Spay and neuter in the Galapagos: Cat and dog overpopulation and the work of Galapagos Preservation Society

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In two recent posts HRC addressed why some people choose not to spay/neuter and the effectiveness of trap-neuter-release programs . To add to these discussions on spay, neuter and animal overpopulation, Danielle Thompson, Executive Director of the Galapagos Preservation Society (GPS), shares the specific issues that the overpopulation of companion animals has caused in the Galapagos environment and community. Detailing the historical and present day causes of companion animal overpopulation, the effects of this overpopulation, and the current work and goals of GPS, Thompson provides insight into why spay and neuter is an integral part of caring for the companion animals in our lives, as well as the free-roaming cats and dogs in our communities.


Spay and neuter in the Galapagos: Cat and dog overpopulation and the work of Galapagos Preservation Society

by Danielle Thompson, Executive Director, Galapagos Preservation Society

Allison Lance first stepped foot on the Galapagos Islands twelve years ago with Sea Shepherd Conservation Society when she helped to deliver the Sirenian, a ship Sea Shepherd donated to the Galapagos National Park to capture poachers. At that time she had to maneuver carefully around iguanas basking in the sun on a rickety dock to get to shore. However, when Allison returned to the islands just a few years later, the old wooden dock had been replaced with a concrete pier and the place where iguanas once lumbered about, dogs and cats now congregated. Today, approximately, 40,000 people inhabit five islands in Galapagos along with thousands of their best friends, dogs and cats.

Humans have visited the Galapagos Islands since the 1500’s, and Ecuador has colonized the Galapagos since 1832. Then as now, humans introduced non-native species, either intentionally or accidentally. Pirates first introduced dogs and cats to the Galapagos Islands and whalers and colonists continued to bring them to the islands. [1] There is now a large free-roaming dog and cat population on the islands.

Free-roaming dogs and cats pose problems to wildlife, public health, and animal welfare in the Galapagos Islands. Introduced species, including dogs and cats, are believed to be the greatest threat to the unique biodiversity of the Galapagos via predation, competition, infectious diseases, and habitat destruction. [2] Both dogs and cats prey on lizards, small tortoises, iguanas and birds. Cats are habitual hunters, catching a high number of native birds and destroying their nests and hatchlings. [3], [4], [5] In addition to preying on wildlife, dogs and cats spread diseases that can affect human health as well as the health of endemic wildlife. Finally, stray and free-roaming dogs and cats suffer a host of problems, including lack of adequate food; water, shelter and veterinary care for injuries and disease.

The eradication of cats and dogs from the Galapagos Islands is challenging. Unlike other introduced animals, cats and dogs are considered companion animals in human-populated areas. [6] Not only do people live with dogs and cats as companions, they also use dogs for guarding property and hunting. Additionally, residents breed dogs and cats and sell the puppies and kittens. Currently, there is no law mandating sterilization or prohibiting breeding.

After Allison found out about the suffering of dogs and cats in Galapagos and the problems they were posing to wildlife, she knew something had to be done. She began working with a group to spay and neuter dogs and cats on the islands. Through that work she realized that while sterilization was essential to stemming the tide of animals, the dogs and cats left to wander the streets after the campaign ended continued to prey on wildlife for the remainder of their lives and thus posed a major threat to the biological diversity of the islands. While there is no shortage of environmental organizations working in Galapagos, only a few groups focused solely on the issues of cats and dogs.

Allison founded Galapagos Preservation Society in 2008 to conserve the fragile island ecosystem of the Galapagos Islands, protect wild animals and promote animal welfare. We humanely remove and re-home dogs and cats who, abandoned by humans, often prey upon native wildlife. We work on public outreach campaigns and education programs to raise awareness about humane treatment of dogs and cats and the threat they pose to wildlife when left to roam. We also work to investigate and expose the trade in dogs and cats and educate people on the threats these animals pose to vulnerable island environments and endangered animals.

GPS envisions a future in which there are no stray or free-roaming dogs and cats on any of the Galapagos Islands. GPS works for a Galapagos where all cats and dogs are cared for and are kept indoors or inside fenced areas so that they no longer pose a threat to indigenous wildlife. GPS further envisions the mandatory sterilization of all cats and dogs on every island, the prohibition of breeding dogs and cats on Galapagos as well as the strict enforcement of the law prohibiting transport of dogs and cats to the islands.

If you would like to find out more about GPS’s work and how you can help, please visit our webpage.


1. Basset, Carol Ann. 2009. Galapagos at the Crossroads: Pirates, Biologists, Tourists, and Creationists Battle for Darwin's Cradle of Evolution. Washington, D.C.: National Geographic Society.

2. Kaiser J. 2001. “Galapagos takes aim at alien invaders.” Science: 293:590–592.

3. Kruuk H and Snell H. 1981. “Prey selection by feral dogs from a population of marine iguanas (Amblyrhynchus cristatus).” J Appl Ecol:18:197–204.

4. Konecny MJ. 1987. “Food habits and energetics of feral house cats in the Galapagos Islands.” Oikos: 50:24–32.

5. Inter-institutional Committee for the Management and Control of Introduced Species (CIMEI). What is an introduced species? [updated unknown; cited 1 Sept. 2010]. Available from

6. Galapagos National Park. Control and eradication of feral cats (Felis catus). [updated 29 June 2009; cited 1 Sept. 2010]. Available from


Danielle grew up in the midwest on the shores of Lake Michigan. In kindergarten she mounted a campaign to save the ants from being squashed and has since worked for human rights, promoted veganism, informed people about cruel and toxic dolphin meat in Japan, campaigned for both farmed and wild animals and most recently helped to sterilize nearly 200 dogs and cats in the Galapagos Islands with Animal Balance. She studied political science and philosophy at the University of Wisconsin and animal and environmental law at Lewis and Clark Law School. She was thrilled to join Galapagos Preservation Society and work to protect both wild native animals and dogs and cats in fragile island eco-systems. Danielle likes to spend her time outdoors and surrounded by animals. To this day she is uneasy when she isn’t living near water.

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