Birds move a lot during their lifetime! One of the most important forms of movement is dispersal: when birds move out of the immediate area in which they were born (natal dispersal) or when they change location between successive breeding attempts (breeding dispersal). Understanding dispersal movements can provide insight into species’ distribution, gene flow and protection needs. Unfortunately, data which demonstrate how far and often birds move during dispersal is difficult to collect and analyse, and so many questions about these behaviours remain unanswered. Ringing data collected by volunteers are a potential source of information on bird dispersal, but specialist methods must be employed if they are to be analysed correctly. In a study conducted in collaboration with BTO, scientists estimated the dispersal patterns of 234 European bird species using data from the EURING (European Union for Bird Ringing) Databank of birds ringed and subsequently re-encountered (either alive or dead). Information on where ringed birds had been recaptured or found dead demonstrated how far they had travelled. The raw data were first processed in order to reduce the bias caused by an uneven ringing effort across the continent. The scientists then used these data to create a ‘dispersal kernel’ for each species. Dispersal kernels describe the number of birds moving different distances; most don’t disperse very far, but a few individuals can move a long way. A number of different methods for estimating dispersal kernels already exist, each of which has its own set of assumptions about the birds’ behaviour, and the team compared four of these to determine which was the best fit for their ringing data. They could then better quantify the bird’s behaviour based on the assumptions of the best fitting method. Being able to describe dispersal in this way makes it possible to incorporate this information into other analyses; for example, investigations into how changes in the environment might influence population change. The scientists were also able to compare dispersal characteristics between the sexes and investigate if the patterns seen were different depending on whether it was natal or breeding dispersal. The scientists found that the data for almost all of the featured species were best described by so-called ‘heavy-tailed’ kernels. This means that for most species, although most individual birds are unlikely to travel far, more individuals than might be expected undertake long-distance movements. These long-distance dispersal events can introduce new species or genes into an area, but they are very rarely detected. By developing these methods as part of this analysis, this paper may help others to make more accurate predictions of bird movements in the future. As predicted, the scientists also found that birds tended to travel further during natal dispersal than breeding dispersal. When leaving the area in which they were born, birds travelled (on average) more than twice the distance they covered when swapping breeding sites (7.74 km compared to 2.83 km). Putting some distance between yourself and your immediate family may help to avoid inbreeding or prevent direct competition with siblings.Surprisingly, the study did not find any widespread sex-biased dispersal patterns. In many bird species, it is thought that the females engage in dispersal more regularly than males; however, these patterns were not replicated in this study. In future, considering how dispersal differences between the sexes might change with age could shed some light on this discrepancy. Testing statistical methods using empirical data is crucial to appraise their accuracy and understand their limitations. The methods included in this study will help future work produce more realistic models, paving the way for scientists to address many of those unanswered questions on avian dispersal patterns. As species continue to adjust their ranges in response to climate change, this information could have considerable conservation value.

New research has revealed the wintering grounds and migration stopovers of British-breeding Wood Warbler, a declining species on the UK Birds of Conservation Concern Red List.

Monitoring biodiversity at large spatial scales and over long periods of time is central to understanding how populations change, and supports conservation planning and the prioritisation of resources by decision-makers. While we have a good understanding of the monitoring frameworks that exist for some taxa, e.g. birds, such understanding is lacking for many others, including reptiles and amphibians. This paper sets out to fill this knowledge gap for UK reptiles and amphibians, identifying existing sources of biodiversity data for these taxa and then characterising the nature of the data management network within which they sit. By using an approach known as network analysis, the team was able to visualise how the reptile and amphibian data were mobilised across the network, i.e. which were the key data sources within the network and how did data flow across the network? It also revealed valuable information on the species recorded and the degree of geographic and spatial coverage over time. Forty-five sources of amphibian and reptile data were identified, which clustered into three main groupings: ‘recording projects’, ‘recording communities’ and ‘digital data platforms’. ‘Recording projects’ involve structured or semi-structured monitoring, the typical projects operated by BTO such as the reptile and amphibian component of BTO Garden BirdWatch. The network analysis revealed that the UK amphibian and reptile monitoring portfolio is dynamic and fragmented, with two data sources sitting outside of the network and many others receiving data but not then sharing this with other sources. While the network as a whole may provide comprehensive information across species and regions, the complexity of the network and the degree of fragmentation means that opportunities to leverage information where and when it is needed are not as good as they could be. If such shortcomings can be addressed then this would benefit reptile and amphibian conservation within the UK.