Turtle doves are one of the fastest declining birds in Europe. Between 1970 and 2011, we lost 93% in the UK, paralleled by a loss in Europe of 69% since 1980. We know that a reduction in available nesting habitat and a reduction in food availability, both in the summer and in their wintering grounds in Africa, are likely to be playing a part in their decline. Turtle doves have fewer nesting attempts per year than in the 1960s leading to half the number of chicks being fledged each year. This alone is enough to explain the dramatic declines in numbers we are seeing.
To be able to help them recover, we need to understand what it is that turtle doves need on their nesting grounds and why they are not producing as many chicks per year. Tony Morris and Jenny Dunn from the RSPB undertook a study to try and identify which features in our farmland areas were important for keeping territorial turtle doves from year to year. To do this they identified sites in East Anglia that had territorial turtle doves a couple of years earlier, and then compared the sites that still had turtle dove territories with those that no longer did. What was different about them, and why were some favoured over others? They chose sites that had not changed over the two years by checking with landowners that they had not removed any trees or scrub, or made any other major land-use changes.
Sadly they discovered that in no more than two years, there was a 34% decline in sites with territorial turtle doves, which reflects the national picture of a decline in the number of occupied grid squares. As their numbers decrease, it is likely that those birds looking for possible nesting sites will pick the best areas. Possibly they would look for areas with better nesting habitat such as scrub, or would better foraging habitat be more important? Is there likely to be any competition with other dove species such as woodpigeons or collared doves? Tony and Jenny aimed to find the answers to some of these questions.
They found that turtle doves were more likely to hold territory in areas where there was a lot of scrub and tall hedgerows, suggesting that remaining birds are selecting the biggest patches of suitable nesting habitat. They also found that the presence of woodpigeons was associated with fewer turtle dove territories. We do not know how much of this is due to competition and how much it is simply that they prefer subtly different nesting habitats to one another. Finally they found that the larger the area of suitable foraging area for turtle doves such as bare ground and fallow, the more turtle dove territories were present.
Turtle doves have had to switch their food from weed seeds to cereal grain due to changes in farming and land-use. The fact that they produce half the number of young per year as they did in the 1960s could be due to their food being of lower quality and less available at certain times during the breeding season. For example, they may face fewer and a reduced range of seeds after returning from migration, a time when they need plentiful, good quality food in order to breed . Turtle doves eat seeds all year, unlike most other dove species that will eat insects and other green plant matter. As this study shows us that both habitat for nesting and habitat for feeding are important when turtle doves are choosing where to nest, one of the ways to help will be to provide plenty of seed food habitats, close to areas of scrub and tall hedgerows where they like to nest.
This work was jointly funded by the RSPB and Natural England through the Action for Birds in England Partnership. The original article can be found in Bird Study, volume 59, issue 4.