Not totally sure but with the newer units you should be able to output a .gpx file from the Bird then take it to the Lowrance unit.
Not sure about this^^^^^^^ but I could be wrong.
You usually have to save the HB files (.hwr) to .gpx and then upload those to some program that will then convert them to Lowrance (.usr). I use the HB program and then use the EasyGPS program to convert to Lowrance (.usr). The EasyGPS program is a free download and I use it to back up all my waypoints so it is good to have.
Do you have the Gateway and NMEA2000 backbone to use the GoTo function?