Effects of a recent volcanic eruption on the isolated population of the iconic red-billed chough in La Palma, Canary Islands.

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The effects of volcanic eruptions on ecosystems, particularly on oceanic islands, have been widely studied because of their important role in land formation, climate patterns and biological processes. Although these phenomena can lead to habitat loss, population decline and even species extinction, their effects on isolated populations, especially vertebrates, are not fully understood due to the paucity of pre-eruption data and in situ observations. Here, we assess the impact of the recent eruption of the Tajogaite volcano in La Palma, Canary Islands, on a unique population of red-billed choughs (Pyrrhocorax pyrrhocorax), an emblematic bird species that symbolises the natural heritage of the island. Pre- and post-eruption surveys showed that the eruption did not significantly affect the overall size or distribution of the population, although the number of choughs decreased after the eruption in the northern and central roosts, and increased in the southern ones. Although the eruption resulted in the release of toxic gases and ash, the observed changes in chough distribution and numbers could be attributed to environmental variability and the use of different foraging areas by individuals rather than direct effects of the volcano. The high mobility of choughs may have allowed them to avoid the negative effects of the volcano in the immediate aftermath of the eruption. Future studies are recommended to assess the long-term effects of volcanic ash on feeding habitats and the possible accumulation of contaminants, such as heavy metals, in the food chain. This will allow not only to monitor the presence of these compounds in ecosystems, but also to understand the response of this species to environmental changes and ensure its conservation.