By Rike Bolam
Dippers are the only songbirds that can swim and feed underwater. The river Derwent offers great habitat for these small but strong birds as it is not polluted and has therefore plenty of food on offer. It also provides plenty natural nest sites for dippers to build their nests and raise broods. Maybe this is why it has one of the highest densities of dippers in the country! We monitor the dippers between Swalwell and Ebchester.
We first started monitoring dipper nests in 2012. The nests are made of moss and can be found in bridges or on cliffs along the river, or even under waterfalls! The nests are usually above running water and when the young birds fledge they can swim straight away. We record the various stages of nest building and egg laying and also ring the young birds in the nest. That way we can monitor in the following years where the birds move and how long they live. We can also estimate if the productivity in a particular year was good or bad.
Monitoring adult survival
In 2016 we have extended our work to include a Retrapping Adults for Survival survey or RAS. This means we collect data that can be used to estimate how long dippers live for. We colour ring the adult birds with red colour rings that have individual codes on, so we don’t have to physically recapture the birds to read the rings. Instead we can search for the birds the following spring using scopes and cameras to see how old they are and if they have moved. We can also estimate the percentage of adults that survived from the previous year.
If you see a colour ringed dipper, please let us know! The only information we need is where you have seen the bird, when, and the number found on the colour ring. Just email us at firstname.lastname@example.org.