David J. T. Douglas

Selection of foraging habitat and nestling diet by Meadow Pipits Anthus pratensis breeding on intensively grazed moorland

Capsule Foraging sites with low vegetation height and density, but with high arthropod biomass, are selected. Aims To test the hypothesis that on intensively grazed moorland, breeding Meadow Pipits forage for nestling food where arthropod prey are most readily available, and therefore that foraging site choice is a function of prey abundance and vegetation structure. Methods Observations of adults provisioning nestlings were made from hides positioned close to 19 nests within grazed, 3.3-hectare experimental plots at Glen Finglas, Scotland. Vegetation height and density and arthropod abundance from mapped foraging sites were compared with control sites. Prey items fed to nestlings were quantified and compared with their relative abundance. Results Meadow Pipits selected foraging sites with significantly lower vegetation height and density, but with significantly higher arthropod biomass. Our data suggest that within foraging sites, Meadow Pipits select particular prey types to provision nestlings, in particular, Lepidoptera larvae, adult Tipulidae and Arachnida. Conclusions In intensively grazed upland systems, it appears that Meadow Pipits select foraging sites that optimize total food abundance and accessibility. In order to understand how anticipated changes to livestock farming in Europe will affect grassland birds, we recommend that future studies should investigate the foraging and vigilance behaviour, diet composition and breeding success of a variety of bird species provisioning nestlings under a range of livestock management scenarios.

Estimating the annual number of breeding attempts from breeding dates using mixture models

Well-established statistical methods exist to estimate variation in a number of key demographic rates from field data, including life-history transition probabilities and reproductive success per attempt. However, our understanding of the processes underlying population change remains incomplete without knowing the number of reproductive attempts individuals make annually; this is a key demographic rate for which we have no satisfactory method of estimating. Using census data to estimate this parameter from requires disaggregating the overlying temporal distributions of first and subsequent breeding attempts. We describe a Bayesian mixture method to estimate the annual number of reproductive attempts from field data to provide a new tool for demographic inference. We validate our method using comprehensive data on individually-marked song sparrows Melospiza melodia, and then apply it to more typical nest record data collected over 45 years on yellowhammers Emberiza citrinella. We illustrate the utility of our method by testing, and rejecting, the hypothesis that declines in UK yellowhammer populations have occurred concurrently with declines in annual breeding frequency.

Contrasting patch selection of breeding Yellowhammers Emberiza citrinella in set‐aside and cereal crops

Capsule No strong determinants of patch selection were found in set‐aside; in cereal fields tractor tramlines were favoured. Aims To examine and compare the factors influencing patch selection by Yellowhammers foraging for nestling food in set‐aside and cereals. Methods Observations of adults provisioning nestlings were made at 21 nests on lowland mixed farmland in northeast Scotland. Vegetation measurements and arthropod abundance from mapped foraging sites were compared with control sites within the same habitats. Results In set‐aside, no differences in vegetation and arthropods were found between foraging and control sites. In cereal fields, tractor tramlines with sparser vegetation than cropped areas were favoured. Conclusions Set‐aside typically offers a heterogeneous sward and birds foraging within this may be less restricted in their choice of accessible foraging sites, relative to the dense swards of intensively managed cereal crops. Recent policy changes have resulted in the reconversion of set‐aside to more intensive cereal cropping; this may reduce the availability of beneficial foraging habitat for farmland birds.

A global threats overview for Numeniini populations: Synthesising expert knowledge for a group of declining migratory birds

The Numeniini is a tribe of 13 wader species (Scolopacidae, Charadriiformes) of which seven are Near Threatened or globally threatened, including two Critically Endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian- Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species’ recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the current population declines of many Numeniini species and provide a template for the conservation of other groups of threatened species.

Provisioning with cereal grain depresses the body condition of insectivorous Yellowhammer Emberiza citrinella nestlings

Capsule The body condition of nestling Yellowhammers was negatively correlated with the amount of cereal grain in the diet. This supports the hypothesis that cereal grain is an inferior nestling food relative to invertebrates. Cereal grain is frequently provisioned to nestlings in a range of bunting species breeding on farmland, suggesting that invertebrates may be limiting in these habitats.

The role of fire in UK upland management: the need for informed challenge to conventional wisdoms: a comment on Davies et al. (2016)

Davies et al. [[1][1]] argue that prescribed burning is an important ecological management tool with deep, historical roots and that debate about the role of fire in management of the UK uplands should be informed and unbiased. We agree on both counts. The Royal Society for the Protection of Birds

The role of habitat change in driving Black Grouse Tetrao tetrix population declines across Scotland

Capsule Black Grouse declines across Scotland were greatest on less heterogeneous moorland, at low to intermediate altitudes and, more weakly, around post-thicket woodland. Aims To examine correlates of change in abundance of Black Grouse across Scotland. Methods Changes in abundance within 5-km squares between national surveys in 1995/96 and 2005 were modelled in relation to measures of habitat cover and woodland age derived from satellite imagery. Results Populations across Scotland were most stable where unenclosed moorland comprised rough grassland, intermediate heather cover and at higher altitude. Declines tended to be greatest in squares which had transitioned from pre-thicket to closed-canopy woodland. Conclusion Moorland will be most beneficial where it is heterogeneous in composition, and the role of woodland maturation in driving regional declines has support, albeit more weakly, at a national scale.

Native woodland creation is associated with increase in a Black Grouse Lyrurus tetrix population

ABSTRACT Capsule: Black Grouse population increases were greatest where new native woodland (NNW) within 1500 m of leks comprised approximately 30% of land area and averaged 5 years old. Aims: To examine whether change in a population of Black Grouse Lyrurus tetrix in Scotland was associated with the creation of native woodland. Methods: We examined whether lek location, size and change in size were associated with habitat and topography surrounding leks. We also examined vegetation differences in NNW and adjacent unplanted moorland. Results: From 2002 to 2012 the number of lekking male Black Grouse increased by 90%. Lek occurrence was positively associated with the amount of NNW edge habitat. Leks were larger where there was more adjacent NNW. Lek increases were greatest where NNW plots comprised approximately 30% land area, and were 5 years old, within a 1500 m radius. Plots aged more than approximately 20 years old were associated with Black Grouse population declines. NNW supported taller and denser important field-layer vegetation than adjacent moorland, likely due to grazing exclusion. Conclusions: Subject to longer-term management commitments to stimulate continued regrowth of the important field layer and maintain benefits for Black Grouse, expansion of native woodland could contribute to landscape-scale recovery of Black Grouse after decades of decline.

Changes in upland bird abundances show associations with moorland management

ABSTRACT Capsule: Changes in abundance of six bird species showed associations with moorland management. Aims: To assess responses of breeding birds to moorland management over a 14-year period. Methods: Vegetation and birds were surveyed at 2–3-year intervals and changes examined in relation to sheep and cattle grazing, vegetation burning and cutting. Results: Seven correlations between change in management and change in bird abundance were detected, and six between change in vegetation and change in bird abundance. On plots where sheep numbers declined, Golden Plover Pluvialis apricaria and Northern Wheatear Oenanthe oenanthe declined. Where a greater area was burned, Golden Plover increased in the initial post-burning period but Red Grouse Lagopus lagopus scotica declined. Eurasian Curlew Numenius arquata and Sky Lark Alauda arvensis increased where a greater area of moorland vegetation was cut. Whinchat Saxicola rubetra declined with increasing cattle numbers on a plot. Conclusions: Bird populations respond to changes in moorland management, but these changes are not always associated with detectable changes in vegetation. These responses of moorland breeding birds to management could help refine agri-environment options and other conservation interventions on moorland. Responses differed between bird species, ideally requiring site-specific planning where managing for multiple species is a goal.

Environmental correlates of breeding abundance and population change of Eurasian Curlew Numenius arquata in Britain

ABSTRACT Capsule: Across Britain, breeding Eurasian Curlew Numenius arquata are less numerous and have shown greater population declines in areas with more arable farming, woodland cover and higher generalist predator abundance. Aims: We present the first national-scale analysis of the potential drivers of Curlew population change in Britain, which is needed to guide conservation action for this globally near-threatened, declining species. Methods: Breeding Bird Survey data and environmental predictors were used to model variation in Curlew abundance in 1995–99 and 2007–11, and population change between these periods. Results: Arable farming and woodland cover were negatively associated with Curlew abundance and population declines. Curlew abundance was positively associated with extent of protected area coverage and gamebird numbers. Abundance and population change were positively associated with cooler temperatures and higher summer rainfall, but negatively associated with numbers of generalist predators. Conclusions: We found support for the negative effects of intensive agriculture, forestry, increases in generalist predator populations and climate warming on Curlew abundance and population change. Effective site protection and measures to reduce generalist predator abundance may be important conservation measures, together with improving breeding habitat quality in the wider countryside.