Monitoring van het voor vogels oogstbare voedselaanbod in de kombergingen van het Pinkegat en Zoutkamperlaag : rapportage tot en met monitoringjaar 2019
Ens, Bruno J. ; Troost, Karin ; Winden, Erik van; Schekkerman, Hans ; Rappoldt, Kees ; Kessel, Jos van; Nienhuis, Jeroen - \ 2020
Nijmegen : SOVON Vogelonderzoek Nederland (Sovon-rapport 2020/25) - 77
Origin and movements of Red-necked Phalarope wintering in the Arabian Sea
Bemmelen, R.S.A. van; Schekkerman, H. ; Tulp, I.Y.M. - \ 2020
Newsletter Indian Ocean Seabird Group (2020)7. - p. 12 - 14.
Changes in the waterbird community of the Parc National du Banc d’Arguin, Mauritania, 1980–2017
Oudman, Thomas ; Schekkerman, Hans ; Kidee, Amadou ; Roomen, Marc Van; Camara, Mohamed ; Smit, Cor ; Horn, Job Ten; Piersma, Theunis ; El-Hacen, El-Hacen Mohamed - \ 2019
Bird Conservation International (2019). - ISSN 0959-2709 - p. 1 - 16.
banc-darguin - bird census - global change - east atlantic flyways - NMDS - population decline - shorebirds - waterbird community
The Parc National du Banc d’Arguin in Mauritania hosts the largest concentrations of coastal waterbirds along the East Atlantic Flyway. In spite of this importance, a review of the changes in the numbers of waterbirds in the area is lacking since the first complete count in 1980. Here we analysed the seven complete waterbird counts made since then, and the additional yearly counts made in one subunit (Iwik region) since 2003.We present evidence for changes in the community composition of waterbirds over the past four decades. Total waterbird numbers showed a decrease between 1980 and 2017, with only Great White Pelican Pelecanus onocrotalus showing a significant
increase in numbers. Five species showed significant declines: Long-tailed Cormorant Phalacrocorax africanus, Red Knot Calidris canutus, Bar-tailed Godwit Limosa lapponica, Eurasian Curlew Numenius arquata, and Western Marsh Harrier Circus aeruginosus. In the remaining species, the variation in numbers between counts was too large, and the number of complete counts too small, for trends to be detected. The yearly counts at Iwik region also showed sharp decreases in the numbers of Red Knot, Bar-tailed Godwit, and Marsh Harrier, but not of Long-tailed Cormorant and Eurasian Curlew. A multivariate analysis revealed a significant effect of year on species composition, which was caused mainly by changes in the species depending on the intertidal mudflats for feeding (generally in decline) vs. the species depending on fish and crustaceans in the sublittoral and offshore zones (often showing increases).
Monitoring van het voor vogels oogstbare voedselaanbod in de kombergingen van het Pinkegat en Zoutkamperlaag : rapportage t/m monitoringjaar 2018
Ens, Bruno J. ; Meer, Jaap van der; Troost, Karin ; Winden, Erik van; Schekkerman, Hans ; Rappoldt, Kees - \ 2019
Nijmegen : SOVON Vogelonderzoek Nederland (Sovon-rapport 2019/22) - 82
A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies
Bemmelen, Rob S.A. van; Kolbeinsson, Yann ; Ramos, Raül ; Gilg, Olivier ; Alves, José A. ; Smith, Malcolm ; Schekkerman, Hans ; Lehikoinen, Aleksi ; Petersen, Ib Krag ; Þórisson, Böðvar ; Sokolov, Aleksandr A. ; Välimäki, Kaisa ; Meer, Tim Van Der; Okill, J.D. ; Bolton, Mark ; Moe, Børge ; Hanssen, Sveinn Are ; Bollache, Loïc ; Petersen, Aevar ; Thorstensen, Sverrir ; González-Solís, Jacob ; Klaassen, Raymond H.G. ; Tulp, Ingrid - \ 2019
Frontiers in Ecology and Evolution 7 (2019). - ISSN 2296-701X - 17 p.
flexibility - itinerancy - migration strategy - Phalaropus lobatus - red-necked phalarope
Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but few studies compare movement strategies among populations using distinct migration routes and wintering areas. In our study, individual movement strategies of red-necked phalaropes (Phalaropus lobatus), a long-distance migratory wader which uses saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed a migratory divide between two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean, and the other breeding in Fennoscandia and Russia migrating
ca. 6,000 km—largely over land—to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, van Bemmelen et al. Contrasting Movement Strategies in Phalaropes birds wintering in the Pacific were stationary in roughly a single area, whereas individuals wintering in the Arabian Sea moved extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.
Broedsucces van kustbroedvogels in de Waddenzee : Resultaten 2015-2016 en trends in broedsucces in 2005-2016
Koffijberg, K. ; Cremer, J.S.M. ; Boer, P. de; Nienhuis, J. ; Schekkerman, H. ; Oosterbeek, K. ; Postma, J. - \ 2017
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 112) - 50
Data have been collected on the breeding success of several characteristic coastal breeding birds in the Wadden Sea each year since 2005. Ten birds species considered representative of specific habitats and food groups are being monitored. The monitoring scheme on breeding success in coastal breeding birds is run as an ‘early warning system’ to follow the reproductive capacity of the bird populations in the Wadden Sea and understand the processes underlying fluctuations in populations. It is a valuable addition to the monitoring of population numbers and is carried out under a trilateral agreement with Germany and Denmark (TMAP). The results from 2015–2016 and an analysis of data series from the period 2005–2016 (sometimes longer) show that several species on average reared too few young to sustain stable population size in many of these years, especially the Eurasian Oystercatcher, Pied Avocet, Common Tern and Arctic Tern, and in recent years also the Black-headed Gull, whose breeding success has significantly declined since 1995. Other species showing a significant decline in breeding success are the Spoonbill and Common Tern. The only species to show any significant improvement in breeding success since 2005 is the Lesser Black-backed Gull
Monitoring van het voor vogels oogstbare voedselaanbod in de kombergingen van het Pinkegat en Zoutkamperlaag
Ens, B.J. ; Krol, J. ; Meer, J. van der; Piening, H. ; Wijsman, J.W.M. ; Schekkerman, H. ; Rappoldt, C. - \ 2015
Nijmegen : Sovon (Sovon-rapport 2015.15) - 54
aardgas - nadelige gevolgen - natura 2000 - kustgebieden - vogels - waddenzee - foerageren - wetlands - groningen - friesland - natural gas - adverse effects - coastal areas - birds - wadden sea - foraging
De gaswinning vanaf de locaties Moddergat, Lauwersoog en Vierhuizen kan effecten hebben op het Natura 2000 gebied Waddenzee. Uit voorzorg vindt de winning plaats volgens het ‘Hand aan de kraan’ principe. In dat kader vindt een uitgebreide monitoring plaats van biotische en abiotische parameters, om te controleren of gaswinning vanaf de bovengenoemde locaties geen meetbaar nadelig effect heeft op de instandhoudingsdoelstellingen van de speciale beschermingzone Waddenzee, waaronder een groot aantal vogelsoorten waarvoor het gebied is aangewezen.
Site-specific dynamics in remnant populations of Northern Wheatears Oenanthe oenanthe in the Netherlands
Oosten, H.H. van; Turnhout, C. van; Hallmann, C.A. ; Majoor, F. ; Roodbergen, M. ; Schekkerman, H. ; Versluijs, R. ; Waasdorp, S. ; Siepel, H. - \ 2015
Ibis 157 (2015)1. - ISSN 0019-1019 - p. 91 - 102.
spatial synchrony - environmental correlation - scale - dispersal - birds - immigration - landscape - density - impact - space
Dynamics of populations may be synchronized at large spatial scales, indicating driving forces acting beyond local scales, but may also vary locally as a result of site-specific conditions. Conservation measures for fragmented and declining populations may need to address such local effects to avoid local extinction before measures at large spatial scales become effective. To assess differences in local population dynamics, we aimed to determine the demographic drivers controlling population trends in three remaining populations of the Northern Wheatear Oenanthe oenanthe in the Netherlands, as a basis for conservation actions. An integrated population model (IPM) was fitted to field data collected in each site in 2007–2011 to estimate fecundity, survival and immigration. Sites were 40–120 km apart, yet first-year recruits were observed to move between some of the sites, albeit rarely. All three populations were equally sensitive to changes in fecundity and first-year survival. One population was less sensitive to adult survival but more sensitive to immigration. A life table response experiment suggested that differences in immigration were important determinants of differences in population growth between sites. Given the importance of immigration for local dynamics along with high philopatry, resulting in low exchange between sites, creating a metapopulation structure by improving connectivity and the protection of local populations are important for the conservation of these populations. Site-specific conservation actions will therefore be efficient and, for the short term, we propose different site-specific conservation actions.
Shorebird incubation behviour and its influence on the risk of nest predation
Smith, P.A. ; Tulp, I.Y.M. ; Schekkerman, H. ; Gilchrist, H.G. ; Forbes, M.R. - \ 2012
Animal Behaviour 84 (2012)4. - ISSN 0003-3472 - p. 835 - 842.
daily energy-expenditure - site selection - parent birds - sandpipers - defense - pigmentation - patterns - habitat - success - waders
Both nest survival and incubation behaviour are highly variable among shorebirds (Charadrii), and we tested whether more conspicuous incubation behaviour increased the risk of nest predation. During 2000-2006, we monitored nest fate at 901 shorebird nests at three study sites across the circumpolar Arctic. Using miniature video recorders and nest temperature sensors, we obtained 782 days of behavioural data for 161 nests of 11 species. We related nest fate to the rate and duration of adults' nest absences or restless movements on the nest, as well as the total proportion of each day that adult birds engaged in these activities. Nest predation was positively related to the proportion of time that each species left the nest unattended. After controlling for species effects, the likelihood of a successful nesting attempt was lower for individuals that spent more time off the nest, but among failed nests, the number of days that a nest survived prior to depredation was not significantly predicted by measures of incubation behaviour. To control for weather or seasonal effects, we paired observations from nests that were ultimately depredated with observations from successful nests of the same species on the same day. In this paired sample (dominated by two species: red phalaropes, Phalaropus fulicarius, and little stints, Calidris minuta), both incubation recesses and restless movements were more numerous among failed versus successful nests. Our results suggest that more conspicuous incubation behaviour is indeed related to a higher risk of nest predation, and that this relationship may underlie patterns of nest survival within and among shorebird species. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Eggs in the Freezer: energetic Consequences of Nest Site and Nest Design in Arctic Breeding Shorebirds
Tulp, I.Y.M. ; Schekkerman, H. ; Leeuw, J.J. de - \ 2012
PLoS ONE 7 (2012)6. - ISSN 1932-6203 - 9 p.
mating system - heat-loss - incubation - predation - expenditure - insulation - sandpipers - selection - clutch - tundra
Birds construct nests for several reasons. For species that breed in the Arctic, the insulative properties of nests are very important. Incubation is costly there and due to an increasing surface to volume ratio, more so in smaller species. Small species are therefore more likely to place their nests in thermally favourable microhabitats and/or to invest more in nest insulation than large species. To test this hypothesis, we examined characteristics of nests of six Arctic breeding shorebird species. All species chose thermally favourable nesting sites in a higher proportion than expected on the basis of habitat availability. Site choice did not differ between species. Depth to frozen ground, measured near the nests, decreased in the course of the season at similar non-species-specific speeds, but this depth increased with species size. Nest cup depth and nest scrape depth (nest cup without the lining) were unrelated to body mass (we applied an exponent of 0.73, to account for metabolic activity of the differently sized species). Cup depth divided by diameter2 was used as a measure of nest cup shape. Small species had narrow and deep nests, while large species had wide shallow nests. The thickness of nest lining varied between 0.1 cm and 7.6 cm, and decreased significantly with body mass. We reconstruct the combined effect of different nest properties on the egg cooling coefficient using previously published quantitative relationships. The predicted effect of nest cup depth and lining depth on heat loss to the frozen ground did not correlate with body mass, but the sheltering effect of nest cup diameter against wind and the effects of lining material on the cooling coefficient increased with body mass. Our results suggest that small arctic shorebirds invest more in the insulation of their nests than large species
Do Uniparental Sanderlings Calidris alba Increase Egg Heat Input to Compensate for Low Nest Attentiveness?
Reneerkens, J. ; Grond, K. ; Schekkerman, H. ; Tulp, I.Y.M. ; Piersma, Th. - \ 2011
PLoS ONE 6 (2011)2. - ISSN 1932-6203 - 9 p.
daily energy-expenditure - incubation schedules - avian embryos - tree swallows - clutch size - wood ducks - temperature - behavior - demands - birds
Birds breeding in cold environments regularly have to interrupt incubation to forage, causing a trade-off between two mutually exclusive behaviours. Earlier studies showed that uniparental Arctic sandpipers overall spend less time incubating their eggs than biparental species, but interspecific differences in size and ecology were potential confounding factors. This study reports on a within-species comparison of breeding schedules and metal egg temperatures in uni- and biparental sanderlings (Calidris alba) in Northeast Greenland in relation to ambient temperature. We recorded incubation schedules with nest temperature loggers in 34 sanderling clutches (13 uniparentals, 21 biparentals). The temperature of a metal egg placed within the clutch of 17 incubating birds (6 uniparentals, 9 biparentals) was measured as an indicator of the heat put into eggs. Recess frequency, recess duration and total recess time were higher in uniparentals than in biparentals and positively correlated with ambient temperatures in uniparentals only. Uniparental sanderlings maintained significantly higher metal egg temperatures during incubation than biparentals (1.4°C difference on average). Our results suggest that uniparental sanderlings compensate for the lower nest attendance, which may prolong the duration of the incubation period and negatively affect the condition of the hatchlings, by maintaining a higher heat flux into the eggs.
Broedsucces van kustbroedvogels in de Waddenzee in 2007 en 2008
Kleunen, A. van; Koffijberg, K. ; Boer, P. ; Nienhuis, J. ; Camphuysen, C.J. ; Schekkerman, H. ; Oosterbeek, K.H. ; Jong, M.L. de; Ens, B.J. ; Smit, C.J. - \ 2010
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 227) - 73
broedvogels - watervogels - voortplantingsvermogen - kustgebieden - monitoring - populatiedynamica - waddenzee - breeding birds - waterfowl - reproductive performance - coastal areas - monitoring - population dynamics - wadden sea
Voor het derde en vierde opeenvolgende jaar werd het broedsucces van een aantal kustbroedvogels in de Waddenzee bepaald. Van Eider, Scholekster, Kluut, Kokmeeuw, Zilvermeeuw en Visdief, alsmede van Kleine Mantelmeeuw en Noordse Stern werd informatie verzamelen over het nestsucces en uitvliegsucces (het uiteindelijke broedsucces). Kennis over de jaarlijkse variatie in broedresultaten bij de verschillende soorten is van belang als een early warning systeem om de 'kwaliteit' (het reproducerend vermogen) van de vogelpopulaties in de Waddenzee te volgen en de achterliggende processen van populatieveranderingen te doorgronden. Directe aanleiding voor het project vormde de evaluatie van de effectiviteit van het nieuwe schelpdiervisserijbeleid en de mogelijke gevolgen voor de voedselvoorziening van schelpdieretende vogels.
Effect van nestbezoek en onderzoek op weidevogels
Goedhart, P.W. ; Teunissen, W.A. ; Schekkerman, H. - \ 2010
Wageningen : Wageningen Universiteit (SOVON-onderzoeksrapport 2010/01) - 84
weidevogels - natuurbescherming - cost effective analysis - ecologische modellering - beslissingsmodellen - grassland birds - nature conservation - cost effectiveness analysis - ecological modeling - decision models
In Nederland wordt veel energie gestoken in het zoeken en beschermen van weidevogellegsels tegen agrarische activiteiten om zo de gestage achteruitgang van weidevogels te stoppen. Jaarlijks betreft dit zo’n 150.000 nesten. Er is echter discussie ontstaan over het positieve effect van dit soort beschermingsmaatregelen omdat het controleren van nesten tot een verhoging van de verliezen zou kunnen leiden; het zogenaamde bezoekeffect. Om dit vast te kunnen stellen is allereerst gezocht naar een berekeningswijze waarmee een eventueel bezoekeffect kan worden aangetoond. Hiervoor zijn in totaal drie verschillende modellen ontwikkeld en getest. De verschillende modellen zijn uitgetest met een gesimuleerde dataset waarin de waarden voor de dagelijkse overlevingskans en het bezoekeffect bekend zijn. De beste schattingen van het bezoekeffect en de dagelijkse overlevingskans worden behaald met een model waarin tevens de broedduur en de eerste eilegdatum zijn gemodelleerd.
Population dynamics of Black-tailed Godwits in the light of heavy metal pollution
Roodbergen, M. - \ 2010
University of Groningen. Promotor(en): T. Piersma, co-promotor(en): Chris Klok; H. Schekkerman. - - 170
limosa limosa - verontreinigde grond - zware metalen - populatiedynamica - contaminated soil - heavy metals - population dynamics
Wat kost het behoud van onze akkervogels?
Bos, J.F.F.P. ; Sierdsema, H. ; Schekkerman, H. ; Scharenburg, C.W.M. - \ 2010
De Levende Natuur 111 (2010)6. - ISSN 0024-1520 - p. 259 - 263.
vogels - bouwland - gemeenschappelijk landbouwbeleid - kosten - agrarisch natuurbeheer - birds - arable land - cap - costs - agri-environment schemes
Het Planbureau voor de Leefomgeving wilde weten welke maatregelen in de Nederlandse landbouw nodig zijn om akkervogeldoelen te halen en wat deze maatregelen kosten. In het rapport "Een veldleeuwerik zingt niet voor niets!" zijn deze vragen beantwoord. Dit artikel geeft de belangrijkste bevindingen.
Adverse effectsof agricultaral intensification and climate change on breeding habitat quality of Blacktailed Godwits Limosa l. limosa in the Netherlands
Kleijn, D. ; Schekkerman, H. ; Dimmers, W.J. ; Kats, R.J.M. van; Melman, T.C.P. ; Teunissen, W.A. - \ 2010
Ibis 152 (2010)3. - ISSN 0019-1019 - p. 475 - 486.
farmland bird populations - lapwing vanellus-vanellus - agri-environment schemes - grassland management - chicks - eggs - biodiversity - intensity - britain - europe
Agricultural intensification is one of the main drivers of farmland bird declines, but effects on birds may be confounded with those of climate change. Here we examine the effects of intensification and climate change on a grassland breeding wader, the Black-tailed Godwit Limosa l. limosa, in the Netherlands. Population decline has been linked to poor chick survival which, in turn, has been linked to available foraging habitat. Foraging habitat of the nidifugous chicks consists of uncut grasslands that provide cover and arthropod prey. Conservation measures such as agri-environment schemes aim to increase the availability of chick foraging habitat but have not yet been successful in halting the decline. Field observations show that since the early 1980s, farmers advanced their first seasonal mowing or grazing date by 15 days, whereas Godwits did not advance their hatching date. Ringing data indicate that between 1945 and 1975 hatching dates advanced by about 2 weeks in parallel with the advancement of median mowing dates. Surprisingly, temperature sums at median mowing and hatching dates suggest that while the agricultural advancement before 1980 was largely due to agricultural intensification, after 1980 it was largely due to climate change. Examining arthropod abundance in a range of differently managed grasslands revealed that chick food abundance was little affected but that food accessibility in intensively used tall swards may be problematic for chicks. Our results suggest that, compared with 25 years ago, nowadays (1) a much higher proportion of clutches and chicks are exposed to agricultural activities, (2) there is little foraging habitat left when chicks hatch and (3) because of climate change, the vegetation in the remaining foraging habitat is taller and denser and therefore of lower quality. This indicates that for agri-environment schemes to make a difference, they should not only be implemented in a larger percentage of the breeding area than the current maxima of 20–30% but they should also include measures that create more open, accessible swards
Een veldleeuwerik zingt niet voor niets! : schatting van kosten van maatregelen voor akkervogels in de context van een veranderend gemeenschappelijk landbouwbeleid
Bos, J.F.F.P. ; Sierdsma, H. ; Schekkerman, H. ; Scharenburg, C.W.M. - \ 2010
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-rapport 107) - 242
vogels - gemeenschappelijk landbouwbeleid - akkerbouw - kosten - agrarisch natuurbeheer - birds - cap - arable farming - costs - agri-environment schemes
Als gevolg van intensivering en schaalvergroting nemen de aan landbouw gebonden vogelsoorten op Europese schaal zowel in aantal als verspreiding af. Door hun verbondenheid met landbouw is het lot van akkervogels nauw gerelateerd aan de effecten van het Europese Gemeenschappelijk Landbouwbeleid (GLB). Afhankelijk van de uitwerking van dit GLB na 2013 neemt de betekenis van gerichte betalingen aan de landbouw voor specifieke doelen, waaronder biodiversiteit, mogelijk toe. Binnen de context van een veranderend GLB enerzijds en biodiversiteitsdoelstellingen voor akkervogels anderzijds, verschaft dit rapport inzicht in de (kosten van) maatregelen die in de Nederlandse landbouw op landelijk niveau nodig zijn om biodiversiteitsdoelstellingen voor akkervogels te behalen. Alle maatregelen richten zich op het voorzien in de ‘grote drie’ voor akkervogels: broedgelegenheid en dekking, voldoende aanbod van toegankelijk zomervoedsel (insectenrijke habitats in nabijheid van nest) en voldoende aanbod van wintervoedsel (graankorrels, onkruidzaden). De geschatte kosten van de maatregelen bedragen minimaal enkele tientallen miljoenen tot maximaal €176 miljoen. Trefwoorden: akkervogels, agrarisch natuurbeheer, Gemeenschappelijk landbouwbeleid, biodiversiteit
Mortality of Black-tailed Godwit Limosa limosa and Northern Lapwing Vanellus vanellus chicks in wet grasslands: influence of predation and agriculture
Schekkerman, H. ; Teunissen, W. ; Oosterveld, E. - \ 2009
Journal of Ornithology 150 (2009)1. - ISSN 2193-7192 - p. 133 - 145.
curlew numenius-arquata - breeding success - duckling survival - pheasant chicks - population - management - birds - brood - parameters - abundance
Grassland-breeding shorebirds show widespread declines due to a reduction in breeding productivity following agricultural intensification. However, there is also concern that increasing predation causes further declines or precludes population recovery. Predation may itself be enhanced by agriculture through changes in habitat or food availability, but little is known about the mortality of nidifugous shorebird chicks. We studied mortality by radio-tagging 662 chicks of Black-tailed Godwit Limosa limosa and Northern Lapwing Vanellus vanellus in 15 farmland sites in the Netherlands. Tagging and handling had no effect on the condition and survival of godwit chicks, but body condition was reduced by 6-11% in lapwing chicks wearing a tag for longer than 3 days. Fledging success was 0 - 24% in both species. Mortality was highest in young chicks but remained considerable until after fledging. Losses were traced mostly to predators (70 - 85%; 15 species, predominantly birds), but at least 5 - 10% were due to mowing, and 10 - 20% were due to other causes, including entrapment in ditches and starvation. Chicks staying in fields that were cut before the next radio check were found much more often as mowing victims and somewhat more often as prey remains than chicks in fields not cut, indicating that predation includes a limited amount of scavenging. The predation hazard for godwit chicks was higher in recently cut or grazed fields than in the tall, uncut grasslands they preferred, while that for lapwing chicks was lowest in grazed fields. In godwit chicks, poor body condition increased mortality risk, not only from starvation but also from other causes. Predation on godwit chicks was thus enhanced by intensive farming through a decline in the availability of cover, augmented by a reduced body condition, possibly due to food availability problems. Changes in farming practice may therefore help reduce predation pressure, though the observed interactions explained only part of the high predation rate in godwits and none in lapwings. Predator abundance has increased in Dutch wet grassland regions, and chick predation has become a factor that should be considered in planning the type and location of conservation measures.
Do meadow birds profit from agri-environment schemes in Dutch agricultural landscapes?
Breeuwer, A.J.G. ; Berendse, F. ; Willems, F. ; Foppen, R. ; Teunissen, W. ; Schekkerman, H. ; Goedhart, P.W. - \ 2009
Biological Conservation 142 (2009)12. - ISSN 0006-3207 - p. 2949 - 2953.
godwit limosa-limosa - farmland - biodiversity - intensification - management - abundance - success
Since 1992 the European Union helps member states to reverse the loss of biodiversity in agricultural landscapes by the financial support of agri-environment schemes. Long-term studies investigating the effects of these schemes are an essential prerequisite for the development of an effective policy to restore biodiversity on farmland. In Dutch meadow landscapes almost all agri-environment schemes focus on the restoration of meadow bird populations by postponement of the mowing date. Between 1990 and 2002 we measured long-term changes in meadow bird densities in areas with and without agri-environment schemes in the Netherlands, both before and after the start of the contract. During these years bird territories were surveyed during five field visits between 15 March and 15 June. Densities of black-tailed godwit (Limosa limosa), and redshank (Tringa totanus) were higher in the areas with management agreements, but these differences were already present before the start of the contracts. After the start of the management contracts densities of black-tailed godwit and oystercatcher (Haematopus ostralegus) did not increase, while those of lapwing (Vanellus vanellus) and redshank even declined relative to the control areas. It is concluded that the current agri-environment schemes are not sufficient to restore meadow bird populations in Dutch agricultural landscapes. In addition to the prescribed postponement of the mowing date, it is probably necessary to raise groundwater levels and to reduce fertilization to allow for the development of an open vegetation structure that will increase chick survival to sufficiently high levels
Body condition of shorebirds upon arrival at their Siberian breeding grounds
Tulp, I.Y.M. ; Schekkerman, H. ; Klaassen, R.H.G. ; Ens, B.J. ; Visser, G.H. - \ 2009
Polar Biology 32 (2009)3. - ISSN 0722-4060 - p. 481 - 491.
calidris-canutus-islandica - red knots - energy-expenditure - tundra arthropods - ellesmere-island - fat reserves - migration - stores - survival - waders
Abstract Arctic breeding shorebirds carry substantial body stores on their long-distance migrations from their non-breeding grounds. Upon arrival at the breeding area the remains of these stores can be used for egg formation, insurance against poor feeding conditions or rebuilding organs. We quantified body condition (body mass, total body water, lean body mass and fat mass estimated using the deuterium dilution method) in seven shorebird species caught upon arrival in the Siberian Arctic. Arrival condition was compared with incubation condition in a subset of species. After correction for structural size, body mass was significantly lower at arrival than during incubation in most of the species (but 3¿18% above lean mass). Fat index (fat mass/lean mass) varied between 5.1 and 13.2%. Fat stores were estimated to enable survival for 0.6 days for the smallest and 2.5 days for the largest species. We discuss possible functions of arrival stores: insurance, egg-formation or rebuilding organs.