During the test, 3 homing pigeons carried 4 GB (gigabytes) for 100 km distance, achieving, what apparently looks as pigeons' world record in data transfer to a given distance. Bandwidth achieved by the pigeons was 2.27 Mbps...Transferring a similar volume of information through a common uplink of ADSL line would have taken no less than 96 hours..."
http://www.notes.co.il/benbasat/5240.asp