Thursday, 19 September 2019

Dippers: a new Retrapping Adults for Survival Project in Glamorgan

Dippers are fascinating birds, unique amongst passerines in their habit of swimming underwater to find their invertebrate prey.  They are currently amber listed in the UK and are a priority species for study under both the British Trust for Ornithology's Retrapping Adults for Survival and Nest Record Scheme.

After several years nest recording dippers along rivers in the east Glamorgan valleys, we have registered a RAS project with BTO.  Our study area includes the Cynon, Ely, Ogmore, Rhondda and Taff valleys. There are just three other such projects across the UK at present. 

Dippers make an ideal species to monitor, being relatively sedentary, territorial and vocal and have among the easier nests to find.  They have a high level of breeding site fidelity, are relatively confiding and regularly seen on territories alongside riverside public footpaths within our study area.

We aim to catch all of the adults within the study area each year, with a minimum of 40-50 adult birds, including 30 retraps or resightings from previous years.  An even amount of effort is put into monitoring birds for a minimum of five years so that high-quality survival rates can be calculated and any changes recorded.

We have chosen to use colour rings, with three black alphanumeric character on an orange ring on the left leg.  Dippers are suited to the use of colour-ringing in this way, where individuals will be re‑sighted in the field relatively easily on territories alongside riverside public footpaths. Their habit also lends themselves to being photographed, where colour-rings can show up quite well for reading. Moreover, colour-rings provide a secondary means of capturing re-sighting data at autumn roost catches, where not all birds are possible to capture.

Birds are caught at the nest, at autumn roosts sites by torchlight and using mist nets over water.  Over one hundred birds have been ringed to date, with colour-ringing commencing this autumn.

We would be grateful to hear news of any colour-ringed dippers encountered by birders and the public.  Please email: eastglambto@gmail.com.

Photos below

Wayne Morris
19/09/2019

Figure 1. Meet A00, an adult female.  The first recruit to the new colour-ringing project.
Figure 2. Bridges often have multiple nests underneath them, with old and new sitting alongside one another.  A successful grey wagtail nest was just a few metres away from this second-brood dipper.
Figure 3. Nest contents can be monitored safely using a small inspection mirror and torch
Figure 4. Rachel Shepherd extracts a dipper from a mist net over water
Figure 5. One of only two nests in the study area that require steps to inspect the contents. Dan Jenkins-Jones is returning a ringed brood safely to the nest.

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