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In the summer of 2002 a combined Dutch-Russian expedition took place to the Willem Barentz field station at Medusa Bay near Dikson in north-western Taimyr, Russia. The expedition was organised by Alterra and the Agricultural Department of... more
In the summer of 2002 a combined Dutch-Russian expedition took place to the Willem Barentz field station at Medusa Bay near Dikson in north-western Taimyr, Russia. The expedition was organised by Alterra and the Agricultural Department of the Dutch Embassy in Moscow. Research questions addressed by the Alterra team and basic results obtained during the 2002 season are presented in
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We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic... more
We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic difficulties associated with precocial development in a cold climate. Growth rate of knot chicks was very high compared to other, mainly temperate, shorebirds of their size, but strongly correlated with weather-induced and seasonal variation in availability of invertebrate prey. Red knot chicks sought less parental brooding and foraged more at the same mass and temperature than chicks of three temperate shorebird species studied in The Netherlands. Fast growth and high muscular activity in the cold tundra environment led to high energy expenditure, as measured using doubly labelled water: total metabolised energy over the 18-day prefledging period was 89% above an allometric prediction, and among the highest values reported for birds. A comparative simula...
Research Interests: Siberia, Ecology, Energy Metabolism, Seasonality, Computer Simulation, and 22 moreAnimal Feed, Birds, Female, Animals, Male, Temperature, Weather, Netherlands, Energy Expenditure, Food Availability, Feeding Behavior, Seasonal variation, Oecologia, Arthropods, Growth rate, Snow Cover, Seasons, Boolean Satisfiability, Simulation Model, Cold Hardiness, Time Budget, and High energy
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Research Interests: Demography, Conservation, Ecology, Population Dynamics, Endangered Species, and 17 moreGlobal change, Ringing, Animals, Raptor, Netherlands, Population Density, Oecologia, Ecosystem, Survival Rate, First Year, Strigiformes, Population Decline, Capture recapture, Conservation of Natural Resources, Road Traffic, Long Term, and Causal Effect
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Black-tailed (Limosa limosa) and Hudsonian Godwits (L. haemastica) are sometimes described as a superspecies. The Black-tailed Godwit is further split into three subspecies on the basis of morphological differences (L. l. limosa, L. l.... more
Black-tailed (Limosa limosa) and Hudsonian Godwits (L. haemastica) are sometimes described as a superspecies. The Black-tailed Godwit is further split into three subspecies on the basis of morphological differences (L. l. limosa, L. l. islandica and L. l. melanuroides). We studied variation in partial mtDNA control region sequences among Black-tailed and Hudsonian Godwits which showed 5% divergence. Black-tailed and Hudsonian
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Previous studies have shown that preen wax composition in some sandpipers shifts from the usual monoesters to diesters during the breeding season, possibly to reduce the ability of mammalian predators to find nests using olfactory cues.... more
Previous studies have shown that preen wax composition in some sandpipers shifts from the usual monoesters to diesters during the breeding season, possibly to reduce the ability of mammalian predators to find nests using olfactory cues. To investigate further the relationship between incubation and wax secretion, we examined seven sandpiper species with different incubation patterns (species in which both sexes incubate, in which only males incubate and in which only females incubate). During the breeding period, diester preen wax was secreted almost exclusively by the incubating sex in species with uniparental incubation, and by both sexes in species with biparental incubation. These findings suggest that diester preen waxes have a function that is directly related to incubation. Unexpectedly, in female-incubating Curlew Sandpiper Calidris ferruginea and Buff-breasted Sandpiper
Tryngites subruficollis , some males also secreted diester preen waxes during the breeding period. This suggests that some males may in fact incubate, that these waxes may be a remnant from their evolutionary past when both sexes incubated, or that males need to be olfactorally cryptic because they are involved in the making of nest scrapes.
The seasonal pattern of preen wax composition was also studied in captive male, female and female-mimicking male (‘faeder’) Ruff Philomachus pugnax. Captive female Ruff changed preen wax composition from monoesters to diesters in the spring despite the fact that no incubation took place. This suggests that circannual rhythms rather than actual incubation behaviour may trigger the shift to diester waxes. All captive male Ruff, including the faeders, continued to secrete monoesters, supporting the hypothesis that only the incubating sex secretes diesters.
Tryngites subruficollis , some males also secreted diester preen waxes during the breeding period. This suggests that some males may in fact incubate, that these waxes may be a remnant from their evolutionary past when both sexes incubated, or that males need to be olfactorally cryptic because they are involved in the making of nest scrapes.
The seasonal pattern of preen wax composition was also studied in captive male, female and female-mimicking male (‘faeder’) Ruff Philomachus pugnax. Captive female Ruff changed preen wax composition from monoesters to diesters in the spring despite the fact that no incubation took place. This suggests that circannual rhythms rather than actual incubation behaviour may trigger the shift to diester waxes. All captive male Ruff, including the faeders, continued to secrete monoesters, supporting the hypothesis that only the incubating sex secretes diesters.
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Between 1982 and 1987, the construction of a storm-surge barrier and two secondary dams in the eastern and northern parts of the Oosterschelde/Krammer-Volkerak area resulted in the loss of 33% of the 170 km2 of intertidal area in the... more
Between 1982 and 1987, the construction of a storm-surge barrier and two secondary dams in the eastern and northern parts of the Oosterschelde/Krammer-Volkerak area resulted in the loss of 33% of the 170 km2 of intertidal area in the estuary. Consequences for non-breeding waterbirds were evaluated on the basis of monthly high-tide counts during five seasons before and three seasons
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The number of waders in the Oosterschelde, S.W. Netherlands, declined after a reduction in intertidal area due to the construction of a storm surge barrier and secondary dams, suggesting that the carrying capacity had been reached... more
The number of waders in the Oosterschelde, S.W. Netherlands, declined after a reduction in intertidal area due to the construction of a storm surge barrier and secondary dams, suggesting that the carrying capacity had been reached (Schekkerman et al., 1993). In this paper we present data on consumption and predation pressure by birds to explore whether the reduction in their
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Research Interests: Avian migration, Biology, Functional Ecology, Animal Ecology, Ecophysiology, and 12 moreEvolutionary Ecology, Avian Ecology, Biological Sciences, Environmental Sciences, Energy Expenditure, Daily Energy Expenditure, High Arctic, Body Mass, Functional, Breeding birds, Allometric Scaling, and Time Budget
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ABSTRACT The resident Greylag goose population in the Netherlands has strongly increased in number which led to conflict with agricultural interests, public concern on goose hunting and legal debate on the need to regulate geese. Such a... more
ABSTRACT The resident Greylag goose population in the Netherlands has strongly increased in number which led to conflict with agricultural interests, public concern on goose hunting and legal debate on the need to regulate geese. Such a debate can be facilitated by insight in population development and the effectiveness of management options. In this paper we analyse the historic population development and apply density independent and density dependent models to investigate possible future population development and the impact of management on this development. We explored the influence of density dependence by applying the amount of gosling rearing habitat as the first limiting factor. The models were parameterised with life-history data of two well studied populations during their exponential growth phase as a proxy for the total Dutch population for which life-history data are unavailable. The effectiveness of two management options aimed to reduce population growth: culling birds and egg reduction are assessed with these models. The developed models can be used as a management tool to evaluate the consequences of different measures in advance of their implementation. The results show significant positive growth rates which approximate the growth rate of the total Dutch population based on census data. With density dependence in the amount of gosling rearing habitat the population will grow for another one or two decades before it stabilizes. Of the two considered management options culling birds is more effective in reducing bird numbers than egg reduction. This conclusion holds both under density independent and density dependent conditions.
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Agricultural intensification, greatly accelerated as a result of the EU Common Agricultural Policy (CAP), has led to drastic reductions in the populations of many wild plant and animal species that used to be characteristic of farmland.... more
Agricultural intensification, greatly accelerated as a result of the EU Common Agricultural Policy (CAP), has led to drastic reductions in the populations of many wild plant and animal species that used to be characteristic of farmland. In 1992, the EU provided the member states with its Agri-environment Regulation 2078/92 to help member states reverse these developments by means of agri-environment schemes. The question is: will the implementation of these schemes be sufficient to restore the biological diversity on farmland? Most studies that have examined the effectiveness of agri-environment schemes have focussed on farmland birds in Great Britain and The Netherlands. So far, the positive effects appear to be limited. Continuous evaluation and adaptation of these schemes is needed to enable the biodiversity on farmland to recover from the EU's former policy.
Research Interests: Program Evaluation, Reproduction, Agriculture, Environmental Monitoring, Biodiversity, and 13 moreMultidisciplinary, Humans, Biological Diversity, Birds, Animals, Netherlands, Great Britain, Agricultural intensification, Common Agricultural Policy, Agricultural landscape, Environment, Member States, and Public Policy
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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... more
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 (1.4uC 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.