I cannot agree with this statement. Whilst it is normal for tits to join feeding flocks in winter, it is also normal for them to break out of winter behaviour during milder spells. It is no accident that nest boxes are checked by potential occupants for the first time in autumn and will be visited regularly through the winter. Many people have reported individual birds or pairs returning to nest boxes every night and there are reports of hammering during the first few minutes before settling for the night.
but they might just be using them as roosting sites. In built-up areas, there is frequently a deficit of cavities, so birds have little choice but to roost in nestboxes, which they then have little choice but to nest in. So, of course, you'd see them visiting throughout the winter (they have no other options!). In natural woodlands, where there is a superabundance of holes, tits usually do not roost in the future nest site until just before the breeding season. That's because they tend to choose a smaller cavity that they can warm up using less energy. A big roomy nest cavity takes a lot of heating up. Many studies of tits have shown this preference.
As for finding old nests, it depends on the maturity of the birds and I have seen bird check but not use a nest known to have been occupied the previous year.
Sorry, Ian, but that doesn't make a rule. If there is a surfeit of holes (which there is in many woodlands), then random chance would mean that they wouldn't use the same site two years in a row. But I've seen birds use the same site several years in a row, but that's not a rule of thumb either.
why?
and you have only made the case for the floor of the box not the entrance.
well the same logic could easily apply - they may peck the entrance to make sure it's solid enough to not be too easy for a woodpecker to break in, or that it isn't going to fall out and reveal the nest.
There is an alternative to my original explanantion in that hammering has the same role as it has with woodpeckers, as a replacement for song.
I've never heard that theory. Would that be as territorial song or sexual song? If territorial, then you'd expect 'hammer duels' between birds/pairs, as with woodpeckers. And I've never seen a report of that. If sexual, then you'd expect the male to be doing the hammering, but it's females that select breeding sites, not males. Males may 'show' females potential sites, but it's the females that choose. And in any case, tits use vocal song/calls at nests when choosing sites. This is well-recorded. So where would a mechanical 'song' fit in?
Nevertheless, this is still territorial behaviour and we should not forget that wood weathers so it is readily apparent if a mark has been freshly made.
but, if your blue tit was inspecting a hole, and saw a nest, how would it know that it was a previous nest of a blue tit, and not a great tit, coal tit, marsh tit, willow tit or crested tit? By the time they're looking into holes in the winter, all those nests will be the same kind of soggy mossy wad. How would the birds be able to tell and work out it was a rival?
No argument here but what do you do about dead eggs and chicks? It is too late to make the adjustment in spring without the risk of causing the birds to abandon before nesting has really begun. .
Well there usually virtually nothing left of dead chicks by autumn (as you'll know if you go looking for rings from dead pulli!), and eggs are usually buried right down and also decompose within about a year.
Again, this is not completely accurate although I do not disagree with your point about the nest becoming degraded as the chicks grow. It is down to individual birds and there are records of birds building a winter roost (including blue tits) this sometimes starts as a display nest in autumn but there are records of blue tits building a winter structure. .
I have seen no refs of tits building nests to roost in in winter. And it is generally assumed that anything that is built in autumn/winter is a result of hormone changes and daylength initiating spring-type behaviour. There are breeding records for many species in autumn. Perrins (British Tits 1979, p. 104/5), who is the authority on tits, it's fair to say, covers roosting behaviour, and queries why tits do not build winter roost nests, as sparrows do. So it's pretty clear that any apparent building is aberrant.
The moss point is irrelevant because individual birds use different materials even when nesting close by. This was shown to good effect on Springwatch.
Ian
I disagree strongly, that's misleading. All tits use moss as the fundamental base of the nest, if they have access to it. Where moss is scarce, they'll use grass. Individuals do vary with the lining of the cup, I agree, but only depending on what is available. If there is a dead pigeon nearby, they'll line it with feathers. If there is a dead deer, they'll line it with fur. I didn't see Springwatch, but I'm pretty sure it wasn't a well-structured trial. Who's to know what was available to each bird? Who's to know if one was in a rush to build? Theer are too many variables, and you can't make a judgement based on Springwatch and what Bill Oddie says. I remember the bollox he was talking about 'bad mothers' one year, because a tit was placing a sunflower heart in the mouths of different chicks. This is perfectly normal with insect prey, as each chick then gets a bit of the juices, but when they're starving and resport to sunflower hearts it doesn't work. But they're locked-in to that behaviour so can't rationalise that. Bill should read more!
