21 December 2017

Return of the winter Blackcaps - a geolocator story

How do migratory birds respond to a changing environment? The answer to this question may help us unlock key insights into the mechanisms behind migration, and predict how animals will adjust to future global change. British Blackcaps may provide key insights into birds’ abilities to evolve changes in migration. Blackcaps are now spending the winter in the Britain and Ireland in greater numbers than ever before - a change BTO scientists have linked to garden feeding and warmer temperatures. But what exactly do they gain by wintering here, and where are they coming from?

Blackcap with first geolocator retrieved - photo by Benjamin Van Doren

As previously reported, last year, researchers from the BTO, Oxford University, and Exeter University began teaming up with bird ringers and garden owners across Britain and Ireland to study the Blackcaps that visit our gardens in winter. Last winter, we fitted 36 Blackcaps with geolocators, miniature devices that track movements throughout the year; however, the birds must be recaptured in order to retrieve the device and data, which can be a challenge.

Excitingly, returning Blackcaps carrying geolocators have been seen in gardens around the country since late November. These early successes would not have been possible without the dedicated BTO ringers, Garden BirdWatch participants, and other volunteers who have contributed so much time and effort to the ongoing study.

Blackcap geolocator movements. Blue dot - wintering site.

On 26 November, Glynne Evans recaptured the first returning individual in his Hampshire garden where it was tagged nine months earlier. Preliminary analysis indicates that the bird left Britain at the end of March and spent the summer in France, before returning by early November. But is this pattern the exception, or the rule? And why did this bird decide to come north for the winter when it was already in southern France? We hope to find the answers to these questions and many others - as the project continues.

Garden ideal for Blackcaps - photo by Benjamin Van Doren

Glynne’s GBW garden has turned out to be an exceptional Blackcap site, with a further tagged bird (analysis in progress) being caught in December, as well as two other colour-ringed birds returning from last year, giving a return rate of 25%, so far. We know very little about their behaviour and movements in winter, so any sightings of colour-ringed birds would also help answer these questions. Glynne provides food for Blackcaps starting relatively early on in autumn—could this partially explain their affinity for his garden?

How can you help? 

Do you have Blackcaps visiting your garden in winter? Look out for Blackcaps with colour rings and note the positions of the colours on each leg, or even better, take a photograph. Observers interested in joining the colour-ringing and tracking efforts can contact Benjamin Van Doren at Oxford (benjamin.vandoren@zoo.ox.ac.uk) or Greg Conway at the BTO (greg.conway@bto.org). Gardens with multiple Blackcaps regularly attending bird feeders are particularly valuable. For further information please see Life Cycle, issue 6 Autumn 2017.

This study is a collaboration between Oxford University, BTO, Exeter University and the Max Planck Institute for Evolutionary Biology, Germany.

26 comments:

  1. Have had a male blackcap visiting since before Christmas .we are in north devon

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    1. Thanks for letting us know Wendy. Please keep a special look out for any with colour rings.

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    2. just seen a Blackcap in our garden today it was with a group of resident sparrows who were quite happy to have him in their gang!!

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    3. sorry , our garden is in Bournemouth.

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  2. We had a male Blackcap visiting our coconut fat feeder for 2 weeks from 16 November at Roskhill, Dunvegan Isle of Skye IV558ZD.
    Sue Wood

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  3. We have a male and female Blackcap that visit our garden every winter for at least the last 5 years. We are located in Odiham Hampshire. RG29 1EB

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  4. Male and female Blackcaps in garden for the last 3 weeks. Brixham, Devon

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  5. We definitely have a male blackcap that visits our garden daily in the Winter. We first saw it last Jan/Feb. I believe I've seen a female blackcap this year too. We'll look out to see if they are ringed and let you know.

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  6. Sandy McWilliams. I have blackcaps in my garden every year from January. This year a male and 2 females. I attract them with a home made fat ball that they can't resist. Blitz sunflower hearts in a food processor until really really fine add Atora suet granules, put into a plastic bag, place bag in microwave for 2 minutes, remove and massage the contents through the bag until well mixed then squeez towards the corner of the bag, twist the bag and tie off. Put in fridge until hard. No dirty saucepans or hands. Co Antrim.

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  7. We spotted a male blackcap in our garden for the first time yesterday 3/2/2018 we are in Solihull West Midlands
    Jayne Edwards

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  8. We have a had a pair of Black caps visiting our garden in Bristol, South West UK since early January, mainly feeding on sunflower hearts which we provide all year through with occasional interest in fat balls. They appear at more or less the same time each year, regardless of the prevailing seasonal weather.

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  9. Male blackcap in my Melksham, Wiltshire garden yesterday. Saw him for the first time (assuming it is the same one) for a day or two last June/July. Never seen one anywhere before.

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  10. We have 2 female blackcaps in our garden in Leicestershire. They have been coming almost daily since the end of January.
    Beth

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    1. Just after posting this we spotted a male blackcap for the first time too.
      Beth

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  11. I have had a female black cap visit my garden today first time ever. Mullion Cornwall

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  12. We have a female blackcap feeding daily in our garden on peanuts, apples and suet balls. I am in north east Lincolnshire in a village called North Thoresby. The bird has been with us for at least two weeks.

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  13. I have had a blackcap visiting the garden since the beginning of the year. It is a female and I have not seen a male. Other years I have seen both sexes and wonder why it is alone.

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  14. My Dorset village garden has had black caps since just before Christmas. Usually one or two of each male and female; last week there four females around the fat cylinder who refused to allow a male access.

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  15. We have had a male Blackcap visit our garden for the last two weeks, first time stayed for about 10 minutes feeding on sunflower hearts, second time just sat in a tree for about 5 minutes. Droitwich Spa, Worcestershire. Nick

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  16. Female black cap regular visitor, Blandford Forum, edge of town garden, including this morning whilst the snow is still falling. Favours scraps and cheese, won't come to fat balls or water nearer to house, takes water from an extra tray away from house, 3 feet off the ground.

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  17. We have a male Blackcap who has been visiting our garden feeders this week during the cold weather, taking suet pellets and pecking at the fat balls. I have also seen Blackcaps feeding on Ivy berries on the railway embankment behind our house. We are in Ipswich, Suffolk.

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  18. Hi, even though we have snow,, there is a solitary male Black Cap on our Feeder, here in Pentewan, Cornwall. It has no rings. Today is the first time seeing it. We have pictures if you want them. Kind regards, Nige Hoar

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  19. Hi, we have a solitary male Black Cap on our Feeder. It has no rings. Visiting in the snow. First time seeing it today. We have some pictures if you want them. Regards Nige Hoar

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  20. Sorry we are in Pentewan, Cornwall Nige.

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  21. Male and female black cap in the garden for the last few weeks (Hillingdon - Greater London). First the male was feeding on pyracantha berries, but they have run out and we have seen little of the male since. However, the female likes the sunflower hearts. She has practically taken up residence in our garden in the last few days - she is sat in our apple tree for most of the day, feeding on and off.
    Not spotted colour rings on either.

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  22. Hi, we had a Blackcap visit our bird table today, we have seen male and females a couple of times in the past few months. We are in Abingdon, Oxfordshire. We have got a few photos but can't see any coloured rings.

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