Habitat associations of Eurasian Skylarks Alauda arvensis breeding on Irish farmland and implications for agri-environment planning

Capsule Skylarks breeding in Ireland prefer extensive grassland habitats and almost completely avoid tillage habitats.

Aims To describe the distribution and habitat use of breeding Skylarks in Ireland, particularly in lowland agricultural habitats, and to use this information to inform conservation measures for this species.

Methods Countryside Bird Survey (CBS) and Farmland Bird Project (FBP) data were examined to determine large-scale (national) distribution and habitat selection, in addition to smaller-scale (farm- and field-level) habitat use. The CBS is a national breeding bird monitoring scheme involving 397 1-km squares. The FBP collected detailed bird and habitat data from 122 farms.

Results CBS and FBP data both showed significant regional differences in breeding Skylark densities, with the highest relative abundances in the northwest and west. Dry grassland/grass moor habitats supported the highest densities of breeding Skylarks in the CBS, which were significantly higher than in improved grassland or tillage. At the farm-level, Skylark numbers were positively related to wetland habitats but negatively associated with trees in field boundaries, dense ground vegetation and overall density of farm boundaries. At the field-scale, larger fields and unimproved grasslands were preferred.

Conclusion Agri-environment measures tailored to region-specific requirements and to the relatively local habitat preferences of target species are required if population declines of species of conservation concern, including Skylarks, are to be reversed.     

Habitat associations and breeding bird community composition within the city of Bristol,UK

Capsule Different urban breeding bird communities are associated with different habitat types, but, although community species diversity varies significantly, total bird density does not.

Aims To investigate the association between breeding bird communities and habitats within Bristol, UK and how these communities vary in terms of species diversity and total bird abundance.

Methods Breeding density data for 70 species in the metropolitan area of Bristol, UK were subjected to de‐trended correspondence analysis to identify the number of different communities present and their indicator species. These data were then used to identify patterns of habitat association with each community and differences in species richness and total bird density.

Results Three communities were identified: a rural community associated with woodland, managed grassland and inland water; a suburban community associated with buildings and residential gardens; and an intermediate community that shared some of these habitat characteristics. Species richness, but not total bird abundance, was lowest in the suburban community.

Conclusion The diversity of species in urban areas appears to be most dependent upon the availability of patches of natural and semi‐natural habitats. Residential gardens support fewer species, but those species that are present may be found at high densities.     

Breeding bird populations of Irish peatlands

Capsule Peatlands are very important habitats for birds despite low species diversity.

Aims To describe the variation in breeding bird populations that occur on different types of Irish peatlands and their associated habitat characteristics.

Methods Bird abundance and diversity were compared between four peatland habitat types (fens, raised bogs, Atlantic blanket bogs and montane blanket bogs) at 12 study sites using transects. Various measures of habitat quality were also taken at each location.

Results Only 21 species were recorded during the study, with Meadow Pipit Anthus pratensis and Sky Lark Alauda arvensis accounting for over 80% of all birds recorded. Fens had greater bird species diversity and densities than the other three peatland types. Raised bogs, Atlantic blanket bogs and montane blanket bogs were very similar in terms of their avian diversity. Each of the recorded bird species was associated with different aspects of the peatland habitat.

Conclusion This study shows that despite the relatively low avian species diversity of Irish peatlands, they are of enormous conservation value due to the presence of species of high conservation concern such as Willow Ptarmigan (Red Grouse) Lagopus lagopus and Eurasian Curlew Numenius arquata.     

The species diversity of New Zealand forest birds: Some possible consequences of the modification of beech forests

The literature on forest birds in New Zealand is examined to see if the consequences of forest modification can be predicted. Forty‐four samples of birds, from North, South, and Stewart Islands, are classified according to four habitats of origin: virgin forest, modified forest, exotic forest, and suburban bush and gardens. An index of bird species diversity (BSD) is calculated for comparison, and where possible densities are tabulated.

Limited samples from modified forests in Westland suggest that the number of species is relatively smaller but the bird density is higher after modification. There do not seem to be any published quantitative data about birds in Westland exotic forests.

Data from the whole of New Zealand show that bird density increases as forest habitats change from virgin, to modified, to exotic, to suburban bush and gardens. BSD and equitability do not differ among these habitats. The number of species of native birds and their diversity decline as the habitat is more extensively altered, but their total density tends to remain constant. More productive forest habitats have the same BSD as other habitats. Diversity seems to be limited by the small variety of bird species available, and the more productive habitats could probably support more species. All habitats had a much higher diversity of birds before colonisation by the European.     

Habitat specialization of birds in the Czech Republic: comparison of objective measures with expert opinion

Capsule Expert‐based classification of bird species as habitat specialists and as generalists agrees with objective measures of species’ habitat requirements based on large‐scale monitoring data.

Aims To compare habitat specialization of 137 common bird species breeding in the Czech Republic using three different measures and to test their relationships to species’ abundance and habitat associations.

Methods Data on bird abundance and surveyed habitats were collected through a standardized monitoring scheme of common breeding species in the Czech Republic. From these data we calculated a quantitative species specialization index (SSI). Canonical correspondence analysis (CCA) was applied to calculate species’ habitat niche breadth and the level of association of each species to the main habitats. A panel of 11 local bird experts classified each species as habitat generalist or habitat specialist.

Results Species classified as habitat specialists by expert opinion showed higher habitat specialization according to the SSI, as well as according to CCA‐based habitat niche breadth. These species were also more closely associated with one of the main habitat types. These relationships were significant even after controlling for abundance.

Conclusions As expert opinion accords with the level of species’ habitat specialization expressed using two quantitative objective measures, we suggest that these characteristics reflect real interspecific variation in the breadth of habitat requirements in birds. Interspecific differences in habitat specialization are not caused solely by the variability in abundance among species.     

The effect of conservation interventions on the abundance of breeding waders within nature reserves in the United Kingdom

Breeding populations of many wading birds have declined globally, primarily caused by habitat degradation and loss. In the UK, population declines have been particularly notable on lowland wet grasslands. In response, some areas of lowland wet grassland have been restored and are under ongoing management to improve the breeding conditions of target species. Here, we assess the efficacy of management measures using a Bayesian framework and controlling for confounding factors. We focus on four wader species, Northern Lapwing Vanellus vanellus, Eurasian Curlew Numenius arquata, Common Snipe Gallinago gallinago and Common Redshank Tringa totanus, that breed in numbers on wet grassland reserve sites in the UK. We collated annual site-specific climate variables, management information (e.g. the creation of wet features and predator control measures) and bird counts between 1994 and 2018. We found the effects of conservation actions varied between intervention types and species. For Lapwing and Redshank, excluding predators by predator-exclusion fencing, especially in combination with fox control, was generally associated with higher breeding counts. For all study species, sites with longer histories of management were associated with higher breeding numbers, with the effect of site age being particularly notable for management on former arable land. Our findings support the effectiveness of targeted conservation actions to achieve high numbers of breeding waders on lowland wet grassland reserves, and also highlight the value of consistent and reliable monitoring data.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Habitat use and densities of co‐existing migrant Willow Warblers Phylloscopus trochilus and resident eremomelas Eremomela spp. in Zimbabwe

Capsule Migrant Willow Warblers occupy more woodland types and occur at higher densities than ecologically‐similar resident Afrotropical warblers.

Aims To compare population densities of Willow Warblers and eremomelas in adjacent acacia, mopane and miombo woodlands, and assess the abundance of potential invertebrate prey in each habitat type, in order to investigate whether Palearctic migrants use more open habitats and are more flexible in habitat use than their Afrotropical counterparts in the same feeding guild.

Methods Using distance sampling we carried out four replicated sets of point counts in acacia woodland and three sets of counts in miombo and mopane between December 1999 and February 2000. We noted the tree species in which we saw warblers foraging and took beating‐tray samples of potential arthropod prey present on tree foliage in each of the three habitats.

Results Willow Warbler density in acacia woodland increased from 1.80 ± 0.54 (se) birds/ha in early December to 7.15 ± 1.41 birds/ha in late January after influxes of later arrivals. Densities of Willow Warblers in miombo and mopane were much lower (1.14 ± 0.28 and 0.38 ± 0.23 birds/ha, respectively) and did not show significant changes. Burnt‐necked Eremomelas averaged 0.74 ± 0.34 birds/ha in acacia woodland, and in miombo densities of Green‐capped and Yellow‐bellied Eremomelas were 0.23 ± 0.17 and 0.34 ± 0.26 birds/ha, respectively. Densities in mopane were too low to estimate reliably. Willow Warblers and Green‐capped Eremomelas showed some apparent preferences in tree species used for foraging but differences in tree use were not obviously related to the abundance of arthropod taxa present as potential prey.

Conclusion Willow Warblers occupied more habitats at greater density than similar Afrotropical warblers. They appear to favour acacia, but their settlement patterns and the reasons for disparities between densities of immigrants and residents are unclear.     

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.     

Winter habitat associations of seed-eating passerines on Scottish farmland

CapsuleExtensive surveys highlighted the importance of weedy fodder brassicas, stubbles and open farmland landscapes to declining birds.

Aims To determine habitat associations of seed-eating passerines on Scottish farmland in winter, and recommend appropriate conservation measures.

Methods Transect surveys were carried out on farmland in 100 1-km squares, containing 2885 fields, across Scotland. Birds, crops, field boundary features and weeds were recorded on three visits. Bird–habitat associations were examined using logistic regression models.

Results Seed-eating passerines were highly concentrated: 100 fields (1.4% of the area surveyed) held half the total count. The highest field densities of birds were recorded in fodder brassica crops and stubbles, averaging 12 and 3.3 birds/ha respectively. In fodder crops, weedier fields held many more birds. Multiple regression analysis emphasized the importance of fodder crops, stubbles and farmyards and suggested that declining bird species preferred more open landscapes. Several bird species were associated with fields containing very weedy patches, and/or weeds of the family Chenopodiaceae. These features were commonest in fodder brassicas. Many of the crop types found to be important as bird habitats in winter have declined in area in Scotland; the availability of seed food in such habitats may also have diminished. Such changes may partly explain recent population declines.

Conclusions Agri-environment measures for seed-eating passerines should support the widespread provision of small areas of seed-rich wintering habitats, such as weedy fodder brassicas and stubbles, especially in open (0–10% woodland and scrub) landscapes in areas with mild winters.     

Combining archive territory mapping data and aerial photography to investigate bird–habitat relationships: a case study from the Lincolnshire coast

Capsule Habitat associations of breeding birds in a complex coastal environment are clear, interpretable and mostly consistent between years.

Aims To match archive territory mapping data with historical aerial photographs and develop data handling and analytical techniques for the study of bird–habitat relationships.

Methods Bird registrations were digitized from archive British Trust for Ornithology Common Birds Census maps and habitat characteristics from contemporaneous aerial photographs. The resulting maps were overlaid and ranks of habitat preference for 15 species calculated using compositional analysis. Similarity analysis identified species with consistent habitat profiles across years. Cluster analysis identified groups of species with similar patterns of habitat use.

Results A total of 5400 registrations of 15 species in 14 habitats were analysed. Of these, 13 species showed stable patterns of habitat association across survey years. Clear differences and similarities in habitat preferences among the species were identified. The results may be used to inform conservation and management programmes in this and similar environments.

Conclusions Extensive archives of bird survey data can be used to study bird–habitat relationships and to measure the effects of natural and anthropogenic environmental change if contemporaneous aerial photographs can be sourced.     

Effect of boundary vegetation and landscape features on diversity and abundance of breeding bird communities of abandoned crop fields in southwest Poland

Capsule The number of territories of birds nesting in abandoned crop fields was most strongly positively affected by field size and the presence of a railway embankment.

Aims To assess the influence of different habitat features on the number of birds nesting in abandoned crop fields.

Methods A breeding bird survey was conducted in spring 2002 using the mapping method on 67 abandoned fields located in southwest Poland. The associations between eight habitat features of the abandoned fields and the numbers of particular species and groups of birds, as well as the whole bird community, were tested with a glm.

Results The models for eight individual species revealed the following ranking, in terms of number of species affected by each predictor: area of fields (5), railway embankments and adjacent crop fields (4), roads and power lines (2), and number of trees (1). The number of the most numerous group of birds (species nesting on the ground, 79% of all breeding pairs) was affected by four predictors: field area, railway embankments, power lines and roads. The number of all birds was affected by six predictors: field area, railway embankments, power lines, roads, ditches and trees.

Conclusion Limited effects of trees, hedgerows and ditches on the number of territories suggest that abandoned fields without woody vegetation are attractive breeding habitats for many farmland birds. One of the effective ways of protecting farmland bird species in central Europe may be the preservation of abandoned fields in their present form, especially those <5 ha in area.     

Long-term population declines in Danish trans-Saharan migrant birds

Capsule Long-distance migrant birds show less favourable trends than sedentary/short-distance species.

Aims To use breeding bird surveys to contrast population trends amongst common species according to their migration pattern.

Methods Changes in abundance of 62 Danish breeding sedentary, short-distance (Europe/North Africa) or long-distance (trans-Saharan) migrants were described by fitting log linear regression models to point-count census data gathered during 1976–2005.

Results Trans-Saharan migrants declined by 1.3% per annum during this period, while short-distance migrants and sedentary species increased by 1.4% and 1.0% per annum, respectively. There were no significant decadal declines amongst species using different summer breeding habitats, except for wetlands, and there was no consistent variation in trends associated with wintering regions or habitats or diet.

Conclusions More information is urgently needed on diet, feeding ecology, habitat requirements, winter distribution and intra-African movements of the commoner European summer visitors to identify causes of the declines and highlight when in the annual cycle detrimental effects occur. Studies linking individuals on their breeding, staging and wintering grounds are especially needed. Danish trends resemble those from elsewhere in Europe, confirming that restoration to favourable conservation status requires inter-continental action to meet European and global targets to reduce or halt biodiversity loss.     

Habitat associations and breeding success of the Chaffinch Fringilla coelebs

Capsule Population trends for Chaffinch on farmland are unlikely to be explained by their preference for non-crop habitats alone.

Aims To investigate the importance of non-cropped habitats for Chaffinch territory distribution, breeding success and foraging habitat selection in Scottish farmland.

Methods Territory distribution, nesting success and foraging behaviour of adults feeding chicks at the nest were recorded and related to habitat composition on two Scottish lowland farms.

Results Higher Chaffinch territory densities were associated with the presence of hedgerows, trees and grass leys, whereas lower densities were found adjacent to winter Barley. Nests were predominantly located in conifer trees and hedgerows. Trees were selected preferentially for foraging. Poor breeding success was detected in nests associated with cereal crops and wider field margins. Farmland in Scotland supported much lower territory densities than in England.

Conclusion Chaffinches rely predominantly on non-cropped habitats for territory establishment, nesting and foraging habitats. Differences in habitat composition between England and Scotland may explain differences in territory densities. However, the Chaffinch's preference for non-crop habitats is unlikely to explain its population trends alone. Immigration from other habitats and/or a decrease in inter-specific competition for resources may also have contributed to the increase in the national farmland Chaffinch population.     

Overcrowding as one of the causes of dispersal of young Tree Sparrows

Capsule Low and variable encounter rates of birds in fragmented arctic‐alpine habitats add difficulty to monitoring their breeding populations.

Aims To quantify seasonal variation in the encounter rates (apparent abundance) of breeding birds in arctic‐alpine habitats in Scotland.

Methods Birds were sampled from 15 repeated linear transects between April and August in 2005 and 2006. glmms (and for scarcer species glms) were used to investigate how the apparent abundance of different species varied between months and years.

Results Three arctic‐alpine specialists (Rock Ptarmigan, Eurasian Dotterel and Snow Bunting) were recorded. The 24 other species recorded included more widely distributed upland species, generalists that also used arctic‐alpine habitats and also some transient species from lower altitude. Overall encounter rates were low (only exceeding 1 bird km^?1 in any month for one species; Meadow Pipits) with marked variation between months. The pattern of seasonal variation in encounter rates varied markedly between species.

Conclusions Low encounter rates and marked variation in apparent abundance will render more difficult efforts to monitor birds in marginal and fragmented areas of arctic‐alpine habitats. Particularly relevant is the potential for changes in the timing of breeding and seasonal movements to influence encounter rates and be falsely interpreted as changes in actual abundance. Monitoring in arctic‐alpine habitats should include both specialist and non‐specialist birds of that habitat, as the latter may be more numerous and, therefore, provide supplementary evidence of temporal or seasonal change.     

湿地公园鸟类栖息地营建研究——以北京琉璃河湿地公园为例

北京地区处于全球候鸟东亚-澳大利西亚的迁徙路线上,是候鸟重要的迁徙路线,近些年,随着人为活动的影响,该区生境破碎化问题愈发突出,直接威胁着本地鸟种和过境迁徙鸟类的生存。为达到保护鸟类多样性的目的,需开展相应的栖息地恢复工作。不同生态类群的鸟类对栖息地有着不同的要求,相同鸟种在不同空间、季节和生活期对栖息地的选择也有着不同的特点。因而,鸟类栖息地恢复应针对目标鸟种根据其繁殖特点、巢位空间分布、食性特点、活动空间特点等进行规划营造。以北京房山琉璃河湿地公园为例,针对项目所在区域的鸟类分布特征,确定目标恢复鸟种,结合项目区现场条件,围绕目标鸟种对于栖息地水系、植被等方面的需求,从岸线重塑、水深设计、植物配置、生态鸟岛等方面规划设计鸟类栖息地修复措施。     

Effects on bird abundance and species richness of edge restructuring to include shrubs at the interface between conifer plantations and moorland

Capsule?Bird species richness and (for most species) abundance were positively related to the extent of shrub cover at the interface between conifer plantations and moorland, but it appears that responses to shrub development vary between different bird guilds.

Aims?To assess the bird assemblages in both winter and breeding seasons at the interface between managed conifer plantations and open moorland, where that interface had been restructured to include a mosaic of shrubs and open ground.

Methods?Timed point counts were used to sample the birds at restructured plantation – moorland interface areas and also in neighbouring plantations (post- and pre-thicket age classes) and neighbouring moorland. Associations between species richness and abundances with measures of shrub cover and composition were assessed using GLMMs.

Results?A total of 60 bird species were recorded including 29 on lists of conservation concern, most of which were associated with shrub interface habitats. Species richness and, for most species, abundance were positively related to the extent of shrub cover. Positive relationships between shrub cover in interface areas and the abundance of some species in neighbouring plantations and open moorland suggested a resource subsidy to birds in neighbouring habitats. In contrast, some birds tended to be less abundant in plantations next to areas with more shrub cover. These species were more abundant in the shrub itself, suggesting redistribution by species with a preference for early successional shrub habitats.

Conclusions?The long-term management of shrub, especially with regard to successional development, is a challenging aspect of forest and landscape management that deserves further study.     

Entry Level Stewardship may enhance bird numbers in boundary habitats

Capsule Hedgerows and margins managed under agri‐environment schemes appear to attract greater numbers of some farmland bird species.

Aims To examine fine‐scale habitat associations of farmland birds to determine whether Entry Level Stewardship, the wider countryside agri‐environment scheme for England, provides a mechanism for affecting population changes.

Methods Ninety‐seven 1‐km squares in East Anglia were surveyed to create two‐dimensional habitat maps showing the location of all habitat patches and associated stewardship management. Modified territory‐mapping techniques were used to produce relative estimates of bird numbers within each discrete habitat patch within each square. The effect of Entry Level Stewardship on species density was then analysed using glms.

Results Boundaries managed under Entry Level Stewardship appeared to attract higher densities of Blue Tits, Dunnocks, Common Whitethroats and Yellowhammers. Margins managed under the scheme also had higher densities of Yellowhammers.

Conclusions Existing boundary habitat management under Entry Level Stewardship may provide a mechanism for increasing the populations of some farmland bird species. Boundary management options should continue to be promoted, although rebalancing the scheme more towards in‐field options is likely to be more widely beneficial.     

Habitat associations and communities of breeding birds in the highlands of south-west Jordan

Abstract

Habitat associations and communities of breeding birds were studied for the first time in a semi-arid region in the southern highlands of Jordan. Birds were censused and habitat variables estimated in different habitat types, ranging from steppe to open, Mediterranean-type woodland. The variation of abundance of several species was explained adequately with multiple regressions of up to five habitat variables. A distinct bird community was identified by using principal component analysis on the highland plateau (e.g. Short-toed Lark, Isabelline Wheatear), in steppe habitats modified by dry farming methods. The plateau was identified as a transition zone of Palaeoxeric/Turkestanian and Mediterranean faunal types. The remainding cluster included species of diverse origins (Palaearctic, Mediterranean, Saharo-Sindian, Afrotropical and others). It was subdivided into three bird assemblages with preferences for following habitat types: Mediterranean-type open woodlands (e.g. Syrian Serin), dwarf shrub formations of higher altitudes (e.g. Spectacled Warbler), dwarf shrub formations, including clearings and the edge of woodlands at lower altitudes (e.g. Scrub Warbler).