Agricultural habitat-type and the breeding performance of granivorous farmland birds in Britain

Conservation concern about granivorous birds has led to the implication of changing agricultural practices as causes of widespread population decline. We investigate relationships between breeding performance and the agricultural environment for ten granivorous farmland bird species (Stock Dove Columba oenas, Skylark Alauda arvensis, Tree Sparrow Passer montanus, Chaffinch Fringilla coelebs, Greenfinch Carduelis chloris, Linnet C. cannabina, Bullfinch Pyrrhula pyrrhula, Reed Bunting Emberiza schoeniclus, Yellowhammer E. citrinella and Corn Bunting Miliaria calandra). We analyse long-term, extensive data from the British Trust for Ornithology's Nest Record Scheme on breeding performance per breeding attempt with respect to farmland type (arable, grazing or mixed) and time (pre- and post-1975–76). The influence of habitat is investigated at two different scales: within the nesting territory and at the landscape level. Relationships between farmland type and (temporal changes in) breeding performance tended to be species-specific, but a few patterns were each common to some species. Improvements in breeding performance occurred across all three farmland types for four declining species. Grazing farmland seems to have deteriorated as breeding habitat for Linnet and arable/mixed farmland for Reed Bunting. Mixed farming at the territory scale supported better breeding performance for four species, three of which (Bullfinch, Yellowhammer and Corn Bunting) have declined concurrently with mixed farming. Pastoral landscapes supported better breeding performance for up to seven species, six of which have undergone large declines. Arable landscapes supported better breeding only for the stable or increasing Chaffinch and Greenfinch. Different relationships between farming regime and breeding performance were found at the two scales considered.     

The Fulmar population of Britain and Ireland, 1959

Despite the severity of the 1978/79 winter, at least 1,714 Blackcaps were reported during a special survey; these were heavily concentrated in western and south-western counties. An increase over recent decades in the numbers of Blackcaps wintering in Britain and Ireland is correlated with expansion of north European breeding populations and with a rise in numbers of autumn migrants passing through British east coast bird observatories. Successful overwintering here is attributed to the way the birds have adapted to taking artificial foods at garden bird tables.     

Abundance,biomass and energy use of native and alien breeding birds in Britain

We quantify the contribution of alien species to the total breeding population numbers, biomass and energy use of an entire taxonomic assemblage at a large spatial scale, using data on British birds from 1997 and 2013. A total of 216 native and 16 alien bird species were recorded as breeding in Great Britain across the two census years. Only 2.8–3.7% of British breeding bird individuals were alien, but alien species co-opted 11.9–13.8% of the energy used by the assemblage, and contributed 19.1–21.1% of assemblage biomass. Neither the population sizes nor biomasses of native and alien species differed, on average, in either census, but alien species biomass is higher than native species biomass for a given population size. Species richness underestimates the potential effects of alien bird species in Britain, which have disproportionately high overall biomass and population energy use. The main driver of these effects is the ring-necked pheasant (Phasianus colchicus), which comprised 74–81% of alien biomass, yet the breeding population of this species is still only a small fraction of the estimated 35 million birds released in the UK in autumn. The biomass of this release exceeds that of the entire breeding avifauna, and suggests that the pheasant should have an important role in structuring the communities in which it is embedded.     

Abundance-range size relationships of breeding and wintering birds in Britain: a comparative analysis

Both breeding and wintering assemblages of birds in Britain exhibit positive interspecific relationships between population size and geographic range size, such that the average density of species is greater if they are more widely distributed Species in common to both assemblages, that is resident species, had greater population sizes, geographic range sizes, and densities in winter In contrast, whilst winter migrants had higher abundances than summer migrants, the range sizes of the former were disproportionately larger still, resulting in a lower density for species that only winter in Britain than for those that only breed Such differences aside, the overall form of the abundance-range size relationship is remarkably similar between the two assemblages and their constituent subsets of species     

Some new approaches to conservation monitoring of British breeding birds

It is important to monitor bird populations both in their own right and as indicators of the general health of wildlife habitats. The objectives of the British Trust for Ornithology's Integrated Population Monitoring programme relate to breeding bird populations in Britain and Ireland and involve the estimation of demographic parameters as well as assessment of numbers. Current programmes for monitoring bird numbers cover the majority of British species; it would be feasible to monitor most of the rest. A new Breeding Bird Survey has been developed to provide effective coverage of all regions and all major habitats in Britain through random sampling, allowing for the marked geographical variation in volunteer observer density. The final choice of a random sample stratified by observer density (with some professional support in regions with few volunteer observers) was based on comparison with alternative stratifications, using data from a 2-year pilot study to assess the number of species adequately covered under various alternatives. A method of assessing whether or not targets are being achieved at any time has been developed: it involves looking back through the data at intervals of 1-year, 4-year, 16-year and longer spans. It will be possible to refine this by incorporating environmental and density-dependent effects into predictive models. The method is illustrated here using Common Birds Census data. We discuss associated problems of statistical inference and of taking decisions under uncertainty. The data provide evidence for large declines in some species, particularly in farmland; the value of birds as general indicators of habitat health is clear. The results of monitoring can be used to illuminate possible causes of problems and to guide both practical steps to ameliorate the problems and research aimed at better understanding the causes. Examples of such research are discussed.     

Colonial breeding and speciation in birds

Summary It was recently suggested that bird species which breed colonially might be under stronger sexual selection, have faster rates of evolution and might therefore speciate more rapidly than bird species which do not. If true, then colonial taxa should contain more species than non-colonial taxa, other things being equal. When similarity through common descent is accounted for, there is little evidence for an association between the number of species in a clade and whether it is colonial or not.     

The relationship between census results and the breeding population of birds on farmland

This is the first paper produced on behalf of the B.T.O. Tit Study Group, using data collected by its members during their regular ringing operations. Recoveries, measurements, weights and moult records are examined and the data have been combined with information from the Nest Record Scheme and the author's field experience over ten years to produce a comprehensive study of Treecreeper breeding biology.     

An enquiry into the recent breeding status of some of the smaller birds of prey and crows in Britain

Eight nestling Sparrowhawks in Northamptonshire were marked with radiotransmitters to determine fledging and dispersal dates and the distances and directions travelled away from the nest. One male left the nest at 26 days old and dispersed 28 days later. Females fledged at 28–30 days old and dispersed 25–27 days later. The birds moved in any direction away from their birthplace with a maximum distance ranging 4–22 km. Although born in coniferous forest, the birds spent most time in scrubland, deciduous woodland and farmland.     

Distribution maps of Bryophytes in Britain and Ireland

Abstract

Eight epithets of Rigodium (R. araucarieti C. Müll., R. argentinicum C. Müll., R. brachypodium (C. Müll.) Par., R. nano-fasciculatum C. Müll. ex Thér., R. pendulum Herz. &; Thér., R. pseudo-thuidium Dus., R. solutum (Tayl.) Par., and R. tamarix C. Müll), lectotypified here, are listed with their nomenclature and pertinent details involving the careful identification of type specimens and original material. For Rigodium solutum (Tayl.) Par., a specimen from Taylor's original herbarium may likely be the holotype but had not been indicated as such by Taylor, the original author. A conservative approach for this situation is taken here by designating this specimen as a lectotype.     

Winter availability of cereal stubbles attracts declining farmland birds and positively influences breeding population trends

Many studies have demonstrated the selection of stubble fields by farmland birds in winter, but none have shown whether provisioning of this key habitat positively influences national population trends for widespread farmland birds. We use two complementary extensive bird surveys undertaken at the same localities in summer and winter and show that the area of stubble in winter attracts increased numbers of several bird species of conservation concern. Moreover, for several farmland specialists, the availability of stubble fields in winter positively influenced the 10 year breeding population trend (1994-2003) whereas hedgerow bird species were less affected. For skylarks and yellowhammers, initially negative trends showed recovery with 10-20 ha of stubble per 1 km square. Thus, agri-environment schemes that promote retention of over-winter stubbles will attract birds locally and are capable of reversing current population declines if stubbles are available in sufficient quantity.