Black rat in the context of "Black Death"

In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms (e.g. nematodes), cells harbouring pathogenic (disease-causing) viruses, or a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.

The Galápagos Islands (Spanish: Islas Galápagos) are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, 900 km (560 mi) west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of slightly over 33,000 (2020). The province is divided into the cantons of San Cristóbal, Santa Cruz, and Isabela, the three most populated islands in the chain. The Galápagos are famous for their large number of endemic species, which were studied by Charles Darwin in the 1830s and inspired his theory of evolution by means of natural selection. All of these islands are protected as part of Ecuador's Galápagos National Park and Marine Reserve.

There is no firm evidence that Polynesians or the Indigenous peoples of South America reached the islands before their accidental discovery by Bishop Tomás de Berlanga in 1535. If some visitors did arrive, poor access to fresh water on the islands seems to have limited settlement. The Spanish Empire similarly ignored the islands, although during the Golden Age of Piracy various pirates used the Galápagos as a base for raiding Spanish shipping along the Peruvian coast. The goats and black and brown rats introduced during this period greatly damaged the existing ecosystems of several islands. British sailors were chiefly responsible for exploring and mapping the area. Darwin's voyage on HMS Beagle was part of an extensive British survey of the coasts of South America. Ecuador, which won its independence from Spain in 1822 and left Gran Colombia in 1830, formally occupied and claimed the islands on 12 February 1832 while the voyage was ongoing. José de Villamil, the founder of the Ecuadorian Navy, led the push to colonize and settle the islands, gradually supplanting the English names of the major islands with Spanish ones. The United States built the islands' first airport as a base to protect the western approaches of the Panama Canal in the 1930s. After World War II, its facilities were transferred to Ecuador. With the growing importance of ecotourism to the local economy, the airport modernized in the 2010s, using recycled materials for any expansion and shifting entirely to renewable energy sources to handle its roughly 300,000 visitors each year.

The Polynesian rat, Pacific rat or little rat (Rattus exulans), or kiore, is the third most widespread species of rat in the world behind the brown rat and black rat. Contrary to its vernacular name, the Polynesian rat originated in Southeast Asia, and like its relatives has become widespread, migrating to most of Polynesia, including New Zealand, Easter Island, and Hawaii. It shares high adaptability with other rat species extending to many environments, from grasslands to forests. It is also closely associated with humans, who provide easy access to food. It has become a major pest in most areas of its distribution.

Isla Cardona, also known as Sor Isolina Ferré Island, is a small, uninhabited island located 1.30 nautical miles (2.41 km; 1.50 mi) south of the mainland Puerto Rican shore across from Barrio Playa, on the west side of the entrance to the harbor of Ponce, Puerto Rico. The small island is considered part of barrio Playa. It is home to the 1889 Cardona Island Light, which is listed in the U.S. National Register of Historic Places. Together with Caja de Muertos, Gatas, Morrillito, Ratones, Isla del Frio, and Isla de Jueyes, Cardona is one of seven islands ascribed to the municipality of Ponce. The island gained notoriety in 2010 when the Puerto Rican Bird Society made it a target for the eradication of the black rat.

Isla de Ratones (Spanish for mice island) is a small uninhabited island off the southern coast of Puerto Rico, off the coast of Ponce. The island is part of barrio Canas in the municipality of Ponce. The island gained attention in 2010 when the Puerto Rican Bird Society made it a target for the eradication of the black rat. While named as one single island, it is actually composed of two islands separated by a few feet of shallow water during high tide, which become a single island at low tide.