Urocyon littoralis (Baird, 1858)
|
publication ID |
https://doi.org/ 10.5281/zenodo.6331155 |
|
DOI |
https://doi.org/10.5281/zenodo.6585167 |
|
persistent identifier |
https://treatment.plazi.org/id/03ACCF40-BF21-FFDF-7E92-F685F6CBD128 |
|
treatment provided by |
Conny |
|
scientific name |
Urocyon littoralis |
| status |
|
21. View On
Island Fox
Urocyon littoralis View in CoL
French: Renard insulaire / German: Insel-Graufuchs / Spanish: Cachalillo islefo
Other common names: Island Gray Fox, Channel Islands Fox
Taxonomy. Vulpes littoralis Baird, 1858 View in CoL ,
San Miguel Island, California, USA.
Urocyon is currently considered a basal genus within the Canidae and has only two surviving members, U. cinereoargenteus and U. lttoralis. The latter is believed to be a direct descendant of the former, having reached the Channel Islands either by chance over-water dispersal or human-assisted dispersal. A series of genetic analyses justifies the current classification of Island Foxes as a separate species and the recognition ofsix subspecies.
Subspecies and Distribution.
U. l. littoralis Baird, 1858 — SW USA (San Miguel I).
U. l. catalinae Merriam, 1903 — SW USA (Santa Catalina I).
U. l. clementae Merriam, 1903 — SW USA (San Clemente I).
U. l. dickey: Grinnell & Linsdale 1930 — SW USA (San Nicolas I).
U. l. santacruzae Merriam, 1903 — SW USA (Santa Cruz I).
U. l. santarosae Grinnell & Linsdale 1930 — SW USA (Santa Rosa I). View Figure
Descriptive notes. Head-body 47-59 cm for males and 45-6-63- 4 cm for females, tail 14- 5-31 cm for males and 11-5-29- 5 cm for females; weight 1-4- 2-5 kg for males an 1-3- 2-4 kg for females. The Island Fox is the smallest North American canid. Males are significantly heavier than females. The head is gray with black patches on the sides of the muzzle, and the upper and lower lips are outlined in black. White patches on the muzzle extend behind the lateral black patches, to the cheek, and blend into the ventral surface of the neck, which is mostly white. There are small white patches on the side of the nose. Variable degrees of white and rufous color on the chest and belly. The body and tail are mostly gray, the tail with a conspicuous black stripe on the dorsal surface ending in a black tip. Pelage is relatively short. Eight mammae are present. Dental formulais 13/3, C1/1,PM 4/4, M 2/3 = 42. Island Foxes typically have fewer caudal vertebrae (15-22) than the Northern Gray Fox (21-22).
Habitat. Present in all habitats on the islands, including native perennial and exotic European grassland, coastal sage scrub, maritime desert scrub, Coreopsis scrub, Isocoma scrub, chaparral, oak woodland, pine woodland,riparian, and inland and coastal dune. Generally not found in areas highly degraded by human disturbance or overgrazing. Recently, Foxes have become scarce owing to precipitous population declines. On the northern Channel Islands declines are principally a consequence of hyperpredation by golden eagles (Aquila chrysaetos); on those islands the foxes are more numerous in habitats with dense cover.
Food and Feeding. Island Foxes are omnivorous and feed on a wide variety of insects, vertebrates, fruits, terrestrial molluscs, and nearshore invertebrates. The relative abundance of insects, mammals, and plant material in the diet has been found to differ by habitat type, and by island, depending upon availability of food items. For example, North American Deermouse (Peromyscus maniculatus) occur at high densities on San Miguel Island, where they constitute a large proportion of Fox diet. On Santa Cruz Island, Jerusalem crickets (Stenopelmatusfuscus) are a principal prey. The fruits of the coastal prickly pear cactus ( Opuntia littoralis ) are a principal food on San Clemente Island. Bird remains in droppings are usually occur infrequently (3- 6%), except in San Miguel Island where bird remains were found in 22% (n = 208). Island Foxes primarily forage alone, by coursing back and forth through suitable habitat patches and then moving past little-used habitats to other suitable habitat patches.
Activity patterns. Island Foxes forage mostly at night, but also during the day.
Movements, Home range and Social organization. Island Foxes typically form monogamous pairs occupying discrete territories. Full-grown young may remain within their natal range into their second year. The home ranges are among the smallest recorded for any canid, ranging between 0-15 and 0-9 km ®*. On Santa Cruz Island, home ranges expanded when neighboring foxes were killed by golden eagles, suggesting that density of foxes and the spatial distribution of neighbors may influence territory size. Foxes communicate using visual, auditory and olfactory cues. Males have been observed chasing and fighting with other males. Foxes demarcate territory boundaries with latrine sites and have been observed urinating as frequently as every 6- 9 m.
Breeding. Foxes breed once a year, mainly in April. Recent research suggests they may have induced ovulation, allowing for plasticity in the timing of reproduction. Litter size varies from one to five, but most litters are smaller, from one to three. Average litter size for 24 dens located on Santa Cruz was 2-2. Weaning is complete by mid- to late June and pups reach adult weight and become independent by September. Although most foxes are typically monogamous, extra-pair fertilization has been recorded: of 16 pups whose paternity was tested genetically, 25% were the result of extra-pairfertilizations. Dens consist of rock piles, dense brush, and natural cavities in the ground or under tree trunks.
Status and Conservation. CITES not listed. Classified as Critically Endangered on The IUCN Red List. Listed by the state of California as “threatened”. Four of the six subspecies were also listed in 2004 as “ USA federally endangered”, including santacruzae, santarosae, littoralis , and catalinae. In recent years there have been catastrophic population declines. Island Fox numbers fell from approximately 6000 individuals to less than 1500 in 2002. The current primary threats to the species include golden eagle predation on the northern Channel Islands and the introduction of canine diseases, especially canine distemper virus (CDV), to all populations. An outbreak of CDV decimated the Santa Catalina Island Fox population from 1998-2000. All populations are small, several critically, and are thus especially vulnerable to any catastrophic mortality source, be it predation, canine disease, or environmental extremes.
Bibliography. Collins (1991a, 1991b, 1993), Collins & Laughrin (1979), Coonan (2002), Coonan & Rutz (2002), Cooper et al. (2001), Crooks & van Vuren (1995, 1996), Elliot & Popper (1999), Fausett (1982), Garcelon, Roemer etal. (1999), Garcelon, Wayne & Gonzales (1992), Goeden et al. (1967), Hall (1981), Kovach & Dow (1981), Laughrin (1973, 1977), Moore & Collins (1995), Roemer (1999), Roemer & Wayne (2003), Roemer, Coonan, Garcelon et al. (2001), Roemer, Coonan, Munson & Wayne (2004), Roemer, Donlan & Courchamp (2002), Roemer, Garcelon etal. (1994), Schmidt et al. (2002), Suckling & Garcelon (2000), Thompson et al. (1998), Timm, Barker et al. (2002), Timm, Stokely et al. (2000), Wayne, Geffen et al. (1997), Wayne, George et al. (1991).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
