Urbanisation is one of the fastest growing forms of land use globally and one of the largest human impacts on the planet. Urban development is a severe and increasing threat to native biodiversity. However, in Britain, there is also demand for new housing and therefore new homes are being built. New research led by the BTO has quantified the effect of new housing on the distribution and activity of bats. This work was based on data from the Norfolk Bat Survey, where members of the public have been borrowing passive detectors to collect data on Norfolk's bats since 2013. This Survey has achieved extensive survey coverage of both urban and rural areas, with about 20% of the county surveyed over the first three years of the project. For each bat species recorded, BTO scientists modelled activity abundance and distribution in relation to habitat, human population and other variables that are likely to influence bats. These models were used to create predictive maps of the bats in Norfolk. Data from the Norfolk County Council on housing plans for the next 10 years were then incorporated to investigate how these predictions would change under the increase in housing. The results showed that the existing housing plans are expected to reduce the abundance and distribution of all bat species currently found in Norfolk. At the 1-km square level these effects were quite severe in some cases. However at a country-wide level, only an extra 0.5% of Norfolk would be built on under new housing plans and consequently bat range and abundance is only expected to decrease by a maximum of 1-2% over this period. The study also explored the influence of mitigation measures; building on habitat least preferred by bats first and siting new houses in areas with fewer bats, or areas with bat species more tolerant to humans. These measures reduced the negative effect of housing for the majority of species, however, different bat species have different needs and requirements and consequently three species did worse under the mitigation scenarios. Mitigation measures will need to be targeted towards particular species of conservation concern to have the desired effect. The techniques used in this study could be usefully adopted for other species or scenarios at a time when wildlife is coming under ever greater pressure from our expanding towns and cities.

Using the BTO’s ring-recovery database we have been able to analyse dispersal movements, with the aim of providing insight into Barn Owl movements in the UK. The results of this work suggest that new, high-quality habitat aimed at mitigating negative effects of HS2 on Barn Owls should be located between 3 km and 15 km away from the railway route, depending on the importance placed on minimising juvenile, as opposed to adult, mortality.

New research involving the BTO has revealed important information about the migration routes and wintering grounds of Nightjar, a species of conservation concern in the UK. Up until very recently our knowledge of Nightjar wintering areas in Africa was almost entirely based on visual observations and just two recoveries from all European ringing activities. Our knowledge of migration was slightly better thanks to the moderate number of ringing recoveries, but these only cover within Europe and a few sites in North Africa. New tracking technology is now vastly improving our understanding of Nightjars' movements, with implications for this species' conservation. The advent of geolocators allowed Nightjars to be tracked for the first time in 2009. These give daily locations accurate to around 100 km, meaning they are more than appropriate for tracking migration routes and wintering area at the continental scale. More recently, GPS devices have become sufficiently small to use, and these provide high precision locations but only once every 10 to 20 days. Using a combination of geolocators and GPS tags, researchers from Hasselt University, Biotrack, and the University of Sorbonne worked with Greg Conway and Ian Henderson from the BTO to examine the migration routes and wintering areas of 11 adult Nightjars marked at breeding sites in the UK, France and Belgium between 2009 and 2015. The results show that the main wintering area is located in the Savannah and scrub forests, to the south of the central African tropical Rainforests, mainly in the southern region of the Democratic Republic of Congo (similar to that favoured by our satellite-tagged Cuckoos). This area has not previously been identified as a wintering area for this species, but now appears to be a very important for Nightjars breeding in western Europe. The study also identified key stopover sites for the first time, on the boundaries of major ecological barriers including the Mediterranean Sea, Sahara Desert and Central African Tropical Rainforest, avoidance of the latter being somewhat surprising given the high insect resource potentially available in such habitat. Major differences in spring and autumn migration were noted, with autumn passage being on a broad front involving a fairly direct crossing of the central Saharan region, while birds in spring took a substantially longer western route back to their breeding grounds, involving a detour via West Africa of around 2000 km. Further work is underway to investigate migration routes and wintering area used by other breeding populations throughout Europe. In the UK, the Nightjar has recently been moved from the Birds of Conservation Concern Red List to the Amber List. By identifying key migration routes and wintering grounds, this study provides important information that will further aid monitoring and conservation efforts of this charismatic species.

One of the great strengths of the BTO is its volunteer networks, and the organisation’s expertise in working with and supporting volunteers delivers valuable monitoring outputs across a broad range of taxa, from deer and butterflies through to bats and bush-crickets. Many of those interested in birds and birdwatching are also interested in other wildlife, and the BTO recognises the contribution that its volunteers can make to our knowledge of habitats and wildlife. This note outlines recent BTO research, monitoring and partnership working involving other taxa.

This report explores means by which a standardised trend analysis of data from the Wetland Bird Survey (WeBS) can aid rapid assessment of condition for non-breeding waterbird SPAs in England. For supporting material please contact Natural England.

Bush-crickets are a little-known group of insects that inhabit our marshes, grasslands, woods, parks and gardens. Some may be seen in the summer when they are attracted to artificial lights, but as most produce noises that are on the edge of human hearing, we know little about their status. There are suggestions that some bush-crickets may be benefiting from climate change, while others may be affected by habitat changes. But how to survey something that is difficult to see and almost impossible to hear? Advances in autonomous recording devices are transforming our understanding of bats, but the large-scale deployment of such devices has the potential to improve our understanding of other species groups that produce loud and characteristic sounds too. The original objective of BTO's Norfolk Bat Survey, led by Stuart Newson, was to trial the recording of bat activity using passive real-time detectors, to gauge the willingness of members of the public to engage in bat monitoring at a large scale, and to determine the suitability of automated identification routines for processing large volumes of citizen-science collected bat recordings. However, it soon became clear that bush-crickets were also being recorded in large numbers. Working with the Museum of Natural History in Paris and Natural England, BTO staff developed a computer algorithm to identify the sounds made by different species of bush-crickets. After carefully validating these state-of-the-art methods using field recordings in Norfolk, the daily activity patterns of different species of bush-cricket was examined to determine where different species live. The Speckled Bush-cricket, for example, would normally be easy to overlook because it occurs in vegetation and stridulates at a frequency too high for humans to hear. With over 260,000 recordings of this species collected through the Norfolk Bat Survey, this study found this species to be common and widespread, with a distribution that extends into the city of Norwich. At the other extreme, Great Green Bush-cricket, previously known from only a few locations in Norfolk, was recorded at two locations, of which one was a new site for this species. This research demonstrates the huge potential to take advantage of established large-scale bat monitoring to also collect high-quality monitoring data for bush-crickets. It is likely that large volumes of information on bush-crickets are already being collected incidentally by bat workers using static detectors, but this information is at best noticed and ignored. This work also marks an important step towards the development of automated sensor networks, which are likely to play growing role in the future biodiversity surveying, and the whole approach enables members of the public to become actively engaged in wildlife monitoring, with important conservation implications.