ALCEDINIDAE KINGFISHERS FAUNA PARAGUAY

ALCEDINIDAE - KINGFISHERS

Ninety-two global species with just five species present in Paraguay - the diversity of kingfishers in the Americas is extremely low and five of the six New World species occur in Paraguay. All New World species belong to the subfamily Cerylinae, which has itself been raised to family level in alternative classifications that recognise the three subfamilies of Alcedinidae as full families. Cerylines are characterised by spotted flight feathers, a lack of blue in the plumage and more or less crested heads. All are fish feeders and live in similar habitats, though sympatric species differ considerably in size. Kingfishers are part of a very ancient lineage and fossil Ceryline kingfishers have been found in Florida, USA from 2 million years ago. Modern day kingfishers are Coraciiformes, being placed in the suborder Alcedines jointly with the Todies (Todidae) and Motmots (Momotidae).
The bill is long, straight and dagger-like, laterally-compressed and makes up a significant proportion of the birds total length. Legs are short and toes are syndactyl - the middle toe is joined to the inner toe for the first third of its length and to the outer one for half its length. Three toes point forwards and one backwards. The green plumage present in the Chloroceryle kingfishers is formed by a combination of general melanization combined with iridescence. Moult pattern is variable though typically ascendant and descendent from P7 and descendent from P1. Iris colour is dark brown in all species. Kingfishers have excellent eyesight and highly-specialised eyes. There is limited eye rotation and movements of the head are used to track prey. Two foveae lie along a horizontal axis, the prey first crosses the monocular fovea and a head movement allows for its binocular fixation on the second fovea. Colour vision is excellent and some species are sensitive to near ultra-violet light. Despite the refraction of light caused by water, kingfishers have no difficulty in compensating for it to capture prey and recorded capture success in wild birds is between 10-50%.
Kingfishers are diurnal and solitary except when breeding, being highly territorial and defending both breeding and non-breeding territories. They typically perch on a low branch with the head bowed at approximately 60º. They bathe by dipping in and out of water several times and retire to a perch to preen. Roosting is in trees or, during the breeding season, in the nest burrows. They fly rapidly with rowing wing beats in larger species, and blurry wing beats in smaller species. Calls of Ceryline kingfishers consist of simple "kek" or "tek" notes as well as rattling calls associated with territorial trespasses (even directed at humans). The diet is almost entirely fish, supplemented with aquatic invertebrates. The density of kingfishers has been correlated with the density of surface-dwelling fish and availability of suitable perches. The size of fish prey taken can be correlated approximately with bill length. Dives may be shallow for surface-dwelling fish or deeper with the wings held back over the body to produce a more streamlined shape. A nictating membrane covers the eyes and the natural buoyancy of the bird is assisted with a few wing beats to return the bird to the surface. Prey items are beaten against a perch to break bones and protective spines and then swallowed head first. Kingfishers are resident, but juveniles disperse widely upon independence in search of their own feeding territories.
Nest burrows are excavated into banks and terminate in a nest chamber. Eggs are smooth, slightly glossy and white in colour. Courtship feeding may be used to establish a pair bond and pairs are monogamous. Nests are excavated by both sexes, though the male does most of the work. Incubation lasts around three weeks. The nest chamber is unlined and after hatching becomes a stinking pit of feces and food remains - chicks may further excavate the chamber to create new unsoiled areas. Chicks hatch naked and blind, feathers emerging in waxy sheaths that give them a hedgehog-like appearance after a few days. They reach sexual maturity at the end of their first year.
Paraguayan kingfishers are sexually dimorphic - this characteristic being more pronounced in Ceryline kingfishers than other subfamilies. There are no discernible differences between the sexes in body size and weight.

REFERENCES
Campbell B & Lack E 1985 - A Dictionary of Birds - T & AD Poyser.
Fry CH, Fry K & Harris A 1992 - Kingfishers, Bee-eaters and Rollers - Helm.
Woodall PF 2001 - Alcedinidae Handbook of the Birds of the World Vol 6 - Lynx Ediciones.