We ringed our first Raven chicks of the year recently – always our earliest species – so that marks the start of another busy season of nest-finding, ringing and monitoring. We have some news to announce; two of our ringers have been granted a licence to fit GPS tags to Goshawks, and we have secured funding to buy eight tags for use this year. Huge thanks to our donors/sponsors, namely the British Trust for Ornithology (BTO), Gloucestershire Naturalists’ Society, Gloucestershire Ornithological Co-ordinating Committee, Forestry England and Mr Richard Webb. This is an important project for us; it is an obvious extension of our work monitoring colour-ringed birds using trail cameras. We hope it will help us to track Goshawks that have had tags fitted to them as young birds in the nest. We should be able to assess their scale of their movement, habitat dependency and dispersal, and interactions with farmland as well as managed forest habitats. We may be able to accumulate information on the last known location of birds and mortality, and to understand the potential for population mixing and recruitment beyond the region. There is also the possibility to assess breeding home range if birds survive to adulthood or are tagged as adults.
This is in effect an extension of a project already being run by BTO staff in Breckland, Norfolk.
Goshawk nest being monitored by a trailcam enabling us to read GRMG colour rings
BTO will license the whole activity, and BTO staff will train 2 GRMG fully-qualified ringers. Read on for full details…
Nationally, the Goshawk is a scarce breeding species and a “Schedule 1” breeding species (protected under the Wildlife and Countryside Act 1982). The species should be a common breeding raptor and although the UK population is slowly increasing, there is much regional variation, potentially due to low recruitment where persecution may pay a role. Very little is known, locally, about seasonal movements, habitat dependency, home range size, or their reliance on specific habitat types such as farmland. Farmland use is relevant given the potential for conflicts with game bird enthusiasts. Winter movements, recruitment potential and connections with more distant breeding populations are also currently unknown. Entirely new information on habitat use and the dispersal would emerge for this population, also giving the potential to compare and contrast with other regions within the UK. We would like to make it known publicly that individuals of these species are being tracked, as a protection measure.
The Goshawk is an elusive species, not amenable to normal visual observation. Advances in remote tracking offer the best opportunity and most objective way of acquiring behavioral data.
Project objectives: Determination of habitat use and dispersal, the farmland interaction and possibly sources of mortality in the Gloucestershire population of Goshawks:
• To track Goshawks, to assess scale of movement, habitat dependency and dispersal; interactions with farmland as well as managed forest habitats.
• Potentially, to accumulate information on the last known location of birds and mortality.
• To understand the potential for population mixing and recruitment beyond the region.
• Potentially to assess breeding home range if birds survive to adulthood or are tagged as adults.
Links between forest, farmland and fenland habitats may be expected, especially for juveniles or females in winter and links to forest edge are predicted. Some exploitation of game bird populations is expected, though varying widely with native prey availability (pigeons, jays and squirrels), sex, age and season.
The devices supplied by a company called Movetech Telemetry, a subsidiary of the BTO. The devices weigh between 18 and 23 grams depending on sex of the carrying bird. The devices are attached on the bird by a harness, which contains a sacrificial thread that is designed to break after around 5 years.
No ill effects have been shown on birds that have been recaptured or have been collected.
The ‘Movetech’ bird-tracking system described here is a bird-borne method of tracking bird movements, by connecting to the mobile phone network. This technique has been successfully applied to similar sized birds (gulls) and raptors (Goshawks, eagles, Ospreys, harriers, Peregrines). the system is much more objective and less labour-intensive than radio-tracking, producing high precision fixed location data, unlike any other currently available method (bar satellite tracking at far greater cost).