Control and eradication of feral cats (Felis catus)
For more information contact:
Víctor Carrión, +593 (0)5 252 6189 Ext. 145, firstname.lastname@example.org
Cats are born predators. In the picture, a feral cat has hunted a marine iguana, an endemic species.
Another species introduced by humans in a time when the nature of the Galapagos was not valued as it is today, its eradication is particularly difficult and expensive due to its level of dispersion, small size, and ability to hide.
Cats were introduced by ships visiting the islands, and by colonists as pets. Historically they have been present on the five inhabited islands (Baltra, Santa Cruz, San Cristóbal, Floreana, and Isabela), as well as in certain areas of northern Isabela, an unpopulated area.
Both domestic cats as those in the wild (or feral) are aggressive predators that attack native wildlife, including birds, lava lizards, and juvenile iguanas in areas of the National Park as well as in populated areas.
Pet... or predator?
Unlike other introduced animals, the cat is a pet in populated areas. Their perception as pets, rather than predators, makes it difficult to control them in populated areas, so their eradication from these islands is extremely difficult.
Cats attack chicks of many types of native and endemic birds.
Therefore, the Program for Control and Eradication of Feral Cats of the Directorate of the Galapagos National Park concentrates its efforts on monitoring and controlling these animals on populated islands, and their eradication on other islands.
The removal of these cats from the islands is an effective way to protect biodiversity. However, compared with other invasive species of mammals, cats are difficult to eradicate.
The largest island on which eradication was achieved is Marion Island, South Africa, a mere 290 km2, during a project that lasted 10 years.
Eradication on Baltra
Baltra Island was chosen as the first project for the eradication of cats for several reasons: first of all it is an island with a small human population and therefore with a low risk of reintroduction of cats; its size is small (26 km²) which facilitates the control and monitoring; in addition it has scanty vegetation with large open areas.
Behavioral studies of feral cats and their most appropriate methods of control revealed that the cats are active during the day and night. Therefore during the day for GNP staff looks for tracks, and if tracks are found traps are set (Tomahawk and Victor type) and poison is set out. At night, monitoring with spotlights was performed and the cats were hunted with rifles.
Traps are the most effective way of hunting.
With the purpose of ensuring total eradication, poison was set out, sodium monofluoroacetate (known as 1080), on bait fish around the island. The island was divided into 13 sectors and 350 poison stations were set and were all consumed.
This methodology has been successful in controlling cats. The population has declined steadily until eradication was achieved. Eliminating the last individuals was more complicated due to the proliferation of rats and mice as a result of climate change, which allowed the recruitment of cubs in 2002. However, adult cats became more vulnerable to being trapped or hunted by 2003, when the rodent population collapsed. By the end of 2003 no sign of survivors was reported on Baltra despite an extensive search.
After the successful cat eradication program on the island of Baltra, the cat control process has improved in priority sites such as the land iguana nesting areas in "Cerro Cartago" on Isabela Island, "Cerro Dragon" on Santa Cruz Island and "Cerro Montura", all breeding sites of land iguanas where juveniles are preyed upon by cats.
A permanent cat control effort is also being performed on Punta Pitt, a place where an important colony of red-footed boobies is settled, and the young were being predated upon by cats.
The eradication of cats from Baltra was possible due to several reasons: it is an island with a small human population, and therefore with a low risk of feline reintroduction; it is small (2.6 km²), which facilitated the control and monitoring process; it does not have abundant vegetation; there are open areas; and there is road infrastructure on the island, which facilitated the movement of the teams.
In 2006 a permanent cat control program was started on the west coast of Isabela Island in order to avoid predation on important seabird colonies located in this area of the island, especially penguins.
Conditions are different in controlled sites, making it necessary to investigate possible methodologies to optimize available resources.
The most effective technique is the use of baited traps, therefore their design and location are the most important factors.
This program has counted on the support of:
The Charles Darwin Foundation for the Galapagos Islands (CDF) is an international nonprofit research organization dedicated to providing scientific research, technical assistance and information in order to ensure the success of conservation in Galapagos.