Savannah Sparrow
Encyclopedia
The Savannah Sparrow is a small American sparrow
. It is the only widely accepted member of the genus
Passerculus. Recent comparison of mtDNA NADH dehydrogenase
subunit
2 and 3 sequence
s indicates that the Ipswich Sparrow, formerly usually considered a good species (as Passerculus princeps), is a well-marked subspecies
of the Savannah Sparrow, whereas the southwestern subspecies should be recognized as distinct species Large-billed Sparrow (Passerculus rostratus) .
It is named after Savannah, Georgia
where one of the first specimens of this bird was collected.
bird
breeds in Alaska
, Canada
, northern, central and Pacific
coastal USA, Mexico
and Guatemala
. The Pacific and Mexican breeders are resident, but other populations are migratory
, wintering from the southern United States across Central America
and the Caribbean
to northern South America
. It is a very rare vagrant to western Europe
.
This species has a typically sparrow
-like dark-streaked brown back, and whitish underparts with brown or blackish breast and flank streaking. It has whitish crown and supercilium
stripes, sometimes with some yellow (more often near the beak
). The cheeks are brown and the throat white. The flight feather
s are blackish-brown with light brown or white border. The eyes are dark. The feet and legs are horn-colored, as is the lower part of the bill, with the upper part being dark grey.
The Savannah Sparrow is a very variable species, with numerous subspecies
, several of which have been split as separate species at various times. The different forms vary principally in the darkness of the plumage. The variation generally follows Gloger's Rule
, with Alaskan and interior races the palest, and southwestern coastal forms the darkest. There are some exceptions though, most conspicuously in some island populations which presumably were strongly affected by founder effect
s. The general pattern of variation has a fairly clear divide, southwest of which the birds become notably darker; this agrees quite well with the limit between P. sandwichensis and P. (s.) rostratus.
The Savannah Sparrows proper (see below) are very similar and migrant birds can not usually be related to a breeding population with certainty. The resident or partially migratory subspecies are well distinguishable by size and, particularly between groups, coloration.
low-growth grassland. They mainly eat seeds, but insects are also eaten in the breeding season. They are typically encountered as pairs or family groups in the breeding season, and assemble in flocks for the winter migration. The flight call is a thin seep. Sensu lato, the Savannah Sparrow is considered a threatened species
by the IUCN. The song is mixture of chirps and trills.
All are migratory; wintering ranges overlap widely.
P. s. wetmorei is a doubtful subspecies which may breed in the mountains of Guatemala. It is known from only 5 specimens, collected June 11–17, 1897, in Huehuetenango Department.
The Belding's (Savannah/Large-billed) Sparrows are all-year residents of salt marsh
es of the California
n Pacific coast. They are dark, rufous, and have rather long but not very hefty bills.
The San Benito (Savannah/Large-billed) Sparrow is a resident bird of the Islas San Benito
off Baja California; a stray bird was observed on Cedros Island
on April 21, 1906.
American sparrow
American sparrows are a group of mainly New World passerine birds, forming part of the family Emberizidae. American sparrows are seed-eating birds with conical bills, brown or gray in color, and many species have distinctive head patterns....
. It is the only widely accepted member of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Passerculus. Recent comparison of 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 and 3 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...
s indicates that the Ipswich Sparrow, formerly usually considered a good species (as Passerculus princeps), is a well-marked subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Savannah Sparrow, whereas the southwestern subspecies should be recognized as distinct species Large-billed Sparrow (Passerculus rostratus) .
It is named after Savannah, Georgia
Savannah, Georgia
Savannah is the largest city and the county seat of Chatham County, in the U.S. state of Georgia. Established in 1733, the city of Savannah was the colonial capital of the Province of Georgia and later the first state capital of Georgia. Today Savannah is an industrial center and an important...
where one of the first specimens of this bird was collected.
Distribution
This passerinePasserine
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...
breeds in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, northern, central and Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
coastal USA, 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...
and Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
. The Pacific and Mexican breeders are resident, but other populations are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, wintering from the southern United States across 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 Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
to northern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It is a very rare vagrant to western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
Description
Sparrow
The sparrows are a family of small passerine birds, Passeridae. They are also known as true sparrows, or Old World sparrows, names also used for a genus of the family, Passer...
-like dark-streaked brown back, and whitish underparts with brown or blackish breast and flank streaking. It has whitish crown and supercilium
Supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line which runs...
stripes, sometimes with some yellow (more often near the beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
). The cheeks are brown and the throat white. The flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...
s are blackish-brown with light brown or white border. The eyes are dark. The feet and legs are horn-colored, as is the lower part of the bill, with the upper part being dark grey.
The Savannah Sparrow is a very variable species, with numerous subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, several of which have been split as separate species at various times. The different forms vary principally in the darkness of the plumage. The variation generally follows Gloger's Rule
Gloger's rule
Gloger's Rule is a zoological rule which states that within a species of endotherms, more heavily pigmented forms tend to be found in more humid environments, e.g. near the equator. It was named after the zoologist Constantin Wilhelm Lambert Gloger, who first remarked upon this phenomenon in 1833...
, with Alaskan and interior races the palest, and southwestern coastal forms the darkest. There are some exceptions though, most conspicuously in some island populations which presumably were strongly affected by founder effect
Founder effect
In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall...
s. The general pattern of variation has a fairly clear divide, southwest of which the birds become notably darker; this agrees quite well with the limit between P. sandwichensis and P. (s.) rostratus.
The Savannah Sparrows proper (see below) are very similar and migrant birds can not usually be related to a breeding population with certainty. The resident or partially migratory subspecies are well distinguishable by size and, particularly between groups, coloration.
Behaviour
These birds forage on the ground or in low bushes; particularly in winter they are also found in grazedGrazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
low-growth grassland. They mainly eat seeds, but insects are also eaten in the breeding season. They are typically encountered as pairs or family groups in the breeding season, and assemble in flocks for the winter migration. The flight call is a thin seep. Sensu lato, the Savannah Sparrow is considered a threatened species
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
by the IUCN. The song is mixture of chirps and trills.
Systematics
Seventeen subspecies (including the Large-billed Sparrows) are currently recognized, though many are only described from wintering birds and a lot of the variation seems to be clinal. Four additional subspecies are not generally accepted anymore. The subspecies are usually divided into several groups:Savannah Sparrows proper
- P. s. labradorius, breeds in Newfoundland, LabradorLabradorLabrador is the distinct, northerly region of the Canadian province of Newfoundland and Labrador. It comprises the mainland portion of the province, separated from the island of Newfoundland by the Strait of Belle Isle...
, and N QuebecQuebecQuebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level.... - P. s. oblitus, breeds in N OntarioOntarioOntario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
and ManitobaManitobaManitoba is a Canadian prairie province with an area of . The province has over 110,000 lakes and has a largely continental climate because of its flat topography. Agriculture, mostly concentrated in the fertile southern and western parts of the province, is vital to the province's economy; other... - P. s. savanna (Eastern Savannah Sparrow), breeds in the NE USA and adjacent Canada (includes P. s. mediogriseus)
- P. s. sandwichensis (Aleutian Savannah Sparrow), breeds on the Aleutian Islands and W Alaskan Peninsula
- P. s. anthinus, breeds in the remainder of Alaska, south and east to central British ColumbiaBritish ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
and north of the Great PlainsGreat PlainsThe Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...
to Manitoba - P. s. brooksi (Dwarf Savannah Sparrow), breeds in southernmost British Columbia to northernmost 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...
- P. s. alaudinus, breeds in coastal northern and central California
- P. s. nevadensis, breeds in the N Great Plains and the Great BasinGreat BasinThe 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...
- P. s. brunnescens, breeds from central Mexico south to Guatemala (includes P. s. rufofuscus)
P. s. wetmorei is a doubtful subspecies which may breed in the mountains of Guatemala. It is known from only 5 specimens, collected June 11–17, 1897, in Huehuetenango Department.
Ipswich Sparrow
Some post-breeding dispersal. Formerly considered a distinct species.- P. s. princeps, breeds almost exclusively on Sable IslandSable IslandSable Island is a small Canadian island situated 300 km southeast of mainland Nova Scotia in the Atlantic Ocean. The island is a year-round home to approximately five people...
- The Ipswich Sparrow is somewhat larger and paler in colour than other eastern Savannah Sparrows. The breast streaks are narrower and pale brown. Some birds overwinter on the island; others migrate south along the Atlantic coast, usually departing later and returning sooner than mainland birds. Some birds interbreed with P. s. savanna in Nova ScotiaNova ScotiaNova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
. These birds frequently raise three broods in a year. This bird was first observed in winter on the dunes near the town of Ipswich, MassachusettsIpswich, MassachusettsIpswich is a coastal town in Essex County, Massachusetts, United States. The population was 12,987 at the 2000 census. Home to Willowdale State Forest and Sandy Point State Reservation, Ipswich includes the southern part of Plum Island...
.
Large-billed Sparrows
The Large-billed Sparrows proper are 2-3 dark, large and strong-billed subspecies:- Passerculus rostratus/sandwichensis rostratus, which breed on the Gulf Coast of NE 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...
and NW SonoraSonoraSonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
(some post-breeding dispersal). - P. r./s. atratus, resident on the coast of central SonoraSonoraSonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
to central SinaloaSinaloaSinaloa officially Estado Libre y Soberano de Sinaloa is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 18 municipalities and its capital city is Culiacán Rosales....
(resident)
Salt marsh
A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...
es of the California
California
California 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...
n Pacific coast. They are dark, rufous, and have rather long but not very hefty bills.
- P. r./s. beldingi, resident on the Pacific Coast from Morro Bay, California, to El RosarioEl RosarioEl Rosario may refer to:*El Rosario, Santa Cruz de Tenerife, Canary Islands*El Rosario, Morazán, El Salvador*El Rosario, a lake located in El Rosario National Park in Guatemala*El Rosario, Baja California, Mexico*El Rosario, Michoacán, Mexico...
, Baja California (includes P. r./s. bryanti) - P. r./s. anulus, resident around Sebastián Vizcaíno BaySebastián Vizcaíno BaySebastián Vizcaíno Bay is a bay along the west coast of the Baja California Peninsula in Mexico. It is part of the El Vizcaíno Biosphere Reserve. It lies off the Pacific coast of Ensenada Municipality and Mulegé Municipality....
, Baja California - P. r./s. guttatus, resident around San Ignacio LagoonSan Ignacio LagoonSan Ignacio Lagoon is a lagoon located Mulegé Municipality in the Mexican province of Baja California Sur, from San Ignacio, Mexico and Highway 1...
- P. r./s. magdalenae, resident around Magdalena BayMagdalena BayBahía Magdalena is a 50 km long bay in Comondú Municipality along the western coast of the Mexican state of Baja California Sur. It is protected from the Pacific Ocean by the sandy barrier islands of Isla Magdalena and Isla Santa Margarita....
The San Benito (Savannah/Large-billed) Sparrow is a resident bird of the Islas San Benito
Islas San Benito
The Islas San Benito lie in the Pacific Ocean off the west coast of the Mexican state of Baja California, 25 km west of Cedros Island. They are part of the Cedros Island delegación, a subdivision of Ensenada , Baja California....
off Baja California; a stray bird was observed on Cedros Island
Cedros Island
Cedros Island is a Mexican island in the Pacific Ocean....
on April 21, 1906.
- P. r./s. sanctorum
- This is a large-bodied and large-billed subspecies, similar to rostratus. They utilize different habitat and their breeding season does not seem to coincide with that of Belding's Sparrows. However, their bill size is due to convergent evolutionConvergent evolutionConvergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
and their habitat choice simply to the lack of alternatives on their barren island home; altogether, it appears to be a fairly recent offshoot from the Belding's Sparrows group. It appears as distinct evolutionEvolutionEvolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
arily from these as does the Ipswich Sparrow from the Savannah Sparrow proper group, only that there seems to have been more gene flowGene flowIn population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
and/or a larger founder population in the case of the latter.
External links
- Species at risk - Ipswich Sparrow
- Savannah Sparrow Species Account - Cornell Lab of Ornithology
- Savannah Sparrow Information and Photos - South Dakota Birds and Birding
- Savannah Sparrow Passerculus sandwichensis - USGS Patuxent Bird Identification InfoCenter