Conflicts in resource use between humans and wildlife populations are increasingly determined through quantitative approaches. To better understand interactions between birds and human activities in the marine environment, telemetry is routinely used to characterize the area use of species, but evaluations are often based on a small number of individuals taken as representative of a local population studied. Furthermore, the relative importance of the number of animals required and for what duration they should be tracked has received little attention. We examined the central-place foraging movements of 24 lesser black-backed gulls (Larus fuscus) from a protected population from 1 March to 31 August during 2010–2013. Using bootstrapping and non-linear modeling, we investigated whether sample sizes were sufficient to characterize offshore area use by considering the cumulative area use for an increasing number of birds and duration of tracking. Box-and-whisker analysis suggested a minimum of 13 birds and a precautionary upper maximum of 41 birds were needed to describe 95% of the estimated area use of the population (defined by 100% occupancy). Tracking fewer birds for longer was more important than tracking more birds for less time. A period of 145 days was required to characterize area use for 13–41 birds; however, offshore areas were used primarily after May, meaning that a 97-day tracking period from May onwards was also representative. Predicted and observed areas were strongly correlated, and the predicted area of 15 birds for 151 days was 91% of the total estimated for the population. These findings suggest that the data were suitable for determining interaction with offshore developments, and were characteristic of the population. This study has revealed the power of a long-term tracking dataset, and has uncovered further complexities surrounding study design and analysis that may shape conclusions drawn. The method and considerations raised have wider applicability for other datasets where human-wildlife resource use conflicts need to be assessed.
Includes annex: Results for Northwest England.
No short- or long-term effects of geolocator attachment detected in Pied Flycatchers Ficedula hypoleuca
Tracking small passerines using miniaturized location tags is a rapidly expanding field of study. In a 1-year study, we tested whether there were any short- or longer-term effects of fitting geolocators weighing 3% of body mass on male Pied Flycatchers Ficedula hypoleuca. In the deployment year, we compared adult provisioning rates to nestlings, nestling growth and nest success between nesting attempts in which adult males were fitted with a geolocator, with control nests where males had the same capture history but were not tagged. We found no difference between treatments in provisioning effort by males or their associated female 2 days after geolocator fitting, in terms of nestling growth, subsequent brood reduction or nest success. Return rate, arrival date on territories, nest timing and breeding parameters were compared between tagged and untagged males in the following breeding season. We found no difference in return rate or arrival date, and no difference in nest timing, fecundity or outcome. Our study suggests that fitting lightweight tags to small passerines need not affect behaviour, breeding or apparent between-year survival. However, tagging new species should still require assessment and comparison with well-matched control cohorts, and it should be recognized that tag effects could vary between years and populations, mediated by environmental conditions.
This research consisted of a literature review and field study which investigated woodland management for birds within
<p>Quantifying the importance of multi‐scale management and environmental variables on moorland bird abundance</p>
Capsule: The use of call-broadcasting significantly increases the number of Tawny Owls Strix aluco
Waders in decline in Strathallan, Scotland
The breeding populations of many different wader species are in decline across the globe, and there is an urgent need for information on how such changes in land management, particularly within farmland, may affect breeding waders. This study by a long-term BTO volunteer explores wader decline in Strathallan, Scotland over a period of 25 years.
Terrestrial laser scanning (TLS) captures the three‐dimensional structure of habitats.
“The BTO is working with others on a programme of research to understand the causes of Curlew decline and guide potential management solutions.
Assessing behaviour of Lesser Black-backed Gulls from the Ribble and Alt Estuaries SPA using GPS tracking devices
Continuing influences of introduced hedgehogs Erinaceus europaeus as a predator of wader (Charadrii) eggs four decades after their release on the Outer Hebrides, Scotland
Non-native predators can cause major declines or even localised extinctions in prey populations across the globe, especially on islands.
A global threats overview for Numeniini populations: synthesising expert knowledge for a group of declining migratory birds
Curlews and godwits - the vanishing tribe
Collaborative research led by the BTO investigates reasons for recent losses in curlews and godwits worldwide and identifies conservation measures which could be put in place to halt the declines.
Predicting the likely impact of urbanisation on bat populations using citizen science data, a case study for Norfolk, UK
The impact of new housing on bat populations
New research from the BTO has examined the effects of projected housing developments on bats, using data citizen science data collected by volunteers taking part in the Norfolk Bat Survey.
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.
Migratory pathways, stopover zones and wintering destinations of Western European Nightjars Caprimulgus europaeus
Unravelling the mysteries of Nightjar migration
New research involving the BTO has revealed important information about the migration routes and wintering grounds of the Nightjar for the first time. Their main wintering area is now known to be 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, while key differences were also found between birds' spring and autumn migration routes.
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.
Potential for coupling the monitoring of bush-crickets with established large-scale acoustic monitoring of bats
Sounding them out: bush-cricket conservation via bat monitoring
New research led by the BTO shows how existing our pioneering bat monitoring work via the Norfolk Bat Survey could improve our understanding of bush-crickets - a species group that is difficult to monitor, being hard to see and almost impossible to hear.
Winter bird ID and WeBS (Residential, Flatford Mill, Suffolk)
Improve your winter bird ID skills and learn all about the Wetland Bird Survey (WeBS) on this weekend residential course for relative beginners and improvers. With a focus on waterfowl and waders, discover more about...
Unlocking the science to reveal the state of nature
David Noble takes a sober look at the latest State of Nature Report.