The
passerine
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
s of the genus ''Aphelocoma'' include the scrub jays and their relatives. They are
New World
The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...
jays found in Mexico, western
Central America
Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
and the western United States, with an outlying population in
Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
. This genus belongs to the group of New World (or "blue") jays–possibly a distinct
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
–which is not closely related to other
jay
A jay is a member of a number of species of medium-sized, usually colorful and noisy, passerine birds in the Crow family, Corvidae. The evolutionary relationships between the jays and the magpies are rather complex. For example, the Eurasian m ...
s,
magpie
Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, and is one ...
s or
treepie
The treepies (known also as crypsirinines from the subfamily's name, ''Crypsirininae'') comprise four closely related genera (''Dendrocitta, Crypsirina, Temnurus'' and ''Platysmurus'') of long-tailed passerine birds in the family Corvidae. There ...
s. They live in open
pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...
-
oak
An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
forests,
chaparral
Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...
, and
mixed evergreen forests.
Systematics
![Floridascrubjay92lg](https://upload.wikimedia.org/wikipedia/commons/0/0b/Floridascrubjay92lg.web.jpg)
Seven species of ''Aphelocoma'' are generally recognized at the present time. They are believed to have evolved in the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
, and the Florida scrub jay is known to have been recognizably distinct and present in its current range for at least two million years. The inland, coastal, and Santa Cruz island populations of the (former) western scrub-jay are now considered three separate species: Woodhouse's, the California and the island scrub jays. Two different populations of the Mexican jay might similarly represent two separate species.
mtDNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ...
NADH dehydrogenase
NADH dehydrogenase is an enzyme that converts nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) to its oxidized form (NAD+). Members of the NADH dehydrogenase family and analogues are commonly systematically named using the for ...
subunit 2
sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...
data
[ is unable to properly resolve the relationships of the species. Judging from New World jay ]biogeography
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
, the unicolored or Mexican jays might represent the most basal lineage; morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
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 two clades which might constitute two separate 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).
The western scrub-jay is now made up of three species. These would be separated by the ]Great Basin
The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...
, with the Pacific coastal lineage (California scrub-jay) and the island scrub-jay, as well as the inland lineage (Woodhouse's scrub-jay), with the Florida scrub-jay being a sister species
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
. This treatment fails to address the problem of birds from inland southern Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
.[ Nonetheless, it is actually ''because'' the molecular diversity pattern is so badly resolved that it supports the view that rapid ]Late Pliocene
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
* ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
of the North American scrub-jays led to the present diversity. Studies on the evolutionary history of ''Aphelocoma'' jays suggests that all New World
The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...
jays originated in North America or Mesoamerica.
Description
''Aphelocoma'' jays are slightly larger than the Blue Jay
The blue jay (''Cyanocitta cristata'') is a passerine bird in the family Corvidae, native to eastern North America. It lives in most of the eastern and central United States; some eastern populations may be migratory. Resident populations are a ...
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, the Unicolored Jay, is blue all over, superficially similar to the Pinyon Jay
The pinyon jay (''Gymnorhinus cyanocephalus'') is a species of jay, and is the only member of the genus ''Gymnorhinus''. Native to Western North America, the species ranges from central Oregon to northern Baja California, and eastward as far as ...
from much further north. The bill, legs, and feet are black.
Behavior
The diet consists mainly of acorn
The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally
two seeds), enclosed in a tough, leathery shell, and borne ...
s and pine nut
Pine nuts, also called piñón (), pinoli (), pignoli or chilgoza (), are the edible seeds of pines (family Pinaceae, genus ''Pinus''). According to the Food and Agriculture Organization, only 29 species provide edible nuts, while 20 are trade ...
s. However, grain, berries, and other fruits are often eaten as well. These birds can also be omnivorous; their diet can include insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s, eggs and nestlings, small frog
A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...
s, mice, and reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s. As food-storing birds, the scrub jays demonstrate a unique episodic memory. They can find their food hiding places with great precision, even several days after the initial cache.
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 is a social system characterized by alloparental care: offspring receive care not only from their parents, but also from additional group members, often called helpers. Cooperative breeding encompasses a wide variety of group ...
systems involving several 'helpers' at each nest, usually relatives of the breeding pair.
Increased prolactin
Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...
in the breeding pair leads to the expression of parental behavior and physiology. The source of the alloparental behavior found in helper birds has been the focus of many studies. A positive correlation was found between increased prolactin levels during the breeding period and helping behavior in non-breeding ''Aphelocoma'' jays. This suggests that helper birds do not simply respond to the calls of the young, but begin to show 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. Scrub jays are members of the family Corvidae, which are considered the most intelligent of the birds and among the most intelligent of all animals.
''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, antagonistic at feeding areas and sometimes regarded as a nuisance.
Notes
References
External links
*
{{Taxonbar, from=Q383469
*
Bird genera
Jays
Taxa named by Jean Cabanis