The value of a random sampling design for annual monitoring of national populations of larger British terrestrial mammals

Making use of an extensive network of volunteer birdwatchers, this study illustrates how a large-scale monitoring scheme originally designed for common breeding birds can be adapted to also provide robust monitoring data for medium- to large-sized, easily detectable terrestrial mammals. Compared with bird monitoring, the monitoring of common and widespread terrestrial mammals is rarely carried out using a well-designed sampling design and is largely restricted to sites selected by the observer or biased towards particular habitats of interest, making it difficult to know whether trends are representative of the populations of interest. In response to the scarcity of reliable mammal monitoring data in the UK, the principal national bird monitoring scheme, the Breeding Bird Survey (BBS), was expanded to collect information on mammals. The focus was on larger, easily detectable species, although observers have the opportunity to record any mammal species. Here, we present population trends at national and regional scales for nine species of common mammal over the first 18 years of BBS mammal monitoring and examine these in relation to our current knowledge on these species. We further discuss the potential of these data for addressing important questions of conservation and management concern which may be difficult to explore with existing data.     

Avian nest predation, competition and the decline of British Marsh Tits Parus palustris

Data from long-term schemes monitoring abundance and breeding performance were used to investigate the patterns and causes of decline of the Marsh Tit Parus palustris in Britain. Data from the British Trust for Ornithology's Common Birds Census (CBC) showed that declines have occurred to a similar extent in both woodland and farmland. Novel analyses of CBC data with respect to the corresponding data on the abundance of potential avian nest predators and competitors provided no evidence that increases in the numbers of either group have had a deleterious effect on the species. There were no significant relationships with predator numbers and all significant relationships with potential competitors were positive, suggesting common responses to environmental conditions rather than any negative effects of increases in competitor populations. Further evidence for a lack of any effect of nest predation comes from the absence of any decline in breeding success and, specifically, in nest failure rates, over time: failure rates actually fell during the period of decline. The most likely cause of the decline is the degradation of woodland habitats, and the specific ways in which this may have affected Marsh Tits (as opposed to congeneric species whose populations are healthier) are discussed.     

Diversity, ecological structure, and conservation of the landbird community of Dadia reserve, Greece

Birds are integral to many environmental monitoring schemes. However, there has been little research on the ecological basis of utilizing bird species as indicators of their respective communities and habitats. We used point counts to survey 72 landbird species, 16 of conservation concern, in the Dadia Nature Reserve, Greece, in order to understand the ecology of bird diversity patterns, analyse community composition, identify species characteristic of major vegetation types, and improve long-term management and monitoring protocols. We sampled 36 sites representing 21 vegetation types. Highly heterogeneous sites were the most species rich and rural mosaics (small fields and pastures of low intensity land use, separated by thick hedgerows and tree lines) were twice as rich as intensified crop monocultures. Using multivariate analysis, we found that vegetation cover and height affected the composition of the avifauna. Twenty-one predefined vegetation categories clustered into eight distinct bird habitat types: field crops, rural mosaics, mosaic sites, poplar trees, broadleaved woods, pinewoods, shrubs, and heaths. Ten bird species were highly characteristic of the main bird habitat types in the study area. Our results emphasize the importance of conserving rural mosaics, hedgerows, and openings within forests for landbird conservation in the Mediterranean countryside. We also provide evidence in support of maintaining horizontal heterogeneity at a local scale. Finally, we suggest that monitoring populations of certain indicator bird species can be a cost-effective and efficient way to monitor the state and habitat quality of the entire landbird community, thereby integrating the knowledge of community structure into conservation decision-making.     

THE HOUSE SPARROW PASSER DOMESTICUS: POPULATION PROBLEMS

Two problems of House Sparrow populations are examined: the influence of habitat on numbers and the variation in a population of House Sparrows throughout the year. Available data on censuses in Great Britain enable the population to be estimated as 10 millions; censuses from several parts of the bird's range suggest that House Sparrow numbers are correlated with the human population, the ratio being 1: 5. The seasonal variation in composition of a population is estimated from observations over five years on House Sparrows breeding on a group of seventeen houses together with breeding and mortality data obtained from British Trust for Ornithology records. The population reaches a maximum at the end of July when it is slightly less than double that at the beginning of the breeding season. It is considered that numbers are controlled by food supply and the colonial behaviour of the bird.     

Volunteer surveys as a means of inferring trends in garden mammal populations

• 1 Habitats associated with humans, and gardens in particular, may prove to be important for populations of certain mammal species. However, means for measuring change in these populations are lacking.
• 2 This paper uses power analyses to examine the potential for mammal observation data, gathered through an extensive volunteer‐based survey of garden birds, to provide measures of population change within garden habitats at both national and regional levels.
• 3 Analyses show that this survey protocol has sufficient power to detect a decline in presence of between 5% and 40% at the national level for 20 of the 24 species included in this study. These results demonstrate that data from volunteer surveys allow the annual monitoring of garden use by a range of mammal species within Britain, and highlight the wider potential of such schemes worldwide.

     

Living on the edge: British and Irish woodland birds in a European context

This paper reviews broad geographical patterns in the species composition of breeding woodland bird communities from Ireland to eastern Europe and outlines how processes affecting woodland birds in Britain and Ireland may differ from those operating in mainland Europe. Bird communities in British and Irish woodlands consist of a subset of the species occurring within European forests at similar latitudes. The occurrence of virtually all groups of forest birds is lower in Britain, and strikingly lower in Ireland, than in other temperate areas of mainland Europe. This phenomenon appears to form part of a west–east gradient in species diversity and is probably not just a consequence of insularity. Across this gradient there appears to be broad geographical constancy in the types (taxonomic, ecological and life-history groups) of species present. There is considerable spatial variation in habitat use by forest species within Europe. Some species in Britain probably use habitats in different ways to elsewhere for reasons related to competition, predation and historical adaptation to landscape change. Several species appear to reach the limits of their geographical ranges within Britain (i.e. in the absence of physical barriers). We suggest that range contraction of one of these species, the Common Nightingale Luscinia megarhynchos , in Britain may partially reflect redistribution into the highest quality areas in response to a wider population decline. It is argued that conclusions drawn from studies of forest birds in Britain do not necessarily apply in other regions and vice versa. There is a need for large-scale studies in Europe of the spatial variation in organization of forest bird assemblages, habitat use and the genetic structure of populations.     

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.     

Validating bird diversity indicators on farmland in east-central Alberta,Canada

Birds can be used as indicators to monitor success of programs encouraging prairie landowners to increase biodiversity. Using a case study from Alberta, Canada, this paper compares bird diversity measures at the farm scale and examines their consistency across different habitat types to test for design, output, and end use validation. Based on 2005 point count data (two types) from 178 sites at 22 farms, we calculated bird species richness, abundance, Shannon index, and Inverse Simpson index.The 50 m radius data produced species richness and abundance measures about half the size as those produced by the unlimited radius data. The bird diversity measures were consistent across habitat types. The 50 m radius data showed differences among 3–5 habitat types, whereas the unlimited radius data showed differences between only two habitat types. Using any bird diversity measure, the wetland/riparian habitat scored highest, followed by homestead, upland forest, native prairie, tame pasture, and cultivated land habitats.Bird monitoring methods should favor fixed over unlimited radius point counts, because of the former's greater discriminating ability. Given that diversity measures are consistent across habitats and are highly correlated, the species richness measure, which is simple and easy to understand, can be used in conversations with landowners and policy-makers.     

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.     

Monitoring change in the abundance and distribution of insects using butterflies and other indicator groups

Conservative estimates suggest that 50-90% of the existing insect species on Earth have still to be discovered, yet the named insects alone comprise more than half of all known species of organism. With such poor baseline knowledge, monitoring change in insect diversity poses a formidable challenge to scientists and most attempts to generalize involve large extrapolations from a few well-studied taxa. Butterflies are often the only group for which accurate measures of change can be obtained. Four schemes, used successfully to assess change in British butterflies, that are increasingly being applied across the world are described: Red Data Books (RDB) list the best judgements of experts of the conservation status of species in their field of expertise; mapping schemes plot the changing distributions of species at scales of 1-100 km2; transect monitoring schemes generate time series of changes in abundance in sample populations of species on fixed sites across the UK; and occasional surveys measure the number, boundaries and size of all populations of a (usually RDB) species at intervals of 10-30 years. All schemes describe consistent patterns of change, but if they are to be more generally useful, it is important to understand how well butterflies are representative of other taxa. Comparisons with similarly measured changes in native bird and plant species suggest that butterflies have declined more rapidly that these other groups in Britain; it should soon be possible to test whether this pattern exists elsewhere. It is also demonstrated that extinction rates in British butterflies are similar to those in a range of other insect groups over 100 years once recording bias is accounted for, although probably lower than in aquatic or parasitic taxa. It is concluded that butterflies represent adequate indicators of change for many terrestrial insect groups, but recommended that similar schemes be extended to other popular groups, especially dragonflies, bumblebees, hoverflies and ants. Given institutional backing, similar projects could be employed internationally and standardized. Finally, a range of schemes designed to monitor change in communities of aquatic macro-invertebrates is described. Although designed to use invertebrates as a bio-indicator of water quality for human use, these programmes could be extended to monitor the 2010 biodiversity targets of the World Summit on Sustainable Development.     

The conservation of declining butterfly populations in Britain and Europe: priorities, problems and successes

The status, ecology and conservation of butterflies in Europe and Britain are reviewed, as a background to the National Trust's past and future contribution to British conservation. Britain has a poor butterfly fauna by European standards, the main areas of endemism and species richness being in the Alps and southern Europe. To date, the main declines among European butterfly populations have occurred across central-northern Europe, with slightly higher extinction rates in mainland countries than in Britain. The main causes of decline are biotope destruction, the loss of certain species' habitats within surviving semi-natural biotopes due to changed land management, and a failure by several species to track the patches of their habitat that are still being generated in modern fragmented landscapes. Until recently, most conservation programmes failed to take account of the latter two factors, resulting in many local extinctions of rare butterfly species even in conservation areas. Recent measures have been much more successful; many were first tested on National Trust properties.     

Status of the Nightingale Luscinia megarhynchos in Britain at the end of the 20th Century with particular reference to climate change

Capsule The population level may be unchanged but the range has contracted.

Aims To establish the current status of the Nightingale in Britain and explore causes for any changes.

Methods Over 3000 sites where Nightingales were known to have occurred since 1980 were surveyed by volunteers between mid-April and early June 1999. A selection of 135 random tetrads were also surveyed to gauge the efficiency of the volunteer survey in locating Nightingales.

Results The survey located 4565 singing male Nightingales while the random tetrad surveys suggest that c. 32% of birds occur away from known sites, increasing the estimate for the British Nightingale population to 6700 males (95% confidence limits 5600–9350) in 1999. A higher proportion of Nightingales was found in scrub (46.7%) than in 1976 (28.4%), suggesting a recent shift in habitat use.

Conclusion There is little evidence of a change in the size of the British Nightingale population, probably because earlier surveys underestimated numbers. The range has contracted markedly over the last few decades and numbers outside the core areas in southeast England are now low. Changes in habitat quality and increasing deer populations have caused decreases on a local scale. Changes in climate on the breeding grounds and general changes in climate or habitat suitability on the African winter quarters are likely to be important in influencing the distribution within England. Models of the effects of future climate change on Nightingale distribution in Britain predict that numbers and range should increase over the next few decades.     

Large-scale habitat use of some declining British birds

1. Large-scale habitat use of eight species of breeding birds was considered using data collected across Britain. The species were skylark Alauda arvensis (L.), dunnock Prunella modularis (L.), blackbird Turdus merula (L.), song thrush Turdus philomelos (L.), starling Sturnus vulgaris (L.), linnet Carduelis cannabina (L.), bullfinch Pyrrhula pyrrhula (L.) and reed bunting Emberiza schoeniclus (L.). All are linked by roughly synchronous population declines over the last 25 years in southern Britain (and mostly in farmland landscapes). Discussion is limited to the conservation status of these species.
2. Breeding densities were estimated for broad habitat types and these were used to estimate population sizes within habitat types. Confidence limits on the estimates were derived using a bootstrap procedure.
3. For most species considered, farmland holds a high proportion of their population (in excess of 50% for four species), reflecting the predominance of this land use across Britain. This suggests that sympathetic changes in farming practices are likely to provide the best mechanism for improving the status of these species.
4. Substantial proportions of particular species occur outside farmland, but different species occur in different habitats. A considerable proportion of skylarks occur on upland moor, bullfinches in wooded habitats, and reed buntings in riparian habitats. Conservation of this group of species thus requires appropriate management of the wider countryside, including their main habitats.
5. Habitats associated with human habitation hold > 20% of the British populations of blackbird, song thrush and starling, and considerable numbers of other species. The management of parks, gardens and other 'green space' may have an important impact on their populations and should not be neglected by conservationists.     

Modelling the recovery of resident shorebirds following a fox eradication program using citizen science data

Historically, the land-based threat to shorebird colonies on Phillip Island, Victoria, Australia, was fox predation. As a result, a fox eradication programme consisting of three phases: knock-down (i.e., 2006), clean-up (i.e., 2011), and post-eradication. In 2011 an effective knock-down was declared, signalling the beginning of the clean-up phase. The purpose of this research is to assess the recovery of six resident shorebird species on Phillip Island following fox removal. The statistical methodologies used are novel for assessing bird species population recovery following a successful predator eradication program. We used citizen science data from 2003 to 2017, extracted from the Atlas of Living Australia. The first analysis method used INLA modelling, which relied on a Negative Binomial distribution for bird counts to look for upward trends in shorebird populations during the fox eradication operation. The second method use changepoint analysis techniques to see whether successive phases of the eradication process were associated with changes in bird population numbers. Four of the six shorebird species investigated responded positively to reduced fox populations over the 15-year study, and all changepoint approaches consistently recognised the start of the clean-up phase, with less consistency identifying the start of the knock-down phase. Since 2006, the INLA models indicate a significant increase in the upward trend of shorebird populations for three of the six shorebird species investigated. Agreement across the four changepoint techniques indicates that changes in bird numbers were associated with the date of the eradication program's clean-up phase for all of these shorebird species. These results demonstrate some promise for these methods to monitor native species recovery during eradication programs.     

Adult sex ratios in wild bird populations

Offspring sex ratios in wild bird populations, and the extent to which they vary from the equality expected by random genotypic sex determination, have received much recent attention. Adult sex ratios (ASRs) in wild birds, on the other hand, remain very poorly described, and many of the questions about them posed by Ernst Mayr in 1939 remain unanswered. This review assesses population-level sex ratio patterns in wild bird populations, with an emphasis on the ASR. A quantitative assessment of over 200 published estimates of ASR, covering species from a wide range of taxa, regions and habitats, supported Mayr's assertion that skewed ASRs are common in wild bird populations. On average, males outnumbered females by around 33%, and 65% of published estimates differed significantly from equality. In contrast, population-level estimates of offspring sex ratio in birds did not generally differ from equality, and mean ASR across a range of wild mammal species was strongly female-skewed. ASR distortion in birds was significantly more severe in populations of globally threatened species than in non-threatened species, a previously undescribed pattern that has profound implications for their monitoring and conservation. Higher female mortality, rather than skewed offspring sex ratio, is the main driver of male-skewed ASRs in birds, and the causes and implications of this are reviewed. While estimates of ASR in wild bird populations may be subject to a number of biases, which are discussed, there is currently no quantitative evidence that an ASR of one male to one female represents the norm in birds. A better understanding and reporting of ASRs in wild bird populations could contribute greatly to our understanding of population processes and could contribute much to theoretical and applied research and conservation.     

Wordbirds: Developing a Web-based Data Collection System for the Global Monitoring of Bird Distribution and Abundance

There is an urgent need to develop simple and effective methods for monitoring bird populations that are cheap to deploy in resource-poor countries. This paper describes a newly developed system, provisionally referred to as, Wordbirds, that will provide a platform for the collection, storage and retrieval of new and existing data from bird observations recorded worldwide. This Internet-based global network of databases will capture field lists and ad hoc sightings routinely gathered by individuals observing birds recreationally and professionally. Huge numbers of lists are collected annually and could provide information on population trends spanning many years. By collecting these records, a valuable resource will be secured with the potential to map and monitor bird distributions and estimate trends in species abundance. An erratum to this article is available at .     

A Niche-Based Framework to Assess Current Monitoring of European Forest Birds and Guide Indicator Species' Selection

Concern that European forest biodiversity is depleted and declining has provoked widespread efforts to improve management practices. To gauge the success of these actions, appropriate monitoring of forest ecosystems is paramount. Multi-species indicators are frequently used to assess the state of biodiversity and its response to implemented management, but generally applicable and objective methodologies for species'' selection are lacking. Here we use a niche-based approach, underpinned by coarse quantification of species'' resource use, to objectively select species for inclusion in a pan-European forest bird indicator. We identify both the minimum number of species required to deliver full resource coverage and the most sensitive species'' combination, and explore the trade-off between two key characteristics, sensitivity and redundancy, associated with indicators comprising different numbers of species. We compare our indicator to an existing forest bird indicator selected on the basis of expert opinion and show it is more representative of the wider community. We also present alternative indicators for regional and forest type specific monitoring and show that species'' choice can have a significant impact on the indicator and consequent projections about the state of the biodiversity it represents. Furthermore, by comparing indicator sets drawn from currently monitored species and the full forest bird community, we identify gaps in the coverage of the current monitoring scheme. We believe that adopting this niche-based framework for species'' selection supports the objective development of multi-species indicators and that it has good potential to be extended to a range of habitats and taxa.     

Pulsed-field gel electrophoresis supports the presence of host-adapted Salmonella enterica subsp. enterica serovar Typhimurium strains in the British garden bird population

Salmonellosis is a frequently diagnosed infectious disease of passerine birds in garden habitats within Great Britain with potential implications for human and domestic animal health. Postmortem examinations were performed on 1,477 garden bird carcasses of circa 50 species from England and Wales, 1999 to 2007 inclusive. Salmonellosis was confirmed in 263 adult birds of 10 passerine species in this 11-year longitudinal study. A subset of 124 fully biotyped Salmonella enterica subsp. enterica serovar Typhimurium isolates was examined using pulsed-field gel electrophoresis to investigate the hypothesis that these strains are host adapted and to determine whether this molecular technique offers greater resolution in understanding the epidemiology of Salmonella Typhimurium infection than phage typing alone. For the two most common phage types, definitive type (DT) 40 and DT56v, which together accounted for 97% (120/124) of isolates, pulsed-field gel electrophoresis groupings closely correlated with phage type with remarkably few exceptions. A high degree of genetic similarity (>90%) was observed within and between the two most common pulsed-field gel electrophoresis groups. No clustering or variation was found in the pulsed-field gel electrophoresis groupings by bird species, year, or geographical region beyond that revealed by phage typing. These findings support the hypothesis that there are currently two host-adapted Salmonella phage types, S. Typhimurium DT40 and DT56v, circulating widely in British garden birds and that the reservoir of infection is maintained within wild bird populations. Large-scale multilocus sequence typing studies are required to further investigate the epidemiology of this infection.     

Declining population trends of European mountain birds

Mountain areas often hold special species communities, and they are high on the list of conservation concern. Global warming and changes in human land use, such as grazing pressure and afforestation, have been suggested to be major threats for biodiversity in the mountain areas, affecting species abundance and causing distribution shifts towards mountaintops. Population shifts towards poles and mountaintops have been documented in several areas, indicating that climate change is one of the key drivers of species’ distribution changes. Despite the high conservation concern, relatively little is known about the population trends of species in mountain areas due to low accessibility and difficult working conditions. Thanks to the recent improvement of bird monitoring schemes around Europe, we can here report a first account of population trends of 44 bird species from four major European mountain regions: Fennoscandia, UK upland, south‐western (Iberia) and south‐central mountains (Alps), covering 12 countries. Overall, the mountain bird species declined significantly (?7%) during 2002–2014, which is similar to the declining rate in common birds in Europe during the same period. Mountain specialists showed a significant ?10% decline in population numbers. The slope for mountain generalists was also negative, but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and Iberian populations were on average declining, while in United Kingdom and Alps, trends were nonsignificant. Temperature change or migratory behaviour was not significantly associated with regional population trends of species. Alpine habitats are highly vulnerable to climate change, and this is certainly one of the main drivers of mountain bird population trends. However, observed declines can also be partly linked with local land use practices. More efforts should be undertaken to identify the causes of decline and to increase conservation efforts for these populations.     

Genetic differentiation of starling (Sturnus vulgaris: Aves) populations in New Zealand and Great Britain

Several hundred starlings (Sturnus vulgaris) were introduced to New Zealand from Great Britain during1860–1880. Allozymic variation at 24 loci was analysed in winter populations sampled at six localities in each country. New Zealand samples had fewer alleles per locus but the same mean heterozygosity (3% per locus) and proportion of polymorphic loci as did British samples. Winter populations in Britain contain European migrants and were genetically homogeneous. Paradoxically, genetic distances among derived New Zealand populations, and between New Zealand and Great Britain were much greater, similar in magnitude to those observed among allopatric populations in other avian species. The geographical pattern of genetic variation in New Zealand suggests that reproductive isolation of populations and random drift have contributed to the development of population differentiation.