (Cramp 1988). Occasionally yellow wagtails take insects from plants in hovering flight (Glutz von Blotzheim cited by Camp 1988). Thus, both ground-dwelling and foliar insects occur in the diet. In England in April-May, birds feeding in flocks at pools took predominantly Diptera (91–98 % by number) and small numbers of Coleoptera, Aphididae and Ichneumonidae. Birds feeding singly at dung pads also took mainly Diptera, with beetles Coleoptera making up 6.4 % of the diet (by number) (Davies 1977). In Russia (Moscow region) in June, jumping plant lice Psyllidae comprised 83 % of the diet (by number), followed by beetles (7 %, mostly Chrysomelidae), while Diptera comprised only 2.3 % of diet (Ptushenko & Inozemtsev cited by Cramp 1988). In other studies, especially from more southern and less humid areas, Coleoptera make up a larger part of the diet (Glutz von Blotzheim & Bauer 1985). Nestling diet is similar to that of adults. In a study from the St. Petersburg region, Diptera comprised 44.8 % (by number) and Ephemeroptera 24.2 % of nestling diet; other items brought to the nests were mainly Odonata, Coleoptera, Trichoptera and small molluscs (Prokofieva cited by Cramp 1988). Risk assessment The yellow wagtail is relevant for the following crop scenario:
As described above yellow wagtails prefer dipterans, which are partly foliage-dwelling. Populations of foliar insects are however not well developed in short grass and quickly disappears after termination. Therefore the diet is assumed to be composed as shown in Table 5.. Table 5.. Estimated diet composition of yellow wagtails feeding in grassland at different stages.
For ground-dwelling arthropods, interception in the crop canopy may be taken into account as appropriate for the growth stage in question. Directory: media media -> Applications to Drill media -> Unicef voices of Youth Chat Theme: Children and aids nigeria and Zimbabwe 13 October 2006 Background media -> Tsunami Terror Alert: Voices of Youth media -> Biblical Eschatology Presentation by: D. Paul Beck May 4, 2016 Ground Rules media -> Guide to completing the collection using the Omnibus system media -> The milk carton kids media -> Events Date and Location media -> The Gilded Age: The First Generation of Historians by H. Wayne Morgan University of Oklahoma, April 18, 1997 media -> Analysis of Law in the United Kingdom pertaining to Cross-Border Disaster Relief Prepared by: For the 30 June 2010 Foreword media -> Cuba fieldcourse 2010 Download 2.61 Mb. Share with your friends:
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