Non-native bird citizen-science survey reveals first results

An ongoing citizen-science initiative focused on introduced bird species across Europe has revealed its initial results.

The Introduced Bird Interaction Survey (IBISurvey) aims to assess the environmental, social, and economic effects of introduced birds in European nations. This project was developed by a group of Portuguese researchers from the University of Évora, who emphasise that reporting the behaviour of n on-native birds — such as feeding on agricultural crops and acting aggressively towards individuals from native species — is essential to determining their impacts. The project's first results were released in April as an online report.

The data collected from 30 March 2021-31 December 2023 was incorporated in the results. In almost three years, 1,481 observations were submitted by 750 participants. In 30 European countries, observations of 75 distinct non-native bird species have been made. Urban areas accounted for 51% of all recordings, with wetlands (27%) and farmlands (9%) following immediately after.

The top 10 list featured several species that are well-known to UK birders, including Ring-necked Parakeet, Egyptian Goose, Mandarin Duck and Canada Goose. There have also been frequent reports of species such as Red-billed Leiothrix and African Sacred Ibis, which are spreading throughout continental Europe.

Egyptian Goose was among the most widely reported non-native species during the survey (Nick Clayton).

The observations made by participants allowed the team of researchers to identify 1,166 interactions between non-native bird species and the environment. Two types of interactions were dominant over all others; specifically, socialisation events between non-native and native species without any aggressive behaviour represented 37% of all interactions, while sightings of non-native birds feeding on ornamental or wild plants represented 28%.

Even though only 8% of the interactions involved attacking a native species, the researchers believe that this figure shouldn't be disregarded. Aggressive events to go unreported because they typically last shorter than non-aggressive interactions. In 79 cases (90%), the victim of an aggressive interaction between a non-native bird species and another animal could be identified. Mallard, including its domestic varieties, was the most frequent target of the non-native birds' aggressive interactions, with 21 recorded observations.

Regarding interactions with plants, participants found non-native birds feeding in many trees of agricultural interest (for example loquats, cherries, almonds, oranges, figs and apples), which may indicate a lower yield in fruit production in regions with a high abundance of non-native birds. The research team emphasises the importance of submitting detailed photos or videos to improve plant species identification, especially grasses and other herbaceous plants, to validate previous observations, to distinguish between extremely similar species (for example Ring-necked Parakeet and Alexandrine Parakeets) and to spot subtle signs of aggression between individuals.

The observations sent by IBISurvey participants have allowed researchers to analyse a set of unique data of valuable importance for the conservation of ecosystems. It will be very important to continue increasing the volume of data to understand the impacts of a greater number of species or whether there are different realities in different environments or countries.

To participate in IBISurvey with your observations of non-native bird species, visit ibisurvey.uevora.pt.