By Jasmine Foster
Dipper ecology
Dippers are one of the many species inhabiting freshwater areas. They play a key role in their environment, keeping the ecosystems they live in stable. However, pollution and other factors are threatening their survival.
Habitat and location
Dippers are found in freshwater habitats in North and South America, Europe, and Asia. They are also found in Morocco in Africa. There are five different species of dipper around the world, whoinhabit banks of fast-moving upland rivers and visit lake shores and sea coasts outside of the breeding season. The species found in the UK is also known as the white-throated dipper or European dipper.
Diet
Dipper diets consist mainly of insects and their larvae. Crustaceans and molluscs are another source of food primarily during winter due to the lack of insect larvae. Additionally, they will sometimes feed on worms, tadpoles, and small fish.
Many types of prey that the dippers depend on are affected by pollution and water acidity, as they cannot survive in modified conditions. With the current state of rivers in the UK, dippers have less access to food which makes it difficult for them to sustain themselves.
Dippers find their prey by foraging in and along the margins of fast-flowing freshwater streams and rivers, perching on the edge of rocks and feeding at the edge of the water. They will often grip the rocks firmly and walk beneath the water until partly or wholly submerged, searching underwater for prey between and under stones and debris. Their wings also allow them to swim, meaning that they can find their prey more effectively.
Behaviour
During the breeding season, dippers will establish breeding grounds along suitable rivers, which they defend against attacks by other dippers. Their nests are made from moss, grass, and rootlets, and have a dome structure with a side entrance hole. They are constructed on ledges, banks, drainpipes, and crevices. The length of these breeding territories are usually between 300 metres and 2,500 metres, sometimes larger. The size is usually dependent on the availability of food throughout the area, and whether there is enough to sustain themselves and their brood.
The three northern dipper species usually have a clutch size of four or five, however clutch sizes of South American species aren’t well known. The incubation period usually lasts 16 to 17 days, after which the hatchlings are incubated by the female for 12 to 13 days and are fed by both parents. The fledging period lasts 20 to 24 days, and young dippers become independent within a couple of weeks of leaving the nest.
Dippers create loud, high pitched calls, similar to other birds inhabiting fast flowing rivers. They are the UK’s only aquatic songbird. Alongside vocalisation they communicate via dipping or bobbing movements, and rapidly blinking to expose the white feathers on their upper eyelids, creating a series of white flashes. This act is carried out for both courtship and threat displays.
Dipper vocalisatons (C) Simon Elliott/Xeno Canto CC BY-NC-ND 4.0
Environmental conditions
Dippers can be sensitive to the pH levels in water environments, and therefore need clear, clean water in their habitat. Heightened acidity in streams due to high levels of pollution can cause issues in reproduction and their survival. This is happening throughout the UK due to agricultural chemicals, sewage, oil pollution, and radioactive substances, causing declines in their population.
Not So Freshwater
Our Not so Freshwater campaign is calling on the UK Government to:
- Reduce pesticide use by 50% (volume and toxicity) by 2030
- Create ambitious targets to restore field margins and riverside ecosystems to reduce field run-off and boost our waters for wildlife and people
If you want to support our campaign, head to our campaign page and write a letter to your MP or subscribe to our newsletter to get regular updates directly to your inbox.