Research

To search scientific abstracts of selected radio-tracking publications, click here. This facility allows you to search projects that might be related to the work you are intending to do.
A major strength of Biotrack is its direct involvement in research, constantly meeting new technological challenges. Right from the start, Biotrack employees were making tags for their own research into goshawks and squirrels. We believe this strong interest in biological research allows us to understand your needs and meet them more effectively.

[Buzzards]  [Nightjars]  [Thrushes &Blackbirds]  [Bearded Tits]  [Barn Owls]  [Sika Deer]  [Vocal Individuality]  [Other Projects] 

Buzzards

Sean Walls has been studying the common buzzard (Buteo buteo) with Robert Kenward and Kathy Hodder, who work for the Centre for Ecology and Hydrology (formerly: Institute of Terrestrial Ecology). The project has been running since 1990 and the long-life tags, mounted with a Teflon ribbon harness, have enabled us to track individuals for 4 years. The main aim of the project is to understand the population dynamics and behaviour of buzzards. These magnificent birds are spreading back into the east of England, from where they were persecuted late last century. Our work has indicated that it may be the philopatric nature of buzzards, rather than continuing persecution, which accounts for apparently slow spread back to their former distribution. From the opposite point of view, we have been exploring possible ways to minimise the conflict between gamekeepers and buzzards. These have included increasing the density of released pheasants and encouraging a shrub layer (approx. 1 m. high) which provides cover for the pheasants. With respect to the general ecology of local buzzard populations, we found that survival is far higher than previous estimates from ring recoveries, and breeding does not start until the buzzards are older than expected. Studying seasonal dispersal and other movements can help us to understand an environment from a buzzard's perspective. Eventually this work can then be applied to rarer species that need a helping-hand towards long-term viability. For associated publications, please search the scientific abstracts using "buzzards" and "Walls".

Nightjars

Since 1985, Brian Cresswell has been a key member of the Dorset Nightjar Project, started in 1980 by amateur ringers in the Stour Ringing Group. Radio-tracking has been crucial to several important discoveries resulting from the work. For example, during their active period (at night) the nightjars did not remain on the heathland where they nest. They made excursions of several kilometres to deciduous woodland, agricultural land and wet meadows for feeding. Measures to conserve nightjars have hitherto concentrated on places where they breed, but this research suggests that it is just as important to conserve their feeding habitat. The current focus of the project is on automatic monitoring of nightjar foraging activity, to learn how it is affected by light level and temperature. It is hoped that collaborative work with other researchers and students will increase the fieldwork input and publications output of the project in the coming years. The Nightjar Project provides a great opportunity for testing new telemetry equipment and techniques. Last year we used Biotrack's new - much smaller - radio tags containing surface-mount crystals (the weight of the smallest tag we produce has now fallen from 0.8g to 0.5g). They worked very well. We have also been testing Lintec flexible Yagis for the past two years, and found them extremely advantageous,especially when ploughing through rhododendron thickets!

Thrushes and Blackbirds

We were closely involved with Ian Hill's doctoral project at the University of Oxford. Ian's study was conducted in the gardens and farmland around Biotrack. His main aim was to establish why the British song thrush (Turdus philomelos) population is in steep decline. To do this he has compared the survival and behaviour of radio-tagged fledgling song thrushes to fledglings of the more common blackbird (Turdus merula). Though a similar species to song thrush, blackbirds have had a stable national population during the period of the song thrush decline. Ian completed his doctorate in 1998. Song thrushes were significantly more mobile than blackbirds when leaving the nest. They continued to drift away from the nest over an extended period and were associated with habitats found in the periphery of the garden. In contrast, blackbirds stayed closer to the nest and then had a few days dispersal before settling into a new range. They associated with the more managed garden centre. Being in more open habitat to begin with, blackbirds suffered higher mortality initially. However, after the blackbirds had dispersed survival improved, whilst song thrush numbers continued to decline markedly. The cooperation between us encouraged new developments including the evolution of a backpack with an elasticated wing loop harness that accommodates growth. The design was presented at the Proceedings of the Fifth European Conference on Wildlife Telemetry (held in Strasbourg in 1996). The project also gave us the opportunity to test our smallest "Pip" transmitters before supplying them to other projects.

Bearded Tits

In 2002, working with The Wetland Trust and an MSc student from Reading University, Brian Cresswell initiated a radio-tracking study of Bearded Tits. The research was conducted at a private nature reserve in East Sussex (UK), and compared the foraging behaviour of adults and independent young. Using 'RANGES 6' range analysis software, we analysed range overlap within and between age classes, looked at habitat preferences and used dynamic interaction analysis to investigate the formation of juvenile pairs (an interesting behaviour in bearded tits). Juvenile females ranged further overall than adult and juvenile males, but their core ranges were the same, suggesting that juvenile females were more excursive. Range overlap within age classes was greater than between age classes at most levels of range core area (as estimated by location data utilisation in cluster analysis). Areas with the densest locations appeared to be exclusive. Adult ranges excluded juveniles, and vice versa, at 65% location data utilisation (65% cores). Adult ranges were exclusive of other adults at 35% cores and juveniles of other juveniles at 20% cores. Dynamic interaction analysis indicated that at least two of the juveniles had formed pairs, but there was little evidence of flocking, and static range overlap was a poor predictor of dynamic associations. The most used habitat in proportion to availability for both age classes was Phragmites. The second most used habitat for adults was Typha, whereas for juveniles it was small pools of open water (probably the water's edge was used).

Barn Owls

Brian Cresswell is leading a study of barn owl dispersal; to investigate movements, habitat use and causes of mortality during their first year of life. This is a joint venture with The Wetland Trust and 'Chalk & Hawks', a European-funded project combining conservation with wildlife tourism. The project started in Sussex in 2003 where we monitored the behaviour of a brood of barn owls before and after tagging (using CCTV). The owls habituated almost immediately to their backpack and harness. In 2004 the study was extended to three more broods (nine birds), this time in Dorset, and three birds which survived now have young of their own. Currently we are seeking funds for a PhD student in 2006 onwards to expand the project and generate more meaningful sample sizes.

Sika deer

Sean Walls is currently advising a local study on Sika Deer, Cervus nipon started by Bournemouth University and the Royal Society for the Protection of Birds to look at the management of the fast increasing population. It is early days, so there are no publications yet.

Vocal Individuality

The ability to distinguish one individual bird from another by its song can add valuable detail to a breeding bird census. It can be used to monitor local movements within and between years, and provide long-term data on survival. It can enable census methods to be calibrated (e.g. how many birds are missed and how many are counted more than once?), such that a more accurate estimate of population size is obtained from basic census methodology. Brian Cresswell initiated a study of Vocal Individuality in reed buntings and Cetti's warblers at a private nature reserve owned by The Wetland Trust in Sussex. Three MSc students from Reading University and University College London have worked on the project since 2002. Sonograms and spectrograms of song recordings from reed bunting and Cetti's warblers have been analysed using discriminant function and cluster analyses. Male Cetti's warblers appear to be highly vocally distinct. Reed buntings also appear to be separable by their song, but may be more variable depending on which neighbouring birds are singing at the same time. The student in 2005 set up an experiment to compare the response of Cetti's warblers to different playback songs (self, known neighbours and strangers), which has yielded some interesting results. The techniques developed in these projects are being used to monitor the number of male Cetti's warblers on the Sussex reserve where the research is taking place.

Other Projects

The members of the Biotrack team have also been involved more briefly with other projects such as an Oxford University expedition to study Giant Jumping Rats in Madagascar, Squirrels in Dorset (UK), Purple Sandpipers in Norway and snipe in Cambridgeshire (UK). For associated publications, please search the scientific abstracts using the species name.