Editing Common kingfisher (section)

==Behaviour==

===Breeding===
[[File: BR ijsvogelwand.jpg|thumb|Volunteers in the [[Flanders|Flemish Region]] of Belgium create a vertical bank in which common kingfishers have subsequently nested annually]]
[[File:Alcedo atthis MHNT ZOO 2010 11 160 Arcy-sur-Cure.jpg|thumb|Eggs of ''Alcedo atthis'', [[MHNT]]]]
Like all kingfishers, the common kingfisher is highly territorial; since it must eat around 60% of its body weight each day, it is essential to 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 underwater. Pairs form in the autumn but each bird retains a separate territory, generally at least {{convert|1|km|mi|frac=2|abbr=on}} long, but up to {{convert|3.5|km|mi|frac=4|abbr=on}} and territories are not merged until the spring.<ref name =Fry/>

The courtship is initiated by the male chasing the female while calling continually, and later by ritual feeding, with copulation usually following.<ref name =BWP/>

The nest is in a burrow excavated by both birds of the pair in a low vertical riverbank, or sometimes a quarry or other cutting. The straight, gently inclining burrow is normally {{convert|60|–|90|cm|round=5|abbr=on}} long and ends in an enlarged chamber.<ref name =BWP/> The nest cavity is unlined but soon accumulates a litter of fish remains and cast [[pellet (ornithology)|pellets]].<ref name=Coward/>

The common kingfisher typically lays two to ten glossy white eggs, which average {{convert|1.9|cm|in|frac=16|abbr=on}} in breadth, {{convert|2.2|cm|in|frac=16|abbr=on}} in length, and weigh about {{convert|4.3|g|oz|frac=32|abbr=on}}, of which 5% is shell.<ref name =BTO/> Both sexes incubate by day, but only the female incubates at night. An incubating bird sits trance-like, facing the tunnel; it invariably casts a pellet, breaking it up with the bill. The eggs hatch in 19–20 days, one or two eggs in most clutches fail to do so because the parent cannot cover them prior. The [[altricial]] young are in the nest for a further 24–25 days, often more.<ref name = Fry/> Once large enough, young birds will come to the burrow entrance to be fed.<ref name=Coward/> Two broods, sometimes three, may be reared in a season.<ref name =BWP/>

===Survival===
The early days for fledged juveniles are more hazardous; during its first dives into the water, about four days after leaving the nest, a fledgling may become waterlogged and drown.<ref name = Fry/> Many young will not have learned to fish by the time they are driven out of their parents' territory, and only about half survive more than a week or two. Most kingfishers die of cold or lack of food, and a severe winter can kill a high percentage of the birds. Summer floods can destroy nests or make fishing difficult, resulting in starvation of the brood. Only a quarter of the young survive to breed the following year, but this is enough to maintain the population. Likewise, only a quarter of adult birds survive from one breeding season to the next. Very few birds live longer than one breeding season.<ref name = rspbst>{{cite web| title= Survival and threats | work= Kingfisher | url= https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/kingfisher/threats/ | publisher= [[Royal Society for the Protection of Birds]] |access-date=23 August 2008 }}</ref> The oldest bird on record was 21 years.<ref name = euringt>{{cite web| title= Longevity list of birds ringed in Europe | work= Kingfisher | url= http://www.euring.org/data_and_codes/longevity-voous.htm | publisher= EURING |access-date=23 August 2008 }}</ref>

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 rivers that would be habitats.<ref name = rspbst/>

This species was killed in Victorian times for stuffing and display in glass cases and use in hat making. English naturalist [[William Yarrell]] also 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.<ref name= Cocker/> Persecution by anglers and to provide feathers for fishing flies were common in earlier decades,<ref name="Coward"/> but are now largely a thing of the past.<ref name = rspbst/>

===Feeding===
[[File:Common kingfishers (Alcedo atthis ispida) male passing fish to female.jpg|thumb|Male passing fish to female in spring courtship ritual]]
[[File:Alcedo atthis - Riserve naturali e aree contigue della fascia fluviale del Po.jpg|thumb|Male fishing in Italy's [[Po River]]]]
The common kingfisher hunts from a perch {{convert|1|–|2|m|ft|0|abbr=on}} 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 {{convert|25|cm|in|0|abbr=on}} below the surface. The wings are opened underwater and the open eyes are protected by the transparent [[Nictitating membrane|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.<ref name= Fry/>

The food is mainly fish up to {{convert|12.5|cm|in|frac=4|abbr=on}} long, but the average size is {{convert|2.3|cm|in|frac=8|abbr=on}}.<ref name="Fry" /> In Central Europe, 97% of the diet was found to be composed of fish ranging in size from 2 to 10&nbsp;cm with an average of 6.5&nbsp;cm (body mass range from <0.1 g to >10 g, average 3 g).<ref name="ReferenceA">{{cite journal |last1=Čech |first1=M. |last2=Čech |first2=P. |name-list-style=amp |title=Non-fish prey in the diet of an exclusive fish-eater: the common kingfisher ''Alcedo atthis''|journal=Bird Study|date=2015|volume=62|issue=4|pages=457–465|doi=10.1080/00063657.2015.1073679|s2cid=85632259|doi-access=free}}</ref><ref>{{cite journal |last1=Čech |first1=M. |last2=Čech |first2=P. |name-list-style=amp |title=The role of floods in the lives of fish-eating birds: predator loss or benefit?|journal=Hydrobiologia|date=2013|volume=717|pages=203–211|doi=10.1007/s10750-013-1625-3|s2cid=16257345}}</ref> [[Common minnow|Minnows]], [[stickleback]]s, small [[common roach|roach]] and [[trout]] are typical prey. About 60% of food items are fish, but this kingfisher also catches aquatic insects such as [[dragonfly]] [[larva]]e and [[water beetle]]s, and, in winter, crustaceans including freshwater shrimps.<ref name=Fry/> Amphibians such as the smooth newt (''Lissotriton vulgaris'') may also constitute part of the diet of this species.<ref>{{cite journal |last1=Davies |first1=Nigel |last2=Allain |first2=Steven J. R. |date=2023 |title=Smooth newts ''Lissotriton vulgaris'' as more than just occasional items in the diet of the Eurasian kingfisher ''Alcedo atthis''|journal= Herpetological Bulletin |volume= 164 |issue=164 |pages=43 |doi=10.33256/hb164.43 |url=https://www.thebhs.org/publications/the-herpetological-bulletin/issue-number-164-summer-2023/3809-13-smooth-newts-i-lissotriton-vulgaris-i-as-more-than-just-occasional-items-in-the-diet-of-the-eurasian-kingfisher-i-alcedo-atthis-i|doi-access=free}}</ref> In Central Europe, however, fish represented 99.9% of the diet (data from rivers, streams, and reservoirs from years 1999 to 2013).<ref name="ReferenceA"/> Common kingfishers have also been observed to catch [[lamprey]].<ref>{{cite journal|last1=Čech|first1=Martin|title=Lamprey (''Lampetra'' sp.) in the diet of common kingfisher (''Alcedo atthis'')|journal=Bulletin Lampetra|date=2017|volume=8|pages=44–47}}</ref> One study found that food provisioning rate increased with brood size, from 1498 g (505 fishes for four nestlings) to 2968 g (894 fishes for eight nestlings). During the fledging period each chick consumed on average 334 g of fish, which resulted in an estimated daily food intake of 37% of the chick's body mass (average over the entire nestling period). The average daily energy intake was 73.5 kJ per chick (i.e., 1837 kJ per 25 days of the fledging period).<ref>{{cite journal |last1=Čech |first1=M. |last2=Čech |first2=P. |name-list-style=amp |title=Effect of brood size on food provisioning rate in Common Kingfisher ''Alcedo atthis'' |journal=Ardea|date=2017|volume=105|issue=1|pages=5–17|doi=10.5253/arde.v105i1.a3|s2cid=90362897}}</ref>

A challenge for any diving bird is the change in [[refraction]] between air and water. The eyes of many birds have two [[Fovea centralis|fovea]]e (the fovea is the area of the [[retina]] with the greatest density of light receptors),<ref name= Sinclair/> and a kingfisher can switch from the main central fovea to the auxiliary fovea when it enters water; a retinal streak of high receptor density which connects the two foveae allows the image to swing temporally as the bird drops onto the prey.<ref name= Schwab/> The egg-shaped [[lens (anatomy)|lens]] of the eye points towards the auxiliary fovea, enabling the bird to maintain [[bird vision|visual acuity]] underwater.<ref name= Sinclair/> Because of the positions of the foveae, the kingfisher has [[monocular vision]] in air, and [[binocular vision]] in water. The underwater vision is not as a sharp as in air, but the ability to judge the distance of moving prey is more important than the sharpness of the image.<ref name= Schwab>{{cite journal| last= Schwab | first= I. R. |author2=Hart N. S. |date=May 2004 | title= Halcyon days | journal=[[British Journal of Ophthalmology]] | volume=88 | issue= 5 | page= 613 |pmid=15129670 | doi =10.1136/bjo.2004.045492 | pmc=1772125}}</ref>

Each [[cone cell]] of a bird's retina contains an oil droplet that may contain [[carotenoid]] pigments. These droplets enhance color vision and reduce glare. Aquatic kingfishers have high numbers of red pigments in their oil droplets; the reason red droplets predominate is not understood, but the droplets may help with the glare or the dispersion of light from particulate matter in the water.<ref name= Schwab/>