Worked with a couple people over the years who straight out said they are hard to deal with. Had much less problems with them than those who said “they could work with anyone”
IIRC the issue with waterfowl conversion was sudden failure of seals, buoyancy and ballast systems.
The seagull program was hit with the extra problems of salt water
Last leak mentioned the advances have made in the house sparrow model, but battery life is still an issue.
Songbirds aren’t used due to birdwatchers; as outlined in the paper “Avain surveillance: security, counter surveillance, and camouflage” read the updated 2019 version.
But if you read the avain replacement system experiment paper you would have seen it was of limited success. Sure pigeons and starlings are no longer real, but those were the only 2 successfully replaced species.