All of the released birds were fitted with wing-tags and radio-transmitters to assist in monitoring their activities and progress, not least to locate and identify them if they moved to other areas or if they were injured or dead. There is a UK-wide wing-tag colour coding system, details of which are shown on the accompanying chart. The colour of the tag on the left wing indicates where it was tagged, whilst the right-wing tag colour shows the year of tagging. Each tag has a coloured band across it, showing the colour of the tag on the other wing. In addition, the tags on each bird show a symbol – usually a number or a letter. A clear reading of one tag would produce sufficient information to identify the bird. For example: an orange tag showing ‘20’ and with a red band at the bottom would indicate a Yorkshire bird tagged in 2003. Wing-tagging has revealed the presence of a number of birds from other areas which have settled and bred in Yorkshire, whilst birds either released in Yorkshire, or reared in nests here, are known to have bred in Northamptonshire, North-East England and Perthshire in 2008. There has been no wing-tagging of Yorkshire Red Kites since 2006.
Radio transmitters, each operating on a different frequency, enabled the progress of newly released birds to be monitored. This was particularly useful in the early days following their release. Each transmitter was fitted with a sensing device which altered the pulse-rate of the signal according to whether the bird was either perched (slow pulse) or flying/feeding/dead (fast pulse). By this means it could be established that a bird was active without it actually being seen. The current cost of transmitters is around £200 each. They have an effective lifespan of two and a half years. Having transmitters on them has enabled a number of dead kites to be located – several of which had died through feeding on illegal poison baits.