What??? Willow tits are in trouble in UK (and arguably more important in a global biodiversity sense than ospreys or white storks, given that ssp. kleinschmidti is confined to Britain).Willow tit (I only know of one site, maybe pollution is wiping them out?)
But they are holding up reasonably well in parts of NE England, they're on both mine and my partner's garden lists in NW Durham / north of Newcastle; what our locations have in common is wet woodland in reasonably close proximity with rotten bark for excavating nesting holes. I'm struggling to see how pollution is wiping them out, I thought GSW predation might be more of an issue?
Surely the answer to this incredibly emotive thread is that some re-introductions have more value than others. Red kites have IMHO been really positive and worth the effort, if our scavenger fauna is confined to corvids and gulls then we would indeed have a very diminished avifauna. But the reintroduction range in NE England is constrained by shooters in the surrounding rural areas, and hasn't been as successful as places such as the M40 corridor.
I'm not sure why efforts have to be made for common cranes when they seem to be recolonising naturally anyway, there are plenty other crane species in far more trouble worldwide that need conservation $$$