Despite efforts on ecosystem restoration and management, biodiversity loss remains one of the major environmental concerns of our time. Beyond the focus on threatened species, animals that indicate ...regional biodiversity hotspots and population trends, such as brood parasites, should also be targeted by conservation actions. We studied how reed habitat quality and management influence brood parasitism rate and offspring survival in Common Cuckoos Cuculus canorus parasitizing nests of Great Reed Warblers Acrocephalus arundinaceus in six reed habitats in an intensive agricultural landscape. Data collected from 45 sites over 13 years showed that the brood parasitism rate was highest on large canals and was positively influenced by the availability of potential perches (Cuckoo vantage points) and the height where host nests were built. Cuckoo chick survival decreased with water depth and was not affected by other factors. Our results suggest that the habitat‐dependent detectability of host nests was central in brood parasitism rate and that water level was central in Cuckoo chick survival. Our study shows that a maintenance of intermediate water levels is the most optimal for maintaining Cuckoo populations in intensive agricultural landscapes. Because brood parasites are excellent bioindicators as their presence predicts regional hotspots of taxonomic and functional diversity as well as population trends in bird communities, knowledge on their habitat requirements is relevant in management targeting diverse bird communities.
We studied how reed habitat quality and management influence brood parasitism rate and offspring survival in Common Cuckoos parasitizing nests of Great Reed Warblers in six reed habitats in an intensive agricultural landscape. Brood parasitism rate was highest on large canals and was positively influenced by the availability of potential perches, while the Cuckoo chick survival decreased with water depth and was not affected by other factors. Our results suggest that the habitat‐dependent detectability of host nests was central in brood parasitism rate and that water level was central in Cuckoo chick survival.
Freshwater wetlands and their biodiversity have suffered substantial losses globally, mainly due to the drainage of wetlands for agriculture. Recent studies suggest that small drainage and/or ...irrigation canals established in lowland areas can function both as partial replacement of wetlands lost and as biodiversity hotspots in agricultural landscapes. However, small canals are usually not protected or managed for biodiversity. We studied whether and how the timing of reed management (removal in winter, in spring, no removal) on small canals affects nest site selection and breeding success in Great Reed Warblers, Acrocephalus arundinaceus, a flagship species of small canals in an intensive agricultural landscape in a five-year quasi-experiment. We found significantly more nests in winter-managed than in non-managed canal sections and hardly any in spring-managed sections. The number of nests also increased with the proportion of reed removed and with reed density. Breeding success measured as the probability of fledging chicks was positively influenced by reed density only and was not affected by management type, nesting height, water depth and water level fluctuation. Reed density had a central role as it mediated the effect of management both on nest site selection and breeding success, likely through better concealment of the nests from predators. Our results suggest that winter management should be favored as much as possible in the conservation of Great Reed Warblers and other reed-nesting passerines, whereas spring management should be avoided as it results in a complete lack of reed or poorly grown reed unsuitable for nest-building by the start of the breeding season. Our study draws attention to the importance of proper management of small canals that can serve as local hotspots of biodiversity in heavily human-modified landscapes, and which thus deserve more conservation attention than they currently have.
Ecosystem restoration implies focusing on multiple trophic levels and ecosystem functioning, yet higher trophic levels, that is, animals, are less frequently targeted by restoration than plants. ...Habitat diversity, the spatial heterogeneity between and within habitat patches in a landscape, is a well‐known driver of species diversity, and offers possible ways to increase species diversity at multiple trophic levels. We argue that habitat diversity is central in whole‐ecosystem restoration as we review its importance, provide a practical definition for its components, and propose ways to target it in restoration. Restoration targeting habitat diversity is used commonly in aquatic ecosystems, mostly to increase the physical diversity of habitats, meant to provide more niches available to a higher number of animal species. To facilitate the uptake of habitat diversity in terrestrial ecosystem restoration, we distinguish between compositional and structural habitat diversity, because different animal groups will respond to different aspects of habitat diversity. We also propose four methods to increase habitat diversity: varying the starting conditions to obtain divergent successional pathways, emulating natural disturbances, establishing keystone structures, and applying ecosystem engineer species. We provide two case studies to illustrate how these components and methods can be incorporated in restoration. We conclude that targeting habitat diversity is a promising way to restore habitats for a multitude of species of animals and plants, and that it should become mainstream in restoration ecology and practice. We encourage the restoration community to consider compositional and structural habitat diversity and to specifically target habitat diversity in ecosystem restoration.
The reproductive period in animals is a demanding part in their life history. In birds, environmental factors, such as adverse weather, predation, or brood parasitism; and/or anthropogenic ...disturbance, can limit breeding success, resulting in failure of clutches. The nest loss in open‐cup nesting passerines is usually replaced with a new nest with a new clutch, however, in some cases the clutch replacement may occur in unusual forms. In this study, we report on three cases of within‐season nest reuse in the Great Reed Warbler. In the first case, a nest was reused for two times in the same season after unsuccessful nesting attempts (two‐time nest reuse). After the nest was depredated the first time, the female laid new eggs that were depredated again, then again the female laid new eggs that produced four fledglings. In the second case, the first clutch was depredated, after which the female laid a new clutch in the same nest that was again depredated. In the third case, the female laid new eggs among the eggs that failed to hatch previously. Our observations tend not to be consistent with the predator avoidance hypothesis because the depredated nests were reused by the parents. The time/energy saving hypothesis or possible deterrence of nest parasitism could explain nest reuse in this study, but because of low number of nests reused compared to the total number of nests found, this phenomenon needs further clarification.
In this study, we report on three extreme cases of within season nest reuse in an open nesting passerine. In first case, one nest successfully fledged young after the nest was reused for the second time (two‐time nest reuse), in the second case, one nest was depredated after nest reuse, and in the third case, the female laid a new clutch among the infertile eggs from the initial clutch. Our results were fairly supported by the predator avoidance hypothesis, they seem more likely to support time/energy saving and anti‐parasitic behaviour.
Ecosystem management often aims to maintain a diversity of habitats to benefit a large number of species within a landscape. We studied the effects of wetland management by low-intensity ...cattle-grazing and late-summer burning on marsh vegetation and globally declining anuran amphibians (frogs and toads) in a previously homogeneous reedbed. Burning effectively removed old reed and increased the variability of reed cover and marsh vegetation by the next spring. However, reed grew back strong in areas burned 2 or 3years before the study, indicating that fire rejuvenates reedbeds. In contrast, cattle-grazing kept reed cover homogeneously low and created open water surfaces. The number of amphibian species and individuals decreased with mean reed cover and old reed density, and increased with variability in reed cover. Correspondingly, amphibian richness and counts were greatest in newly burned areas the next spring. In contrast, a year later, richness and counts were greatest in grazed-only areas, with large decreases in newly burned and control areas. Our results suggest that combined management with grazing and burning can create different habitat patches, some of which will be optimal for amphibians in one year, whereas other patches may become suitable in a subsequent year when successional changes alter previously optimal patches. To maximise optimal habitats, mosaic management should repeat burning once every 2 or 3years in a rotational manner, and also maintain low-intensity cattle-grazing, which controls reeds and benefits amphibians more sustainably. Our study supports spatiotemporally varied management to facilitate habitat heterogeneity and complexity in dynamic landscapes.
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•We managed a wetland to mimic historical wildfires and traditional cattle grazing.•Early autumn fire eliminated old reed but facilitated reed regrowth the next summer.•Frogs and toads preferred newly burned areas but avoided old-burned patches.•Grazing broke up reedbeds and created shallow open water preferred by amphibians.•Mosaic management increased habitat diversity and greatly benefitted amphibians.
Management of reed beds primarily includes controlling water levels and removing vegetation by mowing, burning, or grazing. Although recent studies have demonstrated increased diversity and abundance ...of wetland specialists after reed bed management, documenting demographic benefits to individual species would add additional support to the advantages of appropriate management. Here, we explore the effects of reed management on the philopatry of Great Reed Warblers (Acrocephalus arundinaceus) over 7 yr. Reed beds were managed in the winter by occasional burning at mining ponds and large canals, infrequent burning in marshes, and frequent mowing of small canals. Based on resightings and recaptures of 1,243 adult and 1,428 nestlings individually marked at 57 sites in 6 different reed habitats, we built Cormack-Jolly-Seber models to estimate the apparent annual survival and encounter probabilities of birds banded as nestlings or as adults. Apparent survival varied in time for both age groups and both sexes, suggesting annual fluctuations in survival, whereas encounter probability remained constant across years. The encounter probability of birds banded as juveniles was higher in reed beds with shallower water. The encounter probability of birds banded as adults was higher in reed beds with deeper water for females, and strongly increased with variation in reed management and less strongly with variation in water depth for males. We also found that the few returning juveniles displayed strong philopatry to the reed habitat occupied in their first breeding season. Our study provides evidence that reed management influences the return rates of juveniles and adult males and females in different ways. Spatially variable reed management by mowing or burning should be applied and water of varying depths should be maintained to maximize return rates of Great Reed Warblers.
The decline of farmland bird populations starting in the 1980s has induced intense research on farmland biodiversity conservation in Europe. Although many studies assessing the effectiveness of ...agri-environmental schemes have concentrated on birds, farmland birds, surprisingly, have not yet been targeted directly by permanent, landscape-scale restoration of grassland ecosystems on former croplands in Europe. We compared farmland bird responses to grassland restoration by grass sowing, alfalfa sowing followed by spontaneous grassland recovery, and hay transfer (impact sites) with responses to extensive, low-intensity cropland cultivation (controls) in a Before-After-Control-Impact design, and also compared extensive croplands against a baseline reference of intensive croplands. Point counts in 69 sites on 910 ha in at least two years before and three years after the interventions showed that farmland bird species richness increased in both restored grasslands and in extensive croplands, whereas abundance and Shannon diversity increased only in restored grasslands but not in extensive croplands. Abundance increased in restored grasslands for five farmland species and two species of conservation importance, and in extensive croplands for one farmland and one species of conservation importance. Active restoration by grass sowing increased both species richness and diversity and active restoration by hay transfer increased abundance, while passive restoration targeting spontaneous grassland recovery after alfalfa sowing increased richness and abundance. Extensive croplands had four-five times more species and individuals than intensive croplands. Our results suggest that landscape-scale grassland restoration can locally reverse regional farmland bird declines and can thus be a promising tool in farmland biodiversity conservation.
•Farmland birds continue to decline despite surge of agri-environmental support.•Studied farmland birds on 760 ha restored grassland and 150 ha extensive cropland.•Grassland restoration increased farmland bird abundance and diversity.•Extensive cropping increased richness but not abundance or diversity.•Restoration led to local increase in farmland birds despite country-wide decline.
While some previous investigations have been made into the effects of vegetation structure on the probability of brood parasitism in reed passerines, the effects of vegetation management remain ...unclear. Furthermore, we possess little information on how vegetation density influences the probability of brood parasitism in wide-surfaced reed-beds. The aim of this study was to test how vegetation density and reed management by burning influence the probability of cuckoo (Cuculus canorus) brood parasitism in great reed warbler (Acrocephalus arundinaceus) nests in a wide-surfaced reed-bed with pure reed stands. We found that the probability of parasitism was highest in nests constructed in low reed density, with low annual variation of reed density and low annual variation of nest height. Reed management had no effect on the probability of parasitism. Our results suggest that, in wide-surfaced reed-beds with pure reed stands, nests in sparser reed are more exposed to brood parasitism than those concealed in dense reed. Furthermore, low spatio-temporal variation in reed density and nest height benefit brood parasitism, as it provides a relatively constant number of host nests in a similar spatial distribution in the reed-bed from year to year. Vegetation structure was suggested to have an important role in adaptation of hosts' defence against brood parasites.
The degradation and loss of habitats are one of the major causes of the recent global decline of amphibian populations, and wetland ecosystems are increasingly restored to counter these effects. ...However, there is little information on how restoration of non-wetland habitats such as grasslands affect amphibians in wet-terrestrial habitat complexes. We studied the spatial and temporal impacts of large-scale grassland restoration in wetland buffer zones and ecological corridors on amphibians in Hortobágy National Park (E-Hungary). We used bycatch data on amphibians inadvertently collected over seven years by Barber pitfall trapping in a post-restoration monitoring of invertebrates in restored and natural grasslands. Repeated measures analyses revealed higher abundance and species richness of amphibians from year 2 to 6 after restoration than in years 7 to 10. Early phases of restoration, dominated by weedy and dicotyledonous plants, provided suitable microclimatic refuges and foraging areas to amphibians. The availability of such microhabitats decreased in later phases of restoration, dominated by grasses and a few dicotyledonous plants. Legacy effects were important because fine-scale differences in crop history and seed mixture resulted in variation in total abundance and species richness. Space-for-time substitution analyses two and seven years after restoration also confirmed the temporal differences between early and late phases of restoration. Restored grasslands did not differ from natural grasslands in total abundance, species abundances or species richness of amphibians. Our study demonstrates that increasing the area of grasslands around and among lowland marshes can be an effective tool for conservation because amphibians readily use these areas as refuges or for foraging, movement, migration and dispersal. Restoration of non-wetland habitat can benefit amphibians at the local scale by extending suitable terrestrial habitats and at the landscape scale by establishing functional connectivity between wetlands.
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Intersexual differences in habitat choice can arise if males and females differ in morphology, physiology, niche partitioning, or resource use, and can be influenced by variation in habitat ...structure, quality, and management. To better understand such intersexual differences, we studied habitat choice in female Great Reed Warblers (Acrocephalus arundinaceus), a long-distance migrant flagship species of lowland Palearctic reed (Phragmites australis) habitats. We compared wing length, a widely used proxy for individual quality in passerines, of females nesting in six types of differently managed reed habitats. Our dataset on 391 females nesting in 32 sites over 10 years showed that wing length was significantly greater in mining ponds and medium-sized canals than on large canals. Wing length was negatively related to water level fluctuation and females showed strong philopatry to the habitat type in which they were first captured. In comparison to our previous study on male habitat choice, this study found differences in habitat choice between the sexes. Although long-winged individuals in both sexes preferred habitats with stable water and avoided small canals, longer-winged males preferred large canals with little or no management, whereas long-winged females preferred medium-sized canals with some management. Although these results provide some support for intersexual niche segregation, it is also possible that long-winged females avoid large canals, in which nest parasitism by Cuckoos (Cuculus canorus) is frequent, and/or prefer managed, sparse reed beds with better maneuverability for foraging. Our studies suggest that males may primarily choose habitats with abundant old reed and singing perches, whereas females are less sensitive to environmental variation and may choose nest sites based on male quality or territory quality. For conservation, our studies imply that the maintenance of stable water levels, a low intensity of management and the elimination of Cuckoo perches are likely to benefit both long-winged males and females.
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