Blackcap (Sylvia atricapilla)
Facts & Figures:
Population in 1970: 200,000
Population in 2019: 1,650,000
Change in Population: + 1,450,000
Percentage change: + 825%
Length: 13 cm
Oldest: 10 years 8 months
Eggs: 4-5
Broods: 1-2
A few weeks ago when the classes went to Fairburn Ings we saw a male Blackcap around the feeders at The Pick-Up screen. This was probably a German bird, which decided to risk over-wintering in the UK. It would then be able to return to Germany in good condition ahead of the other Blackcaps which had over-wintered in the southern Mediterranean and Northern Africa, and had to fly back over many more hundreds of miles.
British Blackcaps are now starting to arrive back on their breeding territories and woodland and area of scrub should soon be full of the song of a bird which has been called the “Northern Nightingale.” The melodious song seems start a little scratchily and uncertainly at first, but then it gathers in strength and it soon becomes very loud and has a see-saw quality before stopping suddenly. In addition to their beautiful song, Blackcaps also have a very obvious loud “tack-tack” alarm call. Just occasionally, it is possible to hear Blackcaps making a shrieking call.
Blackcaps are vocally most often confused with Garden Warblers, but the latter bird is much less common, and arrives nearly one month later than Blackcaps. A Garden Warbler’s song babbles along more or less at the same level of intensity, and doesn’t have the loud highs of the Blackcap’s song. It is a much more relaxing bird to listen to.
Blackcaps are larger than Chiffchaffs, and just a little smaller than Sparrows, but they are much sleeker birds than the more rotund Sparrows. I always try and stress my clients to look at the bills of any unknown bird if they can. Sparrows have thick bills at their base ideal for crushing seeds, whilst Blackcaps have thin long bills the ideal shape for catching insects. On migration Blackcaps will fatten up on Autumn berries, and the ones which over winter are actually known to change the shape of their bills, so they can cope with food left out on birds tables. In winter when they can be rather desperate for food, they can be extremely feisty, chasing away anything else which tries to come for the same food. If a Blackcap arrives too early and a day is too cool and there are few insects about, then a Blackcap will turn to ivy berries and the nectar from flowering trees.
Blackcaps appear to be very grey birds, and are the most grey of all the common UK warblers. The adult is grey-brown above and pale grey underneath. The male has the black cap, which lends the species its name, whilst the female and young birds have a rufous brown cap.
Female Blackcap
The best time to see them is when they first arrive as the males will sit in the open, and usually in early April the surrounding trees will be bare. When the leaves come out the singing birds are much more difficult to observe. One of the best local places to see them in May is Millington Wood, because it faces north and is high on the Yorkshire Wolds, so sometimes the leaves come out a fortnight later than in lowland areas with bushes and trees.
A Pair of Blackcaps in winter
It is believed Blackcaps were first mentioned over one thousand years ago when Alefric, Bishop of Eynsham referred to them as a “swertling” in an Anglo-Saxon/Latin vocabulary. They are one of the few bird species, which seemed to be doing better in 2019 than they were in 1970. The population 50 years ago was estimated at 200,000, but now is thought to be as high as 1.65 million!
My video with examples of the Blackcap song from www.birdvoice.net is available here
A Blackcap news story about the evolution changes in winter birds is available here:
The RSPB Blackcap audio file is here
Here’s the BTO video to help separate Blackcaps and Garden Warblers here
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