On Oz telly recently there was a series of programs about various migrations of birds, whales and caribou, hosted by a wally of a veterinarian who kept describing himself as a "vetinarian"; he wanked on about some raptor migrating from Maine to Colombia as the longest migration ever, forgetting about the mutton birds that go from Tasmania to the Bering Sea.
Rant aside, the relevance is that the birds were not large but were carrying transmitters that produced signals receivable by both hand-held receivers with very directional antennae (the sort of thing widely used by field biologists and with a range of about 1km) and satellites that could map their location with almost the same resolution and plot it onto a GIS.
Such instruments (and, importantly, their batteries) would have to be small and light but they seemed to provide no problem, either to the transporting birds nor with longevity of the batteries and could certainly fit into the case for a flute, let alone cases for concers, accodions or pipes. I gather the ones on the whales had small photovoltaic cells topping the batteries up but I can't recall such cells on the birds.