Aphelocoma
Encyclopedia
The passerine
bird
s of the genus Aphelocoma
include the scrub-jays and relatives. They are New World
jays found in Mexico
, western Central America
and the western United States
, with an outlying population in Florida
. This genus belongs to the group of New World (or "blue") jays–possibly a distinct subfamily–which is not closely related to other jays, magpies or treepies (Ericson et al., 2005 ). They live in open pine
-oak
forests, chaparral
, and mixed evergreen forests
.
Six species of Aphelocoma are generally recognized currently, since two taxa formerly treated as races of A. coerulescens were recently split off as separate species (A. californica and A. insularis); the 3 now separate species differ in color and bill size. They are believed to have evolved in the Pleistocene
, and the Floridan species is known to have been recognizably distinct and present in its current range for at least 2 million years (Emslie, 1996 ). Indeed, the inland and coastal populations of A. californica seem to constitute 2 distinct species too, as might different populations of the Mexican Jay (Rice et al. 2003 ).
mtDNA NADH dehydrogenase
subunit
2 sequence
data (Rice et al. 2003 ) is unable to properly resolve the relationships of the species. Judging from New World jay biogeography
, the Unicolored or Mexican Jays might represent the most basal
lineage; morphology
would tentatively lean towards the latter which retains more of the group's color patterns, while the available molecular data allows no robust conclusions whatsoever. In any case, the data of Rice et al. (2003) suggests - albeit also with very low confidence - that the Mexican Jay comprises 2 clades which might constitute different species. However, far too few individuals have been sampled to say anything definite on that matter, except that the lineages - if they indeed exist - do not correspond to the geographical pattern of intraspecific variation (see species article for more).
On the other hand, it is somewhat more likely that the Western Scrub-Jay is made up of 2 species. These would be separated by the Great Basin
, with the Pacific coastal lineage ("California" Scrub-Jay) and the Island Scrub-Jay, as well as the inland lineage ("Woodhouse's" Scrub-Jay) and the Florida Scrub-Jay being sister species. This treatment fails to address the problem of birds from inland southern Mexico
. What is known about the paleogeography of North America supports these findings, but they must be considered preliminary pending analysis of much more data (Rice et al. 2003 ). Nonetheless, it is actually because the molecular diversity pattern is so badly resolved that it supports the view that rapid Late Pliocene radiation of the North American Scrub-Jays led to the present diversity. Recent studies on the evolutionary history of Aphelocoma jays suggests that all New World
jays originated in North America or Mesoamerica (Bonaccorso and Peterson, 2007 ).
and differ in having a longer tail, slightly shorter, more rounded wings, and no crest on the head. The top of the head, nape, and sides of the head are a rich deep blue. Some species have a white stripe above the eye and dark ear coverts. The breast is also white or grey-white and the back is a grey-brown contrasting with the bright blue tail and wings in most species. One species, Unicolored Jay, is blue all over, superficially similar to the Pinyon Jay
from much further north. The bill, legs, and feet are black.
Food is taken both on the ground and in trees. Acorn
s and pine nut
s are the most important foods, making up the great bulk of the diet, with grain, berries and other fruits making up the rest of the vegetable diet. Many insect
s and other invertebrate
s are also taken, and eggs and nestlings, small frog
s, mice and reptile
s.
Wild Aphelocoma jays are frequent visitors at campsites and picnics and have frequently learned to eat from the hands of people where they have become accustomed to being fed.
The nest is in a tree or a bush, sometimes quite low down. The nests are compact and lined with hair and fine roots with an outer diameter of about 30 cm to 60 cm. Usually 2 to 4 eggs are laid and incubated over 14 to 16 days. There are two main variations of egg shell color: green with olive markings or a paler background of grayish-white to green with red-brown markings. The Florida Scrub-Jay and the Mexican Jay both have cooperative breeding
systems involving several 'helpers' at each nest
, usually relatives of the breeding pair.
Increased prolactin in the breeding pair leads to the expression of parental behavior and physiology (Brown and Vleck,1998 ). The source of the alloparental behavior found in helper birds has been the focus of many studies. Recently, a positive correlation between increased prolactin levels during the breeding period and helping behavior in non-breeding Aphelocoma jays was found (Brown and Vleck, 1998 ). This suggests that helper birds do not simply respond to the calls of the young, but begin to shown parental behavior even before the chicks hatch. These data suggest that natural selection may be acting on [Cooperative breeding] in Aphelocoma jays and New World jays in general because the birds are reacting to more than just an environmental stimulus. Studies have also been done on Florida scrub-jays (Aphelocoma coerulescens) and results have confirmed the hypothesis that increased prolactin levels are correlated with an increase in parental behavior in helper birds (Schoech, 1998 ).
Aphelocoma jays are quite vocal and have a huge range of sounds and calls; common calls include a cheek, cheek, cheek and a guttural churring krr'r'r'r'r. Aphelocoma jays are also, like all other jays, often quite aggressive, and antagonistic at feeding areas, and sometimes regarded as a nuisance.
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s of the genus Aphelocoma
include the scrub-jays and relatives. They are New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
jays found in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, western Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and the western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, with an outlying population in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. This genus belongs to the group of New World (or "blue") jays–possibly a distinct subfamily–which is not closely related to other jays, magpies or treepies (Ericson et al., 2005 ). They live in open pine
Pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...
-oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
forests, chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
, and mixed evergreen forests
California mixed evergreen forest
California mixed evergreen forest is an ecoregion, of the temperate broadleaf and mixed forests biome, that occurs in the Pacific Coast Ranges of southwestern Oregon and California, and in the Coast, Transverse, and Peninsular Ranges in California...
.
Systematics
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
, and the Floridan species is known to have been recognizably distinct and present in its current range for at least 2 million years (Emslie, 1996 ). Indeed, the inland and coastal populations of A. californica seem to constitute 2 distinct species too, as might different populations of the Mexican Jay (Rice et al. 2003 ).
- Unicolored JayUnicolored JayThe Unicolored Jay is an Aphelocoma jay native to cloud forests of northwestern Central America and southern and southeastern Mexico, from central Honduras west to central Guerrero, southern Veracruz and extreme southern San Luis Potosi...
, Aphelocoma unicolor – cloudforestsCloud forestA cloud forest, also called a fog forest, is a generally tropical or subtropical evergreen montane moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and...
of southern Mexico east to HondurasHondurasHonduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize... - Mexican JayMexican JayThe Mexican Jay, Aphelocoma wollweberi, formerly known as the Gray-breasted Jay, is a New World jay native to the Sierra Madre Oriental, Sierra Madre Occidental, and Central Plateau of Mexico. It reaches north to eastern Arizona, western New Mexico and western Texas in the United States...
or Gray-breasted Jay, Aphelocoma wollweberi – Sierra Madre OrientalSierra Madre OrientalThe Sierra Madre Oriental is a mountain range in northeastern Mexico.-Setting:Spanning the Sierra Madre Oriental runs from Coahuila south through Nuevo León, southwest Tamaulipas, San Luis Potosí, Querétaro, and Hidalgo to northern Puebla, where it joins with the east-west running Eje Volcánico...
and Sierra Madre OccidentalSierra Madre OccidentalThe Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...
mountains of Mexico, north to southeast ArizonaArizonaArizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, southwest New MexicoNew MexicoNew Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
and westernmost TexasTexasTexas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, US. - Transvolcanic JayTransvolcanic JayThe Transvolcanic Jay is a medium-large passerine similar in size to most other jays, with a blue head, blue-gray mantle, blue wings and tail, gray breast and underparts. The sexes are morphologically similar, and juveniles differ only in having less blue coloration. The iris is brown and legs...
, Aphelocoma ultrmarina - Island Scrub-Jay, Aphelocoma insularis – Santa Cruz IslandSanta Cruz IslandSanta Cruz Island was the largest privately owned island off the continental United States, but is currently part-owned by the National Park service . The island, located off the coast of California, is long and from wide...
off southern CaliforniaCaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... - Western Scrub-Jay, Aphelocoma californica
- California Scrub-Jay, Aphelocoma [californica] californica – coastal western North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
from Washington to Baja CaliforniaBaja CaliforniaBaja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North... - Woodhouse's Scrub-Jay, Aphelocoma [californica] woodhouseii - inland western North America, from OregonOregonOregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
through TexasTexasTexas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and south to northern interior MexicoMexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... - Sumichrast's Scrub-Jay, Aphelocoma [californica] sumichrasti - inland Mexico from GuerreroGuerreroGuerrero officially Estado Libre y Soberano de Guerrero is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo....
and TlaxcalaTlaxcalaTlaxcala officially Estado Libre y Soberano de Tlaxcala is one of the 31 states which along with the Federal District comprise the 32 federative entities of Mexico. It is divided into 60 municipalities and its capital city is Tlaxcala....
to OaxacaOaxacaOaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...
- California Scrub-Jay, Aphelocoma [californica] californica – coastal western North America
- Florida Scrub-Jay, Aphelocoma coerulescens – FloridaFloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
mtDNA NADH dehydrogenase
NADH dehydrogenase
NADH dehydrogenase is an enzyme located in the inner mitochondrial membrane that catalyzes the transfer of electrons from NADH to coenzyme Q...
subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
2 sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data (Rice et al. 2003 ) is unable to properly resolve the relationships of the species. Judging from New World jay biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
, the Unicolored or Mexican Jays might represent the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
lineage; morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
would tentatively lean towards the latter which retains more of the group's color patterns, while the available molecular data allows no robust conclusions whatsoever. In any case, the data of Rice et al. (2003) suggests - albeit also with very low confidence - that the Mexican Jay comprises 2 clades which might constitute different species. However, far too few individuals have been sampled to say anything definite on that matter, except that the lineages - if they indeed exist - do not correspond to the geographical pattern of intraspecific variation (see species article for more).
On the other hand, it is somewhat more likely that the Western Scrub-Jay is made up of 2 species. These would be separated by the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...
, with the Pacific coastal lineage ("California" Scrub-Jay) and the Island Scrub-Jay, as well as the inland lineage ("Woodhouse's" Scrub-Jay) and the Florida Scrub-Jay being sister species. This treatment fails to address the problem of birds from inland southern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. What is known about the paleogeography of North America supports these findings, but they must be considered preliminary pending analysis of much more data (Rice et al. 2003 ). Nonetheless, it is actually because the molecular diversity pattern is so badly resolved that it supports the view that rapid Late Pliocene radiation of the North American Scrub-Jays led to the present diversity. Recent studies on the evolutionary history of Aphelocoma jays suggests that all New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
jays originated in North America or Mesoamerica (Bonaccorso and Peterson, 2007 ).
Appearance
Aphelocoma jays are slightly larger than the Blue JayBlue Jay
The Blue Jay is a passerine bird in the family Corvidae, native to North America. It is resident through most of eastern and central United States and southern Canada, although western populations may be migratory. It breeds in both deciduous and coniferous forests, and is common near and in...
and differ in having a longer tail, slightly shorter, more rounded wings, and no crest on the head. The top of the head, nape, and sides of the head are a rich deep blue. Some species have a white stripe above the eye and dark ear coverts. The breast is also white or grey-white and the back is a grey-brown contrasting with the bright blue tail and wings in most species. One species, Unicolored Jay, is blue all over, superficially similar to the Pinyon Jay
Pinyon Jay
The Pinyon Jay is a jay between the North American Blue Jay and the Eurasian Jay in size. It is the only member of the genus Gymnorhinus, . Its overall proportions are very Nutcracker-like and indeed this can be seen as convergent evolution as both birds fill similar ecological niches...
from much further north. The bill, legs, and feet are black.
Behavior
Acorn
The acorn, or oak nut, is the nut of the oaks and their close relatives . It usually contains a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad...
s and pine nut
Pine nut
Pine nuts are the edible seeds of pines . About 20 species of pine produce seeds large enough to be worth harvesting; in other pines the seeds are also edible, but are too small to be of great value as a human food....
s are the most important foods, making up the great bulk of the diet, with grain, berries and other fruits making up the rest of the vegetable diet. Many insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s are also taken, and eggs and nestlings, small frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, mice and reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s.
Wild Aphelocoma jays are frequent visitors at campsites and picnics and have frequently learned to eat from the hands of people where they have become accustomed to being fed.
The nest is in a tree or a bush, sometimes quite low down. The nests are compact and lined with hair and fine roots with an outer diameter of about 30 cm to 60 cm. Usually 2 to 4 eggs are laid and incubated over 14 to 16 days. There are two main variations of egg shell color: green with olive markings or a paler background of grayish-white to green with red-brown markings. The Florida Scrub-Jay and the Mexican Jay both have cooperative breeding
Cooperative breeding
Cooperative breeding is a social system in which individuals contribute care to offspring that are not their own at the expense of their own reproduction . When reproduction is monopolized by one or few of the adult group members and most adults do not reproduce, but help rear the breeder’s...
systems involving several 'helpers' at each nest
Helpers at the nest
Helpers at the nest is a term used in behavioural ecology and evolutionary biology to describe a social structure in which juveniles and sexually mature adolescents of either one or both sexes, remain in association with their parents and help them raise subsequent broods or litters, instead of...
, usually relatives of the breeding pair.
Increased prolactin in the breeding pair leads to the expression of parental behavior and physiology (Brown and Vleck,1998 ). The source of the alloparental behavior found in helper birds has been the focus of many studies. Recently, a positive correlation between increased prolactin levels during the breeding period and helping behavior in non-breeding Aphelocoma jays was found (Brown and Vleck, 1998 ). This suggests that helper birds do not simply respond to the calls of the young, but begin to shown parental behavior even before the chicks hatch. These data suggest that natural selection may be acting on [Cooperative breeding] in Aphelocoma jays and New World jays in general because the birds are reacting to more than just an environmental stimulus. Studies have also been done on Florida scrub-jays (Aphelocoma coerulescens) and results have confirmed the hypothesis that increased prolactin levels are correlated with an increase in parental behavior in helper birds (Schoech, 1998 ).
Aphelocoma jays are quite vocal and have a huge range of sounds and calls; common calls include a cheek, cheek, cheek and a guttural churring krr'r'r'r'r. Aphelocoma jays are also, like all other jays, often quite aggressive, and antagonistic at feeding areas, and sometimes regarded as a nuisance.
Footnotes
- EtymologyEtymologyEtymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
: Aphelocoma, from LatinLatinLatin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
ized Ancient GreekAncient GreekAncient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
apheles- (from ἀφελής-) "simple" + Latin coma (from Greek kome κόμη) "hair", in reference to the lack of striped or banded feathers in this genus, compared to other jays.