The arrival of flocks or Bohemian Waxwings Bombycilla garrulus in the UK is always a cause for celebration, and many birdwatchers will make the effort to see them during their unpredictable irruptions in search of food, their winter diet consisting mainly of berries. During the winter of 2023-24 a substantial invasion has been reported, and this film was taken in Balham, London, on New Year's Day 2024, where a flock of 14 birds had located an ornamental Vilmorin's Rowan Sorbus vilmorinii laden with a good supply of fruit. Often flocks will seek out a particular tree or bush and proceed to clear it of berries before moving on, and one paradox is that supermarket car parks may be favoured as so many ornamental berry-producing trees have been planted as a part of the landscaping in order to draw attention away from the concrete deserts underneath! Such anthropogenic environments are far removed from their summer habitats in wild and remote areas of the tundra where humans will be rarely - if ever - encountered. It may be the case that some of the older birds in a flock may have visited a productive location during previous irruptions and that they can relocate them. Whether or not this is the case, there had been two relatively recent previous visits to Balham by overwintering flocks of Waxwings during 2010 and 2019, with the latter year also being notable for large flocks of winter thrushes (Redwings Turdus iliacus and Fieldfares T. pilaris). Worthy of note, has been evidence of courtship or pair-bonding reinforcement behaviour (presentation of aphids by one bird to another), indicating that at least some members of the flock had already formed pairs or were in the process of doing so. They are also shown preening, and descending to a roof gutter to drink between feeds and their soft and distinctive contact calls are evident on the film. Their presence has been of some interest to the local residents too!
31 дек 2023
