Turtle Dove Project

 

Even more so than most farmland birds, the UK’s Turtle Dove population has suffered a precipitous 98% decline in the last fifty years and is still falling.

 

The UK population estimate in 2021 was 2092 breeding territories. Turtle Doves have become increasingly restricted to eastern and southeastern England, with 62.5% of the population estimated to occur in three counties: Kent (682 territories; 32.6%), Suffolk (326; 15.6%) and Essex (300; 14.3%). Marden has a significant number of breeding territories due partly to its arable farming with tall hedgerows and patches of scrub.

The fortunes of Marden’s turtle doves have been followed since 2015 when the RSPB and Operation Turtle Dove began trialling provision of supplementary seed in the spring to help the birds on their return from their wintering quarters in Africa. Now, as part of their conservation stewardship agreements with Natural England (NE), and with advice from Kent Wildlife Trust (KWT), local farmers are increasing provision of suitable habitat for the doves. Marden Wildlife volunteers and KWT’s Dr Kirsty Swinnerton are studying the doves’ use of the local farmland so that landowners can be helped to improve provision of natural food (seeds of ‘agricultural weeds’ like Fumitory and Birds’-foot Trefoil), nesting habitat (tall, thick hedges and scrub) and accessible water – as seedeaters, turtle doves get insufficient moisture from their seed diet for them to produce enough ‘pigeon milk’ secreted in their throats to feed their young.

Finding and tracking Marden’s Turtle Doves

By encouraging the public to report the presence of doves via our Marden Wildlife Facebook page, we began to build a picture of where they are across the parish. Given their need for thorny, scrubby nesting habitat, this is frequently on private land, but birds seen feeding on open farmland are more easily recorded. Trailcams on several farmland supplementary feeding sites provided evidence to suggest numbers and distribution but, beyond that, we had no understanding of how birds were using the landscape.

In 2022 we began colour-ringing doves. This was done by ringers fully licensed by the British Trust for Ornithology (BTO). Turtle doves are very shy and therefore difficult to catch, but five birds were fitted with coloured leg rings so they could be identified on sight. From this we confirmed they were regularly using the supplementary feeding sites or were found ‘purring’ on a prominent perch in their breeding territory.

As well as tracking the colour-ringed birds, the trailcams also evidence the numbers of doves using the food. Individual counts of three to four birds in May increased once juveniles fledged, with eighteen birds counted in a single picture in September.

Four of the five colour-ringed birds returned to breed here in 2023 – an adult survival rate of 80% when 50% is the norm. While this was very pleasing, it must be acknowledged our five birds was a very small sample!

Drilling down further

To offer landowners detailed advice, we need to know what features of the landscape are important to the birds. For this we need accurate information on where the doves go to feed, drink, nest, and roost.

In 2023, as well as colour-ringing another five doves with funding from KWT, we fitted three with GPS tags to tack their movements around the area for about a month. This required an additional permit from the BTO and attaching the tags was carried out by KWT’s Dr Chas Holt.

This is Luka (above) with her GPS tag and its two antennae; once released, the bird tucks the thin one trailing behind it in amongst its tail feathers when it preens. Luka flew some distance from the tagging site on the east of the village. When we located her, she had flown 4km due west, but although we connected with her tag, it had malfunctioned and would not transmit its GPS data to our receiver. Fortunately, she was later identified by her colour rings on one of our known breeding sites – complete with a mate and two recently fledged juveniles.

The movements of our second bird, George, not only replicated what we found from the previous year’s study about their use of feeding sites, but also confirmed what is generally expected of breeding turtle doves – he remained within a few kilometres of what we assumed was his breeding territory. We ground-truthed the GPS data by visiting the GPS points to compare them first-hand with the satellite image. Thus, we confirmed he was roosting in scrub on private land (so potentially vulnerable to being ‘tidied-up’ by a new owner). He was spending time feeding with other doves on bare patches of soil on a lightly tilled strip around a rapeseed crop, deliberately provided by the farmer as a conservation measure. There was also easy access to water via a field-corner pond. It was these features that were attracting all the doves to that field.

Those of our third dove (likely an un-paired male we had named Dave) painted a very different picture (see poster below) and raised many questions, not least being the possibility of other breeding doves in the wider area that have yet to be found. Having contacted some of the owners of the land he visited, we are now hoping to carry out further work with some of them.

In the coming months, assuming we can acquire funding, we intend to deploy more tags and, with the help of an MSc student from the Durrel Institute of Conservation and Ecology, to look more closely at turtle dove and nightingale breeding habitat – both share similar habitat but have specific and very different, needs for nesting.

If you are interested in our work and would like to help – we particularly need volunteers to make regular checks of images on trail cameras, and to survey small areas of the doves’ breeding territories – please contact us.

2024 Update

The year has started well. By the beginning of June, five doves we colour-ringed in 2022 had returned to Marden. A 100% survival rate over two years is an excellent figure (albeit still from a small sample) when BTO ringing data suggest annual adult survival is only 50%. The birds in question were all at least a year old when they were first ringed, so will now have completed at least four 11,000km return migrations to Africa. Pictures from trail cameras have also suggested that two of the birds, Yellow/Black and Yellow/Green are a breeding pair. They were originally trapped feeding close to each other, and two years later were captured feeding close together again on a supplementary feeding strip soon after arrival back in Marden. 

However, we have yet to see the five doves colour ringed in 2023. As two of them were juvenile doves, this is perhaps to be expected as fewer than three in five juveniles survive their first year. But there are many places in Marden they could be, so hopefully they will be picked up on camera again.

Four doves have already been trapped and fitted with a GPS tag this year. One of them is one of the five colour-ringed in ’22. It was trapped in exactly the same spot again this year and the tag added. He (Abraham) was trapped feeding next to a female (Sarah) so, again, we suspect they may be a breeding pair and, indeed, the satellite data so far shows them both staying together in the immediate vicinity.