Herewith a few basic and perhaps manifest observations but hopefully they will get further contributions and discussions started. Regarding the GPC estimate (10th Dec) of some 35-40% adults (and so 60-65% first winters) for the large c.400 flock of Waxwings at Burton upon Stather, (plus 'clearly a preponderance of first winters in all flocks seen'), it's interesting to note that re the Marston birds, on 22nd November Alan Ball wrote on LBC sightings:
"Apparently over 70 (Waxwings) this afternoon......but I saw 50+ . There seemed to be very few adults amongst them, suggesting they've had a good breeding year."
Thus from the reported adult/first winter ratio flocks noted so far on LBC, it would appear that the birds did indeed have a good breeding year and our analysed flocks showed the ratio of 2 adults to at least 3 first winter. One assumes a fair number of fledged young never made it to the UK as a result of eg. predation and the perils of a long sea-crossing,....... dangers which adult birds would be more likely to avoid or survive.
From my own observations this year and from the 2010/11 irruption, the berry preference is fairly clear. In the countryside there is a limited choice, of course, of Hawthorn berries and Rose Hips, which are both consumed with relish. In built-up areas, the choice would appear to be : Squashy Guelder Rose (Kalinka,Kalinka, Kalinka moya) and Rowans first,with the Sorbus aucuparia cashmiriana and hupehensis varieties, both with their drooping clusters of white or pink-tinged fruits, being especially popular (Tentercroft Street,Lincoln and Abingdon Avenue, Birchwood, Lincoln). Apples are a constant attraction while they last. Once the Rowans have been depleted and finished in an area, the birds switch to Cotoneasters, Dogwood, Holly, Pyracantha berries, Crabapples and occasional Mistletoe but while Rowan berries are still available, other berries in built-up areas are ignored. Only a few days ago in Gainsborough, I watched a small flock of 8 Waxwings fly over and totally ignore a Cotoneaster laden with gleaming red berries to reach a couple of fruiting Rowans almost bereft of berries. I tasted both berries and they seemed to have the same consistency of ripeness. ( some will say that Waxwings swallow berries whole, anyway).
Finally, once the Cotoneaster, etc, berries are all finished (eg.in March/April in 2011), Waxwings resort to the black berries of Ivy (the 70 birds I saw in Norwich in April 2011 were picking the berries off in fluttering flight without landing), the burgeoning buds of deciduous trees, plus leaflets and even flowers, insect gleaning on branches and also return to aerial flycatching which is so noticeable in the early autumn days. Presumably, in the 1965/66 irruption with flocks as large as 500-1000, plus satisfying the needs of thousands of winter thrushes, berries disappeared at an alarming rate with very few berries and very few Waxwings still remaining by February. Will that happen again this winter?
The insular Brits amongst us tend to think of Waxwings as essentially tree-berry scoffers, and yet once the birds return to their dense taiga forests of Scando-Russia to breed they (and the young) will feed on insects and low-growing soft fruits and shrubby berries throughout the summer.
Freddy
|