This is a truly wonderful time of year to experience a multitude of spring signals, including lengthening evenings, the sound of queen bumblebees on the wing, pretty spring flowers, and, delightfully, once again being able to spot the signs of nesting birds.

There are birds investigating and using nest boxes, flying around with twigs and moss in their beaks as nest construction materials, and even the sand martins are back, where they can be observed moving in and out of nesting walls such as the one at Harpers Island, Cork. A close eye is being kept on newly installed sand martin walls in Ballydehob and Leap, in the hope they will be used this year. 

Last week, we spotted a unique and special bird which was also nesting. This intriguing bird was the dipper (Cinclus cinclus), and while we observed them on the River Ilen, they may be found across the region along rocky, shallow, fast-flowing streams and rivers.

Unique bird

Dippers are the only aquatic songbird in Ireland. Slightly smaller than a blackbird, they produce a melody similar to the songs of sedge and reed warblers and, despite lacking webbed feet, they can swim underwater in a way unlike any other bird.

They walk or dive into the water and use their muscles to stay submerged, gripping the riverbed with their feet and using their short, broad wings to move forward. They essentially fly underwater. As they move beneath the surface, they search through stones and pebbles for invertebrates such as small freshwater shrimp, and caddisfly, mayfly, and stonefly larvae. In common with other aquatic birds, they have dense plumage which helps to keep them insulated.

The common name of the dipper refers to the species' peculiar bobbing behaviour outside of the water, unrelated to the underwater foraging dips they regularly take. They are short-tailed, blackish-brown birds with a large white ‘bib’ on the throat and breast and, as Gaeilge, alluding to this colouration, are called ‘gabha dubh’, meaning blacksmith.

Dippers may be found in Europe, North Africa, and Central Asia, but what makes them even more special is that the birds we see in Ireland are a unique Irish subspecies, Cinclus cinclus hibernicus. They can be distinguished from other subspecies by a rusty brown band where the bib ends on the breast.

Nesting nuptials

As we observed first-hand, dippers breed earlier than many other songbirds, from as early as February onwards, and they synchronise the hatching of their chicks with the peak of freshwater invertebrate abundance. Dippers are monogamous and territorial when it comes to breeding and will defend their stretch of river from interlopers.

Dippers usually nest over fast-flowing water, in riverbanks, behind cascades of water, or perhaps most commonly, under bridges. It is said that the majority of breeding takes place in upland areas, making the sight of a nesting pair near Skibbereen particularly exciting.

Division of labour

Both the male and female contribute to the building of a dome-like nest out of moss, which can be as large as a football. Nests have a small hole as a side entrance and are lined with dry leaves. The nest’s construction reveals another example of adaptation to aquatic environments. The mossy walls provide cushioning from the elements, while the lining, made from deciduous leaves, ensures that any water ingress can quickly drain away.

The female usually lays four or five eggs, which she incubates for an average of 16 days. During this time, the male hunts for food and feeds the female on the nest. After the eggs hatch, both parents feed the nestlings until the chicks are ready to fledge, which seems like a fair deal to me. If conditions are favourable, dippers may have two broods per year, using the same nest.

Water woes

Dippers rely on clean water in the rivers and streams they inhabit. Unpolluted water is vital for both their food supply and breeding. Pollution decreases the diversity of invertebrates on which dippers feed, and tests reveal that chemical pollutants accumulate in dipper eggs.

Unfortunately, water quality continues to decline in Ireland. Figures from the EPA last year reveal that only 52% of our surface waters are in satisfactory ecological condition; this shows ongoing deterioration. Just last month, the EPA announced that there was a 10% increase in nitrogen in rivers in 2025.

The principal threats are nutrients, sediment, and pesticides from agriculture draining into waterways, urban wastewater, and other human activities, along with physical modifications to rivers such as channelling and dredging. The EPA predicts that unless action is taken, Ireland will fail to meet the EU and national goal of restoring all waters to good or better status by 2027.

The situation is at its worst in the southeast of Ireland, but there is also evidence of a downward trajectory closer to home. The Bandon–Ilen catchment spans a large area of West Cork where 113 water bodies are monitored, including 87 rivers and six lakes. While 62% of these were recently tested as being in satisfactory condition, which is above the national average, over a fifth of them have deteriorated.

It is not without hope. Initiatives such as the Lee and Bandon–Ilen Catchment Action Plan, part of the Teagasc Better Farming for Water campaign, aim to coordinate and target actions to reverse the trend of declining water quality. For the sake of dippers, and the entire freshwater ecosystem, I sincerely hope these efforts will improve the quality of water in our rivers, streams, and lakes.