Eelke Jongejans

Eelke Jongejans
Radboud University | RU · Animal Ecology and Physiology

PhD

About

179
Publications
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Publications

Publications (179)
Article
Full-text available
Insects are the most diverse group of animals on Earth, but their small size and high diversity have always made them challenging to study. Recent technological advances have the potential to revolutionise insect ecology and monitoring. We describe the state of the art of four technologies (computer vision, acoustic monitoring, radar, and molecular...
Article
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Europe’s highest densities of breeding Mallards (Anas platyrhynchos) are found in the Netherlands, but the breeding population there has declined by ~30% since the 1990s. The exact cause of this decline has remained unclear. Here, we used an integrated population model to jointly analyze Mallard population survey, nest survey, duckling survival and...
Article
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To study insect decline, an important threat to biodiversity, long‐term datasets are needed. Here we present a study of hoverfly (Diptera: Syrphidae) abundance and diversity in a Dutch forest, surrounded by other forests, and analyse the variation in insect numbers over four decades. Between 1982 and 2021, abundance decreased by 80%. Until 1990, ab...
Article
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Aim In many species, density‐dependent effects on reproduction are an important driver of population dynamics. However, it is rarely considered that the direction of density dependence is expected to vary over space and time depending on anti‐predator behaviour and predator community. Aggregation may allow for effective group mobbing against avian...
Article
The current focus on intensification and maximizing productivity in agriculture can endanger soil biota and the ecosystem services they provide in such a way that it acts counterproductive and increases the dependence on external inputs. In this study, we aimed to identify the factors that are most limiting for the restoration of soil biota and the...
Article
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Worldwide over 910 terrestrial planarian species have been described. They mainly occur in tropical and subtropical regions. In Europe, 22 alien terrestrial planarian species have been recorded over the last decades. In The Netherlands, 9 alien species have been found so far, mostly in greenhouses. Three of these species have established population...
Article
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Understanding which factors cause populations to decline begins with identifying which parts of the life cycle, and which vital rates, have changed over time. However, in a world where humans are altering the environment both rapidly and in different ways, the demographic causes of decline may also vary over time. Identifying temporal variation in...
Article
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To understand the consequences of anthropogenic and environmental changes for wildlife populations, it is important to study how individuals differ in their sensitivity to environmental change, and whether this depends on individual characteristics. An individual’s reproductive performance may provide an integrative, unidimensional proxy of an indi...
Article
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Disturbance may impact individual birds and ultimately bird populations. If animals avoid disturbed sites this may prevent them from being disturbed directly but may also negatively impact their movement patterns and energy budgets. Avoidance is, however, challenging to study, as it requires following individuals over large spatial scales in order...
Article
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Global warming challenges the persistence of local populations, not only through heat‐induced stress, but also through indirect biotic changes. We study the interactive effects of temperature, competition and parasitism in the water flea Daphnia magna. We carried out a common garden experiment monitoring the dynamics of Daphnia populations along a...
Article
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European Turtle Doves Streptopelia turtur have experienced a sharp decline in population numbers over past decades. Much uncertainty exists about the main cause or causes. Several pressures have been suggested, but because they affect different stages of the life cycle of the Turtle Dove, it is difficult to compare their contributions to population...
Preprint
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Due to heterogeneity in presentation and outcome, patients with metastatic disease cannot be considered a single group. The timing, location and combinations of recurrences determine the feasibility of treatment of the individual patient in an era in which the options for local and systemic treatment have expanded. Studies investigating this comple...
Chapter
Various types of demographic data can be collected in the field: population censuses, capture–mark–recapture data, and so on. These data sources share common demographic information about the studied population. Bayesian integrated population models (IPM) make efficient use of these different types of demographic data by jointly analysing them. Thi...
Article
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1. Body condition is an important concept in behaviour, evolution and conservation, commonly used as a proxy of an individual’s performance, for example in the assessment of environmental impacts. Although body condition potentially encompasses a wide range of health state dimensions (nutritional, immune or hormonal status), in practice most studie...
Article
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Shorebird populations, especially those feeding on shellfish, have strongly declined in recent decades and identifying the drivers of these declines is important for conservation. Changing food stocks are thought to be a key driver of these declines and may also explain why trends have not been uniform across Europe's largest estuary. We therefore...
Article
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Individual variation in disturbance vulnerability (i.e. the likelihood that disturbance negatively affects an individual's fitness) can affect how disturbance impacts animal populations, as even at low disturbance levels some individuals could be severely affected and die. Individual variation in vulnerability can arise due to different responses t...
Article
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Significance Various sources have reported insect decline in total biomass, numbers, and species diversity. With German data on a species-rich hoverfly community over 25 y and a theoretical model, we show how these decline rates are interrelated. The relationship between biomass and diversity losses depends on whether common or rarer species are mo...
Article
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Whether females participate in reproduction every year or rather skip years is pivotal information for understanding the dynamics of animal populations. In ectotherms this reproduction frequency might depend on factors like temperature, individual size, and prey availability. Here we studied the reproduction rate of the smooth snake Coronella austr...
Article
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The current distribution of the Northern Wheatear in the Netherlands is largely confined to coastal dune grasslands.This habitat is threatened by loss of natural dynamics, excessive atmospheric nitrogen deposition and declining Rabbit Oryctolagus cuniculus populations. We studied the effects of these pressures on the population numbers, breeding su...
Article
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The ability of a species to adapt to environmental change is ultimately reflected in its vital rates - i.e., survival and reproductive success of individuals. Together, vital rates determine trends in numbers, commonly monitored using counts of species abundance. Rapid changes in abundance can give rise to concern, leading to calls for research int...
Article
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European populations of Common hamster (Cricetus cricetus) have dramatically declined in the last decades, and in many EU countries, the species is on the brink of extinction. In the Netherlands, a research and reintroduction program was started in three areas with hamster-friendly management to reverse the decline of the species. Since 2002, more...
Article
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Many species show large variation in lifetime reproductive success (LRS), with a few individuals producing the majority of offspring. This variation can be explained by factors related to individuals (fixed heterogeneity) and stochastic differences in survival and reproduction (dynamic heterogeneity). In this study, we study the relative effects of...
Article
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Assessing impacts of disturbance over large areas and long time periods is crucial for nature management, but also challenging since impacts depend on both wildlife responses to disturbance and on the spatiotemporal distribution of disturbance sources. Combined tracking of animals and disturbance sources enables quantification of wildlife responses...
Article
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• The consequences of bird mortality caused by collisions with wind turbines are increasingly receiving attention. So‐called acceptable mortality limits of populations, that is, those that assume that 1%–5% of additional mortality and the potential biological removal (PBR), provide seemingly clear‐cut methods for establishing the reduction in popul...
Article
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Feeding specialization is a common cause of individual variation. Fitness payoffs of specialization vary with environmental conditions, but the underlying behavioral mechanisms are poorly understood. Such mechanistic knowledge, however, is crucial to reliably predict responses of heterogeneous populations to environmental change. We quantified spat...
Article
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Many empirical studies motivated by an interest in stable coexistence have quantified negative density dependence, negative frequency dependence, or negative plant–soil feedback, but the links between these empirical results and ecological theory are not straightforward. Here, we relate these analyses to theoretical conditions for stabilisation and...
Article
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Plant species of semi-natural grasslands are threatened by several simultaneous global change drivers, most notably land-use and climate change. In this study, we explore spatiotemporal variation and changes in deterministic (λ) and stochastic population growth rates (λs), and the underlying vital rates of eight populations of Arnica montana at the...
Article
In recent decades, entomologists have documented alarming declines in occurrence, taxonomic richness, and geographic range of insects around the world. Additionally, some recent studies have reported that insect abundance and biomass, often of common species, are rapidly declining, which has led some to dub the phenomenon an “Insect Apocalypse”. Re...
Article
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1. Restoration of degraded ecosystems may take decades or even centuries. Accordingly, information about the current direction and speed of recovery provided by methods for predicting time to recovery may give important feedback to restoration schemes. While predictions of time to recovery have so far been based mostly upon change in species richne...
Article
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We tested the long-term effects of liming on soil micro-arthropods in a stand of Scotch pine on former drift sand in the Netherlands. To counteract the effects of acidification, liming was applied in increasing quantities from 0 (control), 3, 6, 9 and 18 ton ha⁻¹ on experimental plots over the course of 1985 and 1986. Soil samples for chemical anal...
Article
Demographic rates differ between populations and also fluctuate over time, sometimes driving large fitness differences, but the strength of stochastic effects remain heretofore unresolved. We demonstrate the importance of stochastic processes by comparing the drivers of long-term population growth. We quantify stochastic contributions to difference...
Article
Genetically identical individuals can be phenotypically variable, even in constant environmental conditions. The ubiquity of this phenomenon, known as 'intra-genotypic variability', is increasingly evident and the relevant mechanistic underpinnings are beginning to be understood. In parallel, theory has delineated a number of formal expectations fo...
Article
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Recently, reports of insect declines prompted concerns with respect to the state of insects at a global level. Here, we present the results of longer‐term insect monitoring from two locations in the Netherlands: nature development area De Kaaistoep and nature reserves near Wijster. Based on data from insects attracted to light in De Kaaistoep, macr...
Article
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Recent studies have shown a worrying decline in the quantity and diversity of insects at a number of locations in Europe (Hallmann et al. 2017) and elsewhere (Lister and Garcia 2018). Although the downward trend that these studies show is clear, they are limited to certain insect groups and geographical locations. Most available studies (see overvi...
Article
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Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a sp...
Article
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Background Ring wear and loss may have important consequences for mark-recapture studies that aim to estimate survival trends. Our study quantifies the rates of wear and loss from a long-running colour-ringing project of the Eurasian Oystercatcher (Haematopus ostralegus) in the Netherlands. Methods Our analysis included 8909 colour-ringed oysterca...
Article
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As the single opportunity for plants to move, seed dispersal has an important impact on plant fitness, species distributions, and patterns of biodiversity. However, models that predict dynamics such as risk of extinction, range shifts, and biodiversity loss tend to rely on the mean value of parameters and rarely incorporate realistic dispersal mech...
Article
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As the single opportunity for plants to move, seed dispersal has an important impact on plant fitness, species distributions and patterns of biodiversity. However, models that predict dynamics such as risk of extinction, range shifts and biodiversity loss tend to rely on the mean value of parameters and rarely incorporate realistic dispersal mechan...
Article
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Migratory connectivity describes linkages between breeding and non-breeding areas. An ongoing challenge is tracking avian species between breeding and non-breeding areas and hence estimating migratory connectivity and seasonal survival. Collaborative color-ringing projects between researchers and citizen scientists provide opportunities for trackin...
Article
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1Changes in population dynamics due to interacting evolutionary and ecological processes are the direct result of responses in vital rates, i.e. stage‐specific growth, survival and fecundity. Quantifying through which vital rates population fitness is affected, instead of focusing on population trends only, can give a more mechanistic understanding...
Article
Het gangbare gebruik van pesticiden wordt gezien als een belangrijke oorzaak voor de afnames van akkervogels in Europa. Met een publicatie in het wetenschappelijk vakblad Nature droegen de auteurs er toe bij dat neonicotinoiden in het verdachtenbankje terecht kwamen. In dit artikel plaatsen zij deze invloedrijke studie in een breder perspectief doo...
Article
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European badger populations in the Netherlands suffered strong declines in the 1900s, becoming endangered in the 1980s. Despite mitigation actions, recovery of the population has been slow. Here, we use ecological niche modelling, relating 1515 badger sett (burrow) localities to data on topographic, groundwater table, soil type and land-cover varia...
Conference Paper
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Identifying the main drivers of population decline is challenging in migratory species, as they can be affected at different stages of the annual cycle that are geographically separated. Furthermore, the impact of environmental drivers at overwintering sites may not be directly apparent due to carry- over effects (COEs) to the reproductive season (...
Article
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1.Species composition is a vital attribute of any ecosystem. Accordingly, ecological restoration often has the original, or ‘natural’, species composition as its target. However, we still lack adequate methods for predicting the expected time to compositional recovery in restoration studies. 2.We describe and explore a new, ordination regression‐ba...
Article
1.Raising global temperatures are predicted to have strong consequences for ectotherms, as metabolic rates depend directly on external temperatures. To understand consequences for population fitness, a full life‐cycle approach is important because i) temperature can have opposite effects on different vital rates (growth, survival, reproduction), an...
Article
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Roadsides are an important habitat for invasive common ragweed, Ambrosiaartemisiifolia L., by facilitating seed dispersal. Reducing the size of roadside populations is therefore essential for confining this highly allergenic species. Here, we aim to determine the cost-effectiveness of mowing regimes varying in frequency and timing, by analysing pop...
Article
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To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergen...
Article
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Recently, reports of insect declines prompted concerns with respect to the state of insects at a global level. Here we present the results of long-term insect monitoring from two locations, De Kaaistoep, and nature reserves in Drenthe, both in the Netherlands. We report the trends in beetles (Coleoptera), macro-moths (macro-Lepidoptera), caddis ies...
Article
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1.Lianas are structural parasites of trees that reduce the growth, survival and reproduction of their hosts. Given that co‐occurring tree species differ strongly in the proportion of individuals that are infested by lianas (liana prevalence), lianas could differentially impact tree species and thereby influence tree community composition. Surprisin...
Article
To prioritize conservation efforts, it is important to know which plant species are most vulnerable to extinction. Intrinsic extinction vulnerabilities depend on demographic parameters, but for many species these demographic parameters are lacking. Body size has been successfully used as proxy of such parameters to estimate extinction vulnerability...
Article
Phosphorus content of mineral-poor sandy soils is steadily decreasing due to leaching caused by continuous and cumulative acidification and N deposition. Sod-cutting as a traditional restoration measure for heathland vegetation appears to increase P limitation, as most of the P present is in the organic matter being removed by sod-cutting. Mineral...
Article
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Ectotherms tend to grow faster, but reach a smaller size when reared under warmer conditions. This temperature-size rule (TSR) is a widespread phenomenon. Despite the generality of this pattern, no general explanation has been found. We therefore tested the relative importance of two proposed mechanisms for the TSR: (1) a stronger increase in devel...