Tree Sparrow box
This could be because the land use has changed slightly on the farm over the past year with less cereals grown and more areas down to grass for silage. It could also just be that the Tree Sparrows are nesting elsewhere as this can often happen with Tree Sparrows, and large numbers can leave the colony for no apparent reason. I'll have to wait until next year to find out properly.
Surprisingly I ringed a brood of Blue Tits and a brood of Tree Sparrows this morning, and both had only hatched within the last 4-5 days, but they were well developed enough to ring.
Female Blue Tit sitting
It's more boxes for me at weekend, when I head to the uplands and switch to Pied Flycatchers, but not before a session in the reedbed hopefully ringing Reed and Sedge Warblers. I'll keep you posted.