Cuckoos have been documented using a range of host species but most of their eggs are laid in the nests of just a small number of species. Why do they select these species and to what extent might other species be suitable hosts, as yet unused to any great degree? The Cuckoo is a generalist avian brood parasite, known to have utilized at least 125 different bird species as a host within Europe. Despite this, individual female Cuckoos are thought to be host-specific, preferentially laying their eggs in one – or a few – host nests. This has led to individual female Cuckoos being classified into host races, termed ‘gentes’, some 20 of which have been described within Europe. Given the large number of songbird species breeding in Europe, and the relatively few female Cuckoo gentes, it raises the question of what makes a good host. By examining data from three different sources, including nest record data from the BTO, Bård Stokke and colleagues sought to establish which characteristics determined the suitability of a songbird species as a potential Cuckoo host. Some of the characteristics they investigated included nest placement, chick diet, habitat, abundance and the timing of the breeding period. The results of analysing two independent data sets, one from the UK and one from Germany, produced similar results. The analyses revealed that species breeding in forest and rocky areas were used less than species breeding in other habitats; that those feeding their nestlings with plant material were used less often than those feeding their nestlings with invertebrates (though not significantly so in the UK) and that hosts tended to be of intermediate body size and have larger populations. The analyses also showed that, perhaps unsurprisingly, species nesting in cavities are used less frequently than those nesting elsewhere. Nest height, nest depth and overlap in the breeding period did not appear to affect parasitism in any of the data sets examined. Through the work the researchers were able to calculate a ‘host suitability index’ for each of the European species in the study. Interestingly, there was no evidence of a clear separation between suitable and unsuitable host species’ instead, there appeared to be a continuum from low to high suitability. However, all of the species with a recognized corresponding Cuckoo gens are ranked towards the high suitability end of the continuum. The host suitability index could indicate species that might become the focus of Cuckoo nest parasitism in future if, for example, the host population increases because of climate- or habitat- change.

Some bird species provide cultural services, being aesthetically pleasing and having behaviours that people find interesting to watch. Others provide disservices (e.g. gulls, pigeons and corvids) negative for well-being. By documenting how the abundance and richness of species in these two groups correlates with human population density it was apparent that socio-economically deprived areas support low ratios of birds to people, particularly of cultural service species. These results inform management of green space, and provision of feeding and nesting sites, to promote positive interactions between birds and people within urbanised landscapes. Working in collaboration with the University of Exeter, and funded by NERC, researchers carried out extensive bird surveys within an urban area, centred on the towns of Milton Keynes, Luton and Bedford, as part of a wider project investigating urban ecosystem services. These provided measures of the abundance and richness of bird species within both the cultural services (35 species) and disservices (9 species) groups. The research team was able to look at the human population by using data from the 2011 National Census, and to assess socio-economic status by using information published by the Office of National Statistics. Since bird diversity is strongly associated with the structure and availability of urban green space, the team also had to factor in the green space present within the study area. Analyses revealed that the abundance of cultural service species increased with human population density but peaked at c.1,100 people per 500mx500m grid tile. The abundance also increased with the proportion of urban green space. Interestingly, the species richness of cultural service birds decreased with human population density but increased with percentage green space. There was a positive linear relationship between the abundance and richness of cultural disservice species and both human population density and the availability of green space. When the researchers mapped how the abundance of service and disservice birds co-varied with human population density, they found that the two groups of birds showed distinctly different spatial patterns. Service species were most abundant in areas of medium housing density – the suburbs – while disservice birds were most abundant in areas of dense housing, such as those around urban centres. While these different patterns are not a direct consequence of human population density per se, they probably result from spatial differences in urban form, the pattern and management of urban green space, levels of disturbance and the availability of resources, all of which are known to vary along socio-economic gradients. This underlines that people living in different parts of the urban landscape are likely to experience different relationships with wild birds, with the human communities in socially deprived areas exposed to more species with negative behaviours than wealthier communities. A consequence of this is that the increased frequency of negative interactions experienced by these people is likely to shape their connection with nature and support for the conservation of the natural world in a negative manner. The study identifies opportunities to deliver management approaches to counter these unfavourable relationships. Investment in urban green space and its management for cultural service birds is one obvious option, but there are also opportunities at the householder level, through practices such as wildlife gardening. Such householder level approaches can be of wider benefit because their beneficial effects are likely to increase the abundance and richness of cultural service birds in neighbouring gardens, meaning that the actions of a small number of people can provide health benefits for the wider community.

Written by Dave Cromack and drawing on the BTO's expertise, this new book provides the perfect guide to building, erecting and monitoring nestboxes for a broad range of familiar bird species. It includes: Step-by-step illustrated instructions for constructing proven nestbox designs Profiles of garden bird species that regularly use nestboxes Box designs for less common garden visitors Practical advice on the best positions for your nestboxes How to protect nesting birds from cats and other predators The best materials and tools to use Tips on repairing and preserving nestboxes Advice on providing refuges for Hedgehogs and other garden animals Published by BTO Services Ltd with the support of Jacobi Jayne & Company.

Work on emerging infectious diseases and garden birds in the UK has been supported by citizen science projects, most notably Garden BirdWatch, Garden Wildlife Health and the Garden Bird Health Initiative – the latter now superseded by Garden Wildlife Health. Through these schemes, researchers have been able to carry out national surveillance of emerging diseases, including finch trichomonosis, Paridae pox and passerine salmonellosis. This paper, part of a special issue of Philosophical Transactions focusing on wildlife disease issues, reviews the work that has been carried out on these diseases over the past 25 years. It also takes a look at the occurrence of mycotoxin contamination of food residues in bird feeders, which also pose a risk to the health of wild birds.

Currently non-native species are being introduced to countries at an unprecedented rate. These species can have severe detrimental effects on native biodiversity, human health and the economy. Due to population growth, increases in trade and tourism and global warming the likelihood of non-native species arriving and establishing in the UK will be higher in the future. A new study by BTO investigates whether it is possible to predict which non-native species are likely to establish in the UK based on the climate in their native range, thereby enabling early preventative action to be taken. Invasive species can have serious effects in their new home turf; they can be economically expensive, potentially cause health hazards, and they can have a large impact on the native biodiversity. Predicting whether invasive species are likely to colonise the UK is therefore an important priority. This study compared the suitability of the climate in the UK against the native range of 167 potentially invasive, or already established non-native bird species to see which species would be able to expand their range into the UK. Climate parameters that were used included temperature, precipitation and moisture. Values were used for both the current climate and the projected future climate. Results predicted that in the future, the UK climate will be suitable for more non-native species. Currently the UK climate was deemed suitable for 69 out of the 167 species included, but only 44 of those species actually currently occur in the UK. The results also showed that 85% of species that have colonised the UK successfully were found in climatically unsuitable areas. Many of these were usually found in areas that were wetter than their native range. In conclusion, there was no overall support that climate suitability is a reliable predictor of non-native bird species’ ranges, as there are many other contributing factors. Non-native populations are highly dependent on when and where introductions take place. Additionally, local availability of resources and competition with native flora and fauna may prevent establishment. Similarly, some birds which may not be climatically suited to the UK may be able to evolve rapidly to adjust to a different climate, or human influence (such as feeding) may provide them with the resources they need to survive. Regular surveying will be necessary to determine the effect climate change has on bird populations, and on where they may go in future.