Ardea
Official journal of the Netherlands Ornithologists' Union

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Naef-Daenzer B. (1994) Radiotracking of Great and Blue Tits: New tools to assess territoriality, home-range use and resource distribution. ARDEA 82 (2): 335-347
With a newly developed small transmitter, radiotracking of birds with a minimum body mass of 7 g is possible. Its high pulse rate (4-9 Hz) allows birds to be located within a few seconds with a precision of 1.4 degree (SD), i.e. 2.4 m at 100 m bearing distance. Data on the use of individual trees by Great and Blue Tits (Parus major and P. caeruleus) revealed details of home-range use and separation of the home-ranges of neighbouring birds. Within I min, Great and Blue Tits moved over a median distance of 18 m and 10 m, respectively. The range use of the tits was determined to a great extent by the spatial distribution of caterpillars, the main prey during breeding season. Overlaps of neighbouring home-ranges were observed only for areas of low location density. By contrast, the central parts of the home-ranges were used exclusively by the resident pairs. Using the examples given, I discuss four main methodical aspects of radiotracking of small woodland birds: (1) Location probability and basic qualities of the data obtained. (2) Spatial and temporal resolution of tracking data. (3) Tracking of short and medium distance movements. (4) Analysis of territoriality and relationships between neighbours. The new technique greatly improves the observation of small animals under poor visibility conditions. It is, however, limited to a relatively small number of individuals, which has its implications for study design and statistical analysis of the data.


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