island conservation preventing extinctions azores bullfinch

Invasive Plants Imperil Azores Bullfinch

On the São Miguel Island in the Azores Archipelago, Portugal, the Azores Bullfinch and other native flora and fauna are threatened by invasive plants. Fortunately, there is still hope.

Island species around the world are threatened by invasive plants, which alter the balance of specialized island ecosystems. When a non-native plant enters the ecosystem and begins to flourish, it can drastically affect the species interactions on the island, negatively impacting native flora and fauna alike. The Azores Bullfinch is one example of an island species that has been especially hard-hit by invasive plants.

The Azores Bullfinch, a small island bird endemic to the São Miguel Island in the Azores Archipelago, Portugal, was once so common that it was actually considered a pest. However, the Azores Bullfinches are now confined to a small fragmented forest in the mountainous portion of the island due to invasive plants. Azucena de la Cruz, LIFE Terras do Priolo Project Assistant at SPEA (BirdLife in Portugal) explains:

Plants were introduced into the Azores archipelago for various purposes, mainly ornamental and agricultural…Some of those species became invasive and presently cover large areas of the island. Today, more than 60 per cent of the vascular flora of the Azores is considered exotic.

For the Azores Bullfinch this is a particularly serious issue due to their specific feeding habits. The species has evolved to eat what was historically abundant in a given season—such as flower buds in the spring, seeds in summer, fruit in autumn, and fern spores in the winter. The species relies on presence of endemic plants such as Azorean Holly, Hawkbit and the nearly extinct Azorean Plum for sustenance.

The endemic species that the Azores Bullfinch relies upon have become scarce in the past century as the laurel forest has slowly been taken over by invasive plants species, which outcompete the native plants. One species in particular, the Kahili Ginger, is an invasive species that is recognized by the IUCN Invasive species Specialist Groups as one of the 100 worst invasive species in the world. It’s introduction to the Azores has resulted in destruction of 98% of the native forest.


São Miguel Island. Credit: David Stanley

Prior to conservation efforts there were fewer than 300 breeding pairs of Azores, but conservation biologist stepped up to help. Over the course of years, restoration efforts have focused on maintaining and restoring patches of habitat by removing invasive plants and planting native species. The newest step of the project is developing continuous native landscape that will allow the ecosystem to flourish. De La Cruz explains:

The problem with these patches is that invasive plants, which are dominant outside of them, are able to re-enter the area and this obliges continuous maintenance of the areas…For this reason, the building of larger continuous areas was considered necessary in order to reduce the re-entering of invasive plants.

All the work that has gone into this effort has been very beneficial to the Azores Bullfinch, which according to the 2016 IUCN Red List, has had its second downlisting in the last decade and is now considered Vulnerable. This downlisting comes about as the species gets remarkably close to the 1,000 individuals mark, but still remains under serious threat by invasive plants.

Featured photo: Azores Bullfinch perching. Credit: putneymark
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About Emily Heber

Emily is a recent graduate from UC Santa Barbara with a BS in Zoology. As a student, she discovered that she had a passion for the conservation of endangered species and their ecosystems. Her background in informal education has allowed her the opportunity to share her passion for animals with others, something she seeks to continue doing while working with the communication team. In her spare time, Emily enjoys exploring the amazing hiking trails found in Santa Cruz and tries to SCUBA dive whenever possible. Emily is excited to join the Island Conservation team and to help share the amazing work that is being done here.

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