Mysterious blackcaps
WE’VE reached the time of the year when our skies fill with birds on a mission.
Summer migrants get itchy feet and fly off to pastures new, while our winter residents start arriving en masse.
Wetland birds like teal and tufted duck are back in Mere Sands Wood, Brockholes and Seaforth nature reserves, while short-eared owls are sweeping into Lunt Meadows from Scandinavia.
Smaller birds like swallows, chiffchaffs and house martins have started their epic journeys to warmer climates in southern Europe and Africa, with redwings and fieldfares taking their place in our parks, gardens and woodlands.
I’ve also recently spotted blackcaps, a migratory bird common across the UK, perched in berry-laden bushes while out and about.
The blackcap is a medium-sized warbler, mostly found in woodland, tall scrub and gardens.
Dark grey in colour, males live up to their names, sporting black caps atop their head, while females have gingery-brown caps.
I am not sure whether these blackcaps are summer or winter migrants though because, confusingly, these little birds can be leaving or arriving in the autumn months – depending on where they were born.
Blackcaps were once just summer visitors to the UK but, since the 1960s, have been increasingly spotted all year round.
The same birds, however, do not stay all year round.
Summer visitors arrive in April from Spain and start breeding in mid
May, making a neat, cup-shaped nest of dry grass and moss in dense vegetation such as hedges or bramble bushes.
In September and October, these sun-loving blackcaps and their newly-fledged young make the journey south to Spain and are replaced by blackcaps flying in from Germany and north-east Europe.
What has caused this gradual change in the Germanic blackcaps’ behaviour?
We think it may be due to a combination of increasingly milder UK winters and the abundance of wellstocked bird feeders in our gardens.
If this is right, then the blackcap is the first species to change its migration route and destination because of people feeding birds.
Over the years, this has led to changes in the two populations of blackcaps who visit the UK.
Experts have noticed that the blackcaps that spend their winters in the UK have narrower and longer beaks than those that spend their winters in Spain.
This change in beak shape suggests that the blackcaps we see in winter have adapted to a more generalist diet, reflected by observations that blackcaps seem to eat mainly insects in summer but fruit and seeds in winter.
So if you would like to entice blackcaps into your garden this winter, there are many different food options they will enjoy.
They enjoy sunflower hearts, seeds, mealworms, fat suet and fruit such as apples or elderberries.
Be warned though – blackcaps are not good at sharing and will chase other birds away from feeders and tables.
To keep the peace among your feathered friends, offer several food options in different parts of your garden.