Richard Ubels - Academia.edu (original) (raw)

Papers by Richard Ubels

Limosa, 2012

ABSTRACT The Dollard, at the border of the Netherlands and Germany, is part of the Ems-Dollard es... more ABSTRACT The Dollard, at the border of the Netherlands and Germany, is part of the Ems-Dollard estuary in the Wadden Sea (Fig. 1). The estuary is a brackish water tidal area, a habitat which is under severe pressure in NW-Europe. The Dollard is affected by a variety of human disturbances, of which eutrophication is most striking. During the first years of this study, heavy pollution by organic waste discharges from potato starch industry was reduced to virtually zero by the industry heavily investing in procedures to reduce nutrient loads. This paper aimed to map the changes of 16 of the most abundant bird species that are dependent on benthic prey (mainly waders) or seeds (ducks; Fig. 2). This was done during the 20-years lasting process of decreasing eutrophication (1976/77–1995/96) and the subsequent 15-year period without waste discharge (1996/97–2010/11). During the first period, numbers of most of the species dropped (Tab. 1), and the estimated food consumption declined by 3.7% annually (Fig. 4). During the subsequent period of zero-discharge, numbers of most species increased – which was unexpected –, and the calculated consumption by benthivorous waders was estimated to grow by 2.7% each year. The rates of increase in both periods were negatively correlated, i.e. the strongest increase in the second period was for species exhibiting strongest decline in the first (Fig. 3). In contrast, dabbling ducks showed a persistent decline in numbers. Literature data showed clear trends in the biomass of the main food species, the ragworm Nereis spp. Changes in numbers of benthivorous birds (excluding bivalve feeders) corresponded well with these trends. This suggests that food availability was a driving force behind the fluctuations in bird populations. Changes in nutrient input into the estuary may well have been the major cause for both the drop and the subsequent increase in productivity of the benthic prey. During the second period, concentrations of anorganic nutrients (nitrogen and phosphorous compounds) increased, as evidenced by literature data. This time, nutrients were thought to originate from a rapidly expanding agricultural industry (pigs and dairy cattle) in the wide surroundings of the Dollard. In all, fluctuations by benthivorous bird populations in the Dollard estuary were largely ruled by local variations in food supply. Although the nature of eutrophication differed between the two study periods, possibly affecting the ecosystem in dissimilar ways, effects on bird populations seemed similar. Eutrophication seemed to boost total bird numbers, though effects on individual species were highly variable.

Het Vogeljaar, Sep 1, 1991

bioRxiv (Cold Spring Harbor Laboratory), Nov 27, 2020

(word limit 350: 349) 1. Ecological research is often hampered by the inability to quantify anima... more (word limit 350: 349) 1. Ecological research is often hampered by the inability to quantify animal diets. Large-scale changes in arthropod diversity, abundance and phenologies urge the need to understand the consequences for trophic interactions. Diet composition of insectivorous predators can be tracked through DNA metabarcoding of faecal samples, but to validate the quantitative accuracy of metabarcoding, validation using free-living animals for which their diet can be approximated, is needed. 2. This validation study assesses the use of DNA metabarcoding in quantifying diets of an insectivorous songbird. Using camera footage, we documented food items delivered to nestling Pied Flycatchers Ficedula hypoleuca, and subsequently sequenced the Cytochrome Oxidase subunit I (COI) in their faeces. Our special interest was to retrieve the relative contribution of arthropod taxa with a PCR-based protocol. 3. Assessment of taxonomic coverage of the invertebrate COI primers LCO1490 and HCO1777, previously applied in insectivorous songbirds, demonstrated that COI barcodes were

Journal of Avian Biology, May 1, 2019

Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Proceedings of The Royal Society B: Biological Sciences, May 4, 2022

Evidence accumulates that dispersal is correlated with individual behavioural phenotype (dispersa... more Evidence accumulates that dispersal is correlated with individual behavioural phenotype (dispersal syndrome). The evolutionary causes and consequences of such covariation depend on the degree of plasticity versus inheritance of the traits, which requires challenging experiments to implement in mobile organisms. Here, we combine a forced dispersal experiment, natural colonization and longitudinal data to establish if dispersal and aggression levels are integrated and to test their adaptive nature in pied flycatchers (Ficedula hypoleuca). We found that (forced) dispersers behaved more aggressively in their first breeding year after dispersal and decreased their aggression in following years. Strength of dispersal syndrome and direction of fecundity selection on aggression in newly colonized areas varied between years. We propose that the net benefits of aggression for dispersers increase under harsh conditions (e.g. low food abundance). This hypothesis now warrants further testing. Overall, this study provides unprecedented experimental evidence that dispersal syndromes can be remodelled via adaptive plasticity depending on the individuals' local breeding experience and/or year-specific ecological conditions. It highlights the importance of individual behavioural variation in population dynamics.

Bonte vliegenvangers overwinteren in Afrika en broeden in Europa, ook in Nederland. Christiaan Bo... more Bonte vliegenvangers overwinteren in Afrika en broeden in Europa, ook in Nederland. Christiaan Both en Richard Ubels van de Rijksuniversiteit Groningen doen in het Dwingelderveld onderzoek naar hoe deze trekvogels zich aanpassen aan klimaatsverandering. Of daar juist problemen mee hebben. Een gastblog.

Ecology and Evolution, May 1, 2022

The American Naturalist, Apr 1, 2023

Climate change alters ecological interactions, and, because observed phenotypic responses are oft... more Climate change alters ecological interactions, and, because observed phenotypic responses are often insufficient1,2, evolutionary responses are required3. However, these have rarely been reported, and species seem to either adapt through plasticity4 or suffer population declines5. Earlier work suggested that especially long-distance migrants cannot adjust their complex annual cycle by phenotypic plasticity, because they lack predictable cues at their distant wintering grounds6,7. Here we show that the ongoing advance in spring arrival and laying dates in a pied flycatcher population results from cross-generational processes. Using a 51-year time-series we show that during the 25-year period with a strong increase in spring temperature, the population advance in laying dates could only be partly explained by phenotypic plasticity, and primarily resulted from an evolutionary change. Spring arrival from the African wintering grounds advanced simultaneously, and this was unrelated to co...

In seasonal environments variation in food abundance in the non-breeding season is thought to aff... more In seasonal environments variation in food abundance in the non-breeding season is thought to affect songbird population dynamics. In a unique tit-sea buckthorn berry system we can estimate the berry abundance and both the tit consumption and population dynamics. Six hundred nest boxes were available to great and blue tits (Cyanistes caeruleus) for breeding in spring and roosting in winter. We followed the dynamics including the recapture histories of individually marked great tits from 2008-2013. In each year we estimated 1) the winter sea buckthorn berry availability, 2) an index of berry consumption in December based on the colour of the faeces of roosting birds, 3) the number of breeding great and blue tits, 4) both recapture probability and the return rate of the great tits and 5) immigration rates. December berry abundance positively predicted the number of breeding pairs of both species in the subsequent season and great tit return rates in the second half of the winter. There was support for a sex specific berry effect on the adult return rate in the great tit: female return rate was associated less strongly to berry abundance than male return rate. This skewed the sex ratio of the local breeders in the following breeding season. Intriguingly, annual berry consumption in December was not related to berry abundance, and individuals consuming more berries tended to have slightly lower return rates. Reproductive rate was not related to berry abundance. There was hardly support for a relation between immigration rates of first year breeders and berry abundance. Taken together these results imply that berry stock not only affected population size but also the population composition through sex specific exchange with the surroundings. Since population density covaried with berry abundance, density dependent effects provide an alternative explanation for the patterns observed