Will J. Peach

Supplementary feeding of mealworms enhances reproductive success in garden nesting House Sparrows Passer domesticus

Capsule Mealworm provisioning increased clutch size and chick survival in garden-nesting House Sparrows. Aim We tested experimentally whether invertebrate availability limits reproductive success in garden-nesting House Sparrows Passer domesticus. Methods Mealworms were provided in feeders as supplementary food for House Sparrows nesting in suburban and rural domestic gardens. Surveys of provisioning adult sparrows were used to determine mealworm usage and nest outcomes were monitored. Results Provisioning parent sparrows travelled up to 165u2005m from nests to collect mealworms, but most usage of supplementary food was confined to nests within 30u2005m of feeders. Mealworm provisioning increased clutch size and chick survival which together increased fledgling production by 55%. Conclusions Management interventions that increase the availability of invertebrate prey for garden-nesting House Sparrows have the potential to stimulate substantial increases in reproductive success.

Twenty years of local farmland bird conservation: the effects of management on avian abundance at two UK demonstration sites

Capsule At two demonstration farms, Game & Wildlife Conservation Trusts Loddington Farm in Leicestershire and Royal Society for the Protection of Birdss Hope Farm in Cambridgeshire, targeted management led to much faster increases in avian abundance than in the surrounding regions. Aims To compare changes in avian abundance at Loddington Farm since 1992 and Hope Farm since 2000, and relate these to regional trends in bird abundance and to the habitat and predator management conducted at the two sites. Methods Loddington Farm is a mixed arable 292-ha farm in a partially wooded landscape in Leicestershire. It was managed as a shoot from 1993 to 2002, combining habitat management with predator control (stopped in 2002) and winter grain provision (ceased in 2006). Hope Farm comprises a 181-ha mainly arable farm in an open landscape in Cambridgeshire, where habitat management for farmland birds has taken place since 2002. At both sites, breeding bird abundance has been monitored annually. Information on farm management was translated into three variables measuring annual provision of nesting cover, summer food and winter food. The number of Carrion Crow and Magpie territories was used as an index of predator abundance. Results Avian abundance increased at both farms much faster than within their respective regions. Recovery of priority species was positively correlated with the provision of summer foraging habitats and negatively correlated with the provision of supplementary grain during winter. The latter finding was counterintuitive and may reflect an increase in hedgerow provision that coincided with the cessation of grain provision at both farms. The increase in bird abundance was not sustained at Loddington Farm in the absence of predator control, although it was at Hope Farm where predator densities were markedly lower. Conclusion The data from Hope Farm suggest that where predator densities are relatively low (<3 Crowu2009+u2009Magpie pairs/km2 locally, <0.2 Foxes/km2 in spring regionally), recovery of farmland birds can be achieved through habitat management alone. Where predator densities are high (>5 corvid pairs/km2 and >1.1 foxes/km2), as at Loddington Farm, species recovery, particularly of open-cup nesting species, may require predator control as well as habitat management. Further study is needed to confirm this tentative conclusion from only two sites.

Can hedgerow management mitigate the impacts of predation on songbird nest survival

Nest predators can have significant impacts on songbird reproductive success. These impacts may be amplified by habitat simplification and here we test whether sympathetic management of farmland hedgerows can reduce nest depredation, especially by corvids. We test whether songbirds select nest sites according to structural features of hedgerows (including nest visibility and accessibility), and whether these features influence nest predation risk. Songbirds selected nesting sites affording higher vegetation cover above the nest, increased visibility on the nest-side of the hedgerow and reduced visibility on the far side of the hedge. Nest survival was unrelated to corvid abundance and only weakly related (at the egg stage) to corvid nest proximity. Nest survival at the chick stage was higher where vegetation structure restricted access to corvid-sized predators (averaging 0.78 vs. 0.53), and at nests close to potential vantage points. Overall nest survival was sensitive to hedgerow structure (accessibility) particularly at low exposure to corvid predation, while the overall impact of corvid exposure was dependent on the relationship involving proximity to vantage points. Nest survival over the chick stage was much higher (0.67) in stock-proof, trimmed and mechanically cut hedgerows, (which tended to provide lower side visibility and accessibility) than in recently laid, remnant or leggy hedgerows (0.18). Long-term reductions in the management of British hedgerows may therefore be exposing nesting songbirds to increased predation risk. We recommend regular rotational cutting of hedgerows to maintain a dense woody structure and thereby reduce songbird nest predation.

Breeding ecology of Yellow Wagtails Motacilla flava in an arable landscape dominated by autumn-sown crops

Capsule Yellow Wagtails successfully raised two consecutive broods in landscapes dominated by autumn-sown crops and did not require spring crops or fallow plots for later nesting. Aims To assess whether arable landscapes dominated by winter cropping provide habitats that allow Yellow Wagtails to raise two successful broods. To assess the utility of spring cultivated agri-environment fallow plots as a nesting and foraging habitat for Yellow Wagtails. Methods Nesting success and foraging behaviour of Yellow Wagtails was monitored on lowland arable farmland dominated by winter cropping during two successive breeding seasons. Results Yellow Wagtails successfully raised first and second broods mainly in winter cereals, with later nests being more successful. Some nests were initiated in bean fields where egg-stage failure rates were high, probably as a consequence of depredation. Fallow plots were not used for nesting but, along with other areas of sparse vegetation, were regularly used for foraging. Conclusions Yellow Wagtails breeding at relatively low densities achieved high rates of reproductive success in a landscape dominated by winter cereals and with few spring-sown crops. This study suggests that spring-sown crops may not be necessary for Yellow Wagtails to rear two successful broods each summer within arable landscapes.

Influence of crop type and Agri-Environment management on the use of over-winter stubbles by farmland birds in England

Capsule Bunting densities decreased in winter wheat stubbles between November/December and January/February, but not in spring barley stubbles. Aims We investigated bird use and vegetation in relation to Agri-Environment Scheme over-winter stubble type and preceding crop. Methods We surveyed 15–17 fields each of: ‘standard’ Agri-Environment Scheme stubble on Entry Level Stewardship farms (EF6); ‘standard’ Agri-Environment Scheme stubble on Higher Level Stewardship farms (HF6); stubble preceded by low-input cereal (HF15); extended over-winter stubble (EF22) and non-Agri-Environment Scheme stubble in November/December 2011 and January/February 2012. Stubbles were preceded by spring barley or winter wheat crops. Results Previous cropping and time of year were the main factors influencing bird densities: bunting densities declined in winter wheat stubbles between surveys, but not in spring barley stubbles. Conclusion The main factor limiting the ability of over-winter stubbles to reverse national population trends of farmland birds is likely to be scale of provision. However, this study suggests that selecting spring barley crops to leave as over-winter stubbles may benefit granivorous farmland birds.

Effects of fertilizer application on summer usage of cereal fields by farmland birds in central Hungary

Capsule Despite negative effects of inorganic fertilizer on weeds and invertebrates in cereal fields, impacts on bird usage were weak and non-linear. Aim To assess the effects of inorganic fertilizer application to winter cereals on breeding-season usage by farmland birds. Methods We measured bird usage of winter-sown cereal fields across a gradient of inorganic fertilizer inputs and tested for influences of management intensity and availability of semi-natural habitat on species richness and abundance of farmland birds. Results Avian species richness and bird abundance were unrelated to fertilizer inputs, and declined at higher levels of total vegetation cover. Sky Lark abundance increased, while Yellow Wagtail counts declined with the extent of semi-natural habitat. Sky Lark abundance increased with vegetation cover and peaked at an intermediate level of weed species richness. Yellow Wagtail counts peaked at intermediate levels of fertilizer inputs. Conclusions Compared with much of western Europe, cereal production in central Hungary is characterized by modest fertilizer inputs and large areas of semi-natural habitat. There was little evidence that increased applications of fertilizer are likely to have negative impacts on farmland birds, although increased application might reduce habitat suitability for Yellow Wagtails. Loss of semi-natural habitat is likely to have negative impacts on Sky Larks.

Effect of plot type, age and date on seed depletion and bird use of Wild Bird Seed Mixtures in England

Capsule Bird and seed abundances decreased in both standard and enhanced Agri-Environment Scheme seed mixtures (plots of seed-bearing crops) between November and February. Aims We analysed effects of Agri-Environment seed mixture type (‘standard’ or ‘enhanced’), plot age and non-target species on seed and bird abundance. Methods Surveys were conducted in November/December and January/February on 36 standard and 19 enhanced seed mixtures to test effect of plot type and age on abundance of buntings, finches and seeds. Results Bunting and finch densities decreased between January/February and November/December. Seed decreased by approximately 70% between surveys, plot type did not affect depletion. Second-year plots contained nearly 90% less seed, and non-significantly lower bunting and finch densities. Bunting densities were positively related to cereal seed abundance, and finch densities to non-cereal seed; these relationships did not differ between plot types. There was no evidence that non-target species affected use of seed mixtures by target species. Conclusion There was no evidence that plot type affected seed or bird abundances. Increased quality and uptake of Agri-Environment Scheme seed-rich habitats (seed mixtures and over-winter stubbles, possibly alongside well-implemented supplementary feeding) is needed to provide late-winter seed, especially cereals for species of conservation concern.

Population estimates and changes in abundance of breeding waders in Northern Ireland up to 2013

Capsule The third survey of breeding waders in Northern Ireland showed large declines in the abundance of Eurasian Curlew, Northern Lapwing and Common Snipe since 1987. Aims To estimate the size of the breeding populations of selected breeding wader species in Northern Ireland in 2013 and population changes since previous surveys in 1987 and 1999. Methods Complete surveys of all potentially suitable breeding habitats were undertaken in randomly selected 2u2005km squares in each of 146 land-dominated 10u2005km squares across Northern Ireland. Square selection and a two-visit field method replicated previous surveys conducted in 1987 and 1999. Results Northern Ireland breeding populations of Eurasian Curlew, Northern Lapwing and Common Snipe were estimated to be 526 (±95% CI: 252–783), 860 (277–1545) and 1123 pairs (527–1782), respectively. These estimates represent significant declines in abundance of 82%, 89% and 78% respectively since 1987. Conclusion Breeding populations of Eurasian Curlew, Northern Lapwing and Common Snipe have declined dramatically since 1987 and the distributions of all species are becoming increasingly fragmented and restricted towards the western counties of Tyrone and Fermanagh. Urgent conservation action is needed to prevent the disappearance of these species from the wider countryside.

Depleted suburban house sparrow Passer domesticus population not limited by food availability

Little is known about the environmental factors that limit the demography and abundance of wild vertebrates in highly modified urban environments. The House Sparrow Passer domesticus is a globally widespread species whose urban populations have recently undergone substantial declines particularly in Europe. The environmental drivers of these declines remain unknown. In a previous study we showed that invertebrate availability during the breeding season limited reproductive success but not population size in a suburban sparrow population. In this study we test experimentally whether year-round food availability limits demography and population size. Supplementary feeding involved the provision of invertebrate prey (during the breeding season) plus unlimited high-energy seed (year-round) at 33 sparrow colonies spread across suburban London over two successive calendar years. Thirty-three unfed colonies served as controls. Supplementary feeding increased fledgling abundance, but had no impact on overwinter survival or population size. We conclude that this depleted suburban sparrow population is not limited by food availability, and conservation efforts based primarily on food provision are unlikely to succeed. We also tested whether cross-colony variation in sparrow abundance was correlated with a set of potential environmental stressors including measures of predator abundance and pollution. Sparrows were more abundant, or showed more positive temporal changes in abundance, at localities containing large areas of seed-rich habitat and low levels of nitrogen dioxide air pollution. Further research is merited into the potential impacts of air pollution on the fitness of urban birds.

Agri-environment scheme enhances breeding populations of some priority farmland birds in Northern Ireland

ABSTRACT Capsule: The abundance of Tree sparrow Passer montanus, House Sparrow Passer domesticus and Yellowhammer Emberiza citrinella, three priority farmland birds, increased over a 5-year period in response to a targeted agri-environment scheme (AES). Aims: To assess the effects of a targeted AES on the abundance of a suite of farmland bird species over a 5-year period. Methods: We compare temporal changes in abundance of 12 farmland bird species of conservation concern on 33 AES and 22 control farms in County Down, Northern Ireland. Five of these species were designated targets for conservation action under the Countryside Management Scheme (CMS). Results: CMS management was associated with more positive changes in abundance for three of the five target species and more negative changes for one target species (albeit caused mainly by a large reduction at a single farm). CMS management had little influence on the abundance of non-target species or on avian species richness. Farm-scale changes in abundance were generally unrelated to the extent of local CMS provision, the only exception involved House Sparrow and seed-rich winter habitats. Conclusion: This study demonstrates that generic AES land management can improve the population status of target farmland birds on farms with AES management.