WRW #27: Kingfisher - Flash, Splash & Dash!
The cache, a small clear screw-capped plastic bottle, is hidden along this delightful stretch of the river where, although somewhat elusive, you have a good chance of spotting this small but spectacular bird - a flash of colour, a small splash as it dives into the water and expertly grabs a fish and a quick dash back to its perch on a branch overhanging the river to process the catch.
To reach the cache location: a) If heading north from Addingham: park in the High Mill parking area @ N 53 56.874 W 1 52.595 then head north following the Dales Way path into and through the Olicana cottages, then along the riverside trail to the cache, passing other caches along the way or b) If heading south from Farfield: park in the small car park behind Farfield Friends Meeting House @ N 53 57.724 W 1 53.139 pass around the rear of the building, cross over the road and locate the Dales Way footpath heading down towards the river, then follow this to the cache, passing other caches along the way.
The (common, Eurasian or river) kingfisher (Alcedo atthis) is a small kingfisher with seven subspecies within 
its wide distribution across Eurasia and North Africa. It is resident in much of its range, but migrates from areas where rivers freeze in winter. The sub-species found in UK is A.a.ispida.
A sparrow-sized bird, it has the typical short-tailed, large-headed kingfisher profile: blue upperparts, orange underparts and a long bill. It feeds mainly on fish, caught by diving, and has special visual adaptations to enable it to see prey under water. The glossy white eggs are laid in a nest at the end of a burrow in a riverbank.
Its name derives from the Latin alcedo, 'kingfisher' (from Greek ἀλκυών, halcyon) and Atthis, a beautiful young woman of Lesbos, and favourite of Sappho.
It is about 16cm long with a wingspan of 25cm and weighs 34-46G.
The female is identical in appearance to the male except that her lower mandible is orange-red with a black tip. The juvenile is similar to the adult, but with duller and greener upperparts and paler underparts.
Its flight is fast, direct and usually low over water. The short rounded wings whirr rapidly, and a bird flying away shows an electric-blue 'flash' down its back.
It has no song but the flight call is a short sharp whistle, chee, repeated two or three times (listen here). Anxious birds emit a harsh, shrit-it-it and nestlings call for food with a churring noise.
It inhabits clear, slow-flowing streams and rivers, and lakes with well-vegetated banks. It frequents scrubs and bushes with overhanging branches close to shallow open water in which it hunts. In winter it is more coastal, often feeding in estuaries or harbours and along rocky seashores.
It is an important members of the ecosystem and a good indicator of freshwater community health. The highest densities of breeding birds are found in habitats with clear water, which permits optimal prey visibility, and trees or shrubs on the banks. These habitats have also the highest quality of water, so the presence of this bird confirms the standard of the water.
Measures to improve water flow can disrupt this habitat, and in particular, the replacement of natural banks by artificial confinement greatly reduces the populations of fish, amphibians and aquatic reptiles, and waterside birds are lost. It can tolerate a certain degree of urbanisation, provided the water remains clean.
It is resident in areas where the climate is mild year-round, but must migrate after breeding from regions 
with prolonged freezing conditions in winter. Most birds winter within the southern parts of the breeding range, but smaller numbers cross the Mediterranean into Africa or travel over the mountains of Malaysia into Southeast Asia. They migrate mainly at night, and some Siberian breeders must travel at least 3,000 km between the breeding sites and the wintering areas.
Breeding: Like all kingfishers, it is highly territorial - as it must eat around 60% of its body weight each day, it must have control of a suitable stretch of river. It is solitary for most of the year, roosting alone in heavy cover. If another kingfisher enters its territory, both birds display from perches, and fights may occur, in which a bird will grab the other's beak and try to hold it under water. Pairs form in the autumn but each bird retains a separate territory, generally at least 1 km (but up to 3.5 km) and territories are not merged until the spring.
The courtship starts with the male chasing the female while calling continually, and later by ritual feeding, with copulation usually following.
The nest is in a burrow excavated by both birds in a low vertical riverbank, or sometimes a quarry or other cutting. The straight, gently sloping burrow is normally 60-90 cm long and ends in an enlarged chamber. The nest cavity is unlined but soon accumulates a litter of fish remains and cast pellets.
It usually lays 2-10 glossy white eggs, 1-2 of 
which don't hatch because the parent can't cover them. Both sexes incubate by day, but only the female at night. An incubating bird sits trance-like, facing the tunnel. It always casts a pellet, breaking it up with the bill. Eggs hatch in 19–20 days, and the altricial young are in the nest for another 24–25 days, often more. Once large enough, young birds will come to the burrow entrance to be fed. 2-3 broods may be reared in a season.
Survival: The early days for fledged juveniles are more hazardous. During its first dives into water, about 4 days after leaving the nest, a fledgling may become waterlogged and drown. Many young will not have learned to fish by the time they are driven out of their parents' territory, and only about 50% more than a 1-2 weeks. Most kingfishers die of cold or lack of food, and a severe winter can kill many. Summer floods can destroy nests or make fishing difficult, resulting in starvation of the brood. Only 25% of the young survive to breed the next year, but this is enough to maintain the population. Likewise, only 25% of adult birds survive from one breeding season to the next. Very few birds live longer than one breeding season. However, the oldest bird on record reached 21 years!
Other causes of death are cats, rats, collisions with vehicles and windows, and human disturbance of nesting birds, including riverbank works with heavy machinery. Since kingfishers are high up in the food chain, they are vulnerable to build-up of chemicals, and river pollution by industrial and agricultural products excludes the birds from many stretches of otherwise suitable river habitats.
It was killed in Victorian times for stuffing and display in glass cases and for use in hat making. English naturalist William Yarrell reported the country practice of killing a kingfisher and hanging it from a thread in the belief that it would swing to predict the direction in which the wind would blow! Persecution by anglers and to provide feathers for fishing flies were common but are now largely a thing of the past.
Feeding: It hunts from a perch 1-2 m above the water, on a branch, post or riverbank, bill pointing down as it searches for prey. It bobs its head when food is detected to gauge the distance, and plunges steeply down to seize its prey usually no deeper than 25 cm below the surface. If a suitable perch is not available, it may hover above the water before diving in.
The wings are opened under water and the open eyes are protected by the transparent third eyelid. The bird 
rises beak-first from the surface and flies back to its perch. At the perch the fish is adjusted until it is held near its tail and beaten against the perch several times. Once dead, the fish is positioned lengthways and swallowed head-first. A few times each day, a small greyish pellet of fish bones and other indigestible remains is regurgitated.
Minnows, sticklebacks, small roach and trout are typical prey. About 60% of food items are fish, but it also catches aquatic insects such as dragonfly larvae and water beetles, and, in winter, crustaceans including freshwater shrimps.
Status:it has a large global range of about 10 million sq.km. and a large population, with about 160,000-320,000 in Europe alone.
For more information on this beautiful bird see here.
See here for an excellent short video of a kingfisher fishing and here for amazing footage of kingfishers raising chicks inside their nest.