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Earthworms are an important prey for the endangered meadow birds of northwest Europe. Although intensive grassland management with high manure inputs generally promotes earthworm abundance, it may reduce the effective food availability for meadow birds through desiccation of the topsoil, which causes earthworms to remain deeper in the soil. We studied the response of Red Worm Lumbricus rubellus, a detritivore, and Grey Worm Aporrectodea caliginosa, a geophage, to soil moisture profiles in the field and under experimental conditions. Surfacing earthworms were counted weekly in eight intensively managed grasslands (treated with high inputs of slurry by slit injection) with variable groundwater tables in the Netherlands. At each count, soil penetration resistance, soil moisture tension and groundwater level were measured, while air temperature and humidity were obtained from a nearby weather station. The response to variation in the vertical distribution of soil moisture was also experimentally studied in the two earthworm species. In the field, earthworms’ surfacing activity at night was negatively associated with soil moisture tension and positively by relative air humidity. Surprisingly, there was no effect of groundwater level; an important management variable in meadow bird conservation. Under experimental conditions, both L. rubellus and A. caliginosa moved to deeper soil layers (>20 cm) in drier soil moisture treatments, avoiding the upper layer when moisture levels dropped below 30%. Synthesis and applications. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above −15 kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface. Foreign Language Samenvatting Regenwormen zijn een belangrijke prooi voor weidevogels in Noordwest‐Europa. Hoewel intensief landgebruik met een hoge mestgift over het algemeen resulteert in hoge dichtheden aan regenwormen, zou het wellicht de beschikbaarheid voor weidevogels kunnen verlagen doordat de toplaag van de bodem sneller uitdroogt waardoor regenwormen dieper in de grond blijven. We onderzochten de response van de Rode Worm Lumbricus rubellus, een detritus‐eter, en van de Grijze Worm Aporrectodea caliginosa, een bodem‐eter, op verschillende bodemvochtcondities in het veld in graslanden die gebruikt worden in de melkveehouderij en in het lab onder gecontroleerde omstandigheden. In Zuidwest‐Friesland werden in het voorjaar van 2015 op acht graslanden met hetzelfde intensieve beheer (bemesting d.m.v. drijfmestinjectie) en bodemtype, maar met verschillende grondwaterpeilen, wekelijks oppervlakte‐actieve regenwormen geteld. Bij elke telling werd ook bodemdoordringbaarheid, bodemvochtspanning en grondwaterpeil gemeten. Meteorologische data werd verzameld bij een weerstation in de buurt. In het lab werd gekeken naar de verticale distributie van de twee soorten regenwormen bij verschillende bodemvocht omstandigheden. De oppervlakte‐activiteit van regenwormen wordt bepaald door hoge luchtvochtigheid en lage bodemvochtspanning. Verrassend genoeg vonden we geen effect van grondwaterpeil op regenwormen activiteit. Beide soorten regenwormen gaan dieper de bodem in wanneer het bodemvochtgehalte in te toplaag onder de 30% zakt. Synthese en toepassingen. In intensief beheerd grasland dat bemest wordt door middel van drijfmestinjectie, neemt de beschikbaarheid van regenwormen voor weidevogels af door uitdroging van de toplaag van de bodem. Dit kan worden voorkomen door de toplaag vochtig te houden met een vochtspanning hoger dan ‐15kPa. Omdat we geen effect van grondwaterpeil vonden, denken we dat in deze graslanden het te laat omhoog brengen van het grondwaterpeil in het voorjaar en het gebruik van mestinjectie het uitdrogen van de bodemtoplaag heeft versterkt. Weidevogelbeheer zou dus gebaat zijn bij een andere vorm bemesting dat regenwormen activiteit aan of vlakbij het bodemoppervlak promoot. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above −15 kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface.

As a result of increasingly intensified agricultural practices in Europe over the last century, agroecosystems have experienced severe biodiversity declines. Among the species experiencing negative population trajectories in agricultural habitats are meadow and farmland birds, which have suffered a loss in both habitat and food availability in cultivated fields. In Denmark, biotope plans (a requirement to establish small agro-environmental habitats on properties with stocking of game birds) have been implemented as a measure to mitigate biodiversity declines in the agricultural landscape and, in this paper, we investigate to what extent these initiatives fulfil the intended purpose with respect to birds in the breeding season. We demonstrate that some initiatives like hedgerows, areas of open vegetation, scrub, and lakes seemed to increase avian diversity locally, but also that other measures such as vegetation strips, grass strips, and bare soil strips had little effect given the current implementation of these initiatives. Benefitting species were mostly scrub- and woodland species that now inhabited previously open landscapes after the establishment of suitable habitats, and the initiatives failed to show clear positive effects on meadow birds and farmland birds for which they were originally intended. The most commonly registered species in our data set was (released) Pheasant Phasianus colchicus, which emphasised that the stocking of game birds can have a clear effect on avian species composition in areas where this practice is exercised. Future studies are needed to clarify how this stocking may affect local biodiversity of different taxonomic groups.

1. Intensification of agricultural use of grassland habitats has been linked to the declines of many farmland bird species, several of whom have been in decline for multiple decades despite agri-environmental schemes. In the Netherlands, where most grasslands have been transformed into well-drained monocultures managed for maximal dairy production, schemes that aim to protect nests from agricultural activities are the most popular. The cause of the failure of these schemes, however, seems poor recruitment of farmland birds. 2. Using the black-tailed godwit Limosa limosa limosa as our model species, we tested the hypothesis underlying the most popular agri-environmental schemes that there are no differences in condition at hatch, growth, and apparent survival rates between chicks raised on monocultures compared with chicks from herb-rich meadows with high water tables, often managed, for the sake of grassland birds, in traditional ways. We also compare the growth rates from both habitat types with those of chicks from dairy farmland from 1976 to 1985, a time when population declines of godwits first became visible. 3. Hatchling mass did not differ between chicks from herb-rich meadows and grassland monocultures, but chicks hatched on monocultures were on average 14—16% lighter at fledging, and had 4% smaller bills than chicks hatched on herb-rich meadows. The growth rates of female chicks hatched on herb-rich meadows were similar to those of chicks measured from 1976 to 1985. Males fledged lighter and smaller than females. 4. Apparent survival during the first year of life for chicks hatched on herb-rich meadows was 2·5 times higher than that of chicks hatched on grassland monocultures. The apparent survival on herb-rich meadows seems sufficient for a stable population. 5. Synthesis and applications: We found striking differences between chicks hatched on modern grassland monocultures and herb-rich meadows. That chicks hatched on monocultures had lower growth and survival rates than chicks on meadows indicates that these chicks suffer a higher risk of starvation and/or predation. These findings imply that the most often applied agri-environmental schemes (i.e. payments per clutch found and postponed mowing), are not effective. Instead, these schemes could even encourage maladaptive habitat choice. Conservation efforts should thus focus on the provision of herb-rich meadows with high groundwater tables.

Farmland birds are among the most threatened bird species in Europe, largely as a result of agricultural intensification which has driven widespread biodiversity losses. Breeding waders associated with grassland and arable habitats are particularly vulnerable and a frequent focus of agri‐environment schemes (AES) designed to halt and reverse population declines. We review existing literature, providing a quantitative assessment of the effectiveness of policy and management interventions used throughout Europe to improve population and demographic metrics of grassland‐breeding waders. Targeted AES and site protection measures were more likely to be effective than less targeted AES and were ten times more likely to be effective than would be expected by chance, particularly for population trend and productivity metrics. Positive effects of AES and site protection did not appear synergistic. Management interventions which had the greatest chance of increasing population growth or productivity included modification of mowing regimes, increasing wet conditions, and the use of nest protection. Success rates varied according to the species and metric being evaluated. None of the policy or management interventions we evaluated were associated with a significant risk of negative impacts on breeding waders. Our findings support the use of agri‐environment schemes, site protection, and management measures for grassland‐breeding wader conservation in Europe. Due to publication bias, our findings are most applicable to intensively managed agricultural landscapes. More studies are needed to identify measures that increase chick survival. Despite broadly effective conservation measures already in use, grassland‐breeding waders in Europe continue to decline. More research is needed to improve the likelihood and magnitude of positive outcomes, coupled with wider implementation of effective measures to substantially increase favorable land management for these species. Our findings support the use of agri‐environment schemes, site protection, and conservation management measures such as grassland, wet feature, and predation management for grassland‐breeding wader conservation in Europe. Despite broadly effective conservation measures already in use, grassland‐breeding waders in Europe continue to decline. To reverse declines, wider implementation of effective measures is needed to substantially increase the amount of land managed favorably for these species.

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 nest predators while aggregation may also attract mammalian predators, causing negative density dependence. We aim to quantify spatial variation in the effect of conspecific breeding density on nest survival in a mobbing bird species (Eurasian oystercatcher; Haematopus ostralegus) and identify whether this variation in density dependence can be explained by the predator community. Location Country‐wide (The Netherlands). Methods We integrated reproductive data with breeding territory maps of Eurasian oystercatchers and occupancy maps of avian and mammalian predator species across the Netherlands for a 10‐year period. Results Spatial variation in the composition of the predator community explained the effects of neighbour density, showing decreasing nest survival when both conspecific density and mammalian dominance increased. Also, heterospecific density (from breeding godwits and lapwing) has an additional effect on the oystercatcher nest survival. Strikingly, this pattern did not extend to mammal‐free island populations. Main conclusions Our study provides evidence that both the strength and sign of density dependence can vary spatially within species, implying that it is dangerous to generalize results from a single local population to large‐scale management implications and modelling exercises. The study also suggests that conservation actions that aim to attract breeding birds should be prioritized in areas with fewer mammalian predators, but this idea requires further testing on island populations.

Throughout the world, intensive dairy farming has resulted in grasslands almost devoid of arthropods and birds. Meadow birds appear to be especially vulnerable during the chick-rearing period. So far, studies have focused mainly on describing population declines, but solutions to effectively stop these trends on the short-term are lacking. In this study at a single farm, we experimentally manipulated soil moisture through occasional irrigation, to mitigate against early season drainage and create favorable conditions for the emergence of above-ground arthropods during the meadow bird chick rearing phase. To guarantee the presence of at least a sizeable arthropod community for the measurement of effects of wetting, we selected a farm with low intensity management. The land use and intensity of the study site and surroundings were categorized according to the national land use database and quantified using remote sensing imagery. From May 1 to June 18, 2017, we compared a control situation, with no water added, to two wetting treatments, a \"short-term\" (3 weeks) treatment based on wetting on warm days with a sprinkler system and a \"long-term\" treatment next to a water pond with a consistently raised water table from 2010. We measured soil temperature, soil moisture and resistance as well as the biomass of arthropods at 3-day intervals. Flying arthropods were sampled by sticky traps and crawling arthropods by pitfall traps. Individual arthropods were identified to Order and their length recorded, to assess their relevance to meadow bird chicks. The land use analysis confirmed that the selected dairy farm had very low intensity management. This was different from most of the surrounding area (20 km radius), characterized by (very) high intensity land use. The experiments showed that irrigation contributed to cooler soils during midday, and that his happened already in the early part of the season; the differences with the control increased with time. In the short- and long-term treatments, soil moisture increased and soil resistance decreased from the mid-measurement period onward. Compared with the control, cumulative arthropod biomass was higher in the long-term treatment, but showed no change in the irrigation treatment. We conclude that small-scale interventions, such as occasional irrigation, favorably affected local soil properties. However, the effects on above-ground arthropod abundance currently appear limited or overridden by negative landscape-scale processes on arthropods.

Agricultural intensification has modified grassland habitats, causing serious declines in farmland biodiversity including breeding birds. Until now, it has been difficult to objectively evaluate the link between agricultural land‐use intensity and range requirements of wild populations at the landscape scale. In this study of Black‐tailed Godwits Limosa limosa, we examined habitat selection and home range size during the breeding phase in relation to land‐use intensity, at the scale of the entire Netherlands. From 2013 to 2019, 57 breeding godwits were tracked with solar‐Platform Transmitter Terminals (26–216 locations [mean: 80] per bird per breeding phase) and used to estimate their core (50%) and home ranges (90%). Of these, 37 individuals were instrumented in Iberia and therefore unbiased toward eventual breeding locations. The tracks were used to analyse habitat selection by comparing the mean, median and standard deviation of land‐use intensity of core and home ranges with matching iterated random samples of increasing radii, that is, 500 m (local), 5 km (neighbourhood), 50 km (region) and the whole of The Netherlands. Land‐use intensities of the core and home ranges selected by godwits were similar to those at the local and neighbourhood scales but were significantly lower and less variable than those of the region and the entire country. Thus, at the landscape scale, godwits were selected for low‐intensity agricultural land. The core range size of godwits increased with increasing land‐use intensity, indicating high agricultural land‐use intensity necessitating godwits to use larger areas. This is consistent with the idea that habitat quality declines with increasing land‐use intensity. This study is novel as it examines nationwide habitat selection and space use of a farmland bird subspecies tracked independently of breeding locations. Dutch breeding godwits selected areas with lower land‐use intensity than what was generally available. The majority of the Dutch agricultural grassland (94%) is managed at high land‐use intensity, which heavily restricts the viability of breeding possibilities for ground‐nesting birds. The remote sensing methodology described here illustrates the potential to study entire wild populations from the local field level to their whole spatial range. Overzicht Door de intensivering van de landbouw zijn grasland‐habitats veranderd, waardoor de biodiversiteit van landbouwgrond, inclusief broedvogels, ernstig is afgenomen. Tot nu toe was het moeilijk om het verband tussen de intensiteit van het landgebruik in de landbouw en de eisen die wilde populaties aan hun leefgebied stellen objectief te beoordelen op landschapsschaal. In dit onderzoek naar Grutto's (Limosa limosa limosa) hebben we de habitatkeuze en de grootte van het leefgebied tijdens de broedfase onderzocht in relatie tot de intensiteit van het landgebruik, op de schaal van heel Nederland. Van 2013 tot 2019 werden 57 broedende grutto's gevolgd met satellietzenders. Dit leverde 26 ‐ 216 bezochte plekken (gemiddeld: 80) per vogel per broedseizoen op. Hiermee konden we de omvang van het kern‐ (50%) en het overige leefgebied (90% van alle bezochte plekken) schatten. 37 individuen werden voorzien van een zender in Spanje of Portugal; daarvan hadden we dus geen voorkennis over de uiteindelijke broedlocaties. Om de habitatselectie te analyseren werd het gemiddelde, de mediaan en de standaarddeviatie van de landgebruiksintensiteit van kern‐ en overige leefgebieden vergeleken met overeenkomende herhaalde willekeurige steekproeven uit al het beschikbare habitat met toenemende stralen, d.w.z. 500 m (lokaal), 5 km (buurt), 50 km (regio) en heel Nederland. Landgebruiksintensiteiten van de door grutto’s daadwerkelijk geselecteerde kern‐ en leefgebieden waren vergelijkbaar met die op lokaal en buurtniveau, maar waren significant lager en minder variabel dan die van de regio en het hele land. Grutto’s kozen op landschapsschaal voor landbouwgronden met een lage gebruiksintensiteit. De grootte van het kerngebied nam toe naarmate de intensiteit van het landgebruik toenam. Dit suggereert dat grutto's grotere gebieden moesten gebruiken bij een hogere intensiteit van het landgebruik in de landbouw. Dit komt overeen met het idee dat de habitatkwaliteit afneemt naarmate de intensiteit van het landgebruik toeneemt. Grutto’s hadden daardoor een groter gebied nodig om in al hun behoeften te voorzien. Deze studie is nieuw omdat het onbevooroordeeld landelijke habitatselectie en ruimtegebruik van een boerenlandvogel inzichtelijk maakt. In Nederland broedende grutto's selecteerden gebieden met een lagere landgebruiksintensiteit dan algemeen beschikbaar was. Het grootste deel van het Nederlandse landbouwgrasland (94%) wordt beheerd met een hoge landgebruiksintensiteit, wat de geschiktheid als broedplek voor grondbroedende vogels sterk beperkt. Dit onderzoek laat zien dat met behulp van “remote sensing” het mogelijk is om wilde populaties in z’n geheel te bestuderen, van het lokale perceelsniveau tot hun hele verspreidingsgebied. At the scale of the entire Netherlands, black‐tailed godwits (tagged with satellite transmitters on their stopover sites [N = 37]) strongly selected for low‐intensity agricultural land, while high‐intensity land use remained largely unused. In addition, the core range size of breeding godwits increased with increasing land‐use intensity.

Increasing goose population sizes gives rise to conflicts with human socioeconomic interests and in some circumstances conservation interests. Grazing by high abundances of geese in grasslands is postulated to lead to a very short and homogeneous sward height negatively affecting cover for breeding meadow birds and impacting survival of nests and chicks. We studied the effects of spring grazing barnacle geese Branta leucopsis and brent geese Branta bernicla on occupancy of extensively farmed freshwater grasslands by nesting and brood‐rearing waders on the island Mandø in the Danish Wadden Sea. We hypothesized that goose grazing would lead to a shorter grass sward, negatively affecting the field occupancy by territorial/nesting and chick‐rearing waders, particularly species preferring taller vegetation. Goose grazing led to a short grass sward (<5 cm height) over most of the island. To achieve a variation in sward height, we kept geese off certain fields using laser light. We analyzed effects of field size, sward height, mosaic structure of the vegetation, proximity to shrub as cover for potential predators, and elevation above ground water level as a measure of wetness on field occupancy by nesting and chick‐rearing waders. The analysis indicated that the most important factor explaining field occupancy by nesting redshank Tringa totanus, black‐tailed godwit Limosa limosa, oystercatcher Haematopus ostralegus and lapwing Vanellus vanellus as well as by chick‐rearing black‐tailed godwit and lapwing was short vegetation height. Distance to shrub cover and elevation were less important. Hence, despite very intensive goose grazing, we could not detect any negative effect on the field occupancy by nesting nor chick‐rearing waders, including redshank and black‐tailed godwit, which are known to favor longer vegetation to conceal their nests and hide their chicks. Possible negative effects may be buffered by mosaic structures in fields and proximity to taller vegetation along fences and ditches. Grazing by high abundances of geese in grasslands is postulated to lead to a very short and homogeneous sward height negatively affecting cover for breeding meadow birds and ultimately impacting survival of nests and chicks. Despite very intensive goose grazing in spring, our field study could not detect any negative effect on the field occupancy by nesting nor chick‐rearing waders.

Agri-environment schemes are an instrument used by western European countries to counteract the negative effects of contemporary agriculture on biodiversity, but not much is known about their effectiveness. We investigated the ecological effects of Dutch agri-environment schemes aimed at promoting botanical diversity or meadow birds, and we tested whether the effectiveness of the schemes depends on landscape type or structure. In three different types of landscape, we surveyed plants, birds, bees, and hover flies on 78 paired fields that either had agri-environment schemes or were managed conventionally, and we collected data on a range of different environmental variables. Neither plant species richness nor abundance of meadow birds was higher on fields with agri-environment schemes. Landscape type had a significant effect on both species groups, but the effects of the schemes were independent of landscape type. Neither the diversity of plants nor the abundance of birds was related to any of the environmental variables. Agri-environment schemes designed to promote plant species richness or bird abundance did have positive side-effects because they enhanced the species richness of bees and hover flies, irrespective of the type of landscape. Furthermore, landscape type, groundwater level (hover flies), and area of wooded edges (bees) significantly affected both species groups. The failure of the schemes to promote the target species may be related to the high intensity of land use in The Netherlands. Simple conservation measures taken by farmers may not be sufficient to counteract the impact of factors that are often controlled at the landscape level (e.g., hydrology). Similar studies in other countries are needed to place the results of our study into a European context.

In the Netherlands, breeding populations of wader meadow birds are in sharp decline. One possible cause is that breeding areas are becoming less open because of tall trees and other factors. The effects of tree lines are generally studied by means of transversal studies spanning a short period of time. We report on a longitudinal field study from 1993 to 2010 into the breeding densities of Eurasian Oystercatcher (Haematopus ostralegus), Northern Lapwing (Vanellus vanellus), Black-tailed Godwit (Limosa limosa) and Common Redshank (Tringa totanus) in the Demmerik polder, the Netherlands. One part of this polder, a nature reserve, has an older tree line, while two agricultural parts are divided by a newly developing tree line. As the tree line in the agricultural parts was developing, foraging families of Greylag Goose (Anser anser) showed a strong increase in only one of these parts during the breeding season. During the same period, the density of avian predators also increased in the whole polder. Analysis shows waders avoid trees in both situations: with an existing tree line (a static situation) and with a growing tree line (a dynamic situation). We investigated the possible role of geese and avian predators in explaining the decline in density of breeding wader meadow birds, by systematic comparison of several different models. In these models, the effect of the growing tree line has the greatest impact on breeding meadow birds. Models with geese describe the trends of breeding wader meadow birds better than those including avian predators, but since these two variables, geese and avian predators, are confounded, no definitive conclusion can yet be drawn. Potential explanations of and functional mechanisms behind the strong decline in breeding meadow bird populations in this area are discussed.