Celeus (bird)

Rufous-headed woodpecker (Celeus spectabilis)

The genus Celeus was introduced by the German zoologist Friedrich Boie in 1831.[4] The type species was subsequently designated as the blond-crested woodpecker (Celeus flavescens) by the English zoologist George Robert Gray in 1840.[5][6] The generic name is from the Ancient Greek word keleos for a "green woodpecker".[7]

This genus is a member of the Picini tribe in the subfamily Picinae of the woodpecker family, Picidae.[8] Most of the 13 species of Celeus are polytypic, with the C. occidentalis, C. tinnunculus, C. castaneus, C. galeatus and C. obrieni being exceptions as monotypic. Head markings were the main diagnostic feature for taxonomy until recent molecular phylogenetic analysis brought changes to the species list. Benz and Robbins (2011) in their DNA analysis of this genus found the species C. loricatus - C. torquatus as basal taxa.[9] Recent DNA analysis placed the rufous woodpecker, previously thought to belong to Celeus, in Micropternus brachyurus.[10][11] Subspecies caatinga woodpecker (C. spectabilis obrieni) previously thought extinct was captured, using a mist net by A.D Prado in Tocantins in 2006, and was elevated in 2008 to Kaempfers woodpecker (C. obrieni).[12] The scaly-breasted woodpecker's English name has recently changed to scale-breasted woodpecker.[13][14] The South Asian rufous woodpecker (Micropternus brachyurus) is a peculiar species that was formerly placed in Celeus too. However, its similarity seems to be due to convergent evolution, as it does not even seem to belong to the same tribe of Picinae as Celeus does.

Postcranial homogeneity in woodpeckers has made genus identification of fossils difficult and no Celeus fossils are noted.[15] An example of a woodpecker fossil, Bathoceleus hyphalus, was found in 1959 in the Bahamas in a limestone Pleistocene sinkhole, and is believed to be the earliest recorded North American Picidae dated at 2.588 – 0.012 mya.[9] The origin of the genus Celeus is ambiguous; it is not believed to have originated in Central America and may have come originally from Eurasia.[9][16]

Late Pliocene continental interchange of C. loricatus and C. torquatus occurred with the opening of the Isthmus of Panama 3.1 - 4.0 mya as part of the Great American Interchange, with later radiations of these birds back across the Isthmus. Quaternary environmental changes are thought to be responsible for the relatively recent gene flow of this genus and for the shallow genetic structures of the remaining Celeus sister taxa with some of the species capable of dispersal to form allopatric, or isolated, communities.[17] Corridors may have opened up in the last glacial period (21 ka years before the present) that may have enabled westward movement of species in this genus.[17]

The genus contains the following 13 species:[18]

• Cinnamon woodpecker, Celeus loricatus
• Waved woodpecker, Celeus undatus
• Scaly-breasted woodpecker, Celeus grammicus
• Chestnut-colored woodpecker, Celeus castaneus
• Chestnut woodpecker, Celeus elegans
• Pale-crested woodpecker, Celeus lugubris
• Blond-crested woodpecker, Celeus flavescens
• Ochre-backed woodpecker, Celeus ochraceus
• Cream-colored woodpecker, Celeus flavus
• Rufous-headed woodpecker, Celeus spectabilis
• Kaempfer's woodpecker, Celeus obrieni
• Ringed woodpecker, Celeus torquatus
• Helmeted woodpecker, Celeus galeatus

The online edition of the Handbook of the Birds of the World has split the ringed woodpecker creating two more species: the Amazonian black-breasted woodpecker (Celeus occidentalis) and the Atlantic black-breasted woodpecker (Celeus tinnunculus). Neither of the splits was supported by the results of molecular genetic studies.[19][20] These splits have not been adopted by the online edition of the Clements Checklist of Birds of the World maintained by ornithologists at Cornell University,[21] nor in the lists maintained by the American Ornithological Society.[22][23]

Female helmeted woodpecker formerly (Dryocopus galeatus) - now (Celeus galeatus)

The birds of the genus Celeus generally weigh between 63–172 g (2.2–6.1 oz); the heaviest of this genus is the scaly-breasted woodpecker (C. grammicus). Length, from tip of bill to tip of the tail, is between 19–32 cm (7.5–12.6 in). They are generally not sexually dimorphic and have evolved specialised morphology to match their unique lifestyle.[3]

The beak differs from other woodpeckers in that it is mainly curved, not long and without nostril feathers. Like other woodpeckers its beak has a chisel like cutting edge. A hard rhamphotheca[24] and complex beak microstructures strengthen the bill for pounding and drilling.[3][25] The tail has evolved for support, clinging and climbing, acting as a third leg or tripod. The pygostyle (tail vertebrae) is larger for strong tail muscles to be inserted and it is more or less stiff. There are six pairs of tail feathers, the middle feathers of which have strong central shafts for extra support.[3] The feet are zygodactyl, with scansorial abilities, and therefore adapted to climbing vertical surfaces, however, they are not as specialised as other woodpeckers for this purpose. The first toe is short, the 4th toe being shorter or of equal length to remaining two toes. Most species in this genus use a bipedal hopping movement on vertical and horizontal surfaces. Claws have evolved for climbing.[3]

Male chestnut-colored woodpecker (Celeus castaneus), Costa Rica

Celeus species use their tongue to capture food. The tongue is long and capable of lateral movements. Due to its length the tongue does not have the usual tongue retractor muscle found in most birds, instead, there is an elongated tongue muscle (the Branchiomandibularis) along with bones of the hyoid horn, which provide increased tongue protraction.[26] Retraction of this long tongue may find it wrapped around an eye socket between the skull and the skin.[3] [27]

Head crests are bushy, shaggy or peaked in typical woodpecker style and, along with flight and body feathers, are chestnut colours of brown, black and cream (some almost yellow). There is a greater or lesser degree of barring (bars or stripes of feather colour) and sexual dimorphism badges are mainly between the bill, eye and chin of males. These sexual badges are usually red. The oil gland is particularly large in this genus.[3] Plumage convergence has been noted in divergent lineages possibly as a form of territorial mimicry but no real conclusions have been made as yet.[28][13]

Pale-crested woodpecker (Celeus lugubris)

The ringed woodpecker (Celeus torquatus), the chestnut woodpecker (Celeus elegans) and the cream-colored woodpecker (Celeus flavus) are distributed widely throughout northern South America with remaining species having smaller ranges from Central, Southern and Eastern America to West Panama. The Amazon basin contains the greatest species diversity of the Celeus genus.[9] Celeus species inhabit diverse environmental regions and conditions from moist lowland forests and forest edges, swamps, heavily degraded woodlands and some species are found in Savannas.[9][3] Of note the pale-crested woodpecker (Celeus lugubris) prefers dry Chaco woodland, semi decayed forests and Cerrado woodlands whilst the rufous-headed woodpecker (Celeus spectabilis) and Kaempfer's woodpecker (Celeus obrieni) favour bamboo forests. Species range from sea level to 1,100 m (3,600 ft).[3]

Male blond-crested woodpecker (Celeus flavescens)

Woodpeckers are usually amicable around humans, adapting to manmade environments mainly for nesting and feeding. They can be considered a nuisance when nesting activities involve agricultural damage. Utility poles, housing insulation, wood cabins, wooden houses and shutters are used by this genus often resulting in structural damage. Humans have had a large impact on this genus through extensive habitat degradation and loss and early specimen collections which may have led to declining populations.[35] Provision of nest boxes for this species has been unsuccessful.[3]

Four species in the genus are on the IUCN Red List accounting for 27% of the woodpecker family.[13] Red listed species are C. torquatus, C. obrieni, C. tinnunculus and C. galeatus. All are threatened due to deforestation, habitat degradation and fragmentation.[36] Conservation actions are limited to surveys and some habitat protection. The helmeted woodpecker (C. galeatus) protected by law and is a flagship species for educating school children.[37] [38]

• ffrench, Richard (1991). A Guide to the Birds of Trinidad and Tobago (2nd ed.). Comstock Publishing. ISBN 978-0-8014-9792-6.
• Hilty, Steven L (2003). Birds of Venezuela. London: Christopher Helm. ISBN 978-0-7136-6418-8.
• Stiles and Skutch, A guide to the birds of Costa Rica ISBN 0-8014-9600-4