Blackbilled Streamertails (Trochilus scitulus): Hummingbirds Native Only to Jamaica

Novice birdwatchers and collectors sometimes confuse black-billed (Trochilus polytmus) and red-billed (Trochilus scitulus) streamertail hummingbirds. Education, experience, and expertise ultimately converge to emphasize recognizable differences in appearance and bio-geography for researchers and viewers. But confusion oftentimes emerges in regard to whether a subtlety in color or variation in size falls within the range of an existing species or leads to the unveiling of something new.

• For example, specimens exhibit color changes from museum ambiences and preservatives.
• Red-bills get yellow with age and demise but never go all-dark like black-bills in life and death.

The above-mentioned fact and other deep truths of body sizes and distributional ranges in fact inspire the taxonomic separation of black-bills and black-tipped red-bills.

Småland-born Swedish nobleman Carl Linnaeus (May 23, 1707 – January 10, 1778) garners kudos for describing red-billed streamertails to wildlife-loving amateurs and professionals in 1758. South Reading-born Massachusetts ornithologist William Brewster (July 5, 1851 – July 11, 1919) and Watertown-born Massachusetts zoologist Outram Bangs (January 12, 1863 – September 22, 1932) get credited for identifying black-bills in 1901. Both taxonomies honor the Caribbean Land of Wood and Water’s bio-geography. Jamaican bio-diversity indeed prompts:

• Genoa-born Italian explorer Christopher Columbus (October 31, 1451? – November 26, 1504) going speechless before Madrigal de las Altas Torres–born Spanish Queen Isabella I (April 22, 1451 – November 26, 1504);
• Killyleagh-born British physician Sir Hans Sloane (April 16, 1660 – January 11, 1753) launching London’s British Museum collections.

Black-bills answer to two categories of names. One classification conserves such common, non-scientific, popular terminology as:  

• Black-billed doctor bird;
• Black-billed hummingbird;
• Black-billed longtail;
• Black-billed ribbon-tail;
• Black-billed scissors-tail;
• Black-billed streamertail;
• Black-bill;
• Eastern ribbon-tail;
• Eastern scissors-tail;
• Eastern streamertail;
• Jamaican black-bill.

English-language designations get bolstered by respectively easterly and northerly influences with:

• Colibri à bec noir (“Hummingbird with [a] black beak”) from French-speaking Haiti;
• Colibrí portacintas piquinegro (“Hummingbird, ribbon-carrying [and] black-beaked”) from Spanish-speaking Cuba.

It is supplemented by the binomial (“two-name”), Greek / Latin, taxonomic terminologies of science. It represents the juxtaposition of:

• The genus name Trochilus, from the Greek noun τρόχιλος for “little bird,” traditionally translated as “wren”;
• The species name scitulus, from the Latin adjective scitus for “handsome.”

The description “handsome little bird” indeed applies to the black-billed streamer-tailed hummingbird male. The male black-bill has:

• All-black, downward-curving, short, slender bill;
• Black, ear-tufted, small head;
• Dark emerald-green underside;
• Dark grass-green back, rump;
• Glossy emerald-green, small body;
• Green-edged upper-tail and wing coverts (cover, outer, upper feathers);
• Iridescent black throat;
• Purple-black tail with -- except during the juvenile and molting male stages -- two dark blue-green, long, narrow, trailing, white-tipped feathers whose fluted, scalloped insides emit high-pitched, in-flight hums and whines;
• Purple-brown wings;
• Yellow-brown mandibles.  

Black-billed, streamer-less females have:

• Grass-green backs, rumps, upper-tail and wing coverts;
• Green-spotted necks, sides, throats;
• Grey-brown, little heads with occasional green-tipped feathers;
• Pale-looking tail coverts and undersides;
• Purple-brown, white-tipped outer tail-feathers;
• Yellow-brown mandibles.

Female and male black-billed ribbon-tailed hummingbirds can breed year-round in their native northeast Jamaican niches to:

• The north of the Rio Grande and John Crow Mountains;
• The south of the Morant River.

During any month, males therefore communicate their readiness by engaging in u-shaped flights which showcase their waving scissors-tails. But both genders particularly favor:

• Breeding between October and May;
• Nesting between April and June.

They get together about 9.84 – 13.12 feet (3 – 4 meters) above ground level. As mothers-to-be, females then have sole responsibility for building on horizontal, low-lying, skinny branches cup-shaped nests of:

• Camouflage-friendly moss on the exterior;
• Soft down, fibers, and hairs on the interior.

Nests include spider webs to expand as hatchlings grow.

Every successful mating ends in two bean-sized white eggs. Incubation lasts 14 – 20 days. Blind, immobile, naked hatchlings must dominate within 21 days:

• Consuming regurgitated, semi-digested insects pushed directly from throat to stomach by maternal beaks;
• Emitting a high-pitched teeet-teeet, loud chink-chink, metallic ting-ting, and sharp tee-tee.  

Mothers occupy separate nests during their chicks’ last week of dependence. Juveniles remain recognizable with:

• Brown-yellow culmens (topside ridges of upper mandibles);
• Buff-yellow lower mandibles;
• Grey-green undersides;
• Grey-spotted crowns.

They will mature to:

• Adult bodies 3.25 – 3.94 inches (8.25 – 10 centimeters) long, plus 5.91- to 7.09-inch (15- to 18-centimeter) streamers for males;
• Arthropod-, nectar-, pollen-dominated diets;
• Solitary life cycles and natural histories -- apart group-breeding -- within loose community networks.

Scientists devote themselves to never-ending series of inquiry and interpretation. Accuracy insists upon investigative advances and technological breakthroughs. A case in kind is the revision after the re-examination of 144 museum-stored, streamer-tailed specimens in 1901. Scientists generally let some uncertainty remain in taxonomies since animals and plants individualize appearances and dimensions. But updates may lead to reconsidering subtleties in:

• Behavior;
• Color;
• Distribution;
• Size.

Such modernizations result in querying the significance of:

• All-black bills, restricted bio-geographies, and smaller measurements;
• Occasional ruby-colored throat feathers.

The question of black beaks, coastal ranges, and diminutive configurations reveals the eastern species’ separate homeland and identity. Perhaps the next revisionist round will resolve the rare frequency and typical infrequency of ruby-throated doctor birds.

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet. 

Male Red-Billed Streamertail (Trochilus polytmus): distinguished by bill coloring from related avian Jamaican endemic, Black-Billed Streamertail (Trochilus scitulus)
Lime Tree Farm, Blue Mountains, Saint Andrew Parish, southeastern Jamaica: DickDaniels (http://carolinabirds.org/), CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Red-billed_Streamertail_male_RWD4.jpg

Famed Swedish faunal and floral polymath Carl Linnaeus (Carl von Linné) described Jamaican endemic hummingbird, Red-Billed Streamertail.
1982 bronze sculpture by Robert Berks (born 1922); Chicago Botanic Garden, Cook County, northeastern Illinois: Stefanie Seskin, CC BY SA 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Statue_-_Father_of_Botany.jpg

William Brewster (July 5, 1851 – July 11, 1919): American ornithologist co-described Black-Billed Streamertail with American zoologist Outram Bangs (January 12, 1863 – September 22, 1932) in 1901.
portrait signed and dated December 1916
H.W. Henshaw, "In Memoriam: William Brewster," The Auk, Vol. XXXVI (January 1920), Plate I, frontispiece: Public Domain, via Biodiversity Heritage Library @ https://www.biodiversitylibrary.org/page/15938473

Male Black-Billed Streamertail (Trochilus scitulus)
Black-billed streamertails inhabit Jamaica's two easternmost parishes. Portland Parish is located on the northeast coast; Saint Thomas occupies the southeast coast.
northeastern Jamaica: dominique sherony, CC BY SA 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Trochilus_scitulus.jpg

Distribution map of Black-billed Streamertail
Adapted from BirdLife International. 2016. Trochilus scitulus. The IUCN Red List of Threatened Species 2016: e.T22687474A93153647: Cephas, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Trochilus_scitulus_map.svg

View of the Rio Grande, which separates Blue and John Crow mountains in its riverine sashay through northeastern Jamaica
Rising on the Blue Mountains' northern slopes and flowing into the Caribbean at St. Margaret's Bay, Rio Grande passes through dramatic, wild scenery, making it popular for rafting. Rio Grande rafting reputedly was pioneered by Aussie actor Errol Flynn.
southeastern Portland Parish, near border with Saint Thomas Parish; northeastern Jamaica: Michael L. Dorn (Edu-Tourist), CC BY-SA 2.0, via Flickr @ https://www.flickr.com/photos/mdorn/20499632/

Male Black-Billed Streamertail: graceful aerialist
John Crow Mountains, Portland Parish, northeastern Jamaica: Ron Knight (sussexbirder), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/sussexbirder/8082137661/

On June 20, 1894, Lionel Walter Rothschild, 2nd Baron Rothschild (February 8, 1868 – August 27, 1937) displayed two Trochilus specimens that he deemed as new species due to rare ruby spots on their throats.
Namesake of their collector, C.B. Taylor of Jamaica, Aithurus (now Trochilus) taylori is an elusive rarity that seems to add a third species to Jamaica's endemic streamertail genus.
"Start of the Blue Mountains just north of Kingston, Jamaica"
(WT-shared) Bz3rk at wts wikivoyage, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Start_of_the_Blue_Mountains_just_north_of_Kingston,_Jamaica.jpg

Black-Billed Streamertails' homelands in eastern Jamaica include southeastern sector, which includes terminus at island's easternmost point, Point Morant.
Jamaica's oldest lighthouse, erected in 1841, Morant Point Lighthouse was designed by Alexander Gordon (May 5, 1802-May 14, 1868) as Western Hemisphere's first cast iron lighthouse.
Saint Thomas Parish, southeastern Jamaica; eastward view of Point Morant on Jamaica Channel: Michael L. Dorn, CC BY SA 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:View_of_Morant_Point_Lighthouse_Facing_East_II.jpg

Stream and sleepy town of Priestmans' River are the type locality of Trochilus scitulus, collected by William Earle Dodge (W.E.D.) Scott (April 1852-August 21, 1910) on February 11, 1891, and described by Brewster and Bangs in 1901.
Law 7 of Laws of Jamaica Passed in 1881 authorized raising money for bridges in Portland (including Priestman's River Bridge), Saint Mary and Saint Thomas parishes; Law 33 of Laws Passed in 1887 enabled erection of the bridges.
ca. 1890-1895 photograph; Colonial Office photographic collection (reference number CO 1069-370-45): The National Archives UK, No known copyright restrictions, via Flickr @ https://www.flickr.com/photos/nationalarchives/7642884578/

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