Information on the status of biodiversity is crucial for species conservation and management. Large scale assessments are only feasible through citizen science but some taxa are poorly monitored because few people specialise in them. This paper explores how to alleviate this problem by using data collected for poorly monitored species as an add-on to existing bird surveys. Volunteer schemes enable the large-scale surveillance and monitoring of wildlife populations across the UK, but such schemes are more effective for some species groups (e.g. birds) than others. This is partly a result of where volunteer interests are focussed and partly a consequence of the ease with which different species may be encountered and identified in the field. The UK’s mammals present particular challenges for monitoring; they are ecologically diverse and vary in both size and activity, leading to substantial differences in detectability. Consequently, there is no single survey technique that is adequate for all (or even most) species. Some of the UK’s mammals are known to cause problems for other species, or to cause economic damage, while others are of conservation concern, making robust assessment of their populations a priority. One way to increase our understanding of UK mammal populations is to tap into an existing monitoring framework, aimed at different taxa but through which this additional information may be collected with little additional cost or effort. One of the few examples of this approach is the collection of data on the relative abundance of mammals by participants in the BTO/JNCC/RSPB Breeding Bird Survey (BBS). Starting in 1994, BBS was designed to monitor widespread breeding birds but the survey was extended to include mammals (as an optional component) in 1995. The stratified random approach used by the survey enables the collection of robust mammal data from 90% of the almost 4,000 1-km squares covered annually. Mammal trends are estimated every year, delivering trend information for the UK as a whole, for the four individual countries and for nine regions within England. While information on the national and regional trends has already been published, this paper presents additional information on spatial variation in the relative abundance of mammals, importantly exploring how this has changed over time. The BBS mammal data are very valuable and can, for example, be used to identify the reasons behind the trends being document in mammal populations. The analyses presented by Dario Massimino, Sarah Harris and Simon Gillings reveal the patterns of change for nine UK mammal species. They also reveal those parts of the UK where each of the nine species is most abundant. Although widespread, Rabbit shows statistically significant declines across Scotland and most of England. Brown Hare also shows significant declines across large areas, with these particularly evident in the south-east of England, Wales, north-west England and south-west Scotland. Worryingly, the Mountain Hare population has undergone large declines in abundance within a significant part of its core Scottish range. Another mammal suffering from large scale declines is the Red Fox, with populations in central-southern England and eastern Wales declining by between 20% and 50% over the study period. Three of the four deer species studied showed increasing abundance across a significant part of their UK ranges, and only Red Deer appears stable. Grey Squirrel populations have remained largely stable except at their expanding northern limit. The results of this work demonstrate how robust models of relative abundance and change can be secured for secondary taxa within an existing and structured monitoring approach. There are, as the authors discuss, strengths and limitations to adding secondary taxa to an existing survey in this way, but, as this paper demonstrates, the ability to monitor the changing status of these nine mammal species provides much-needed information.

Includes the results from the 2017 breeding season. It also features articles on turning a Tree Sparrow project into a RAS, monitoring Swallows, devising a Corn Bunting nesting project, and mentoring nest recorders.

Citizen science is increasingly recognised as one of the most cost-effective means of achieving large-scale and long-term biodiversity monitoring. We’re quite familiar with this concept for birds and butterflies, but what about for habitat? Historically, changes in habitat or land cover in the UK have been recorded through two main approaches: professional field data collection and remote sensing using satellites. Both have major limitations: field surveys are costly and can only cover small areas, whereas remote sensing can cover the whole country but with less detail and greater uncertainties. BTO scientists were keen to see if habitat data collected by volunteers for the Breeding Bird Survey (BBS) could contribute to understanding how habitats have changed. Over 2,500 BBS volunteers have recorded the habitats along their survey transects since 1994, from city centres to mountain tops. These data were used to quantify change over time in the reporting of different habitats in the British countryside. Increases in woodland cover were detected, in particular, mixed woodland, and declines in farmland cover, particularly livestock farming were also found. Whilst the estimate of habitat area matched existing data well, estimates of habitat change did not. These results are encouraging considering that habitat recording on BBS was not designed for the purpose of habitat monitoring. This work shows that volunteers can play a significant role in monitoring of habitats provided clear protocols are followed that have been designed with habitat monitoring in mind.

Woodcock, along with many other woodland bird populations, have been in long-term decline. Habitat change has been indicated as a possible cause for some species, but evidence is sparse for others, including Woodcock, due to an incomplete knowledge of their habitat requirements, which we can now examine. National BTO/GWCT Woodcock surveys undertaken in 2003 and 2013 provided data from 807 and 823 randomly selected 1 km squares, respectively. Woodcock counts were compared with a range of landscape-scale habitat variables as well as local habitat measures recorded by surveyors, using generalised linear mixed models. Habitat variables were measured at a variety of spatial scales using ring buffers, however high correlation between scales limits interpretation. The results show that, at large landscape scales, breeding Woodcock abundance was correlated with total woodland area and woodland type. Woodcock were more abundant in woods containing a more heterogeneous mix of woodland habitat types and in woods further from urban areas. On a smaller spatial scale, Woodcock were less likely to be found at sites dominated by Beech and more likely to occur in woods containing Birch. The Woodcock’s association with large, heterogeneous woods and the apparent attractiveness of certain woodland types present the most relevant topics for future research into the role of habitat change in long-term declines.

Although we have lost over three-quarters of the UK Cuckoo population, we are unsure of the causes of this decline. Alongside this, the strong divide in northern and southern populations of Cuckoo and their local trends are cause to question why the local differences arise. This study, led by PhD student Chloe Denerley and using BTO's BBS data, used local data from Devon in comparison against data on Cuckoos and their hosts, habitats, and prey items. In Devon, Cuckoos were more likely to be found in areas with semi-natural habitat and more Meadow Pipits (but fewer Dunnocks) and with a higher number of moth species, which are predated by Cuckoos in late summer. Across the UK, Cuckoos have become more associated with upland heath with Meadow Pipits, and with wetland habitats with Reed Warblers, and the distribution of Cuckoos shifting from south to north within the UK. The abundance of moth species preyed upon by Cuckoos has declined four times faster than that of other moths. Overall, the results suggest that Cuckoos have contracted out of the farmed countryside and into heathlands and the uplands. Coordinated monitoring of moth, host and Cuckoo numbers across such projects could tell us much about the long-term prospects for reversing Cuckoo population decline in the UK