The wildlife here has no defences, because for most of its history nothing arrived that it needed defending against. Almost everything threatening these islands now came off a boat. The reason the archipelago still works is that Ecuador has spent decades taking those things back off again, in what became the largest island restoration ever attempted — and it is worth knowing what that involved, and what is still not solved.
The main threat to Galapagos wildlife is not tourism. It is introduced species — goats, rats, cats, pigs, fire ants and invasive plants that arrived on ships and out-competed or ate animals that evolved without predators. The response has been decades of active eradication, including Project Isabela, which ran from 1997 to 2006 and removed more than 140,000 goats from over 500,000 hectares of northern Isabela, Santiago and Pinta. The problem still unsolved is Philornis downsi, an introduced parasitic fly first found here in 1997, whose larvae attack nestlings and which is implicated in the decline of the critically endangered mangrove finch. Visitors matter at the border: the $20 INGALA card process screens baggage, and fresh produce and seeds are restricted.
Everything that makes the wildlife here remarkable is the same thing that makes it vulnerable. These islands are volcanic, they rose from the sea floor, and they have never been attached to a continent. Everything living on them arrived by air, by sea, or on something else that did. Over hundreds of thousands of years, the survivors evolved in the absence of the pressures that shape mainland species.
The obvious result is the tameness that visitors come for. A mockingbird lands on your hat because nothing in its evolutionary history taught it that a large mammal is dangerous. The less obvious result is that a tortoise lays its eggs in a shallow nest with no defence against a rat, and a ground-nesting bird has no strategy for a cat.
So when a goat steps ashore, it is not simply another herbivore joining an ecosystem. It is a large, fast-breeding grazer in a place where the native vegetation never developed grazing defences and where the giant tortoises, which are slow, cannot compete for the same plants.
The list below is not exhaustive, and the status column is the part that changes — these are active programmes, not settled history.
| Introduced species | What it does | Where the response stands |
|---|---|---|
| Goats | Strip vegetation to bare ground, out-compete giant tortoises for food, and cause erosion that changes whole hillsides | Removed from northern Isabela, Santiago and Pinta under Project Isabela, 1997–2006 |
| Rats and mice | Eat eggs and hatchlings, particularly of tortoises, petrels and ground-nesting birds | Eradicated from several islands; ongoing programmes and constant reinvasion risk from shipping |
| Feral cats | Prey on hatchling tortoises, iguanas, lava lizards and birds | Controlled rather than eliminated on the inhabited islands |
| Pigs and donkeys | Pigs dig up tortoise and turtle nests; donkeys trample and graze | Removed from Santiago alongside the goat programme |
| Fire ants | Attack hatchlings and invertebrates, and displace native ant species | Localised control; no archipelago-wide solution |
| Invasive plants (blackberry, guava, quinine) | Smother the native highland scalesia forest, which is where several endemic landbirds live | Ongoing control; among the hardest problems to reverse |
| Philornis downsi | Larvae feed on nestlings in the nest, killing broods of landbirds | Unsolved. No established field-scale control |
Between 1997 and 2006, a programme called Project Isabela removed introduced grazers from northern Isabela, Santiago and Pinta — more than 140,000 goats across over 500,000 hectares, at a cost of around US$10.5 million. Santiago alone accounted for roughly 79,600 animals and northern Isabela roughly 62,900. At the time it was the largest island restoration effort ever attempted anywhere.
The techniques were not gentle and they were not simple: ground hunting, aerial work, and the use of tracked animals to locate the last survivors, because the final few percent of a population are always the hardest and leaving them means starting again in a decade.
What matters is what happened next. On Santiago, vegetation that had been grazed to the ground for over a century began to return, and with it the conditions that tortoises and land iguanas need. Restoration here is not a matter of removing a pest and declaring victory; it is removing the pressure and then waiting years to see whether the system reassembles itself. On the goat islands, it largely has.
"Guests are usually surprised by the scale of it. They arrive thinking conservation here means telling tourists not to touch the animals, and it does include that, but the real work was a decade-long operation to take a hundred and forty thousand goats off three islands. When you walk on Santiago now and see vegetation, that is not how it looked when I started in this business."
— Marcelo Guerrero, Co-Owner
A page that only reports successes is not worth trusting, so here is the one that is going badly.
Philornis downsi is a fly, introduced and first recorded in the islands in 1997. The adults are harmless. The larvae are not: they live in birds' nests and feed on the nestlings, and a heavily infested nest can lose its entire brood. Because it operates inside the nest, on chicks, it bypasses everything that makes adult Galapagos birds resilient.
It has spread across the archipelago and it is implicated in the decline of the mangrove finch, one of the rarest birds in the world, which survives in a very small area of western Isabela. Work is ongoing — nest treatment, biological control research, captive rearing of the most threatened species — but there is no established, field-scale solution. That is simply the current position, and anyone telling you otherwise is ahead of the evidence.
This is where a visitor's own trip intersects with the problem. Almost every serious introduction arrived with people or cargo, so the border is not at the shoreline — it is at the mainland airport before you board.
Your $20 INGALA transit control card is issued as part of a process that includes screening baggage for organic material, and fresh produce, seeds and raw plant matter are restricted into the archipelago. There is inspection between islands too, for the same reason: a rat or a seed that reaches an island that does not have it is a new problem.
Practically: pack sealed, processed snacks rather than fresh fruit, and leave raw nuts or seeds in their shell at home. Check your boots and daypack for soil and seeds if you have been hiking on the mainland. None of this is theatre.
The tension is real and worth stating without defensiveness, given that we sell these trips for a living.
On the harmful side, more people means more flights, more cargo, more demand for imported goods, and more pathways for something to arrive. Population growth on the inhabited islands and the shipping that supports it are a larger pressure than guided visitors on itineraries are.
On the other side, park entry fees fund management directly, the guiding requirement and the site quotas keep visitor impact concentrated and supervised, and a visiting public that understands the place is where political support for protecting it comes from. Those are genuine, and they do not cancel the first list.
We are not the right people to settle that for you. What we can say is that the rules constraining your trip — the guide, the trail, the distance, the hours — exist because the alternative was tried elsewhere and did not go well.
Every rule on a Galapagos itinerary has a reason attached, and knowing the reason makes them easier to keep.
"The assumption I correct most often is that tourism is the main threat. It is a pressure, and we should be straight about that. But the animals that were actually disappearing were disappearing because of goats, rats and cats, and the fly that is threatening the finches now arrived on cargo, not on a cruise. If you want to know what your visit does, look at where the park fee goes."
— Evelyn Duran, Co-Owner
Introduced species, first and foremost — goats, rats, cats, pigs, fire ants and invasive plants that arrived with people and preyed on or out-competed animals that evolved with no defences. Population growth on the inhabited islands and the shipping that supplies them are the pathways that keep bringing new arrivals. Climate variability and illegal fishing pressure sit alongside those.
The mammals are the ones people know: goats, rats, mice, feral cats, pigs and donkeys. The plants are arguably harder to reverse, particularly blackberry, guava and quinine, which smother the native highland forest. And Philornis downsi, an introduced parasitic fly, is currently the most serious threat to Galapagos landbirds.
They strip vegetation to bare ground, out-compete giant tortoises for the same plants, and cause erosion that changes entire hillsides. They also breed fast. On Santiago and northern Isabela the damage ran for over a century before Project Isabela removed more than 140,000 of them between 1997 and 2006.
Fresh produce, seeds and raw plant matter are restricted, and baggage is screened at the mainland airport as part of the INGALA transit card process. Sealed, processed food generally travels; fresh fruit and raw nuts in the shell do not. There is inspection between islands too, so the same applies once you are there.
It is a pressure and also a funding source, and both are true at once. Guided itineraries with site quotas concentrate and supervise visitor impact; park entry fees pay for management. The larger pressures come from resident population growth and the shipping that supports it. We sell these trips, so weigh our view accordingly.
Active eradication of introduced mammals, control programmes for invasive plants, captive breeding and repatriation of tortoises, biosecurity screening at the ports and airports, and research into controlling Philornis downsi. Project Isabela, which cleared goats from three islands between 1997 and 2006, remains the largest island restoration attempted anywhere.
An introduced parasitic fly, first recorded in the islands in 1997. The adults are harmless but the larvae live in birds' nests and feed on nestlings, and a badly infested nest can lose its whole brood. It has been implicated in the decline of the critically endangered mangrove finch. There is no established field-scale control for it yet.
Come and see what the work protected. Tell us your dates and what you most want to see, and we will build the trip around it — including the highland forest and the tortoise reserves, which are where the restoration story is most visible.
Talk with an expert insider: USA & Canada 1-773-280-9571 · Ecuador +593-987-004-404 · [email protected]
Read more: conservation efforts in the Galapagos, the marine reserve expansion, and the Galapagos giant tortoise.
