Studies on breeding shorebirds at Medusa Bay, Taimyr, in summer 2001

In the Summer of 2001 a combined Dutch-Russian expedition took place to the Willem Barentz field station at Medusa Bay near Dikson in north-western Taimyr. The expedition was organized by Alterra, the Working Group for International Waterbird and Wetland Research (WIWO) and the Agricultural Department of the Dutch Embassy in Moscow. The results obtained by the Alterra team are presented in this report. Subjects of study generally concerned breeding biology of arctic breeding shorebirds, especially aspects related to timing of breeding and adult body condition. This report's purpose is not to discuss the findings thoroughly but merely to summarize the research questions addressed and present all basic information collected during the 2001 season. Topics included are spring arrival and autumn departure of waders from the tundra, breeding phenology, nest success, biometrics of adult waders, chick growth rate, return rates of adult shorebirds, and seasonal and weather-related variation in arthropod availability. Where useful, results are compared with data collected in a previous expedition in 2000. More elaborate analyses and discussion of the data will be made elsewhere

Modelling population effects of juvenile offshore fish displacement towards adult habitat

Recent studies of fish distribution patterns highlight shifts in the spatial distributions of particular life-stages. Focus has thus far been on changes in habitat use and possible drivers for these changes. Yet, small-scale shifts in habitat use of certain life stages may have profound consequences on population dynamics through changes in resource use and competition. To explore this, a conceptual stage-structured model was developed with 3 stages and 2 resources and allowing a move of large juveniles from the shallow to the deep habitat. Large juveniles compete with small juveniles in shallow waters and with adults in deeper waters. Alternative stable states occur, with one state dominated by small juvenile biomass and the other dominated by adult biomass.The model results show for both states that while large juvenile biomass responds to a change in time spent in the deep habitat, the biomass of small juveniles and adults is barely affected. Between the 2 states there is a profoundly different population response to increased fishing mortality. In the adult biomass dominated state, adult biomass is hardly affected while juvenilebiomass increases until population collapse, with increased fishing. In the small juvenile dominated state, adult and small juvenile biomass decrease, and large juvenile biomass increases. This state persists at much higher fishing mortality than the adult biomass dominated state. This study highlights that safeguarding nursery functions in a changing environment requires monitoring of juvenile life-stages in a range of habitats and a spatially adaptive management strateg

High daily energy expenditure of incubating shorebirds on High Arctic tundra: a circumpolar study

1. Given the allometric scaling of thermoregulatory capacity in birds, and the cold and exposed Arctic environment, it was predicted that Arctic-breeding shorebirds should incur high costs during incubation. Using doubly labelled water (DLW), daily energy expenditure (DEE) during incubation was measured in eight shorebird species weighing between 29 and 142 g at various sites in the Eurasian and Canadian High Arctic. The results are compared with a compilation of similar data for birds at lower latitudes. 2. There was a significant positive correlation between species average DEE and body mass (DEE (kJ day−1) = 28·12 BM (g)^0·524, r^2 = 0·90). The slopes of the allometric regression lines for DEE on body mass of tundra-breeding birds and lower latitude species (a sample mostly of passerines but including several shorebirds) are similar (0·548 vs 0·545). DEE is about 50% higher in birds on the tundra than in temperate breeding areas. 3. Data for radiomarked Red Knots for which the time budgets during DLW measurements were known, indicated that foraging away from the nest on open tundra is almost twice as costly as incubating a four-egg clutch. 4. During the incubation phase in the High Arctic, tundra-breeding shorebirds appear to incur among the highest DEE levels of any time of the year. The rates of energy expenditure measured here are among the highest reported in the literature so far, reaching inferred ceilings of sustainable energy turnover rates.

Connectivity between migrating and landlocked populations of a diadromous fish species investigated using otolith microchemistry

Smelt Osmerus eperlanus has two different life history strategies in the Netherlands. The migrating population inhabits the Wadden Sea and spawns in freshwater areas. After the closure of the Afsluitdijk in 1932, part of the smelt population became landlocked. The fresh water smelt population has been in severe decline since 1990, and has strongly negatively impacted the numbers of piscivorous water birds relying on smelt as their main prey. The lakes that were formed after the dike closure, IJsselmeer and Markermeer have been assigned as Natura 2000 sites, based on their importance for (among others) piscivorous water birds. Because of the declining fresh water smelt population, the question arose whether this population is still supported by the diadromous population. Opportunities for exchange between fresh water and the sea are however limited to discharge sluices. The relationship between the diadromous and landlocked smelt population was analysed by means of otolith microchemistry. Our interpretation of otolith strontium (88Sr) patterns from smelt specimens collected in the fresh water area of Lake IJsselmeer and Markermeer, compared to those collected in the nearby marine environment, is that there is currently no evidence for a substantial contribution from the diadromous population to the spawning stock of the landlocked population

Eggs in the Freezer: Energetic Consequences of Nest Site and Nest Design in Arctic Breeding Shorebirds

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

Vis in de Voordelta: nulmetingen 2007 in het kader van de aanleg van de Tweede Maasvlakte

Dit is de rapportage van de aanvullende, tweede nulmeting van vis in het kader van het monitoring- en evaluatie programma dat moet leiden tot bijstelling van het compensatie programma voor de geplande aanleg van de Tweede Maasvlakte. Het Project Mainportontwikkeling Rotterdam (PMR) heeft onder andere als doel een oplossing te bieden voor het (dreigende) ruimtetekort in de Rotterdamse haven. Onderdeel van dit project is de aanleg van nieuw havengebied in de Voordelta, de Tweede Maasvlakte. De bijbehorende natuurcompensatie is een wettelijke verplichting op grond van de Europese Vogel- en Habitatrichtlijn (RIKZ 2004). Om de circa 1000 hectare landaanwinning volgens Europese richtlijnen voldoende te compenseren, is voorgesteld een zeereservaat in de Voordelta in te stellen. Op basis van de verwachte verbetering van de natuur in het reservaat, wordt momenteel uitgegaan van een reservaat dat tien keer zo groot is (30.000 ha) als het stuk zee dat door de landaanwinning verloren zal gaan. Om na te gaan of de effecten van de landaanwinning (Tweede Maasvlakte, MVII) tijdig en afdoende worden gecompenseerd door de natuurcompensatiemaatregelen moet een monitoring- en evaluatieprogramma worden uitgevoerd. De uitkomsten van dit programma kunnen aanleiding geven tot een eventuele bijstelling van het compensatieprogramma

Herziening spieringadvisering

Het huidige spieringprotocol voor de openstelling van de visserij op spiering in het IJsselmeer en Markermeer-IJmeer dateert uit 1997 en is herzien in 2007. Het ministerie van LNV heeft aan WMR gevraagd om een advies over de herziening van het huidige afwegingskader (protocol). In 2013 is ook geprobeerd het protocol aan te passen, waarbij is geadviseerd om dit te doen door middel van een ecosysteemmodel (Osmose). Het model bleek niet uitvoerbaar omdat niet alle hiervoor benodigde gegevens en kennis aanwezig was. Om die reden is er nu een meer pragmatische en eenvoudiger aanpak toegepast

Toestand vis en visserij in de Zoete Rijkswateren: 2012 Deel I: Trends van de visbestanden, vangsten en ecologische kwaliteit ratio's

De visstand bemonsteringen die in opdracht van RWS Waterdienst plaatsvinden maken deel uit van een uitgebreider programma: de Monitoring van de Waterstaatkundige Toestand des Lands (MWTL). In de loop der tijd is uit pragmatische overwegingen de uitvoering en financiering van de visstand bemonsteringen verdeeld over RWS en Min EZ, waarbij grofweg RWS de vismonitoring in de rivieren en delta uitvoert en Min EZ de vismonitoring in het IJsselmeer en Markermee

POTENTIAL EFFECTS OF CLIMATE CHANGE ON ELEVATIONAL DISTRIBUTIONS OF TROPICAL BIRDS IN SOUTHEAST ASIA

Environmental conditions during the neonatal period can affect the growth, physiology, behavior, and immune function of birds. In many avian studies the nestling environment includes investigator handling of young, which may be stressful. While neonatal handling is known to affect the adult phenotype in rats, the effects of handling on development have rarely been examined in wild birds. We examined the effect of short, repeated periods of neonatal handling on avian growth and immune system development. We subjected American Kestrels (Falco sparverius) and European Starlings (Sturnus vulgaris) to 15 min of daily investigator handling throughout the nestling period, while controls remained undisturbed. Immediately prior to fledging we assessed cutaneous immunity, humoral immunity, mass, and degree of fluctuating asymmetry. Daily handling did not significantly affect any of these measurements. We also addressed the possibility that treatment differences would appear only when birds were challenged with a more substantial stressor by bringing birds into captivity for 24 hr. Captivity did not affect mass, but significantly lowered the cutaneous immune response, although this was independent of treatment. Therefore, brief periods of investigator handling did not appear to affect immune or morphological development in these species, whereas 24 hr of captivity resulted in suppressed cutaneous immune responses