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The article presents a study which examined the diet and prey-size selection by Black-tailed Godwits during fall migration in salt ponds of southern Europe. The study involves field observations, analysis of droppings, and prey abundance, which contributes to better understanding of stopover ecology in the areas. It was observed that godwits positively picked out the chironomid, despite the availability and abundance of several possible macroinvertebrate prey species, which constituted more than 95 percent of the items present in the droppings.

Agricultural intensification is one of the main drivers of farmland bird declines, but effects on birds may be confounded with those of climate change. Here we examine the effects of intensification and climate change on a grassland breeding wader, the Black-tailed Godwit Limosa l. limosa, in the Netherlands. Population decline has been linked to poor chick survival which, in turn, has been linked to available foraging habitat. Foraging habitat of the nidifugous chicks consists of uncut grasslands that provide cover and arthropod prey. Conservation measures such as agri-environment schemes aim to increase the availability of chick foraging habitat but have not yet been successful in halting the decline. Field observations show that since the early 1980s, farmers advanced their first seasonal mowing or grazing date by 15 days, whereas Godwits did not advance their hatching date. Ringing data indicate that between 1945 and 1975 hatching dates advanced by about 2 weeks in parallel with the advancement of median mowing dates. Surprisingly, temperature sums at median mowing and hatching dates suggest that while the agricultural advancement before 1980 was largely due to agricultural intensification, after 1980 it was largely due to climate change. Examining arthropod abundance in a range of differently managed grasslands revealed that chick food abundance was little affected but that food accessibility in intensively used tall swards may be problematic for chicks. Our results suggest that, compared with 25 years ago, nowadays (1) a much higher proportion of clutches and chicks are exposed to agricultural activities, (2) there is little foraging habitat left when chicks hatch and (3) because of climate change, the vegetation in the remaining foraging habitat is taller and denser and therefore of lower quality. This indicates that for agri-environment schemes to make a difference, they should not only be implemented in a larger percentage of the breeding area than the current maxima of 20–30% but they should also include measures that create more open, accessible swards. [ABSTRACT FROM AUTHOR]

The article explores the work and the studies conducted by the Caribbean Animal Health Network (CaribVET) avian influenza (AI) working group. The CaribVET working group for AI developed tools for AI surveillance in the Caribbean region. It has also launched various studies to assess the prevalence of AI virus (AIV) in the region, including a wild bird survey on the role of migratory birds in AI ecology. The protocol for epidemiologic surveillance of avian influenza in the Caribbean is explained, along the data on fighting cocks and AI risks in the Caribbean region. According to the authors, animal health network is relevant to research on AI risk and AIV ecology.

The article presents a study which determines the possibility of migratory shorebirds exposure to cholinesterase-inhibiting pesticides in agricultural sites in North and South America. It evaluates the exposure of migratory shorebirds to organophosphorus and carbamate compounds by comparing its plasma cholinesterase activities and body masses. The result suggests that shorebirds have no acute exposure to the pesticides, however, buff-breasted sandpipers were expose in South America.

Interference competition is often due to kleptoparasitism (food stealing). In which case, the attack distance, the distance over which one animal attacks another in an attempt to steal food, determines to a large extent the competitor density range over which interference significantly affects the intake rate of foraging animals. We develop a simple model of kleptoparasitism containing three parameters: attack distance, the density of foraging animals and a single dimensionless parameter α which summarizes the non-geometrical aspects of the interference process. Dominant and subdominant animals are not considered separately. The model predicts that the average intake rate will decrease exponentially with animal density and that a measure of the strength of interference depends on attack distance squared. The simple model is compared with a much more detailed individual-based foraging model from the literature. Simulated average intake rates are indeed well approximated by an exponential decrease with competitor density. Also the measure of interference behaves in the way expected from the simple model. By explaining the shape of the relationship between intake rate and animal density, the simple model provides insight into the behaviour of the detailed behavioural model. Insight into the role of geometry is important in the interpretation of field results and in the further development of detailed foraging models. [Copyright &y& Elsevier]

Copyright of Hydroécologie Appliquée is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

1. Thirgood & Redpath (2008) propose ways in which red grouse : hen harrier conflicts could be resolved. It has also been suggested that grouse management could accept lower bag sizes (number of birds shot) thus reducing the need for intensive management of predators and habitats. This would allow hen harriers to co-exist more easily on grouse moors. 2. We compare the bags, costs and incomes from these less intensive forms of grouse shooting with the more intensive driven shooting. 3. Allowing high density grouse moors to decline to low density ones will result in greater loss of income than the corresponding saving of costs. This can result in moor owners abandoning grouse management and thus gamekeepers losing their employment. 4. Losing gamekeepers from the uplands would jeopardize the protection of heather moorland and Special Protection Areas for birds, large areas of which are keepered and which currently support high numbers of breeding waders. 5. Synthesis and applications. We agree with the study by Thirgood & Redpath that consideration of social and economic factors will be needed to resolve conflict but a reduction in management effort from driven to walked-up shooting is not the answer. A more satisfactory approach to the harrier : grouse conflict could be to try to reduce harrier predation by means of diversionary feeding and to address the problem of the rapid build-up in harrier numbers by exploring the use of a ceiling on harrier densities. [ABSTRACT FROM AUTHOR]

Aim Many wader populations around the world are declining as a consequence of habitat degradation or loss. It is therefore important to identify species-specific habitat demands accurately and to define the important factors explaining species distribution, in order to develop tools that can be used in conservation planning. The aim of this study is to create reliable, functional and ecologically interpretable predictive distribution models for five breeding wader species. Location The archipelago of SW Finland in the Baltic Sea. Methods We used multivariate adaptive regression splines (MARS) to create single-species and multiresponse distribution models based on 525 study islands and 12 abiotic and biotic environmental variables. Model evaluation was carried out on independent data not used in model building (100 + 116 islands). The models were tested for discrimination with receiver-operating characteristic statistics and for calibration with Millers calibration statistics (MCS). Results The single-species models for the turnstone ( Arenaria interpres), redshank ( Tringa totanus) and oystercatcher ( Haematopus ostralegus) showed good predictive abilities, regarding both discrimination and calibration, when evaluated on independent data. The multiresponse models for the less prevalent species, common sandpiper ( Actitis hypoleucos) and the common ringed plover ( Charadrius hiaticula) had better discriminative abilities than the single-species models. The most influential predictor overall was occurrence of small larids. Exposure, area of forest and low and flat areas were also important, as well as shore habitats. Main conclusions We found that the ability of MARS to fit non-linear and multiresponse models makes it a useful method to quantitatively relate species occurrence to environmental characteristics of a complex environment. [ABSTRACT FROM AUTHOR]

Wet-dry tropical estuaries are extreme environments driven by wet season rainfall and runoff events. The biota associated with these systems are highly adapted to large fluctuations in salinity. There are few examples globally where water extraction for human needs has not yet had a major impact on freshwater flow volumes and seasonal variability in these systems. Therefore, this study examined the importance of seasonally variable flow on intertidal macrobenthic (>0.5 mm mesh size) abundance and species composition in a pristine, wet-dry tropical estuary and nearshore environment. The focus was on intertidal mud- and sandflats where macrobenthos are known to be an important food source for endangered migratory shorebirds and fisheries species in the region. Macrobenthos on the intertidal flats were sampled on four occasions spanning the late-dry, late-flood, and early-dry periods across four years. Across all sites, total macrobenthic abundance was significantly lowest during the late-flood period, when the salinity was low, and highest in the late-dry season, under hypersaline conditions. In the muddy estuarine intertidal flats, the dominant macrobenthic group was polychaetes. In contrast, in the sandy nearshore intertidal flats, bivalves dominated in the late-dry and early-dry. However, during the late-flood, when salinities were at their lowest, the nearshore intertidal flats experienced almost complete loss of bivalves. Although flow had short-term negative effects on some species, it is clear that macrobenthos recruitment back into the intertidal flats had begun once the tide re-established in the early-dry. The differences in the flood response between polychaetes and bivalves likely reflects differences in their life history strategies, with the burrowing and swimming behaviour of polychaetes likely to be providing the ability to seek refuges during low salinity periods. Macrobenthic abundance was also correlated with benthic chlorophyll a concentrations, likely reflecting that both primary and secondary production is impacted by flow. This study suggests that macrobenthos abundance, and species dominance is driven by the seasonal changes in flow in this pristine system, demonstrating the important role of freshwater inputs. [Display omitted] • This tropical estuary had a relatively high abundance of macrobenthos on the mudflats compared to other studies in tropical estuaries. • Seasonal freshwater flow reduced macrobenthic abundance and diversity in the short term. • The dominant group, polychaetes, was less impacted by floods than bivalves. • Floods bring nutrients which, on longer timeframes, fuel estuarine primary productivity which is available for macrobenthos. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the taxonomic, geographic and temporal variation in avian influenza prevalence among shorebirds on the Pacific coast of the U.S. Real-time reverse transcriptase-polymerase chain reaction and virus isolation were used to test shorebirds for avian influenza virus. Virus was detected from Dunlin, Western Sandpiper, Long-billed Dowitcher and American Avocet. Diagnostic tests suggested poor functioning of traditional virus isolation methods. Since most diagnostic reagents and procedures are optimised for identifying viruses in poultry, the ability to identify the full range of influenza A subtypes is limited.

The distribution of golden plover across Scotland was modelled using land cover and management variables, and used to highlight the spatial association between golden plover abundance and current and proposed wind farm developments. Overlap was greatest in three biogeographical zones (the Western Isles, the Western Central Belt and the Borders Hills) and was estimated at ca. 5% of the biogeographical population in each case. New field data were used to predict the effects of wind farm development on golden plover populations, employing a conservative analytical approach to detect statistically significant wind farm related effects. The results provide evidence of significant avoidance of wind turbines by breeding golden plovers to a distance of at least 200 metres. Furthermore, wind farm sites appear to support lower densities of golden plover than predicted by the distribution model for sites without wind farms. Therefore, there is evidence for negative effects of wind farm developments on golden plover, and we suggest strategies to reduce any potential conflict between the need to promote wind energy and the need to maintain golden plover populations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As part of the ‘International Cyanide management code for the manufacture, transport, and use of cyanide in the production of gold’, companies voluntarily commit towards keeping the weak-acid-dissociable (WAD) cyanide concentrations in tailings below 50 mg l−1. Day and night-time observations were made in winter at the tailings storage facility (TSF) of the Mponeng mine of AngloGold Ashanti, and extensive surveys of the surroundings were made for mortalities. The cyanide levels never exceeded 50 mg l−1 WAD. No dead birds or mammals were found. Twenty-five bird species were recorded in and around the TSF and the associated return water dams (RWDs), with 20 occurring only in the surrounding grasslands or RWDs, and five (four wader species and a sand martin) on the TSF. The wading birds were most likely feeding on dead insects from the pond surface, as they adjusted their locations according to wind direction. Other birds actively avoided the TSF water, suggesting a locally learned behaviour. Whether this avoidance will also hold for migratory birds or natal dispersal of local birds in summer necessitates further investigation. A better understanding of the TSF–wildlife interactions would lead to improved measures to reduce environmental risks. [ABSTRACT FROM AUTHOR]

Abstract: In estuarine sediment flats benthic macroinvertebrates are intensively consumed by a variety of predators, such as aquatic birds and nekton (mostly fish and crustaceans). However, there is still a lack of conclusive studies that evaluate if this predation has a relevant impact on the populations of those invertebrates, which are a key element of the estuarine food chain. In the Tagus estuary we experimentally tested and quantified the impact of predation on the polychaete Hediste diversicolor, one of the most important prey for a variety of predators in many estuaries. Using an exclusion experiment, we compared the seasonal variation in the densities of H. diversicolor from February to November in sediment plots (1) available to both bird and nekton predators, (2) just to nekton, and (3) without predators. We also followed changes in the abundance of potential predators throughout the study. The lowest densities were systematically observed in the plots accessible to all predators, followed by those which excluded just birds, and finally by those that excluded all predators. The exclosures were in place for 9months, at the end of which the average density of H. diversicolor in the plots protected from all predators was eight times greater than in those without any protection. These results demonstrate that predation had a major impact on the densities of H. diversicolor. The relative importance of bird and nekton predation varied along the study, and this seems to be determined by different peaks of abundance of the two types of predators. However, when present in high densities, birds and nekton seem to have a similar impact on H. diversicolor. Our results suggest that predation is a key factor on the population dynamics of H. diversicolor. In addition, the levels of predation that we observed suggest that this polychaete can be a limited resource, and this could have major ecological consequences for predators for which it is a key prey. [Copyright &y& Elsevier]

Numerous studies have documented behavioural changes in wildlife because of human disturbance. Disturbance may threaten waders if there are no alternative habitats or foraging times. Here we compared human and dog densities, natural and anthropogenic disturbance rates, prey availability and wader foraging rates at five sites in and around Khao Sam Roi Yod National Park, Thailand, with different shorebird densities, to assess whether disturbance forced wintering waders to under-use high quality sites consistently. We also examined diel and tidal variability in prey densities and tested whether people and dogs cause temporary displacement or reductions in foraging rates. Although there were significant differences in shorebird, human and dog densities as well as anthropogenic disturbance rates and prey availability amongst the five sites, there was no indication that birds were being displaced from the highest quality habitat. There was little die! or tidal variation in most types of prey. People did not temporarily displace waders but did reduce foraging rates. The availability of high quality, alternative foraging habitat with low human disturbance, and nocturnal prey availability, along with the lack of any short-term displacement of birds from areas of high disturbance suggest that disturbance is unlikely to affect wader fitness in this National Park. By examining a range of important habitat characteristics and wader spatial distributions, our study demonstrates a method and a theoretical framework to evaluate the possible impacts of human disturbance on wildlife. [ABSTRACT FROM AUTHOR]

Two phases of an experimental reduction in management at Langholm Moor in southwest Scotland provided an insight into factors that determined trends in the abundance of moorland birds. In 1992 the historical control of breeding Hen Harriers Circus cyaneus stopped and in 2000 grouse moor management was discontinued. Golden Plover Pluvialis apricaria, Lapwing Vanellus vanellus, Curlew Numenius arquata and Red Grouse Lagopus lagopus scoticus declined, whilst Carrion Crow Corvus corone and Snipe Gallinago gallinago increased. Hen Harriers increased from two to 20 breeding females, then declined back to two. Lapwing abundance was positively associated with that of Hen Harriers, and moorland passerines (Skylark Alauda arvensis, Meadow Pipit Anthus pratensis and Stonechat Saxicola torquata) were negatively associated. Golden Plover, Lapwing, Curlew, Red Grouse, Skylark and Hen Harrier were more abundant when the moor was managed for grouse, whilst Carrion Crow, a common predator of clutches of ground-nesting birds, increased during the second half when management ceased. Increased Crow numbers, together with an increase in Red Foxes Vulpes vulpes, probably contributed to the observed bird declines. [ABSTRACT FROM AUTHOR]

Abstract: Like many other coastal regions of the world, open-soil agricultural lands in the Fraser River Delta provide roosting and feeding habitat for non-breeding shorebirds that supplements intertidal habitat. Focusing on dunlin (Calidris alpina pacifica), black-bellied plover (Pluvialis squatorola), killdeer (Charadrius vociferus), and their avian predators (raptors), diurnal and nocturnal high tide surveys were conducted across the non-breeding period, October–April (1998–2000). All three shorebirds showed positive relationships with laser leveling, and recent manure and fertilizer application. Day length was negatively related to field use by dunlin, but positively related for black-bellied plover and killdeer. Amount of recent precipitation was positively related to dunlin and negatively related to black-bellied plover and killdeer field use. Results suggest that providing a mosaic of different crop types, autumn mowing, laser leveling, application of fertilizer and manure, and minimizing habitat fragmentation through maintenance of large fields are habitat management strategies that may enhance farmland for shorebirds during the non-breeding season in this region. [Copyright &y& Elsevier]

Many shorebird populations show evidence of declines. To identify the causes is a key issue in developing comprehensive shorebird conservation plans. In coastal areas, shorebirds are vulnerable to effects of shellfish and baitworm digging, including reduction of the food supply. The mudsnail Hydrobia ulvae is often reported to be the dominant inhabitant of intertidal mudflats, and is common in the diet of migrating and wintering shorebirds. This prosobranch mollusc lives at or just below the surface of intertidal mudflats, so it might be directly damaged and killed or buried within the mud by hand diggers. We studied the short-term effects of digging by hand on the availability of mudsnail to shorebirds. Twenty centimetres deep core samples were collected from undisturbed and recently disturbed intertidal mud. The total mudsnail density and biomass per core sample was similar in disturbed and undisturbed mud. However, mudsnail density and biomass were significantly lower in disturbed mud than in undisturbed mud when only the upper five centimetres of the mud were compared. If only the mudsnails found in this surface layer are potentially available for shorebirds, the available mudsnail density and biomass fraction for shorebirds had decreased by 62.6 ± 11.4% and 75.7 ± 7.2% in disturbed mud, respectively. The potential impact of this decreasing mudsnail fraction on shorebirds is addressed. [ABSTRACT FROM AUTHOR]

Abstract: Estuarine intertidal flats are often exploited by humans and waders since they provide food, particularly shellfish. This raises important conservation issues. Waders can be affected by shellfishing activities in multiple ways, such as a reduction of the available shellfish, disturbance by the presence of shellfishers on their feeding areas, and changes in micro-habitat, due to sediment reworking. In this study we quantified the impact of traditional shellfishing on waders in the Tagus estuary. Particular attention was given to hand-raking of clams Scrobicularia plana, which constitutes most of the consumed food by waders. Shellfishers did not cause a relevant depletion of clams for waders; they removed less than 0.3% of its total production and focused on size classes that were usually not taken by birds. Hand-raking caused temporary changes in the vertical distribution and availability of invertebrate prey in the sediment. However, this did not affect the bird''s feeding rates, presumably because prey availability remained above the threshold at which intake rates are expected to decline. The presence of shellfishers in the birds foraging areas potentially affects waders by keeping them away from foraging areas, but even the most affected species lost less than 10% of their foraging grounds due to this factor. Overall, we conclude that the current low harvesting levels of shellfishing are compatible with the preservation of the estuary as a key site for waders. Nevertheless, simulations showed that traditional shellfishing could have much greater potential to affect waders through disturbance than through prey removal. The results for the Tagus show that even small harvest rates, representing a negligible loss of food for waders and potentially considered sustainable by shellfish managers, could have a great impact on waders due to increased disturbance. This effect of disturbance likely occurs in most estuaries and should be taken into consideration when planning shellfish harvesting in important wader feeding areas. [Copyright &y& Elsevier]

Abstract: The aim of this study was to analyse the occurrence of corncrakes in two Swedish meadow sites managed by mowing and grazing, but also with abandoned meadows. Most corncrakes (58%) on meadows were found in unmanaged areas without subsidies to the farmers (i.e. areas with tall vegetation). Several corncrakes (62%) were found in restored areas, managed for less than 10 of the last 40 years, fewer (38%) in areas under continuous management. Vegetation height was negatively associated with number of years of management the last 40 years, and the continuously managed areas were avoided by corncrakes. Sites where corncrake territories occur regularly should be managed to maintain tall vegetation suitable for the species, which requires increased use of mowing. However, the results from our study also suggest that yearly mowing might result in a vegetation structure that is avoided by corncrakes. To achieve a balance between tall grassy vegetation and prevention of succession to scrub a possible management regime would therefore be mowing at intervals of a few years. [Copyright &y& Elsevier]

Ground-nesting birds have declined world-wide, probably partly due to high nest predation. A non-lethal method for decreasing predation uses protective cages at nests. Tests have mainly looked at the effect of such nest exclosures on hatching success and adult predation, but several additional aspects need to be explored for a comprehensive evaluation of this conservation technique. Here, we test the effect of nest exclosures in two common European shorebirds: northern lapwing (Vanellus vanellus) and redshank (Tringa totanus), measuring hatching success, incubation length, hatching synchrony, hatchability, partial clutch loss, chick condition, and adult predation. In both species, protected nests had higher hatching success than unprotected nests. Taking into account incubation time, nest abandonment, hatchability and partial clutch loss, protected nests still hatched more young than unprotected controls. In lapwings, but not in redshanks, protected nests were incubated longer, but this did not impair the condition of lapwing chicks. Protected redshanks suffered increased predation on incubating adults, which often sit on the nest until a predator is close by. Our results emphasize the need for caution in the use of nest exclosures, particularly in redshanks and other species with similar incubation behaviour. Exclosures can, however, be a useful management tool in shorebirds that leave their nest early, when an approaching predator is still far away. [Copyright &y& Elsevier]

1. In migratory species, early arrival on the breeding grounds can often enhance breeding success. Timing of spring migration is therefore a key process that is likely to be influenced both by factors specific to individuals, such as the quality of winter and breeding locations and the distance between them, and by annual variation in weather conditions before and during migration. 2. The Icelandic black-tailed godwit Limosa limosa islandica population is currently increasing and, throughout Iceland, is expanding into poorer quality breeding areas. Using a unique data set of arrival times in Iceland in different years for individuals of known breeding and wintering locations, we show that individuals breeding in lower quality, recently occupied and colder areas arrive later than those from traditionally occupied areas. The population is also expanding into new wintering areas, and males from traditionally occupied winter sites also arrive earlier than those occupying novel sites. 3. Annual variation in timing of migration of individuals is influenced by large-scale weather systems (the North Atlantic Oscillation), but between-individual variation is a stronger predictor of arrival time than the NAO. Distance between winter and breeding sites does not influence arrival times. 4. Annual variation in timing of migration is therefore influenced by climatic factors, but the pattern of individual arrival is primarily related to breeding and winter habitat quality. These habitat effects on arrival patterns are likely to operate through variation in individual condition and local-scale density-dependent processes. Timing of migration thus appears to be a key component of the intricate relationship between wintering and breeding grounds in this migratory system. [ABSTRACT FROM AUTHOR]

1. Recent theoretical modelling has provided important insights into how habitat loss may affect local populations through impacts on individual fitness (survival, body condition, fecundity). Despite this, attempts to provide empirical evidence of such impacts on displaced individuals have been limited. Using a before-after-control-impact (BACI) approach, we report how a sudden loss of wintering habitat impacted on the body condition and survival of redshank Tringa totanus. 2. The intertidal mudflats of Cardiff Bay, UK, were inundated with freshwater in November 1999 following impoundment by a barrage, resulting in the displacement of c. 300 redshank to adjacent habitat on the Severn Estuary. Movements and the survival of these birds were monitored through observations of colour-marked individuals. Comparative survival rates were calculated for marked populations at the main recipient site, Rhymney, and a control site. 3. Displaced redshank had difficulty maintaining their mass in the first winter post-barrage closure: adults previously only recorded at Cardiff Bay were significantly lighter than those previously recorded at Rhymney. 4. Survival rates of displaced redshank also declined. The estimated annual survival of adult Cardiff Bay redshank fell from 0·846 in the 2 years pre-barrage closure to 0·778 in the 3 following years because of a significant decline in winter survival ( P = 0·0006). In comparison, there was no significant change in the survival of adult Rhymney redshank, and adult survival at the control site was actually greater post-barrage closure than beforehand. The lack of decline in these rates and the similarity between those of Cardiff Bay adults pre-barrage closure and Rhymney adults indicate that the increase in winter mortality of Cardiff Bay birds resulted from their displacement. 5. Synthesis and applications. This study provides the first conclusive empirical evidence that habitat loss can impact individual fitness in a bird population. Adult redshank displaced from Cardiff Bay experienced poor body condition and a 44% increase in mortality rate. Without an increase in the recruitment of first-winter birds, such a change is likely to reduce substantially local population size. The results reported here should help to inform governments, planners and non-governmental organizations (NGOs) seeking to understand how developments might impact on animal populations. [ABSTRACT FROM AUTHOR]

Abstract: Survey data on breeding wader densities and grazing intensity on coastal meadows on the Baltic island of Öland from 1988, 1998 and 2003 were used to evaluate density and density-changes of four common and widespread wader species, lapwing Vanellus vanellus, redshank Tringa totanus, oystercatcher Haematopus ostralegus and ringed plover Charadrius hiaticula in relation to grazing intensity. Population trends over time and changes in densities in relation to changes in grazing management were evaluated. Both wader densities and the environmental variable grazing intensity demonstrated significant spatial autocorrelation, but all main results were unaffected when accounting for spatial structure in the statistical tests. Breeding densities of investigated species were positively related to grazing intensity and local changes in grazing management affected the local change in wader densities. However, average grazing intensity increased over time whereas wader numbers generally remained constant or declined. Thus, changes in grazing intensity could not explain changes in overall breeding numbers. One explanation for this is probably that grazing mainly affected distribution of birds. Some evidence of a buffer effect was found in the redshank and ringed plover, in which breeding densities declined proportionally more in non-shore than in shore habitat. This was probably due to a redistribution of birds to shore habitat. It is concluded that grazing management is essential for the occurrence of waders, but might not be sufficient to ensure long-term viability of wader populations on coastal meadows. [Copyright &y& Elsevier]

Abstract: Iceland is responsible for many internationally important populations of breeding bird species, yet very little is currently known about how these species use the habitats available to them. Lowland areas of Iceland, in particular, have undergone significant landscape changes over the last century, such as widespread drainage of wetlands and conversion to agriculture, changes in grazing pressure and recently, extensive afforestation. The impact of these changes on breeding bird species will depend on the relative importance of different habitats for each species, and the threats facing those habitats. Here we report the results of a large-scale survey of the factors influencing patterns of habitat selection of eight populations of Charadriiform bird species throughout lowland Iceland; oystercatcher Haematopus ostralegus, golden plover Pluvialis apricaria, dunlin Calidris alpina, snipe Gallinago gallinago, whimbrel Numenius phaeopus, black-tailed godwit Limosa limosa, redshank Tringa totanus and arctic skua Stercorarius parasiticus. Ordination analyses and multiple logistic regression models are constructed to explore the components of habitats that influence the distribution of these species. Five of the eight species analysed showed significant preferences for lowland wetland habitats and four significantly selected areas containing wet features such as pools and high water tables. These results allow us to identify future conflicts in land use that are likely to result from government-supported large-scale afforestation of lowland areas and hydro-electric developments. [Copyright &y& Elsevier]

1. Buffer effects occur when increases in population size result in an increasing proportion of a population inhabiting poor quality sites. When there are fitness costs to inhabiting poor sites, buffer effects can potentially regulate population sizes. In migratory populations, the regulatory capacity of buffer effects will clearly be influenced by their role in both the breeding and nonbreeding seasons, but previous studies have been restricted to one season only. 2. Icelandic black-tailed godwits Limosa limosa islandica are currently increasing in number and previous studies have revealed a large-scale buffer effect operating on the wintering grounds. 3. Here, we reconstruct the pattern of population expansion and colonization of new breeding grounds, in relation to breeding habitat quality, to investigate whether a buffer effect is also operating during the breeding season. 4. Godwit breeding success is higher in marsh habitats than in dwarf-birch bogs. Prey densities are also higher in marsh habitats, and breeding success increases with the density of shallow pools, which are more common on marsh sites. Large lowland basins with higher marsh coverage were colonized earlier than small ones with low marsh coverage. Recent colonizations have been into basins that are closer to occupied sites and have higher cover of dwarf-birch bog. 5. Thus godwits appear to be expanding into poorer quality breeding habitat as well as poorer quality winter habitat. The large spatial scale of these analyses and the fitness costs of occupying poor quality sites suggest that this double buffer effect is likely to play a key role in regulating this expanding population. In most migratory populations, some level of density dependence is likely to operate at both ends of the range. Double buffer effects may therefore be a common phenomenon and an important mechanism regulating migratory populations. [ABSTRACT FROM AUTHOR]

The loss of feeding areas may pose a threat to many wintering waders because increased competition arising from reduced foraging space may force birds either to emigrate or to die. This has been demonstrated to occur in northwest European estuaries, but virtually no studies have been performed in the estuaries of southern Europe, where the loss of supratidal habitats (salines and saltmarshes), rather than intertidal habitats, are currently the main threat to waders’ habitats. If these habitats are lost, waders may be forced to move to the intertidal mudflats, perhaps increasing competition between individuals and ultimately leading to starvation or emigration. We tested this hypothesis in the Mondego estuary, a small estuary on Portugal’s west coast, which is presently under heavy human pressure. We used indirect methods to test for the occurrence of both components of intra-specific competition: interference and prey depletion. We found no evidence that either interference or depletion competition was occurring at present, either on the mudflats or in the salines. Overall, the results suggest that the intertidal mudflats may still be able to accommodate birds displaced from the destroyed supratidal salines, but modelling is required to predict the effect that the combined loss of feeding area and foraging time that this would entail would have on their fitness, and thus numbers. [ABSTRACT FROM AUTHOR]

Abstract: It is increasingly important to be able to monitor and maintain the quality of estuaries for overwintering shorebirds. Bird numbers alone are not sufficient to indicate quality nor, as recent research shows, can it be assumed that site quality is being maintained simply because there is enough food to meet the birds’ physiological demands; i.e., the amount of food available per bird in autumn needs to be greater than the amount eaten. But how much greater? We used a simple individuals-based and behaviour-based model to explore the factors that affect the relationship between overwinter mortality and the amount of food available per bird in autumn (the food:bird ratio). The aims were to explore how the natural history characteristics of a shorebird species affected the shape of this relationship, in order to identify characteristics of the system that should be included in any monitoring programme of site quality. In all cases there was a minimum threshold food:bird ratio above which mortality did not vary and below which mortality increased steadily. The amount of food per bird required at the threshold varied from one to six times the amount actually consumed by each bird during winter, depending on the amount of realism included in the model. The minimum threshold ratio was most strongly influenced by the shape of the relationship between intake rate and prey density – the functional response – and, when interference competition occurred, by the distribution of the birds’ main food supply. Simulations with realistic spatial distributions of prey predicted that the minimum required amount of food per bird would be between two and five times the amount actually consumed. The threshold approach could provide a simple method of monitoring estuary quality based on food supply and bird numbers. It also provides a potentially clearly-defined and unambiguous measure of the carrying capacity of a site. If applied to a sufficient number of real estuaries, general guidelines for maintaining estuary quality based on estuary characteristics, food supply and bird species might be established. [Copyright &y& Elsevier]

Most studies of climate-driven changes in avian breeding phenology have focused on temperate passerines, yet the consequences of such environmental change may be more deleterious for other avian taxa, such as arctic and sub-arctic waders (Charadrii). We therefore examine large-scale climatic correlates of the breeding phenology of one such species (golden ploverPluvialis apricaria), and the timing of emergence of their adult tipulid prey, to assess the potential for climate change to disrupt breeding performance. Golden plover first-laying dates were negatively correlated with both March and April temperature, the mean laying date of first clutches was additionally negatively correlated with March rainfall. The timing of final laying dates were negatively correlated with April temperature only. The timing of tipulid emergence was negatively correlated with May temperature. In combination with historical climatic data, these models suggest a 9-day advancement of golden plover first-laying dates occurred during the 1990s, although this remains within the range of natural variation for the twentieth century. The magnitudes of predicted changes in mean and final laying dates, and the timing of tipulid emergence, were smaller. Climate predictions for 2070-2099 suggest potential advances in first-laying dates by 25 days, whilst the timings of mean and final laying dates are predicted to change by 18 days and 13 days, and tipulid emergence by 12 days. Given the importance of adult tipulids to young golden plover chicks, these changes may result in a mismatch between the timing of first-laying dates and tipulid emergence, so reducing the success of early breeding attempts. Modelling suggests that these changes could reduce breeding success in a South Pennines population by about 11%. [ABSTRACT FROM AUTHOR]

The distributions of eight out of nine common species of waders (Charadrii) overwintering on UK estuaries have changed in association with recent climate change. These birds represent a high proportion of various populations from breeding grounds as far apart as Greenland to the west to high-arctic Russia to the east. During warmer winters, smaller proportions of seven species wintered in south-west Britain. The distributions of the smaller species show the greatest temperature dependence. The opposite was found for the largest species and no relationship was found for a particularly site-faithful species. In north-west Europe, the winter isotherms have a broadly north to south alignment, with the east being colder than the west. The average minimum winter temperatures across the UK having increased by about 1.5°C since the mid-1980s, the temperatures on the east coast during recent winters have been similar to those of the west coast during the mid-1980s. On average, estuaries on the east and south coasts of Britain have muddier sediments than those on the west coast and thus support a higher biomass of the invertebrate prey of waders. We suggest that, with global climatic change, the advantage gained by waders wintering in the milder west to avoid cold weather-induced mortality is diminished. Consequently, more choose to winter in the east and thus benefit from better foraging opportunities. The implications of these results are considered in terms of a site-based approach to wildlife protection used in Europe and elsewhere. [ABSTRACT FROM AUTHOR]

The use of the countryside for recreation has increased dramatically in recent years. This has led to concern amongst conservationists about the effects increased human disturbance may have on important wild animal populations. In the UK, recent legislation has widened the level of access to upland habitats, which support internationally important breeding bird populations. Determining the extent to which recreational disturbance affects upland breeding birds is therefore a conservation priority. We used data collected over 13 years to investigate the impact of recreational disturbance on the distribution and reproductive performance of golden plovers breeding in close proximity to the Pennine Way, an intensively used long-distance footpath. Importantly, the Pennine Way was resurfaced in 1994 to prevent further erosion of the surrounding vegetation. We were therefore able to examine if the response of golden plovers to recreational disturbance was influenced by changes in the intensity and extent of human activity resulting from the resurfacing work. Before the Pennine Way was resurfaced, golden plovers avoided areas within 200 m of the footpath during the chick-rearing period. At this time over 30% of people strayed from the footpath and the movement of people across the moorland was therefore widespread and unpredictable. Following resurfacing, over 96% of walkers remained on the Pennine Way, which significantly reduced the impact of recreational disturbance on golden plover distribution; golden plovers only avoided areas within 50 m of the footpath at this time. Despite the clear behavioural responses of golden plovers to the presence of visitors, there was no detectable impact of disturbance on reproductive performance. In many countries, a conflict arises between the use of the countryside for recreational purposes and the protection of habitats or species of high conservation value. However, this study suggests that the implementation of simple measures to influence visitor behaviour can dramatically reduce the impact of recreational disturbance on wild animal populations. [Copyright &y& Elsevier]

Meadow bird agreements are the most important Dutch agri-environment schemes, both in terms of uptake and of aim. Meadow bird agreements postpone the first agricultural activities on grassland thus reducing egg and chick mortality due to mowing or grazing. We investigated the conservation effects of meadow bird agreements by analysing settlement densities of meadow birds on 34 fields in 1989, 1992 and 1995 in the province of Zeeland, The Netherlands. We compared territory numbers on fields with meadow bird agreements with paired nearby control fields that were conventionally managed. In 1995, the number of territories of black-tailed godwit (Limosa limosa), lapwing (Vanellus vanellus) and the total number of meadow birds were significantly higher on fields with conservation management. These differences were partly caused by the higher quality (i.e. higher groundwater level) of fields with meadow bird agreements. Population trends were similar on fields with and without meadow bird agreements and the observed difference in settlement density in 1995 was already present in 1989. Furthermore the effectiveness of the scheme did not increase with time. Thus we found no conclusive evidence that the conservation measures themselves did result in higher territory numbers. Currently, we do not have sufficient ecological and behavioural knowledge of meadow birds to explain why the higher reproductive success does not result in higher settlement densities. [Copyright &y& Elsevier]

Abstract The Charadrii (shorebirds, gulls and alcids) are one of the most diverse avian groups from the point of view of sexual size dimorphism, exhibiting extremes in both male-biased and female-biased dimorphism, as well as monomorphism. In this study we use phylogenetic comparative analyses to investigate how size dimorphism has changed over evolutionary time, distinguishing between changes that have occurred in females and in males. Independent contrasts analyses show that both body mass and wing length have been more variable in males than in females. Directional analyses show that male-biased dimorphism has increased after inferred transitions towards more polygynous mating systems. There have been analogous increases in female-biased dimorphism after transitions towards more socially polyandrous mating systems. Changes in dimorphism in both directions are attributable to male body size changing more than female body size. We suggest that this might be because females are under stronger natural selection constraints related to fecundity. Taken together, our results suggest that the observed variation in dimorphism of Charadrii can be best explained by male body size responding more sensitively to variable sexual selection than female body size. [ABSTRACT FROM AUTHOR]

Great Britain''s wintering coastal wader populations have been estimated for the period 1994/1995–1998/1999 from data provided from two sources: the Wetland Bird Survey (WeBS) and the Non-estuarine Coastal Waterfowl Survey (UK-NEWS). New methodology for estimating the number of wintering waders is applied. It imputes (fills in) the value of missing counts before estimating the population size of each species as being the mean of the largest annual count made between November and March over the relevant 5-year period. This methodology has led to an 11% larger estimate of the number of waders present on Great Britain''s coasts than the traditional approach based on averaging just January counts over a 5-year period, and it suggests that Great Britain''s coastline supports ca. 2.1 million waders. Updated values are presented from which site evaluations based on 1% of the national population can be derived. Great Britain is of considerable international importance for waders. It holds >25 and >50% of the flyway populations of nine and four species of wader, respectively, but for the first time since the start of monitoring in the early 1970s, the historical increase in the number of predominantly coastal waders wintering in Great Britain is coming to an end. Seven of the 14 species that have shown population changes of >5% since the last set of 1987/1988–1991/1992 population estimates have declined in numbers. The possible causes of the fluctuations in wader populations, such as climate change and changing nutrient inputs to coastal waters are discussed. There is an urgent need to identify the causative factors leading to these declines, and to use the new population estimates to identify new sites that should be afforded legal protection, an action that should help Great Britain maintain its internationally important wader populations. The decrease in the updated population estimate of Eurasian oystercatcher, for example, has made it possible to determine that 19 rather than 17 sites in Great Britain are worthy of statutory protection on the basis of holding 1% or more of its national population. [Copyright &y& Elsevier]

Many species of shorebird typically forage almost exclusively on intertidal habitats. When such strongly maritime species choose to forage on non-intertidal habitats, it may either be a response to deteriorating intertidal conditions or to the discovery of more profitable resources in non-intertidal areas. Methods which allow distinction between these two will clearly be important for identifying problems in intertidal habitats. Since January 1998, turnstone (Arenaria interpres) on the Wash estuary, eastern England have been foraging on the docksides of Port Sutton Bridge (mainly on spilt wheat and fishmeal), fields and river edges, resulting in concern that intertidal food supplies were no longer sufficient to support the population. We quantified the distribution and behaviour of turnstone within the Wash in relation to season, tidal state and weather and used a depletion model to predict the number of turnstone that could be supported by the port, under a range of resource densities and environmental conditions. Numbers of turnstone on non-intertidal habitats increased over the winter and use of the port was significantly greater around high tide and on colder days. The depletion model showed that under virtually all conditions, the port could support a much greater proportion of the turnstone population than current peak numbers. The use of non-intertidal habitats therefore suggests that the preferred intertidal food supplies are not currently capable of supporting the turnstone population throughout the winter. Habitat switches such as this can potentially be important advance warnings of ecological changes for species, which have not yet led to reductions in population size. [Copyright &y& Elsevier]

Abstract: Global climate change may affect the internationally important populations of waders (Charadrii) throughout their annual ranges and in a variety of ways. Within Britain, those waders that winter on estuaries are likely to be affected in two principal manners: increasingly mild winter weather already appears to have affected the distributions of the waders within Britain and rising sea level threatens to alter coastal habitats. Wader densities are largely dependent on the availability of their invertebrate prey, which, in turn depends on the nature of the estuarine sediments, itself a function of estuary morphology. Thus changes in estuary morphology, such as might occur with sea level rise, can affect wader density. Models have thus been developed that allow wader densities to be predicted from readily measured aspects of estuary morphology. The MONARCH project used case studies which employed a Geographical Information System, digital elevation models, coastline management plans and sea level rise predictions to simulate incremental increases in sea level for two estuaries. At each increment, values of morphological measurements required by the models were extracted and wader densities were modelled. In both case studies the densities of wader species favouring muddy sediments decreased under management scenarios that allowed land behind existing sea defences to be reclaimed by the sea. However, the models suggest that where changes in estuary morphology were sufficiently large to bring about a decrease in bird densities, generally as a result of increased estuary width leading to sandier sediments the associated increased area more than compensated for the assumed degradation of habitat such that larger numbers could be accommodated overall. [Copyright &y& Elsevier]

Summary 1.Human disturbance of wildlife is widely considered to be a serious conservation problem. However, despite many qualitative studies, little attempt has been made to assess whether human presence limits the number of animals that sites can support. This can be quantified by incorporating measures both of human presence and of resource distribution into analyses of population distribution. The effects of disturbance can then be measured from any reduction in resource use at disturbed sites, which in turn indicates any reduction in the number of animals supported. 2.Shorebirds are often considered highly susceptible to disturbance because of their very obvious flight responses to humans and because they use areas that are generally subject to high levels of human recreational use. 3.This study addressed the effect of human presence on the distribution of black-tailed godwits Limosa limosa islandica on coastal areas in eastern England. We identified the prey types selected by godwits and related their depletion to different levels and types of human disturbance at a range of spatial scales. 4. Three methods of analysis are described: simple regressions of the effect of human activity on the number of godwits supported; multiple regression analyses of the effect of human presence and prey density on godwit numbers; and analyses of the effect of human presence on prey density at the end of the season. The latter method assumes that godwits are responsible for the majority of resource depletion. None of the analyses showed any effect of human presence on the number of godwits supported by the food supply at any of the spatial scales examined. 5.Many species may appear to avoid human presence but this may not reduce the number of animals supported in an area. Assessing the influence of disturbance on the relationship between animal distribution and resource distribution provides a means of assessing whether numbers are constrained by disturbance. [ABSTRACT FROM AUTHOR]

The surveillance of behavioral interactions between individuals in bird populations is important to understand social dynamics and explain distribution patterns caused by competition for food and space. For waterbirds, little is known about interactions between individuals at high-tide roosts. In the present study, we used surveying with unmanned aircraft systems (UASs) to provide enhanced information on previously hidden aspects of the highly dynamic communities of roosting waterbirds in the non-breeding season. Fine-scale density estimations, derived from aerial photos obtained with UASs, were used as a measure to explain intra- and inter-species interactions for 10 selected waterbird species on a major roost site in the Danish Wadden Sea. Uniquely defined density distributions were detected, which, to some degree, were dependent on species and species size, with smaller waders exhibiting densely packed flocks (e.g., dunlin Calidris alpina and golden plover Pluvialis apricaria ), whereas larger species, such as ducks and geese (Anatidae) exhibited lower densities. Multi-species flocks were observed to occur frequently (31.9%) and generally resulted in lower densities than single-species flocks for each of the species involved. Furthermore, it has been demonstrated that UAS aerial photos can be used both to assess positions for roosting waterbirds and to classify habitats (i.e., mudflats, vegetated areas, waterline, and flooded areas) during high-tide. This facilitated the collection of precise data for temporal habitat choices for individual species when using the studied roost site. Our study highlights UAS surveys as an effective tool to gather hitherto unobtainable data for individual occurrences of roosting waterbirds on a spatiotemporal scale.

The use of intertidal areas of the Tagus estuary by birds was re-analysed, based on data from 1990 to 1993, to describe (i) the temporal and spatial patterns of use of intertidal areas, (ii) the diet of birds during winter and (iii) the habitat selection patterns of feeding birds, during winter. The most common birds in the estuary were gulls, waders and ducks. Highest densities were recorded for most species in autumn and winter. The spatial distribution of birds in the intertidal areas of the estuary did not vary significantly across seasons, although broader distributions occurred when bird populations were present in high numbers. In autumn, use of intertidal areas was highly variable. Specific areas in the estuary were identified as holding important densities of birds, or having a high species richness. The most abundant species selected feeding areas according to sediment type, although the presence of channels, saltmarsh or humans also influenced the distribution of birds. The invertebrates Carcinus maenas, Hediste diversicolor and Scrobicularia plana were identified as key prey species. Plant material was important as food for ducks. Implications of these findings for the management of the estuary are discussed. [ABSTRACT FROM AUTHOR]

The relationship between bill morphology and preening behaviour was studied in 11 species of waders. On the assumption that species with long bills might be less efficient at preening than birds with short bills, the hypothesis was tested that long-billed species devoted more time to preening than short-billed species. Results showed a positive relationship between bill length and time spent preening, supporting the hypothesis. However, bill width, bill depth and curvature were not related to preening behaviour. [ABSTRACT FROM PUBLISHER]

The relationship between relative body condition (deviation from expected mean body weight) and burying depth was investigated in five macro-zoo benthic species living in a marine intertidal habitat. Body weight increased with depth when animals of the same size were compared. The increase amounted to 50% in the clam Scrobicularia plana, ca. 40% in the worm Nereis diversicolor, 25% in the clam Macoma balthica and 20% in the cockle Cerastoderma edule and the clam Mya arenaria. Only a part of the prey was within reach of some feeding wader species. Therefore prey value may be overestimated if one does not take into account the fact that shallow and accessible prey often have a relatively poor body condition. [ABSTRACT FROM AUTHOR]