The lovely warm weather of today is forecast to continue into next week, and on your daily exercise walks and in your gardens, the song of a new bird will soon be joining the others (such as blackbird, robin and goldfinch)… and it is the blackcap!
This small warbler is a bit of a Jekyll-and-Hyde in terms of its habits- while we have over 900,000 pairs breeding in the UK each summer, thousands now also overwinter here. But, recent studies of ringed birds have shown that the birds that spend the winter in the UK are not the same birds that breed here, but instead have come from further east, especially Germany. These ‘European’ blackcaps are also a little bigger (which probably helps them cope in a colder climate) compared to our summer birds which spend our winter in Africa and southern Europe. If you are lucky, this past winter you may have seen one in your garden feeding on fruit and seeds (another adaptation to winter conditions) that you have put out for other birds you might normally expect to see!
However, the switchover between the winter and the summer blackcaps takes place in Spring- and they are beginning to arrive right now. If you are out on your daily exercise walks, and pass by anywhere overgrown, untidy and sheltered, listen out for their lovely song: https://www.youtube.com/watch?v=GKPhFPTyxpI
You may also see them- they shuffle about in bushes and scrub, often singing at the same time as looking for food. Or the males may be a bit more dedicated about it and stay in the same spot near the bush edge, trying to project their sound as far as it will carry. Male birds are what give the blackcap its name, whereas females have a warm, gingery brown cap instead of a black one.
Photo credit: Male (top) and female (bottom) blackcaps, both from Wikimedia Commons
They’ll be singing for a few weeks, but May is when the nest-building and egg-laying really gets underway. A male blackcap will build several very basic nests (almost a skeleton of a proper nest) near his favoured song posts, and will show any interested female his collection. If she likes any of the locations, she will show it by adding material herself for another four or five days, until the nest is complete and ready to hold eggs.
Then, the female will lay an egg per day until she has four or five in the nest (pairs have been known to have as little as two eggs, or as many as seven, but five is the average) and will start to incubate them when she has laid the second-to-last one. Interestingly, both pairs will share the incubating but only the female will do so at night!
The young chicks, which hatch eleven days into the incubation, are fed on a diet rich in insects, mainly caterpillars and craneflies. Though when caterpillars run low in June, if there are still chicks to feed they tend to get a lot of beetles instead! Adult birds eat a lot of insects too, though during migration and when they have just arrived in the UK they will seek out nectar, pollen and ivy berries to keep them going until insect numbers build up enough to make it worth looking for them. We will keep our summer blackcaps until late August and September, when they will begin to move south through Europe, in 50km bursts. Sometimes birds will travel as far south as central Africa while others might not attempt to cross the Sahara and may stay in Greece, Turkey or north Africa. And then our trickle of winter birds will return to us from Germany and eastern Europe… and the cycle will begin all over again!
I hope this blog has been interesting. If you want to read more about blackcaps then the BTO Birdfacts website is a good place to start: https://app.bto.org/birdfacts/results/bob12770.htm
I have a lovely book at home called The Blackcap, by C.F. Mason which is a treasure trove of information- if you can get hold of a copy via the internet, as it was written in 1995! We hope you continue to stay safe and well in the coming week, and enjoy connecting with nature whenever your routine allows it, whether that be on your exercise walk or in your back garden. Next weeks’ blog will be all about willow warblers… they are next up in the procession of spring migrant birds to reach us!
written by Heidi Jones
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