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Den Burg, Netherlands

Jiguet F.,CNRS Science Conservation Center | Devictor V.,Montpellier University | Ottvall R.,Lund University | Van Turnhout C.,Dutch Center for Field Ornithology | And 3 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2010

Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the species ranges. After controlling for factors already reported to affect bird population trends (habitat specialization, migration distance and body mass), we found that populations breeding close to the species thermal maximum have lower growth rates than those in other parts of the thermal range, while those breeding close to the species thermal minimum have higher growth rates. These results were maintained even after having controlled for the effect of latitude perse. Therefore, the results cannot solely be explained by latitudinal clines linked to the geographical structure in local spring warming. Indeed, we found that populations are not just responding to changes in temperature at the hottest and coolest parts of the species range, but that they show a linear graded response across their European thermal range. We thus provide insights into how populations respond to climate changes. We suggest that projections of future species distributions, and also management options and conservation assessments, cannot be based on the assumption of a uniform response to climate change across a species range or at range edges only. © 2010 The Royal Society. Source

Mandema F.S.,University of Groningen | Tinbergen J.M.,University of Groningen | Ens B.J.,Dutch Center for Field Ornithology | Bakker J.P.,University of Groningen
Journal of Coastal Conservation | Year: 2013

The purpose of this study is to experimentally determine the differences between four grazing treatments on the trampling of nests. Additionally, we examine to what extent the trampling probability of nests is higher close to a source of fresh water. We compare the trampling of artificial nests in five different grazing treatments in an experimental design. We use buried clay pigeon targets as artificial mimics of bird nests to obtain reliable estimates of trampling risk and compare these with real nests. We find that horses trample significantly more artificial nests than cattle resulting in lower survival rates of artificial nests under horse grazing than under cattle grazing. For both horses and cattle, we find a clear trend, approaching significance, towards more trampling at higher numbers of livestock. We found that more artificial nests are trampled closer to a freshwater tank. The survival probability of artificial nests in cattle grazed treatments in this study is found to be in the same range as real nests in the study area and very close to the survival probability of Northern Lapwing (Vanellus vanellus) nests under cattle grazing in a different system. We recommend that horses should not be used as grazers for management purposes in areas with high densities of birds' nests in order to minimize the risk of nests being trampled. Additionally, we confirm that the location of freshwater tanks has an important effect on the distribution of livestock and hence on trampling of nests. © 2013 Springer Science+Business Media Dordrecht. Source

Klaassen R.H.G.,Lund University | Ens B.J.,Dutch Center for Field Ornithology | Shamoun-Baranes J.,University of Amsterdam | Exo K.-M.,Institute of Avian Research | Bairlein F.,Institute of Avian Research
Behavioral Ecology | Year: 2012

Migrating birds are believed to minimize the time spent on migration rather than energy. Birds seem to maximize migration speed in different ways as a noteworthy variation in migration strategies exists. We studied migration strategies of a flight mode and feeding generalist, the Lesser Black-backed Gull Larus fuscus, using GPS-based satellite telemetry. We expected the gulls to achieve very high overall migration speeds by traveling via the shortest direct route, traveling during a large part of the day and night, and making few and short stopovers. Fourteen individuals were tracked between the Dutch breeding colony and the wintering sites in England, southern Europe and northwest Africa. The gulls did not travel via the shortest possible route but made substantial detours by their tendency to follow coasts. Although the gulls traveled during most of the day, and sometimes during the night, they did not achieve long daily distances (177 and 176 km/day in autumn and spring, respectively), which is explained by the gulls stopping frequently on travel days to forage. Furthermore, due to frequent and long migratory stopovers, their overall migration speed was among the lowest recorded for migratory birds (44 and 98 km/day, in autumn and spring, respectively). A possible explanation for the unexpected frequent stopovers and low migration speeds is that gulls do not minimize the duration of migration but rather minimize the costs of migration. Energy rather than time might be important for short-distance migrating birds, resulting in very different migration strategies compared with long-distance migrants. © 2011 The Author. Source

Kampichler C.,Netherlands Institute of Ecology | Kampichler C.,Juarez Autonomous University of Tabasco | van Turnhout C.A.M.,Dutch Center for Field Ornithology | van Turnhout C.A.M.,Radboud University Nijmegen | And 2 more authors.
PLoS ONE | Year: 2012

Human land use and climate change are regarded as the main driving forces of present-day and future species extinction. They may potentially lead to a profound reorganisation of the composition and structure of natural communities throughout the world. However, studies that explicitly investigate both forms of impact-land use and climate change-are uncommon. Here, we quantify community change of Dutch breeding bird communities over the past 25 years using time lag analysis. We evaluate the chronological sequence of the community temperature index (CTI) which reflects community response to temperature increase (increasing CTI indicates an increase in relative abundance of more southerly species), and the temporal trend of the community specialisation index (CSI) which reflects community response to land use change (declining CSI indicates an increase of generalist species). We show that the breeding bird fauna underwent distinct directional change accompanied by significant changes both in CTI and CSI which suggests a causal connection between climate and land use change and bird community change. The assemblages of particular breeding habitats neither changed at the same speed and nor were they equally affected by climate versus land use changes. In the rapidly changing farmland community, CTI and CSI both declined slightly. In contrast, CTI increased in the more slowly changing forest and heath communities, while CSI remained stable. Coastal assemblages experienced both an increase in CTI and a decline in CSI. Wetland birds experienced the fastest community change of all breeding habitat assemblages but neither CTI nor CSI showed a significant trend. Overall, our results suggest that the interaction between climate and land use changes differs between habitats, and that comparing trends in CSI and CTI may be useful in tracking the impact of each determinant. © 2012 Kampichler et al. Source

Mandema F.S.,University of Groningen | Tinbergen J.M.,University of Groningen | Ens B.J.,Dutch Center for Field Ornithology | Bakker J.P.,University of Groningen
Ardea | Year: 2014

In this study we examined the effect of different livestock grazing treatments on breeding bird densities in a salt marsh habitat. To avoid an experiment on the large scale needed to directly measure grazing effects on bird densities, we followed a two-step approach. First, we measured vegetation micro-patterns (mosaic of lower vegetation and taller patches at 4×4 m) around Common Redshank Tringa totanus and Eurasian Oystercatcher Haematopus ostralegus nests and at random sites paired with these nests sites to judge suitability of micro-patterns for nest building. Secondly, we measured micro-patterns at 120 permanent plots in five different experimental grazing treatments to determine how grazing affects micro-patterns. We compared low stocking density of both cattle and of horses, high stocking density of cattle and of horses, and intermittent grazing with a high stocking density of cattle (i.e. yearly intervals of grazing and no grazing). Redshank and Oystercatcher nests occurred in sites with taller vegetation and more pronounced micro-patterns than found at random sites. Paddocks grazed with low densities of livestock or with a high density intermittent grazing treatment had micro-patterns preferred by the birds. We conclude that Redshanks and Oystercatchers may benefit in terms of potential nest sites from grazing at low livestock densities or at intermittent stocking densities through effects of grazing on micro-patterns in the vegetation. Source

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