Bird-borne satellite transmitters: current limitationsand future prospects

Benvenuti S.

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Abstract:

The paper provides a brief account on satellite tracking, a new promising method for studying bird migration and orientation. This method is based on two Tyros-N satellites which receive and locate the signals emitted by bird-borne transmitters. The literature on this topic is stili very limited, due to the fact that this technique, which is only a few years old, has not yet left the pionieristic phase. However, technical problems concerning the weight of transmitters - and their short operative lifetime - which presently pose severe limits to experimentation, will supposedly be overcome soon by the progress of technology. New generations of transmitters, and possibly other satellite systems equipped with mare advanced onboard instruments, will certainly provide relevant infarmation on the many challenging questions related to avian migration and navigation which cannot be answered by conventional methods. Preliminary results from a satellite tracking experiment on migrating Brent Geese, recently run by the research team which the authar belongs to, are briefly reported. Despite the limited operative lifetime of transmitters, this method allowed us to reconstruct a large portion of the geese' flight paths from their main staging sites in Iceland to the breeding grounds on Canadian arctic islands, and also to investigate the experimental birds' orientational strategies.