Fieldwork at the Galápagos

The comeback of rare species: Floreana's ecological restoration

18. March 2025 Guest article by Sonia Kleindorfer and Lauren Common

The Floreana Island Restoration Project currently is the largest and most ambitious restoration initiative in the Galápagos archipelago. Follow the exciting fieldwork of behavioural biologist Sonia Kleindorfer and her team as they monitor and protect the diverse wildlife of Floreana Island.

Floreana Island aerial view

The Galápagos Islands have played a crucial role in shaping our understanding of life on Earth. Volcanic in origin, they formed just 3 million years ago – relatively young in geological terms. Isolated from mainland Ecuador, these islands have become a natural laboratory for studying the formation of new species. © Sonia Kleindorfer

Floreana rainforest

Harsh conditions dominate the islands, alternating between long dry spells and unpredictable bursts of abundance. This volatility fosters rapid evolutionary change, sometimes happening before your eyes. The islands continue to be a living testament to how environmental change drives evolutionary and ecological transformations. © Sonia Kleindorfer

Medium Ground Fink

Darwin’s finches exemplify one of the fastest known rates of speciation among terrestrial vertebrates, with 17 distinct species evolving in just 1.5 million years. Remarkably, none of these species are known to have gone extinct, making them a rare example of an intact adaptive radiation. © Andrew Katsis

From Pirates to Conservationists

Since 2004, we have been working on Floreana Island, home to the critically endangered Darwin's Medium Tree Finch and the Floreana ecological restoration project. Within the Galápagos archipelago, Floreana has the longest history of human settlement: it was first used as a pirate hideout in the 1600s, then as a penal colony in the 1800s, before being settled in the early 1900s. Since humans arrived, Floreana Island has experienced countless species introductions, including goats, pigs, rats and cats, and the highest percentage of native species extinctions in the Galápagos.

About 15 years ago, the Galápagos National Park began island-wide control of introduced species to protect native wildlife. Their toughest challenge – the eradication of mice, rats, and cats – began in 2023 and is ongoing, expected to take several years. Significant progress has already been made: populations of these invasive mammals has been drastically reduced. Within just the first year and a half of eradication efforts, rare species have made an impressive comeback, including the the Galápagos rail, which had not been seen on the island since 1835.

On the island of Floreana, in the south of the Galápagos archipelago, five Darwin's finch species have gone extinct in the past 100 years alone. In this video, behavioural biologist Sonia Kleindorfer explains how she and her team are bringing the extinct species back to the Galapagos Islands. Over the next ten years, they will carry out a comprehensive monitoring programme to observe how the ecological system recovers without invasive species such as rats. © University of Vienna/Communications

The Floreana ecological restoration project

conducts long-term monitoring of nesting success, behaviour, morphology, song, personality, and genetic change in Darwin’s finches on Floreana Island
studies the impact of introduced parasites and predators
monitors ecosystem-level changes in collaboration the Galapagos National Park and the University of Vienna
will reintroduce 12 locally extinct species across the next decade

More details about the project, the team & contact info

Monitoring long-term behaviour of Darwins´s finches

The Darwin’s finch team begins their day early, rising at 4:30am for a 5:30am departure. Our main highland sites are at the base of the Cerro Pajas volcano and Asilo de la Paz, with two lowland sites along the coast.

On catching days, we set up a series of mist-nets – long nets made from a thin nylon mesh – to capture finches, allowing us to take blood samples and individually mark them with identifying leg bands. This allows us to recognise individual birds across years and monitor their long-term behaviour and survival. Just yesterday, we discovered that a Medium Tree Finch we recaptured was 18 years old!

Placing a tag on the back of a Darwin’s finch

Some birds are fitted with VHF tags, enabling us to observe their movements across the landscape. We track them either on foot, using a hand-held radio telemetry ... © Sonia Kleindorfer

Track Darwin’s finch movement with the drone

... or via a drone-based receiver and antenna. By combining these methods, we can cover larger areas and collect accurate position data. © Sonia Kleindorfer

Banding and measuring a Galápagos flycatcher

Banding and measuring a Galápagos flycatcher © Lauren Common

Personality of birds influence their survival

Our team have been systematically measuring personality in the birds of Floreana for the past five years. We measure personality across five main axes: boldness, aggressiveness, activity, sociability, and exploration. Our focus is on how these traits shift over time and influence the survival and reproductive success of individual finches.

Researchers take audio recordings of birds

On days when we do not catch birds, we monitor Darwin’s finch breeding activity. Male finches build display nests and sing to attract a female. Once a male attracts a female, we conduct nest observations and record parental care behaviour. © Sonia Kleindorfer

We have maintained detailed records of all song syllable types for many years, allowing us to track annual changes in popular songs – such as which male is singing which tune and how these trends evolve over time.

Listen to the singing of three Darwin´s finch species: a Medium Tree Finch, a Small Ground Finch and a Small Tree Finch

Higher nesting success due to eradication of rats

Not all breeding attempts are successful, as invasive predators and parasites threaten the nest. Rodents, cats or smooth-billed ani prey upon eggs and chicks. The parasitic larvae of the avian vampire fly suck the blood of chicks at night.

Researschers spraying critically endangered medium tree finch nests with insecticide

To further protect the finches, we manually spray nests with insecticide and install feather dispensers treated with insecticide. Darwin’s finches collect the treated feathers to line their nests, effectively introducing the insecticide to combat the fly larvae. PhD student Barbara Kofler developed the spraying device we used. © Sonia Kleindorfer

A Galápagos flycatcher inspects a newly placed nesting material dispenser

A Galápagos flycatcher inspects a newly placed nesting material dispenser. The material dispensers are treated with insecticide and the birds collect it to line their nest – effectively combating the invasive parasitic avian vampire fly. The dispenser project is done in collaboration with Birgit Fessl and the Charles Darwin Foundation. © Sonia Kleindorfer

After lunch, we disassemble inactive nests to count the number of vampire flies. These detailed records provide valuable insights into nesting success and inform the national park authorities about prevailing threats. In the past, we observed very high rates of nest predation from rats. However, since the implementation of rodent eradication efforts, rat numbers have declined, and nesting success has soared.

Short-eared owls are tagged with GPS sensors

Between sunset and sunrise, as the Darwin’s finch team retires for the evening, the short-eared owl team is just getting started. Led by Petra Sumasgutner, the team has developed and perfected an ingenious system for capturing owls.

Short eared owl by night

Short-eared owls on Floreana Island are incredibly habituated to humans, making them unusually approachable. To date, the team has captured, banded, conducted personality tests and measured the plumage variation of over 100 owls on the Galapagos. © Petra Sumasgutner

Prior to the eradication program in 2023, the owl team also assisted in transferring 65 owls, which are now being kept on Santa Cruz Island for safekeeping while poison is used to eradicate invasive species. These owls will remain there until the rodenticide from the rodent eradication program is flushed from the ecosystem. Once it is deemed safe, these owls will be released back onto Floreana Island. Each individual will be tagged with a GPS tag and an accelerometer, allowing unprecedented insight into their survival and behaviour – including their hunting of Darwin’s finches, lizards, geckos and moths.

Ecological restorations needs backing of local community

Because we have been working on Floreana Island since 2004, it is fair to say that we have become part of the community. It is a wonderful feeling to return each year and be warmly greeted. Over the years, several community members have worked with our team, and many young residents are eager to volunteer and gain experience.

Large-scale ecological restoration takes years of planning, coordination, and securing local community engagement, representation, and participation. Being a part of the Floreana community is undoubtedly one of the greatest privileges of our careers.

Competing in the community bread eating competition on Floreana

February 12, which marks both Charles Darwin’s birthday and the day Ecuador annexed the Galápagos Islands, heralds a week of celebration on the island. During this time, everyone comes together for a festival of feasts and sporting events, our research team included. We compete vigorously, such as in the community bread eating competition. We can proudly say that we won a few of the challenges. © Sonia Kleindorfer

Visions for the future: reintroduce 12 extinct species

The Galápagos are preparing for the next phase of the restoration project, which will involve reintroducing 12 locally extinct species that still thrive on other Galápagos islands, including the Galápagos tortoise, four species of Darwin’s finch, the little vermillion flycatcher, and the Galápagos hawk. Our team's role is to monitor the ecological, behavioral, and genetic changes in the island’s bird populations following these reintroductions.

Our team returns every January through April and hopes to continue doing so for at least the next 10 years, monitoring the Darwin finches, short-eared owls, and any ecological changes following these eradication and reintroduction programs. With 20 years of baseline data, we are in a prime position to assess the impacts of this ambitious restoration effort. By tracking ecological shifts, behavioural adaptations, and genetic diversity, we aim to ensure the success of this long-term conservation initiative and contribute valuable insights for future restoration projects.

The University of Vienna is a strong partner in the Floreana Ecological Restoration Project, partnering with the community and many organisations, including the Galápagos National Park, Jocotoco, Island Conservation, Durrell Wildlife Conservation Trust, and SigFox. The restoration of Floreana is an encouraging example of what can be achieved when we work together in diverse and inclusive teams informed by science, culture, and goodwill.

Podcast with Sonia Kleindorfer (in German)

Podcast An der Quelle #3: Sonia Kleindorfer

Was wir von Graugänsen über uns selbst lernen können

Verhaltensforscherin Sonia Kleindorfer untersucht auf den Spuren von Konrad Lorenz das komplexe Sozialverhalten von Graugänsen und setzt sich erfolgreich für Biodiversität und Naturschutz ein – von Grünau bis Galapagos.

© KLF

© KLF

Sonia Kleindorfer is a leading researcher in animal behavior, exploring how individual differences in risk-taking and development influence biological fitness. Her work takes her across Austria, Australia, and the Pacific Islands (Galápagos, Fiji), with past fieldwork in Papua New Guinea and Tanzania. She is a Professor of Biology at the University of Vienna and the Director of the Konrad Lorenz Research Center for Behaviour and Cognition.

Originally from Philadelphia, she was a Professor of Animal Behaviour at Flinders University in South Australia (2002–2018). When she's not studying Darwin's finches in the Galápagos, she loves learning about the fascinating greylag goose!

© KLF

© KLF

Lauren Common is a post-doctoral researcher at the Konrad Lorenz Research Center at the University of Vienna. She has been working with Sonia Kleindorfer on Darwin’s finches since 2018, with a fascination for birds, nests and even the parasites who inhabit them. Lauren’s research focuses on avian reproductive behaviour, particularly focused on nest building, parental care and personality.

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