Ringing the Changes at Dersingham Bog NNR - a NATURAL ENGLAND project
Dersingham Bog NNR supports a wide variety of flora and fauna and has important populations of breeding heathland birds. It contains one of the last remaining fragments of lowland heathland in eastern England. Since 1960, 85% of the UK’s heathland has been lost, resulting in significant declines in the many species that are dependent upon it.
The heathland is a product of thousands of years of active management by local communities. Prior to the industrial revolution the heath was essential to the survival of the local inhabitants providing the food, fuel and building materials they required to survive.
The reserve supports nationally important numbers of breeding Nightjar as well as being home to locally scarce breeders such as Woodlark and Stonechat.
Nightjar breeding pairs number 16 – 20 with a high of 28 churring males in 2003. More recently numbers have dropped, with 12 churring males in both 2012 and 2013. Stonechats on the site have gone from 5 pairs in 2011 to only two breeding pairs in 2013; the first recorded territory on site was in the year 2000. Woodlarks have stayed fairly stable with an average of 3 pairs a year with the first pair being recorded in 1996 and in 2013 four pairs were recorded.
As part of the ongoing restoration and management works at Dersingham Bog a project began to monitor the breeding success of these three key species. The aims of the project are to see the effects of management works; public access, weather and predators on the success of nesting Stonechat, Woodlark and Nightjar, and how this may affect the future management of parts of the site. The project is also looking at the movements of birds away from the site and how birds move into and out of the population as well as the interaction between sites.
The site receives some 15,000 visitors annually and with that number there are increased pressures from people straying off the path and of dogs off the lead. Weather also plays a big part in the fortunes of birds on the site. Another aim of the project is to understand the habits and requirements of nesting birds and this will allow us to look at fine tuning the management of the site to improve breeding success if required.
In early 2012 the team at Dersingham Bog NNR teamed up with the North Norfolk Farmland Study & Ringing Group (NNFS&RG) and site volunteers to begin monitoring the nests on the site, and what factors if any were affecting the productivity. As well as nest monitoring the NNFS&RG set up a colour ringing project on Woodlark and Stonechat chicks as well as general ringing of Nightjar chicks. With training from the British Trust for Ornithology and the NNFS&RG the project began.
By ringing the birds the volunteers and reserve team are able to monitor the bird’s movements on the site and the surrounding countryside. By colour ringing individual birds, the team are able to give a life history of each individual bird and its movements without the need for future recapture. This would also link up two existing projects already running in the county one on the North Norfolk coast and one in the Brecks. In the subsequent years the team will be able to monitor individuals to a specific nest and area of the reserve and study the birds much easier.
In 2012 nest monitoring began in earnest with volunteers from Natural England and the NNFS&RG putting in c150 hours nest recording. In the first year of nest recording and ringing on site some 10 Stonechats, 9 Woodlark and 21 Nightjar were rung from 3 Stonechat, 2 Woodlark and 18 Nightjar nests.
Overall findings from the first year were certainly that the numbers of Nightjar territories were much down on previous years from 22 to 12. This seems to be due to the poor migration that occurred in 2012. Of the 18 nests that were found three failed at the egg stage and two failed at the chick stage. According to the British Trust for Ornithology’s nest finding guide, on average 60 Nightjar nests are found annually meaning this data is not only important on a local level but important nationally.
Three Stonechat nests were found with all of them being successful although two of them did not have full broods. The nests contained five, three and two chicks.
There were two confirmed pairs of Woodlark on the site with two nests rung. There were also two unconfirmed breeding territories on the site. Adjacent to the reserve a pair of woodlark was found with two nests located. One nest was rung. In total 9 Woodlark chicks were rung on the site.
In 2013 the project continued where it left off in 2012 with surveying and monitoring beginning in February for the season ahead. In addition the project was able to liaise with local ringers at Snettisham Coastal Park to ring the young Stonechat of a nest there, with the hope of further understanding the movements of Stonechat in the local area.
In total 14 Stonechats, 8 Woodlark and 30 Nightjar were rung from 5 Stonechat, 4 Woodlark and 18 Nightjar nests. Of the 18 Nightjar nests in comparison to 2012, only one nest failed and this was at the egg stage. Nightjars seemed to have a very good year with the weather being much drier later on in the season. This year it was noted that there not as many first broods found as second with only six first broods found. Of the second broods eleven were found indicating that although the males where churring and on territory early on in the year some of the females didn’t arrive on site until later on in the season. Many of the female’s nests were within a relatively short distance of last year’s and one was even within centimetres of a 2013 site.
Only one Stonechat pair was successful at Dersingham Bog raising and fledging a total of 10 chicks and the nest at Snettisham Coastal Park raised a further four. One pair of Stonechats seemed to have a torrid year with the first nest containing a small clutch of three eggs which failed and the second attempt also of three eggs with eventually one being left in the nest which again failed. Thoughts on this pair were that the bird was either an immature or there were some fertility issues.
Of the four Woodlark nests found one failed fairly early on in the season and interestingly this was in a similar area to the failed Nightjar and second Stonechat pair, perhaps indicating that the failure of these nests may not have been entirely down to the weather. These birds were in a much busier part of the reserve and close to the main paths which are walked by members of the public. Further monitoring of nests in this area over time should allow us to build up a better picture of the effects of disturbance.
Before the start of the ringing project on Dersingham Bog NNR, the site had already played host to two colour ringed Stonechats with a further third bird recorded in 2013. These birds have an interesting history with them all being ringed in the North Norfolk coast area. One bird was on site in the winter of 2010, another in 2011 which is thought to have bred on site and the third recorded in 2013 which in this case did definitely breed on site. What is interesting is that there seems to be a definite movement of birds from the North Norfolk Coast in the winter to Dersingham Bog NNR, with at least two of the birds almost certainly staying to breed on the site and then returning to the North Norfolk Coast area to winter. Detailed recovery histories are recorded below.
X718465* 5M 19/04/2010 Weybourne Camp, Nr Weybourne Norfolk
RR 14/08/2010 Cley-Next-the Sea Norfolk
RR 23/02/2011 Cley-Next-the Sea Norfolk
RR 24/03/2011 Dersingham Bog NNR, Norfolk
RR 15/08/2011 Dersingham Bog NNR, Norfolk
RR 23/09/2011 Cley-Next-the Sea Norfolk
RR 06/12/2011 Cley-Next-the Sea Norfolk
L034438* 4M 11/08/2010 Weybourne Camp, Nr Weybourne Norfolk
RR 06/09/2010 Weybourne Camp, Nr Weybourne Norfolk
RR 29/11/2010 Dersingham Bog NNR, Norfolk
RR 16/03/2011 Weybourne Camp, Nr Weybourne Norfolk
RR 17/10/2011 Weybourne Camp, Nr Weybourne Norfolk
L217122# 1 18/05/2012 Kelling Heath, nr Holt Norfolk
RR 23/06/2012 Kelling Heath, nr Holt Norfolk
RR 19/11/2012 Dersingham Bog NNR, Norfolk
RR 07/03/2013 Dersingham Bog NNR, Norfolk
RR 07/04/2013 Dersingham Bog NNR, Norfolk
RR 09/04/2013 Dersingham Bog NNR, Norfolk
RR 17/04/2013 Dersingham Bog NNR, Norfolk
RR 12/05/2013 Dersingham Bog NNR, Norfolk
RR 05/06/2013 Dersingham Bog NNR, Norfolk
RR 07/06/2013 Dersingham Bog NNR, Norfolk
RR 03/07/2013 Dersingham Bog NNR, Norfolk
RR 04/07/2013 Dersingham Bog NNR, Norfolk
RR 14/07/2013 Dersingham Bog NNR, Norfolk
* X718465 and L034438 were both rung as adult males
# L217122 was originally rung as pulli on the nest and has subsequently been identified as a female.
2013 also saw the start of a personal project by Tom Bolderstone of natural England to monitor a number of nest-boxes on site as well as including the scope to monitor any ad-hoc nests that were found on site.
The idea behind this was twofold, one to monitor the boxes to see the success or failure of the nests and monitor these over time to see how they are affected by climate and food availability. Secondly, to also provide a training opportunity in pulli ringing and nest monitoring. With support from the NNFS&RG a total of fifty nest boxes were numbered and GPS marked for future monitoring. In total 19 Coal Tit, 64 Blue Tit and 8 Great Tit were rung on site. In addition 2 Linnet, 1 Willow Warbler and 1 Chiffchaff nest were also found and monitored on site with 8 Linnet pulli, 5 Chiffchaff, 4 Willow Warbler and 3 Kestrels rung.
By monitoring the boxes each year we will be able to build up a picture of how they are used and to relate this to weather and hydrological data. This also allows us to monitor the species that are found in the woodland areas of the reserve and understand how the populations of these species are faring on the site and how they use the reserve.
The project has a bright future with the hope of learning more about Stonechat, Woodlark and Nightjars. The hope is over the next few years to continue the nest monitoring and colour ringing and build up a greater picture of how birds use the site and input this data into the national datasets. The ongoing monitoring will also provide training for the NNFS&RG on ringing and monitoring heathland species. Further analysis of the data will allow us to assess the success of the heathland breeding birds on the site and what management provisions we may need to provide to improve nesting success.
We hope to test the viability of catching adult Nightjars in 2014 and fitting them with satellite tags. We hope that by using a satellite tag we will be able to not only monitor the bird’s use of a site, but also whether the birds are using any areas outside of the site for feeding and foraging and therefore reduce the need for recapturing the bird. Another possibility is to monitor where the birds winter which at present very little is known about.
One of the main priorities over the project is to gain sightings and records of colour ringed birds. This allows us to build up a very detailed picture of the birds and their movements across not just the site but further afield and this is something that we are unable to do on our own.
Sightings of any colour ringed Stonechat or Woodlark on the reserve at Dersingham Bog NNR is very useful and could yield birds from other sites. Sightings can be emailed to Thomas.email@example.com and will be replied with a full history of the bird, where possible. Any birds that have not been rung on site will be forwarded on to the relevant ringer who will contact you regarding the details of the bird. Colour ringed Stonechat or Woodlark seen in the local area are also welcome as this is another important part of the project.