![]() Very frequent and accurate positions can be obtained without either disturbing the birds or leaving scent marks that may attract predators. Clearly, the new, cost-effective GPS telemetry offers new and better opportunities for studying small-scale brood movement. When inside plantations, they did not discriminate between remaining there and moving into nearby old forest, but they tended to move faster in plantations than in old forest. When broods were inside old ‘natural’ forest, they remained there instead of moving into plantations. Strong autocorrelation among successive positions made us examine habitat selection using a binominal choice method for each brood separately. The two oldest broods whose initial age was seven days moved faster than the two younger broods whose initial age was two and three days, respectively. Broods moved almost continuously during the 24-hour cycle, presumably foraging, although their speed was slower at night. The movement patterns of the four broods were quite similar, with a mean speed of 83.2 m ± 9.9 (SE) per hour during the 4.5-day tracking period. A total of 1,277 positions were obtained (84% of potential maximum), of which 77% were within 20 m of the true position of the brood. In our study area (Varaldskogen) with moderate topography, the GPS technology performed quite well. With a storage capacity of 450 positions, movements could be monitored for ca 4.5 days. The GPS units were programmed to record positions every 15 minutes, the shortest interval possible. Hens of four broods with chicks 2-7 days old were captured and fitted with 90-g backpacks containing GPS units and VHF transmitters. Using GPS satellite telemetry, we studied the movement patterns of young capercaillie broods: 1) to test if this new technology could be applied to gain more detailed insight into behaviour and habitat selection at a small spatial scale, and if so, 2) to compare the broods' relative use of planted and older, naturally regenerated forests. High mortality among chicks, due to fragmentation and changes in habitat caused by commercial forestry, is considered one of the main reasons for the general decline in capercaillie Tetrao urogallus in boreal forests. ![]()
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December 2022
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