Colour rings are easy to read in the field and with photographs and quick replies the information is useful and very interesting.
Likewise these coded rings are probably better although good photos are often essential to read the code easily. Only one ring required!
(L41 ringed Maletangen, Norway 12/09/2016 observed Newbiggin by the Sea 04/01/2017)
This bird has been reported more than 12 times, showing the usefulness of these rings.
(2H62, originally ringed at Great Yarmouth Beach (13/11/2013) and has wintered at Newbiggin every year since.
Metal rings are no longer of any real use (my opinion). Only useful if re-trapped. According to BTO figures less than 1% are re-trapped. (I assume many of the re-traps are controls giving little new info.)
Other considerations which need to be taken into account. There should not be a culture of 'Ringers Ticks', birds should not be paraded before the cameras (release them straight away) and on bigger projects you need more ringers present. (To fix flags, colour rings, transmitters etc. at least ten minutes per bird. If you catch 6 birds the last one ringed will have been in a bag/cage for an hour.)
I hold my hands up and admit that I saw my one and only Radde's Warbler because the ringer waited a short time for local birders to arrive.
A lot more local study work i.e. feeding patterns, breeding success could easily be achieved by putting in the hours with a pair of binoculars. I'm not sure much is achieved by constant effort sites and tape luring other than a raised stress level in the birds.
Finally I do believe some of the projects especially the Harrier and Cuckoo satellite tagging projects are helping us learn some valuable information.
My opinions only!