Island scrub jay

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Island scrub jay
Island Scrub Jay Aphelocoma insularis.jpg
On Santa Cruz Island, California
Status TNC G1.svg
Critically Imperiled  (NatureServe) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Aphelocoma
Species:
A. insularis
Binomial name
Aphelocoma insularis
Henshaw, 1886
Aphelocoma insularis range.png
   Year-round resident range on Santa Cruz Island

The island scrub jay (Aphelocoma insularis), also known as the island jay or Santa Cruz jay, is a bird in the genus, Aphelocoma , which is endemic to Santa Cruz Island off the coast of Southern California. Of the over 500 breeding bird species in the continental U.S. and Canada, it is the only insular endemic landbird species. [3]

Contents

Description

The island scrub jay is closely related to the California scrub jay (the coastal population found on the adjacent mainland), but differs in being larger, more brightly colored, and having a markedly stouter bill. They will bury, or cache, the acorns in the fall and may eat them months later. They also eat insects, spiders, snakes, lizards, mice and other birds' eggs and nestlings.

Taxonomy

The island scrub jay was first described by American ornithologist Henry Wetherbee Henshaw in 1886 [4] and an archaeological specimen at site SCRI-192 dating from the 1780s-1812 on Santa Cruz Island is the earliest evidence of the bird in the historic period. [5] This bird is a member of the crow family, and is one of a group of closely related North American species named as scrub jays. These were formerly treated as a single species, the scrub jay (as Aphelocoma coerulesens), with five subspecies, [6] but are now considered four species: the Florida scrub jay (A. coerulescens), the island scrub jay, the California scrub jay (A. californica), and Woodhouse's scrub jay (A. woodhouseii). DNA studies indicate that the island and coastal forms have long been isolated from their relatives inland. [7] The relationships within the genus have been studied in several papers (e.g. [8] )

Island scrub jays seem to be incapable of crossing to the mainland. However they were once present on three of California's northern Channel Islands, San Miguel Island, Santa Rosa Island, and Santa Cruz Island where they persist today. [9] Reliable historical observer records for island scrub jays in addition to Santa Cruz Island include only a single 1892 account on neighboring Santa Rosa Island, only about 10 km (6 mi) away. [5] The historic observation on Santa Rosa Island is supported by a Pleistocene archaeological record of a single island scrub jay femur from a Late Pleistocene-Holocene site (SRI-V-3) found by Paul Collins of the Santa Barbara Museum of Natural History. [5] There are also two Late Holocene archaeological remains found in San Miguel Island cave sites. [9] There are no definite occurrences of a scrub-jay on any other of the Channel Islands, or on the Coronado Islands, only 13 km (8 mi) from the mainland.

Early studies suggested that the ancestor of the present population was storm-borne or carried on driftwood to Santa Cruz, or that the colonization occurred during a period of glaciation 70,000 to 10,000 years ago, when sea levels were much lower and the channel between the coast and the islands was correspondingly narrower. [10] More recent DNA studies show that, although other island endemics such as the island fox and the Santa Cruz mouse may have diverged from their mainland relatives around 10,000 years ago, the scrub jays separated in a period of glaciation around 151,000 years ago. The most recent analysis indicates that the island scrub jay has been evolving in isolation for approximately one million years, [8] i.e. over multiple glacial cycles. Up to about 11,000 years ago, the four northern Channel Islands were one large island, so island scrub jays must have been present on all four islands initially, but became extinct on Santa Rosa, San Miguel and Anacapa after they were separated by rising sea levels. [11]

Distribution and habitat

The island scrub jay is found today only on Santa Cruz Island, the largest of California's Channel Islands with an area of 250 km2 (96 mi2). [12] The island is a nature reserve, the eastern 24% being administered by National Park Service as the part of the Channel Islands National Park and the rest of the island by the Nature Conservancy. [13] Fossil remains for island scrub jays have been found on Santa Rosa and San Miguel Islands. [14]

Island scrub jays occur in oak chaparral and bishop pine ( Pinus muricata ) woodland on Santa Cruz Island. Island scrub jays in pine habitat have longer, shallower bills than individuals in oak habitat; variation in bill shape is heritable, and individuals mate nonrandomly with respect to bill morphology. [15]

Breeding

Females lay 3 to 5 eggs. Incubation lasts approximately 20 days. These jays are generally monogamous and, unlike some other jays, are not cooperative breeders. Both sexes build a nest 1 m (3 ft) to 8 m (26 ft) above the ground. Further details in. [16]

Etymology

The genus name, Aphelocoma, comes from the Latinized Ancient 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. The species name, insularis, comes from the Latin for "from an island".

Conservation status

The island scrub jay is classed as vulnerable on the IUCN Red List because its small range makes it potentially vulnerable to a catastrophic incident such as disease or a large fire that destroys their habitat. [1] Population size in 2008 and 2009 was estimated to be 1700 - 2300, making this one of the rarest songbird species in the United States. [17] The entire range of island scrub jays is currently protected in Channel Islands National Park and the species is not at imminent risk of extinction. However, the establishment of West Nile virus (WNV) in southern California in 2003 may pose a threat if it crosses to Santa Cruz Island from the mainland. Corvids are especially vulnerable to WNV. In addition, the increased occurrence of wildfires in southern California may portend a catastrophic fire there. [3] Shrub cover has increased since the removal of sheep (1980–91) and feral pigs (2005–07) from Santa Cruz Island, which may increase the fire risk. [3] Overgrazing by non-native ungulates may have caused extirpation of island scrub jays on Santa Rosa Island. Re-establishing a second population of island scrub jays on Santa Rosa Island and San Miguel Island may accelerate the restoration of native plant and tree species because of the scatter-hoarding seed caching behavior of Aphelocoma species. [3]

Human interaction and uses

The Chumash people who were the original inhabitants of the northern Channel Islands may have eaten the local scrub jay, or used its feathers for decoration, since they are known to have made feather bands including jay feathers on the Californian mainland. Human activities may have contributed to the presumed extinction of the island scrub-jay from the smaller islands. [11]

Related Research Articles

<i>Aphelocoma</i> Genus of birds

The passerine birds of the genus Aphelocoma include the scrub jays and their 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 jays—possibly a distinct subfamily–which is not closely related to other jays, magpies or treepies. Within this group, according to a 2023 molecular analysis, Aphelocoma is the sister group to a clade consisting of Cyanocitta and Gymnorhinus. They live in open pine-oak forests, chaparral, and mixed evergreen forests.

<span class="mw-page-title-main">Channel Islands (California)</span> Archipelago off the coast of southern California, US

The Channel Islands are an eight-island archipelago located within the Southern California Bight in the Pacific Ocean, off the coast of California. They define the Santa Barbara Channel between the islands and the California mainland. The four Northern Channel Islands are part of the Transverse Ranges geologic province, and the four Southern Channel Islands are part of the Peninsular Ranges province. Five of the islands are within the Channel Islands National Park. The waters surrounding these islands make up Channel Islands National Marine Sanctuary. The Nature Conservancy was instrumental in establishing the Channel Islands National Marine Sanctuary.

<span class="mw-page-title-main">Channel Islands National Park</span> National park in California, United States

Channel Islands National Park is a national park of the United States, which consists of five of the eight Channel Islands off the coast of California. Although the islands are close to the shore of the densely populated state, they have been relatively undeveloped. The park covers 249,561 acres (100,994 ha), of which 79,019 acres (31,978 ha) are federal land.

<span class="mw-page-title-main">Island fox</span> Species of fox

The island fox is a small fox species that is endemic to six of the eight Channel Islands of California. There are six subspecies, each unique to the island it lives on, reflecting its evolutionary history. They are generally docile, show little fear of humans, and are easily tamed. Island foxes played an important role in the spiritual lives of native Channel Islanders. They have been likely semi-domesticated as pets, used as pelts, or for other functions, like pest control.

<span class="mw-page-title-main">Santa Cruz Island</span> Island in California, United States

Santa Cruz Island is located off the southwestern coast of Ventura, California, United States. It is the largest island in California and largest of the eight islands in the Channel Islands archipelago and Channel Islands National Park. Forming part of the northern group of the Channel Islands, Santa Cruz is 22 miles (35 km) long and 2 to 6 miles wide with an area of 61,764.6 acres (249.952 km2).

<span class="mw-page-title-main">Torrey pine</span> Species of pine tree in California

The Torrey pine is a rare pine species in California, United States. It is a critically endangered species growing only in coastal San Diego County, and on Santa Rosa Island, offshore from Santa Barbara in Santa Barbara County. The Torrey pine is endemic to the California coastal sage and chaparral ecoregion.

<span class="mw-page-title-main">Island spotted skunk</span> Subspecies of carnivore

The island spotted skunk is an insular endemic carnivore and a subspecies of the western spotted skunk. Little is known about their exact variations from the mainland spotted skunk and variations between locations, resolution of which awaits further genetic and morphologic evaluation. The skunk is only currently found on two islands off the southern coast of California. Its presence has been recorded on San Miguel Island, but it has since been declared extinct in that area. The Channel Island skunk is one of two terrestrial carnivores on the islands, the other being the island fox. It is designated as a species of special concern by the state of California.

<span class="mw-page-title-main">Mexican jay</span> Species of bird

The Mexican jay 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 and parts of the southwestern United States. In May 2011, the American Ornithologists' Union voted to split the Mexican jay into two species, one retaining the common name Mexican jay and one called the Transvolcanic jay. The Mexican jay is a medium-sized jay with blue upper parts and pale gray underparts. It resembles the Woodhouse's scrub-jay, but has an unstreaked throat and breast. It feeds largely on acorns and pine nuts, but includes many other plant and animal foods in its diet. It has a cooperative breeding system where the parents are assisted by other birds to raise their young. This is a common species with a wide range and the International Union for Conservation of Nature has rated its conservation status as being of "least concern".

<span class="mw-page-title-main">California scrub jay</span> Species of bird in the crow family

The California scrub jay is a species of scrub jay native to western North America. It ranges from southern British Columbia throughout California and western Nevada near Reno to west of the Sierra Nevada. The California scrub jay was once lumped with Woodhouse's scrub jay and collectively called the western scrub jay. The group was also lumped with the island scrub jay and the Florida scrub jay; the taxon was then called simply scrub jay. The California scrub jay is nonmigratory and can be found in urban areas, where it can become tame and will come to bird feeders. While many refer to scrub jays as "blue jays", the blue jay is a different species of bird entirely.

<span class="mw-page-title-main">Unicolored jay</span> Species of bird

The 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 Potosí. It is apparently a basal member of its genus. At Montebello, Chiapas, it is a cooperative breeder, and is not known to perform mating dances.

<span class="mw-page-title-main">Pygmy mammoth</span> Species of mammoth

The pygmy mammoth or Channel Islands mammoth is an extinct species of dwarf mammoth native to the northern Channel Islands off the coast of southern California during the Late Pleistocene. It was descended from the Columbian mammoth of mainland North America, which are suggested to have colonised the islands around 250–150,000 years ago. At only 1.72–2.02 m (5.6–6.6 ft) tall at the shoulder, it was around 17% the size of its mainland ancestor. The species became extinct around 13,000 years ago, co-inciding with major environmental change and the arrival of humans in the Channel islands.

<i>Asio</i> Genus of birds

Asio is a genus of typical owls, or true owls, in the family Strigidae. This group has representatives over most of the planet, and the short-eared owl is one of the most widespread of all bird species, breeding in Europe, Asia, North and South America, the Caribbean, Hawaii and the Galápagos Islands. Its geographic range extends to all continents except Antarctica and Australia.

<span class="mw-page-title-main">Florida scrub jay</span> Species of bird

The Florida scrub jay is one of the species of scrub jay native to North America. It is the only species of bird endemic to the U.S. state of Florida and one of only 15 species endemic to the continental United States. Because of this, it is keenly sought by birders. It is known to have been present in Florida as a distinct species for at least 2 million years, and is possibly derived from the ancestors of Woodhouse's scrub jay.

<i>Phacelia insularis</i> Species of plant

Phacelia insularis, the coast phacelia is a rare species of phacelia. It is endemic to California, where it has a disjunct distribution.

<span class="mw-page-title-main">California coastal sage and chaparral</span> Mediterranean forests, woodlands, and scrub ecoregion in Mexico and the United States

The California coastal sage and chaparral is a Mediterranean forests, woodlands, and scrub ecoregion, defined by the World Wildlife Fund, located in southwestern California and northwestern Baja California (Mexico). It is part of the larger California chaparral and woodlands ecoregion. The ecoregion corresponds to the USDA Southern California ecoregion section 261B, and to the EPA Southern California/Northern Baja Coast ecoregion 8.

<span class="mw-page-title-main">California interior chaparral and woodlands</span> Forests, woodlands, and scrub ecoregion in California, United States

The California interior chaparral and woodlands ecoregion covers 24,900 square miles (64,000 km2) in an elliptical ring around the California Central Valley. It occurs on hills and mountains ranging from 300 feet (91 m) to 3,000 feet (910 m). It is part of the Mediterranean forests, woodlands, and scrub biome, with cool, wet winters and hot, dry summers. Temperatures within the coast can range from 53° to 65 °F and 32° to 60 °F within the mountains. Many plant and animal species in this ecoregion are adapted to periodic fire.

Dow's puffin is an extinct seabird in the auk family described in 2000 from subfossil remains found in the Channel Islands of California. It was approximately as large as the modern horned puffin and its beak appeared to have been an intermediate between the rhinoceros auklet and the horned puffin. It lived during the Late Pleistocene and Early Pleistocene on the Channel Islands, where it nested alongside the ancient murrelet, Cassin's auklet and Chendytes lawi.

<span class="mw-page-title-main">Woodhouse's scrub jay</span> Species of bird

Woodhouse's scrub jay is a species of scrub jay native to western North America, ranging from southeastern Oregon and southern Idaho to central Mexico. Woodhouse's scrub jay was until recently considered the same species as the California scrub jay, and collectively called the western scrub jay. Prior to that both of them were also considered the same species as the island scrub jay and the Florida scrub jay; the taxon was then called simply the scrub jay. Woodhouse's scrub jay is nonmigratory and can be found in urban areas, where it can become tame and will come to bird feeders. While many refer to scrub jays as "blue jays", the blue jay is a different species of bird entirely. Woodhouse's scrub jay is named for the American naturalist and explorer Samuel Washington Woodhouse.

The wildlife of the Channel Islands of California is wide and diverse, including many endemic species. While the land wildlife is slightly limited, there being only one large, naturally predatory, and native mammal, the small island fox, marine life can include anything from kelp forests to great white sharks.

<span class="mw-page-title-main">Daisy Cave</span> Archeological site in California

Daisy Cave, also known as CA-SMI-261, is an archeological site located on San Miguel Island in California. San Miguel Island is the westernmost island in the Channel Islands. The island sits between the Santa Barbara Channel and the Pacific Ocean and is often notably battered by winds all year round, but the Daisy Cave itself provides solace from the weather and has served as an effective shelter time and time again. The cave appears to have multiple archaeological deposits, in which artifacts ranging from the "terminal Pleistocene to the present." San Miguel was once part of a larger 'Superisland,' connected with Santa Rosa, Santa Cruz and Anacapa to make up Santarosae. Santarosae existed as the 'superisland' until as recent as 10,000 years ago, with some estimation.

References

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  2. "NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved 19 April 2022.
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  15. Langin, Kathryn M.; Sillett, T. Scott; Funk, W. Chris; Morrison, Scott A.; Desrosiers, Michelle A.; Ghalambor, Cameron K. (2015). "Islands within an island: Repeated adaptive divergence in a single population: REPEATED ADAPTIVE DIVERGENCE WITHIN A POPULATION". Evolution. 69 (3): 653–665. doi: 10.1111/evo.12610 . PMID   25645813. S2CID   10916622.
  16. Caldwell, Luke; Bakker, Victoria J.; Sillett, T. Scott; Desrosiers, Michelle A.; Morrison, Scott A.; Angeloni, Lisa M. (2013). "Reproductive Ecology of the Island Scrub-Jay". Condor. 115 (3): 603–613. doi: 10.1525/cond.2013.120028 . ISSN   1938-5129. S2CID   45886719.
  17. Sillett, T. Scott; Chandler, Richard B.; Royle, J. Andrew; Kéry, Marc; Morrison, Scott A. (2012). "Hierarchical distance-sampling models to estimate population size and habitat-specific abundance of an island endemic". Ecological Applications. 22 (7): 1997–2006. Bibcode:2012EcoAp..22.1997S. doi:10.1890/11-1400.1. ISSN   1051-0761. PMID   23210315. S2CID   12163232.

Further reading