Recent changes in the abundance of British upland breeding birds

Capsule Breeding wader populations have more often shown declines than passerine populations during the last 10–20 years.

Aims To determine abundance changes in British upland breeding birds during the last 10–20 years.

Methods We re-surveyed 1348 km², in nine study areas, of the British uplands in 2000 and 2002, which had been previously surveyed between 1980 and 1991. In addition, we included data from recent repeat surveys in four other upland areas, covering approximately 365 km², to broaden the scope of our study.

Results We found evidence of widespread population declines in three species of breeding waders, Lapwing Vanellus vanellus, Dunlin Calidris alpina and Curlew Numenius arquata. Among the passerines, some species declined, including Twite Carduelis flavirostris and Ring Ouzel Turdus torquatus, while others showed strong gains, including Stonechat Saxicola torquata and Raven Corvus corax.

Conclusion Overall, abundance changes were characterized by a high degree of variability across study areas, even when close together. This variability may have been partly due to the different time intervals between the original and repeat surveys. Improved upland breeding bird population monitoring is needed to allow better detection of trends. Action is needed to restore upland breeding bird populations in areas where they have declined.     

Population estimates,trends and habitat associations of breeding Lapwing Vanellus vanellus,Curlew Numenius arquata and Snipe Gallinago gallinago in Northern Ireland in 1999

Capsule Declines in the breeding populations of Snipe, Lapwing and Curlew were recorded between April and June 1999 and compared with previous estimates in 1987.

Aims To compare populations of non-coastal breeding waders between 1987 and 1999.

Methods In 106 2 km × 2 km square tetrads, observers recorded the number of breeding pairs of waders and habitat details on 1:10 000 scale maps.

Results A significant decline of c. 60% for Lapwing and Curlew, and a non-significant decline of 30% for Snipe was recorded over 12 years. Concentrations of these species were found in County Tyrone, but Counties Antrim, Down and Armagh supported few breeding pairs of any species. Very few pairs of any species were recorded on improved grassland despite its widespread availability.

Conclusion A successful conservation strategy for these species must address the wider countryside and not just key sites. Intensive pastoral farming in upland and lowland areas and activities such as drainage and peat extraction will further reduce the suitability of open habitats for these wader species.     

Population changes of breeding waders on farmland in relation to agri-environment management

Capsule Population response of breeding waders to agri-environment management varied between management options and species; implementation has been on too small a scale to reverse national population declines.

Aims To test whether numbers of five breeding wader species have shown a more positive response between 1992 and 2005, at sites with appropriate agri-environment management, than at sites that have remained outside such schemes.

Methods Using data from 60 pairs of farmland study areas in Scotland first surveyed in 1992/93, before agri-environment scheme (AES) implementation, and again in 2005, after scheme implementation, we tested at both site and field scales whether changes in the abundance of five breeding wader species were associated with AES management options designed to benefit these species.

Results Changes in breeding wader abundance were more positive on sites in AES, especially for Northern Lapwings Vanellus vanellus and Common Redshanks Tringa totanus, even though management had not been targetted specially at breeding waders on those sites. However, AES management was associated only with modest population increase for Common Redshanks, and a reduction in the magnitude of decline for Northern Lapwings. At the field scale, there was evidence for Northern Lapwings, Common Redshanks and Common Snipe Gallinago gallinago that options which limited grazing and other agricultural activity were associated with more positive outcomes than those which also manipulated water levels.

Conclusions AES management for breeding waders slowed, and in some cases reversed, breeding wader decline at field and farm scales. These benefits were from options that limited grazing and agricultural operations during the breeding season, but not those that also aimed to raise water levels. A possible explanation is that when wetland options are applied to agriculturally marginal fields, grazing reduction or abandonment, and succession to rank vegetation cover then occur over the course of 5-year agreements, with detrimental effects for breeding waders. Verification arrangements need to be robust enough to guard against this. Levels of agri-environment provision in 2005 were too limited and too poorly targeted at remaining key areas for breeding waders to be able to halt or reverse national population declines.     

Long-term trends in the abundance of breeding Lapwing Vanellus vanellus in relation to land-use change on upland farmland in southern Scotland

Capsule A long-term decline on this habitat is shown to be associated with the intensification of agricultural management, particularly the occurrence of field drainage.

Aims To assess long-term trends in the number of breeding Lapwing and determine the relationship between these trends and changes in agricultural management on an upland study area.

Methods Breeding Lapwing were counted along two road transects in nine years between 1980 and 2002, and on one extensive plot in 1980, 1990 and 2000. Counts along the road transects were made from a vehicle and the fields used for nesting were recorded. Changes in field management along the transects were monitored annually between 1980 and 1990, and habitat composition assessed in 1980, 1985, 1990 and 2000.

Results During the first 20 years of study the number of breeding Lapwing declined substantially on all three count areas and by 77% overall, with further declines on both transects in 2002. The area of unimproved grassland and arable on these transects also declined substantially due to conversion to improved grass. Fields that comprised either unimproved grassland or arable were most likely to hold nesting Lapwing, while the chance of a field losing its nesting Lapwing was positively associated with the occurrence of drainage. Drainage and conversion to improved grass were closely linked.

Conclusions Agricultural intensification is a probable cause of decline in the number of breeding Lapwing in upland areas. Such declines may have been widespread in upland areas following increased agricultural intensification in recent decades.     

Identifying important bird habitats in a sub-arctic area undergoing rapid land-use change

Capsule Habitats in lowland South Iceland sustain bird populations of international importance, with highest densities in wet habitats.

Aims In areas important for biodiversity there is an urgent need to assess large-scale variation in the biodiversity value of habitats to inform management. We carried out a large-scale survey to assess the conservation value of sub-arctic, Icelandic bird habitats.

Methods Bird counts were carried out on 200 transects in the five most common vegetated habitat types in South Iceland. Based on these counts, breeding bird density and diversity were compared between habitats and total population sizes of common species in these habitats were calculated.

Results Overall, eight species (seven waders and Meadow Pipit) composed over 95% of all birds counted. The combined density of those species exceeded 275 birds/km² in all habitats. The two wettest habitat types had the highest density of birds.

Conclusion Wet habitats in lowland South Iceland held particularly high densities of breeding birds, notably waders, which constitute populations of international importance. Wet habitat types are generally of higher value for more species, than dryer ones.     

Declines of ground-nesting birds in two areas of upland farmland in the south Pennines of England

CapsuleWe present evidence of large declines in numbers of breeding waders and passerines in some upland areas since the 1970s.

Aims Changes in numbers of ground-nesting birds are documented for two areas of the Pennines and are qualitatively related to recent land-use history.

Methods Territory mapping was used to estimate bird numbers on two areas (76 and 99 ha) in the Pennines for which more than 10 consecutive years of data were available from the BTO's Common Birds Census archives.

Results At both sites there were large declines in Lapwing Vanellus vanellus, Snipe Gallinago gallinago, Skylark Alauda arvensis, Twite Carduelis flavirostris and Reed Bunting Emberiza schoeniclus. The two sites differed in the timing of the declines but for Twite the trends were almost identical. By the late 1990s, numbers of most ground-nesting birds were far lower than in the 1970s. There was relatively little change in numbers of species breeding at either site.

Conclusions Progressive changes in land-use, involving loss of rough grassland and a switch from dairy to sheep farming, may have contributed to the declines at one of the sites. However, there was no obvious change in land-use or habitat loss at the other site where population declines began 5 to 10 years earlier. Such declines have probably occurred widely in moorland-edge areas during the last 30 years and multiple factors may be responsible.     

Soil pH and organic matter content add explanatory power to Northern Lapwing Vanellus vanellus distribution models and suggest soil amendment as a conservation measure on upland farmland

Habitat associations of farmland birds are well studied, yet few have considered relationships between species distribution and soil properties. Charadriiform waders (shorebirds) depend upon penetrable soils, rich in invertebrate prey. Many species, such as the Northern Lapwing Vanellus vanellus, have undergone severe declines across Europe, despite being targeted by agri‐environment measures. This study assessed whether there were additive effects of soil variables (depth, pH and organic matter content) in explaining Lapwing distribution, after controlling for known habitat relationships, at 89 farmland sites across Scotland. The addition of these soil variables and their association with elevation improved model fit by 55%, in comparison with models containing only previously established habitat relationships. Lapwing density was greatest at sites at higher elevation, but only those with less peaty and less acidic soil. Lapwing distribution is being constrained between intensively managed lowland farmland with favourable soil conditions and upland sites where lower management intensity favours Lapwings but edaphic conditions limit their distribution. Trials of soil amendments such as liming are needed on higher elevation grassland sites to test whether they could contribute to conservation management for breeding Lapwings and other species of conservation concern that depend upon soil‐dwelling invertebrates in grassland soils, such as Eurasian Curlew Numenius arquata, Common Starling Sturnus vulgaris and Ring Ouzel Turdus torquatus. Results from such trials could support improvement and targeting of agri‐environment schemes and other conservation measures in upland grassland systems.     

Red foxVulpes vulpes density and habitat use in a rural area of western Poland in the end of 1990s, compared with the turn of 1970s

The red foxVulpes vulpes (Linnaeus, 1758) density and habitat use were studied in open farmland of western Poland, where forests covered only 6% of the area. During 1997-2000, nocturnal spotlight counts (in spring and early winter), the location of breeding sites and snow tracking were carried out, and the feeding habitat was described based on the stomach content of shot individuals. The average fox density estimated on the ground of spotlight counts was 1.02 individuals/km2 in spring and 1.63 ind./km2 in early winter, while the winter density obtained from the results of track counts was 1.26 ind./km². The average breeding population density, calculated as the double density of breeding sites (mean 0.31/km²), amounted to 61% of the average total spring density, which indicates the occurrence of surplus individuals in the population. The searching intensity of farmland by foxes did not changed with the increasing distance from forests, but relatively larger number of individuals was observed <0.5 km than 0.5–1.0 km away from settlements. Out of 81 identified breeding sites, 17% were located in forests and 83% in farmland. The predominant ingredients of the fox’s diet were farm livestock and small rodents (44.4 and 43.8% of the stomach content volume, respectively). The fox density in the study area was 5.4 times higher, compared with the turn of the 1970s, and changes in the habitat use consisted of more intensive occupation of open farmland and the use of human-produced food. Thus, these changes may have been among reasons of the increase in the fox density in western Poland.     

The Crested Lark Galerida cristata as an example of a bird species that benefits from agricultural management in western Poland

ABSTRACT

Capsule: The Crested Lark Galerida cristata as an example of a species which selects habitats which have undergone agricultural intensification.

Aims: To describe habitat preferences of the Crested Lark in western Poland.

Methods: We surveyed 30 randomly chosen study plots (1?km²) in western Poland to detect breeding pairs of Crested Larks. Sentinel and direct observations in the field were used to provide habitat data. Generalized linear mixed models were used to determine what type of environments habitats were selected by the Crested Larks.

Results: We recorded a total of 106 pairs of Crested Larks in 30 study plots. Birds inhabited farmland environments, where their preferred habitats included buildings, silage, and arable land with cereals.

Conclusion: Silage, which is associated with agricultural intensification within agricultural landscapes, increased the chances of the occurrence of Crested Larks.     

Does intensive goose grazing affect breeding waders?

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.     

Factors influencing the nesting success of Lapwings Vanellus vanellus and behaviour of Red Fox Vulpes vulpes in Lapwing nesting sites

Capsule Lapwing nest predation was negatively correlated to nest density, while Lapwing alarm duration in response to foxes was positively correlated with the number of Lapwing broods present.

Aims To identify factors affecting Lapwing nest predation and Red Fox search effort.

Methods Lapwing nest success was monitored at four sites in 1996, seven sites in 1997 and six sites in 1998. In 1997 we mapped the position of all Lapwing nests in order to determine distances between nests, and the proximity of linear features and potential avian predator perches to each nest. From April to June 1998 we carried out 199 hours of nocturnal observations at six Lapwing nesting sites using night vision equipment.

Results The risk of nest predation was significantly higher for more isolated nests. Nocturnal observations showed that of all the nocturnal predators, foxes were the most active at Lapwing nesting sites. However, fox search effort in Lapwing colonies was relatively low, averaging 57 s/ha per visit. Foxes spent significantly longer foraging near breeding Lapwings (measured as duration of alarm calls) when more broods were present. Fox search effort (s/ha per hour of observation) tended to be greater in areas of high waterbird density.

Conclusion The lack of positive density-dependent nest predation, the relatively low search effort of foxes near Lapwing nesting sites and the high nest success sometimes achieved in areas with foxes all suggest that Lapwing nest predation by foxes is ‘incidental’. Lapwing chicks are probably more vulnerable to predation by foxes than clutches.     

Further observations on a Callunetum intensively grazed by mountain hares (Lepus timidus L.)

Summary

Heavy utilisation by mountain hares checked the growth of Calluna so that mean height was only 12 cm thirty years after the 0.2 ha area was burnt. Cover and biomass increased gradually over the thirteen years studied, from 59 to 85% and 300 to 580 g/m² respectively. Differences in sward height were maintained, the greater utilisation of short heather being offset by greater growth. Compared to ruminant-grazed Calluneta, the hare-grazed sward had a distinctive, compact form, and biomass was great relative to cover and height because of the many shoots. Non-ericoid angiosperms had little cover.     

Synergies between site protection and agri‐environment schemes for the conservation of waders on lowland wet grasslands

Two conservation strategies have been put in place in Europe to address precipitous population declines of wading birds that breed on lowland wet grasslands. These are site protection and agri‐environment schemes (AESs) and the two are rarely compared, or their synergy assessed. Increasingly, efforts to recover populations of previously widespread species follow a landscape‐scale approach whereby habitat improvement takes place at key sites through partially overlapping protected area management and AESs. To investigate whether site protection and AESs improve the conservation status of breeding waders and how these interact, we partially repeated a 2002 survey of breeding waders on protected areas (nature reserves and Sites of Special Scientific Interest) and sites with wader‐specific AES options in England in 2009 and 2010. We then assessed the individual and combined effects of these delivery mechanisms on field occupancy, breeding density and population change of four species of declining wader (Northern Lapwing Vanellus vanellus, Common Snipe Gallinago gallinago, Eurasian Curlew Arquata numenius and Common Redshank Tringa totanus). Although results for Curlew differed from the other species, in general field occupancy was positively influenced by conservation delivery mechanisms, with the highest occupancy and breeding densities on land where site protection was combined with wader‐specific AES options. Field occupancy varied between different types of AES, with higher occupancy associated with higher‐level options in fields, particularly those on nature reserves. Outside nature reserves, the history of AES management did not influence wader populations, but within nature reserves and on fields that gained AES management between 2002 and 2009–2010, populations of Curlew and Snipe were more likely to have persisted and population change in Snipe and Lapwing was more positive. We conclude that the conservation of breeding waders will be most effective when site protection and AES management are combined on the same land. Using limited AES money to support management for breeding waders on, around and between the existing network of protected sites will protect remaining populations while presenting opportunities for population expansion in future.     

Distribution shifts in wintering Golden Plover Pluvialis apricaria and Lapwing Vanellus vanellus in Britain

Capsule The winter distribution of Golden Plover and Lapwing has shifted east since the mid-1980s, perhaps in response to climate change.

Aims To combine analyses of winter trends on wetlands and flocks on farmland to assess the current status of Golden Plover and Lapwing in one of their main wintering regions.

Methods Winter trends were derived from monthly counts on estuaries and wetlands for the period 1974–2002 (the Wetland Bird Survey). Winter distribution on farmland was assessed using casual records of large flocks and surveys of a stratified random sample of 1-km squares (the Winter Farmland Bird Survey).

Results Regional trends showed a pronounced increase in numbers of both species since 1974 on the east coast, with a smaller increase on the south coast. Numbers in the west and north tended to decline. Flocks on farmland were concentrated in eastern Britain unlike the situation in the 1980s.

Conclusions The winter distribution of Golden Plover and Lapwing has shifted to the east, resulting in large numbers on the east coast and in the arable east of Britain. The implications of this shift, especially in relation to known habitat associations, are discussed.     

Foraging ecology and spatial behaviour of the red fox (Vulpes vulpes) in a wet grassland ecosystem

We investigated diet composition, habitat selection and spatial behaviour of the red fox (Vulpes vulpes) in relation to the availability of wader nests in a coastal polder area in southwest Denmark. The predatory role of the red fox in wet grassland ecosystems has profound implications for conservation status of declining populations of grassland breeding waders. However, few studies have focussed on the foraging ecology and behaviour of the red fox in these landscapes. Faecal analyses revealed that fox diet consisted of birds (43 % of prey remains?/?32 % of biomass), rodents (39 %?/?21 %), sheep (mainly as carrion, 14 %?/?41 %) and lagomorphs (4 %?/?7 %). Charadriiformes (including waders) comprised 3–12 % of prey remains throughout the year. Telemetry data and spotlight counts indicated that foxes did not select areas with high densities of breeding waders, suggesting that foxes did not target wader nests while foraging. Foxes maintained stable home ranges throughout their lives, indicating that the area sustained a permanent fox population all year round. The population densities, estimated from spotlight surveys, were 0.74 visible foxes km^?2 (95 % CI; 0.34–1.61) on the preferred breeding habitat for waders and 1.21 km^?2 in other open habitats such as cultivated fields. Our results indicate that red fox predation on wader nests is incidental, consistent with the notion that red foxes are generalist predators that opportunistically subsist on many prey groups.     

Correlates of distribution and nesting success in a Welsh upland Eurasian Curlew Numenius arquata population

Capsule: Habitat structure and composition explained spatial variation in breeding distribution and nesting success in a declining upland Eurasian Curlew Numenius arquata population in North Wales.

Aims: To identify environmental correlates of Curlew breeding distribution, nesting success and change in distribution.

Methods: Thirty random 1?km squares stratified by historical population trend were surveyed for Curlew density and nesting success, and habitat- and predation-related variables in a landscape containing agriculturally improved farmland, and moorland that was partly protected and subject to grazing reductions for nature conservation. Analyses tested for associations between Curlew measures and environmental variables.

Results: Curlew breeding density declined by 29% between 1994 and 2008, and was highest in squares comprising a mixture of moorland and agriculturally improved farmland, and in squares with lower vegetation density and higher cover of Nardus stricta (characteristic of rough grazing). Nesting success was positively associated with cover of Trichophorum germanicum (characteristic of mire). Vegetation density was lower than average in squares with the highest Curlew densities, while in the protected area vegetation density was higher than average.

Conclusion: Habitat and vegetation variables influenced Curlew distribution and nesting success in North Wales, largely in line with previous results but with no evidence for predator-related influences. Habitat condition for Curlew in the protected area could probably be increased through targeted increases in grazing alongside the protection of priority habitats.     

A survey and GIS-based estimate of the breeding population of Great Snipe Gallinago media in Central Norway

Capsule By using a GIS-model to identify suitable breeding habitats for Great Snipe in Central Norway, we estimated a total of 276 leks holding approximately 2700 males.

Aim To estimate the size of the Great Snipe population in central parts of the species remaining breeding areas in Western Europe.

Methods GIS-analysis identified an area of 528?km² as suitable habitat for Great Snipe in the total study area (22?000?km²). Complete surveys were made in 8% of these habitats by using a subset of 53 sampling areas.

Results A total of 28 Great Snipe leks were found within the sampling areas. Ten of these were found in previously known lek areas, while 18 leks were found in areas with no previous knowledge of leks. Extrapolating the lek density and the lek size found in the surveyed areas, resulted in a total estimate of 276 Great Snipe leks holding approximately 2700 lekking males. The leks were found on open fens along the forest edge and were mainly situated on base-rich bedrocks. Mean altitude of the leks was 570?m.

Conclusion The total population of Great Snipe in Norway was previously assumed to comprise 5000–15?000 lekking males or ‘pairs'. By extrapolating the densities of leks found in Central Norway to a national scale, we expect the true breeding population of Great Snipe to be approximately 13?500 males. Changes in the elevation of the tree limit and increased overgrowth, as a result of reduced grazing pressure and/or global warming, are possible threats that may reduce the availability of preferred Great Snipe habitats and increase population fragmentation.