Mammal Species of the World
- Original description: Merriam, C.H., 1897. Proceedings of the Biological Society of Washington, 11:175.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (<100-250 square km (less than about 40-100 square miles)) Most commonly encountered on Guadalupe Island and vicinity, off the Pacific coast of Mexico. Sometimes appears along California coast (e.g., see Hanni et al. 1997). Breeds on eastern coast Guadalupe Island; an incipient breeding colony occurs on Isla Benito del Este off central Baja California (Maravilla-Chavez and Lowry 1999). Each year 2-6 adult males and juveniles are seen on San Nicolas Island and San Miguel Island, California (California Department of Fish and Game 1990). A female and pup recently were seen on San Miguel Island, California (Melin and DeLong 1999). Adult males and nonbreeders also have been observed at the Farallon Islands, California (Matthews and Moseley 1990), though this was not mentioned by Reeves et al. (1992). Historical range may have extended from the Revillagigedo Islands (Mexico) northward to coastal waters of west-central California (Belcher and Lee 2002). Aurioles-Gamboa et al. (1999) discussed the southernmost records of this species, which extend to Guerrero, Mexico.
The northernmost border of the range of A. townsendi is the Channel Islands, CA. The southern range border is Cedros Island, Baja California, Mexico. The only current breeding area is on Guadalupe Island, 290 km west of Baja California. The Guadalupe fur seal is the rarest of the fur seals, and it is also the only species of Arctocephalus found in the Northern Hemisphere. They have also been sighted as far south as Puerto Gurrero, near the Mexico/Guatemala border, as far north as the Point Reyes National Seashore in California, and possibly in the Gulf of California. It is possible that the true range of the species is underestimated due to the rarity of sightings.
Biogeographic Regions: nearctic (Native ); pacific ocean (Native )
- Aurioles-Gamboa, D., C. Hernandez-Camacho. April 1999. Notes on the southernmost records of the Guadalupe fur seal, *Arctocephalus townsendi*, in Mexico. Marine Mammal Science, 15(2): 581-583.
- Seal Conservation Society, 2001. "SCS: Guadalupe fur seal" (On-line). Accessed Tuesday, 20 November 2001 at http://www.pinnipeds.fsnet.co.uk/species/guadfur.htm.
U.S.A. (Farallon Islands of CA) south to Mexico (Islas Revillagigedo)
The fur of Guadalupe fur seals is brownish gray dorsally, with a silvery and yellowish-gray "mane" on the nape of the neck. Their snouts are pointed, with a rust-orange color on the sides.
This species has great sexual dimorphism. Adult males usually weigh about 124 kg, and may get up to 160 kg, females weigh about 50 kg, rarely over 55. Males grow up to 1.9 m long, females to 1.4 m.
(Whitaker 1997; Wickens & York 1997)
Range mass: 50 to 160 kg.
Range length: 1.9 (high) m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Length: 220 cm
Weight: 159000 grams
Size in North America
Average: 2.2 m males; 1.5 m females
Range: 1.9-2.4 m males; 1.4-1.9 m females
Average: 190 kg males; 50 kg females
Range: 150-22- kg males; 40-55 kg females
Catalog Number: USNM 83617
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Male; Adult
Preparation: Partial Skull
Collector(s): C. Townsend
Year Collected: 1892
Locality: Guadelupe Island [= Isla Guadalupe], W side, on beach, Baja California, Mexico, North America, North Pacific Ocean
- Type: Merriam, C. H. 1 Jul 1897 . Proceedings of the Biological Society of Washington. 11: 178.
Habitat Type: Marine
Comments: Occurs on island shores with solid rock and large lava blocks, usually at the base of tall cliffs. Often occupies caves along east shore of Guadalupe Island.
Young are born on rocky shore or in coastal cave. Shelter from direct sunlight and access to water for cooling may be important factors in selection on breeding/birthing sites (Reeves et al. 1992). Reproductive males apparently are faithful to particular breeding sites over a number of years (Reeves et al. 1992).
Habitat and Ecology
Guadalupe Fur Seals are polygynous, with males establishing territories that are occupied by an average of six females. Pups are born from mid-June to August with a median birth date of 21 June. Male tenure on territories lasts at least as long as 31 days. Males defend territories with vocalizations, displays, and mutual displays with neighbouring bulls. Fighting between males is rare once territories are established. Females select only male territories that provide cover and shade from the sun and all territories occupied by females are fronted by water and include tidal pools. Adult females enter the water daily, presumably for cooling, while otherwise âashoreâ attending their pups. Most animals breed in small caves, grottos, and cliff and boulder areas on the rugged east coast of volcanic Guadalupe Island. A small breeding colony was discovered on the east side of the easternmost parts of the San Benitos Islands in 1997, and it appears to be growing annually. During the breeding season of 2007, Guadalupe Fur Seals were seen on the three islands of San Benito.
Females returning to the rookery for the first time usually arrive at night or early in the morning. Estrous occurs 5-10 days after a female gives birth, and females can leave for their first foraging trip right after mating, or stay on the colony for another few days before departing. Foraging and attendance patterns are not well-known but the limited information indicates that females may travel from 700 to 4,000 km during feeding trips lasting from 4 to 24 days. Pups are weaned at 9â11 months, and females with pups can be seen on or around the island throughout the winter and into the spring.
Knowledge of activities and behaviour at sea, away from Guadalupe Island, are limited to a handful of records. At sea, they appear to be mostly solitary. In recent years they have been reported in small numbers throughout the summer in waters off Southern California and northern Baja California by long range sport fishing boats pursuing albacore. Observations of animals in captivity suggest that they spend a considerable amount of time grooming while floating at the surface. They often rest at the surface in the characteristic southern fur seal, head-down posture. They also float with one or more flippers extended out of the water. When travelling rapidly, they have been observed to âporpoise.â
Prey preference and foraging activity are poorly known. Feeding habits based on scat analysis at San Benito Islands indicated that 95% of the prey items were squid species dominated by the market squid (Loligo opalescens) which made up 65% of the identifiable prey. Stomach contents retrieved from stranded animals included a variety of squid, bony fishes, and crustaceans, including vertically-migrating species.
Killer whales and sharks, particularly Great White Sharks which are regularly seen at Guadalupe Island in the summer, are undoubtedly predators of Guadalupe Fur Seals, although there is no evidence in the literature to support this assumption. A wound on a male from a Cookie-cutter Shark bite has been reported.
Guadalupe fur seals only live on rocky coasts and in the caves found along these shores. They can dive to an average maximum depth of 17m for an average of 2.5 minutes.
Range elevation: 0 (high) m.
Range depth: onshore to 17 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: coastal
- Whitaker, J. 1997. National Audubon Society Field Guide to North American Mammals. New York: Alfred A. Knopf.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Remains in vicinty of breeding area throughout the year, though wandering individuals are sighted regularly off the California coast.
Comments: Diet apparently includes squid and lanternfish (Reeves et al. 1992). Population is not thought to be food limited nor to compete with other pinnipeds for food resources (Peterson et al. 1968).
Guadalupe fur seals eat a variety of fish, including lantern fish, mackerel, and fish in the muctophid family. Squid also constitute a major part of their diet. In all cases, the seals swim out to sea and dive for their prey items. During the breeding season, females make 2 to 6 day forging trips to sea, coming onshore in between each trip in order to suckle their pups.
Anchovy otoliths (bony concretions formed in the ears of fish) have been found the the digestive tracts of Guadalupe fur seals, but they are believed to be remains left from feeding of the seals by fishermen.
(Hanni et al. 1997; Seal Conservation Society 2001; Whitaker, 1997)
Animal Foods: fish; mollusks
Primary Diet: carnivore (Piscivore , Molluscivore )
The Guadalupe fur seal plays the role of predator in the shoreline communities it inhabits.
Known prey organisms
This list may not be complete but is based on published studies.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 5
Comments: Two breeding colony occurrences.
2500 - 10,000 individuals
Comments: Historical population was at least 30,000. Reduced to near extinction by the fur seal trade. Population increased in the early 1900s to at least 1073 in 1978 and 1600 in 1984; total count in 1987 was 3259 at Guadalupe Island, including 468 adult males, 78 subadult males, 1134 females, 472 juveniles, and 998 pups (Reeves et al. 1992). Total population now about 7000 (Wicken and York 1997).
Life History and Behavior
Females give birth in May, June, and July (mainly mid-June), 3-6 days after arriving at rookery. Mating occurs 7-10 days after female gives birth. Females make periodic feeding trips to sea after mating, and they may continue to haul out and nurse their young through the following spring. Male territories include 2-8 females.
Guadalupe fur seals have a polygynous breeding system, which involves a male seal with a territory (a bull) defending both his terriory and the females in his harem. The harem numbers between 4 to 12 females, each of which typically have one pup that they nurse.
Mating System: polygynous
Male Guadalupe fur seals are territorial, like other fur seals. They defend harems that number an average of 6.2 breeding females for each territorial bull. Males will defend their territory for 35 to 122 days. Unlike most other seal species, the males of A. townsendi occasionally observe their harems from the water. Female Guadalupe fur seals mate 7-10 days after giving birth to a pup conceived the previous year (post-partum estrus). Females lactate for an average of 9-11 months; how this related to the actual length of time before weaning is unclear.
(Whitaker, 1997; Wickens & York, 1997)
Breeding season: 15 June - 22 July
Average number of offspring: 1.
Average gestation period: approximately 12 months.
Average weaning age: most likely 11 months.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Parental Investment: female parental care
Molecular Biology and Genetics
Barcode data: Arctocephalus townsendi
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Arctocephalus townsendi
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G1 - Critically Imperiled
Reasons: Two breeding colonies (Guadalupe Island, Isla San Benito del Este, Mexico); formerly, breeding probably occurred also on islands along the California coast; restricted range is due to near extermination by excessive harvest; current population of 7,000+ is increasing.
Other Considerations: Presumed extinct after 19th century commercial harvesting. Rediscovered (1949) on San Nicolas Island, California.
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1994Vulnerable(Groombridge 1994)
- 1990Vulnerable(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
- 1986Vulnerable(IUCN Conservation Monitoring Centre 1986)
- 1982Vulnerable(Thornback and Jenkins 1982)
Date Listed: 03/11/1967
Lead Region: National Marine Fisheries Service (Region 11)
Where Listed: Entire
Population location: Entire
Listing status: T
For most current information and documents related to the conservation status and management of Arctocephalus townsendi , see its USFWS Species Profile
The Guadalupe fur seal was nearly hunted to extinction in the 1880's, with the known population numbering only 7 individuals in 1892. Other than two males sold to the San Diego Zoo in 1928, only one other GFS was sighted until 1954. Guadalupe Island was declared a seal sanctuary by the Mexican government in 1975. The Guadalupe fur seal was first placed on the "threatened" list in the US on March 11, 1967. By 1984 there were 1,600 seals in the Guadalupe Island population, including around 650 new pups. Current estimates place the population number at >7,000 individuals. Despite the bottlenecks of the late 1800's, there still remains a high level of genetic variability in the population. The population of Guadalupe fur seals is growing at the rate of 11.5% per annum.
(Bernardi et al. 1998; Seal Conservation Society, 2001; USFWS 2001; Whitaker 1997; Wickens & York 1997)
US Federal List: threatened
CITES: appendix i
IUCN Red List of Threatened Species: near threatened
Global Short Term Trend: Increase of 10 to >25%
Comments: Increasing in recent decades after near extinction.
Degree of Threat: A : Very threatened throughout its range communities directly exploited or their composition and structure irreversibly threatened by man-made forces, including exotic species
Comments: Formerly decimated by hunting. Currently, the species is vulnerable to mortality from oil spills, and offshore oil and gas exploration may affect potential habitat off California coast (Matthews and Moseley 1990). USAF space shuttle program's sonic booms could cause disturbance. Three of nine stranded individuals found recently in central and northern Clifornia had experienced entanglement in fishing gear or marine debris (Hanni et al. 1997).
Although the Guadalupe Fur Seal population is steadily growing, the species is still at risk because the total population remains low and nearly all pup production occurs at only one island. Also, since the species passed through a genetic bottleneck and probably recovered from a very small number of individuals, there may be a lack of genetic diversity within the surviving population (Weber et al. 2004).
The feeding ground of the species occupies the region around Guadalupe and San Benito Islands and the lower part of the California Current. This region is influenced by human population centres with contaminant runoff, extensive oil tanker traffic and offshore oil extraction activity from southern California. Like all fur seals, Guadalupe Fur Seals are vulnerable to oil spills because of their dependence on their thick pelage for thermoregulation. Guadalupe Fur Seals share most of their haulout and breeding sites with California Sea Lions, which have suffered from viral disease outbreaks in the past, and which could be a vector for transmission of diseases from terrestrial sources to Guadalupe Fur Seals, because of their extensive use of coastal areas.
No conflicts with commercial fisheries are known to exist at the present time, although gillnet and set-net fisheries probably take some animals, as is probably also the case for entanglement in marine debris. There is a possibility of negative interactions between Guadalupe Fur Seals and lobster fishermen when the seals occupy inshore areas to breed and out, particularly if the population continues to increase.
Biological Research Needs: Research the possibility of translocating animals to historic breeding areas. Investigate effect of feral goats on Guadalupe Island.
Global Protection: Few (1-3) occurrences appropriately protected and managed
Comments: Guadalupe Island was declared a wildlife sanctuary by Mexico in 1922; confirmed by new decree in 1972. Species is fully protected under various international conventions and national (U.S. and Mexican) and state laws.
Needs: Protect all existing and potential breeding sites from habitat degradation and disturbance.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Positive
Prehistorically, A. townsendi may have been hunted by Chumash Indians at San Miguel Island and other Channel Islands in California. The seal produces a rich, dense fur that was highly prized up until recent times, with the species nearly driven to extinction by seal hunters in the 1880's. In 1892, only seven individuals were known to exist. The population has rebounded, and the trade in the fur of Guadalupe fur seals is prohibited.
(Melin & DeLong 1999; Whitaker 1997)
Guadalupe fur seal
The Guadalupe fur seal (Arctocephalus townsendi) is one of six members of the fur seal genus Arctocephalus. Sealers reduced the population to just a few dozen by the late 19th century, but the species had recovered to 10,000 in number by the late 1990s. Many individuals can be found on Mexico's Guadalupe Island.
Guadalupe fur seals are sexually dimorphic in size, with the males being much larger than females, although few specimens have been measured. Individuals of both sexes are dark brown or dusky black, with the guard hairs on the back of the neck being yellowish or light tan. Pups are born with a black coat similar to that of adults. Observations suggest reproductive males are faithful to particular sites over a number of years. Tenure of territorial males lasts from 35–122 days. Births occur from mid-June through July, with most births taking place in June. The seals are one of the few with visible earflaps, confirming it is not a Phocidaen/true seal.
Guadalupe fur seals breed along the eastern coast of Guadalupe Island, approximately 200 km west of Baja California. In addition, individuals have been sighted in the southern California Channel Islands, including two males who established territories on San Nicolas Island.
Impacts on Guadalupe fur seals
The major cause of the Guadalupe fur seal's decline was commercial hunting in the late 18th and early 19th centuries. The species was exterminated in southern California waters by 1825. Commercial sealing continued in Mexican waters through 1894.
Conservation and recovery efforts
The species is listed as endangered by the U.S. National Marine Fisheries Service under the Endangered Species Act. The principal cause of the decline in Guadalupe fur seals was commercial sealing. The species is now protected from such activity throughout its range, and the magnitude of the threat to the species is considered to be low. The portion of the Guadalupe fur seal's range which is under U.S. jurisdiction is at the limit of the species range. No activities in areas under U.S. jurisdiction are known to be adversely affecting recovery of this species now. Therefore, management activities in the U.S. portion of its range are not likely to contribute substantially to recovery. However, Guadalupe fur seals are protected from federal actions that are likely to jeopardize the species through interagency coordination under Section 7 of the Endangered Species Act. No other specific actions necessary for the recovery of the species have been identified, and no direct recovery actions are being implemented.
Names and Taxonomy
Comments: Has been regarded as conspecific with Arctocephalus phillipii by some authors (e.g., Hall 1981). Considered a distinct species by Jones et al. (1992), Wozencraft (in Wilson and Reeder 1993, 2005), and Reeves et al. (1992).
Gardner and Robbins (1998) pointed out that Otoes and Halarctus are the earliest available generic names for northern and southern fur seals, respectively; they have petitioned the ICZN to preserve the generic names Callorhinus and Arctocephalus for these seals.