Guadalupe Island was a major destination for
Russian and
American fur hunters seeking the
Guadalupe fur seal (
Arctocephalus townsendi) in the 18th and 19th centuries. Captain Auguste Duhaut-Cilly reported in 1827 that a
Sandwich Islands (Hawaiian Islands) brig "had spent several months there and collected three thousand sealskins". The northern elephant seals managed to survive, and were finally protected by the
Mexican government in 1922. Guadalupe shares the
California chaparral and woodlands ecoregion with the
Channel Islands of California in the United States, but the island was at one time practically denuded of all plants higher than a few centimeters by up to 100,000
feral goats. Originally brought to the island in the 19th century by
European whalers and sealers for provisions when stopping over, the population eventually eliminated most vegetation; the number of feral goats declined to a few thousand. Before this collapse, the main impact of the feral goat population was about the turn of the 19th/20th century. Naturalist A. W. Anthony wrote in 1901: "It is directly due to the despised Billy-goat that many interesting species of plants formerly abundant are now extinct, and also that one or more of the birds peculiar to the island has disappeared, and others are following rapidly." Of the four large tree species on Guadalupe Island (the
Guadalupe palm,
Guadalupe cypress,
island oak, and
Monterey pine), there were only old individuals left; the
California juniper population had entirely disappeared. As the feral goats ate any seedlings that managed to germinate, no regeneration of trees was possible. Water, formerly plentiful as the common fogs condensed in the forests of the northern end of the island, today only occurs in a few scattered pools and springs. Because the springs were a critical emergency water supply for the human inhabitants, protective measures including feral goat fences were installed beginning in 2000, allowing new seedlings of many species to survive for the first time in 150 years.
Seacology, a non-profit environmental group located in Berkeley, CA, provided funding to the Island Conservation & Ecology Group for the construction of 10 fenced
exclosures to keep feral goats out of the most sensitive areas of Guadalupe Island. In November 1850, U.S. Army Lt.
George H. Derby passed the island on his expedition in the U.S. Transport
Invincible. He described it thus: "This island is about 15 miles length and 5 in width. It is rocky + mountainous but capped with vegetation and is reputed to be thickly inhabited by wild goats of unusual size. Water is found upon the eastern shore and the Island is frequently visited by small vessels engaged in the capture of the sea elephant numbers of which animals are found upon its coast." Many islands or
marine species that reside on or near Guadalupe also frequent the Channel Islands, and vice versa. In stark contrast to the rampant extinction of terrestrial life that happened at the same time, Guadalupe was the last refuge for the
northern elephant seal (
Mirounga angustirostris) and the
Guadalupe fur seal (
Arctocephalus townsendi) in the 1890s. The island has been a
pinniped sanctuary since 1975. The movement of the cool, nutrient-rich water current promotes phytoplankton production and attracts both coastal and deep-water species, including spanish mackerel, yellowfin tuna and
great white sharks. Guadalupe is considered one of the best spots in the world for sightings of the great white shark (
Carcharhodon carcharias), because of its clear water and large population of pinnipeds, their primary prey. Because of the aggregation of over 350 identified white sharks, the island has hosted a recreational cage diving industry from one boat in 2005, to as many as eight operators in 2019, bringing thousands of shark enthusiasts to the island. In 2019 the Mexican Department SEMARNANT suspended cage diving and sport fishing between May and December to evaluate tourism’s impact on the several hundred protected white sharks congregating there. The Mexican Government said the closure was intended to gather information to adopt the best sustainability practices that guarantee their conservation. As of January 10, 2023, cage diving with great white sharks at Isla Guadalupe, Mexico, is permanently prohibited. The Mexican Government’s ban covers all tourism inside the reserve, including film production and liveaboard diving. The island has been recognised as an
Important Bird Area (IBA) by
BirdLife International.
Habitat types Before the
extirpation of the
feral goats, surveys found eight major land
habitats on Guadalupe: •
Camissonia guadalupensis ssp. guadalupensis – endemic •
Castilleja fruticosa – endemic •
Cistanthe guadalupensis – endemic •
Hesperocyparis guadalupensis (Guadalupe cypress) – endemic •
Cryptantha foliosa – endemic •
Deinandra frutescens – endemic •
Deinandra greeneana ssp. greeneana – endemic •
Deinandra palmeri – endemic •
Dudleya guadalupensis – endemic •
Dudleya virens ssp. extima – endemic •
Eriogonum zapatoense – endemic •
Erysimum moranii – endemic •
Eschscholzia elegans – near-endemic •
Eschscholzia palmeri – endemic •
Galium angulosum – endemic •
Githopsis diffusa var. guadalupensis – endemic •
Hemizonia frutescens – endemic •
Hemizonia greeneana ssp. greeneana – endemic •
Hemizonia palmeri – endemic •
Heteromeles arbutifolia var. macrocarpa – probably endemic •
Lavatera lindsayi – endemic •
Lupinus niveus – endemic •
Marah guadalupensis – near-endemic or endemic •
Perityle incana – endemic •
Phacelia phyllomanica – endemic •
Pinus radiata var. binata (Guadalupe Monterey pine) – near-endemic or endemic •
Satureja palmeri – endemic; rediscovered in 2001–2003 surveys •
Senecio palmeri – endemic •
Sphaeralcea palmeri – endemic •
Sphaeralcea sulphurea – endemic •
Stephanomeria guadalupensis – endemic •
Triteleia guadalupensis – endemic
Extinctions Numerous
taxa have gone
extinct due to the habitat destruction by the
feral goats, which in turn rendered the endemic fauna vulnerable to predation by introduced
feral cats and adverse weather by depriving them of shelter. There have been 5–6 extinctions of birds: •
Guadalupe Bewick's wren (
Thryomanes bewickii brevicauda), the late 1890s • Guadalupe
spotted towhee (
Pipilo maculatus consobrinus), the late 1890s •
Guadalupe caracara (
Caracara lutosa), 1906 – intentionally made extinct by humans, ironically because it occasionally preyed on young goats •
Guadalupe red-shafted flicker (
Colaptes auratus rufipileus), 1906 – the island was later recolonized by individuals of an extant mainland red-shafted
northern flicker subspecies (which one is unknown) •
Guadalupe storm petrel (
Hydrobates macrodactyla), the 1910s •
Guadalupe ruby-crowned kinglet (
Corthylio calendula obscurus) – close to extinction (if, indeed, it still exists); it was not observed in 2000, despite thorough searches Globally extinct plant taxa from Guadalupe Island are: •
Castilleja guadalupensis •
Hesperelaea palmeri •
Pogogyne tenuiflora and one species of plant
incertae sedis ==Notes==