Tag: non-native species

First national assessment identifies 271 established non-native species in Türkiye, with climate change to accelerate invasiveness risks

271 established non-native species in Turkey with an increased risk of invasiveness under future climate warming scenarios.

A team of researchers, led by Dr. Ali Serhan Tarkan, has published the first nationwide assessment of established non-native species in Türkiye in the journal NeoBiota.

The study identifies 271 species that may pose significant threats to the country’s biodiversity, ecosystem functioning, and socio-economic systems, providing a crucial baseline for future conservation and biosecurity efforts.

Using a recent global database of non-native established species, the researchers initially identified 1,092 non-native species within Turkish borders. Through a rigorous review by taxonomic experts, the team filtered out native, cryptogenic, and non-established species, narrowing the focus to 271 confirmed established species.

Invasive freshwater fish (Carassius gibelio). Photo credit to: Esra Baycelebi.

Of these, marine species are by far the most prevalent, with 198 classified as strictly marine, followed by 42 terrestrial and 27 freshwater species. This trend reflects Türkiye’s extensive coastlines along the Black, Aegean, and Mediterranean seas, which offer vast ecological niches.

Furthermore, the coastal regions, characterized by dense populations, robust economies, and intensive trade networks, create multiple human-mediated pathways that can facilitate the introduction and establishment of non-native species.

Number of established species in each administrative area of Türkiye based on GBIF records. Gray areas represent administrative areas without non-native species based on GBIF. The marine area represents the Exclusive Economic Zone (extracted from Marine Regions marineregions.org, Flanders Marine Institute 2023). Credit to Tarkan et al., 2026.

The assessment also revealed a clear west-to-east gradient, with non-native species concentrated in the western part of the country and decreasing toward the east. The highest concentrations were found in Kayseri and Muğla, each hosting 37 established species, followed closely by Antalya with 34.

In terms of biogeographic distribution, nearly half of the established species originated from the Indo-Malayan realm, followed by the Australasian realm.

A significant concern raised by the researchers is the substantial impact gap in national reporting. Specifically, the majority of established non-native species in Türkiye had no reported impacts (n = 224; 83%), although this number decreased to 157 (59%) at the global scale.

Doughnut plot indicating the species by (a) impacts and (b) impact mechanisms. Credit to Tarkan et al., 2026.

While only 17% of established species currently have documented impacts within Türkiye, 41% of these same species are known to cause impact elsewhere.

These findings suggest that many species in Türkiye have not yet undergone formal impact assessments. Among those with known effects, ecological and environmental damages were the most frequently cited, primarily driven by biological mechanisms such as competition, predation, and rapid growth.

The outlook for species already established in Türkiye is particularly concerning. Currently, 50% of the 62 species screened using the Aquatic Species Invasiveness Screening Kit pose a high to very high risk of invasiveness. These proportions are projected to exceed 60% under future climate warming scenarios.

Coordinated national efforts will be essential to mitigate the long-term impacts on Türkiye’s biodiversity and ecosystems.

the researchers conclude

The study therefore underscores the urgent need for systematic monitoring, improved impact assessments, and climate-informed risk management strategies.

Original source:

Tarkan AS, Yapıcı S, Kurtul I, Błońska D, Vilizzi L, Baş Sermenli H, Farooq S, Aldemir C, Uçma Uysal T, Giannetto D, Bilge G, Çiftçioğlu M, Najafi-Majd E, Aktay-Sözüer L, Kaya C, Bayçelebi E, Aydın İ, Haubrock PJ, Briski E, Soto I (2026) The first national assessment of established non-native species in Türkiye. NeoBiota 105: 297-317. https://doi.org/10.3897/neobiota.105.176362

Australian winged wētā population in Auckland increasing, posing a threat to native invertebrates

In a peer-reviewed study published in the Journal of Orthoptera Research, the insect has been traced back to its origin in Queensland.

A fearsome-looking insect commonly referred to as “winged wētā” may look like a flying wētā, but it is not a wētā at all. It belongs to the family of the raspy crickets, which is not native to New Zealand. Like all of its family members, it has the ability to secrete silk from its mouth parts, which it uses to build shelters in foliage.

A close-up photo of a brown cricket resting on a green fern leaf.
Adult male winged wētā (Pterapotrechus salomonoides) in its natural habitat. Photo by Danilo Hegg

The “winged wētā” was first detected in Auckland in 1990. Within thirty years, it had expanded its range north to Cable Bay, Northland; east to Coromandel Peninsula, and south to Raglan, Waikato. While sightings in New Zealand became more and more numerous, the insect remained unidentified. New Zealand entomologist Danilo Hegg recently travelled to Queensland, Australia, to trace the “winged wētā” back to its population of origin and put a name to the species. In a peer-reviewed study now published in the Journal of Orthoptera Research, Hegg showed that the insect originates from the montane rainforests south of Brisbane, at the border of Queensland and New South Wales.

A map of Australia and New Zealand highlighting specific locations in Queensland and New South Wales, including Brisbane, Tamborine Mountain, and Auckland.
Collection localities in New Zealand and Australia.

“The insect is heavily built, has relatively short wings, and is a poor flyer,” says Hegg. “While Australian butterflies do occasionally reach our shores carried by westerly winds, the 2,300km journey across the Tasman Sea is almost certainly too much for the winged wētā. It is highly unlikely that it would have reached New Zealand by natural means”. Australian insects carried by the wind may land anywhere between Cape Reinga and Rakiura / Stewart Island. The fact that the “winged wētā” was first detected in Auckland, New Zealand’s largest import hub, only adds weight to the hypothesis of an accidental introduction by anthropogenic means.

Not only has the “winged wētā” been expanding its range in New Zealand; it has also been building up numbers. Its population density has at least quintupled in Auckland during the past twelve years. And like many other invasive species, it appears to be found in higher numbers in its new territory than in its country of origin. “In Queensland, I could spend a night out and find one or two individuals at most. In Auckland, I was able to capture seven specimens in a two-hour walk” says Hegg.

A photo of two crickets nestled together inside curled green leaves.
Nymphs of winged wētā (Pterapotrechus salomonoides) in rolled leaves held together by silk strands

The “winged wētā” is an omnivore and an agile hunter. Strictly nocturnal, it prowls in the foliage in trees and pounces on any invertebrate that is small enough for it to tackle. Observations conducted in captivity and in the wild have shown that the “winged wētā” preys on just about anything that moves at night. Including juvenile Auckland tree wētā, one of New Zealand’s largest insects.

A close-up photo of a brown cricket resting on a green leaf and holding insect wings in its mandibles.
A winged wētā (Pterapotrechus salomonoides) Nymph with winged termite (Schedorhinotermes sp.) prey.

Given its high population density and its predatory habits, there are concerns the invasive insect could have an impact on New Zealand’s native invertebrate wildlife. “There is still a lot we don’t know” says Hegg “we need to study its diet in the wild, and we need to understand whether the winged wētā is also taking hold in intact native forest habitats, or only in urbanised areas, where the majority of the sightings are. But it poses a threat that needs to be taken seriously”.

New Zealand’s invertebrates are already being decimanted by introduced rodents, mustelids, hedgehogs, cats and wasps. The Australian winged wētā is only going to add to their woes.

Research article:

 Hegg D (2025) An Australian raspy cricket established in New Zealand, Pterapotrechus salomonoides (Orthoptera, Gryllacrididae), with notes on ecology and first description of the male. Journal of Orthoptera Research 34(1): 77-94. https://doi.org/10.3897/jor.34.134391

Invasive species as biomonitors of microplastics in freshwater ecosystems?

Microplastics forming the disproportionate amount of plastic garbage, and catfish have become numerically dominant in some ecosystems thanks to their tolerance to pollution and anoxic environments.

Armored catfish (Pterygoplicthys spp.) and microplastics, as invasive species and emerging contaminants, respectively, represent two socio-environmental problems in the globalized world, since both have negative effects on faunistic communities and freshwater habitats, as well as on rural community fisheries and public health.

Non-native invasive species of armored catfish have become numerically dominant in some ecosystems, with efforts to eradicate them a seemingly endless task. Due to this, a possible scenario of biological homogenization in Mesoamerica can be expected, mainly given by the wide dispersion of the Pterygoplichthys species, added to the introduction of other non-native catfish species.

Photo: Miguel Ángel Salcedo. Drawing: Diana Ríos-Hernández.

The omnipresence of plastics in terrestrial and aquatic environments is caused by their excessive use and inadequate management of waste. The discarded plastics are fragmented, degraded, and dissolved by solar radiation, wind, and water, among other agents, to be incorporated into the food web in aquatic environments.

Microplastics found in the digestive tract of armed catfish (Pterygoplichthys spp.)

Both persist in the aquatic environment, microplastics forming the disproportionate amount of plastic garbage, and catfish thanks to their tolerance to pollution and anoxic environments, and their ability to survive for several hours breeding atmospheric oxygen. What is the relationship between the two? Microplastics, depending on their origin and composition, are sedimented in the wetlands, where they can be ingested by detritus feeders, such as armored catfish, mainly in areas where there is runoff or discharge of liquid waste.

In this context, we ask ourselves, can armored catfish be used as biomonitors of microplastics deposited in wetlands? Taking the above into consideration, the doctoral student Gabriela Angulo-Olmos under the guidance of the researchers Nicolás Álvarez-Pliego, Alberto J. Sánchez, Rosa Florido, Miguel Ángel Salcedo, Allan K. Cruz-Ramírez and Arturo Garrido Mora from the Laboratorio de Humedales, from the División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco, decided to answer the aforementioned question based on the numerical dominance of armored catfish recorded in the aquatic ecosystems of the Metropolitan Area of Villahermosa (MAV) in the coastal plain of the Gulf of Mexico.

A) Study area; Metropolitan Area of Villahermosa. Map modified from INEGI (2021). B) La Pólvora lake (Satélite Airbus 2023).

The stomach contents of the specimens from a lake located in the MAV were reviewed and the results showed that all the specimens had consumed microfibers. This result corroborated that these organisms can ingest sedimented microplastics due to their benthophagous habits.

Microplastics. Image by Oregon State University under a CC BY-SA 2.0 license.

The use of armored catfish as a resource in the food industry has had positive results, but is still insufficient. Therefore, we propose that another option to control their populations is to subtract and use this organism to verify which are the most frequent and abundant emerging contaminants deposited in the bottoms of urban wetlands.

Research article:

Angulo-Olmos G, Alvarez-Pliego N, Sánchez AJ, Florido R, Salcedo MÁ, Garrido-Mora A, Cruz-Rámirez AK (2023) Microfibers in the gut of invasive armored catfish (Pterygoplichthys spp.) (Actinopterygii: Siluriformes: Loricariidae) in an urban lake in the floodplain of the Grijalva River basin, Mexico. Acta Ichthyologica et Piscatoria 53: 81–88. https://doi.org/10.3897/aiep.53.102643

Where did all those insects come from? Tracking the history of insect invasion in Chile

Going through centuries-old literature, researchers compiled a database of the exotic insects established in the country.

Guest blog post by Daniela N. López, Eduardo Fuentes-Contreras, Cecilia Ruiz, Sandra Ide, Sergio A. Estay

Understanding the history of non-native species arrivals to a country can shed light on the origins, pathways of introduction, and the current and future impacts of these species in a new territory. In this sense, collecting this information is important, and sometimes essential, for researchers and decision makers. However, in most cases, reconstructing this history takes a lot of work. Finding antique references is hard work. To add more complexities, changes in the taxonomy of species or groups could be frustrating as we try to track the moment when a species was referenced in the country for the first time, sometimes centuries ago. Of course, we only learned about these issues when, almost seven years ago, we thought that compiling a database for the exotic insects established in Chile would be interesting to people working on invasive species in the country.

Tremex fuscicornis caught in Chile. Photo by Sergio Estay

First, we collected information from physical and electronic books and journals available in our institutional libraries, but soon we noticed that we needed a more significant effort. In Chile, the National Library and The National Congress library allowed us to review and collect information from texts, in many cases, over a hundred years old. We also had to request information from foreign specialized libraries and bookstores. Sometimes, we had to negotiate with private collectors to buy antique books or documents. When we figured the first version of the database was ready, we began a second step for detecting errors, correcting the taxonomy, and completing the information about the reported species.

Ctenarytaina eucalypti individuals and damage in Chile. Photo by Sergio Estay

The analysis began when we finally completed the database. What types of questions could we answer using this data? Was the database complete enough to detect historical, biogeographic, and ecological patterns? Two competing hypotheses were the starting point for the study at this stage. On the one hand, the species that dominated the non-native insect assemblage could have come from original environmental conditions that matched Chile’s. Or, the pool of non-native insects arrived using pathways associated with the country’s economic activities, regardless of their origin.

We found records of almost 600 non-native insect species established in continental Chile. Most species corresponded to Hemiptera (true bugs and scales, among others) from Palaearctic origin and were linked to agriculture and forestry, as we initially hypothesized. These characteristics point to the central role of intercontinental human-mediated transport in structuring non-native insect assemblages in Chile. Non-native insect introductions began immediately after the arrival of Europeans to the central valley of Chile and have shown an enormous acceleration since 1950. Using data on the economic history of Chile, we can preliminary link this acceleration with the strong development in agriculture and forestry in Chile after World War II and the increase in intercontinental air traffic.

Exotic aphids in garden in Chile. Photo by Sergio Estay

The development and analysis of this database gave us some preliminary answers about the ecology of invasive insect species and opened the door to new questions. Also, this is a work in progress. We need the scientific community’s support to improve and correct the records, provide new reports and collect further references to support the database. Our data and analysis may be representative of other countries in South America. Similarities between our countries can facilitate using this information to manage recent introductions and prevent significant economic, social, or environmental damage.

Reference

López DN, Fuentes-Contreras E, Ruiz C, Ide S, Estay SA (2023) A bug’s tale: revealing the history, biogeography and ecological patterns of 500 years of insect invasions. NeoBiota 81: 183-197. https://doi.org/10.3897/neobiota.81.87362

How non-native tree species affect biodiversity

Non-native forest tree species can reduce native species diversity if they are planted in uniform stands, finds an international review study.

Non-native forest tree species can reduce native species diversity if they are planted in uniform stands. In contrast, the effects of introduced species on soil properties are small. This was found by an international review study with the participation of the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Curse or blessing? Opinions are divided on non-native tree species. In addition to native species, many foresters also plant non-native species that can withstand the increasing summer drought. In various parts of Europe, the latter are already important suppliers of timber. However, conservationists fear ecological damage, for example if native species are displaced or tree pathogens and insect pests are introduced.

In Switzerland, Douglas fir is partly used for afforestation. However, large pure stands, such as those found in Germany, are prohibited there. Photo by Thomas Reich

Now a team of European researchers, led by Thomas Wohlgemuth of WSL, has looked at the state of knowledge on the ecological consequences of alien tree species in Europe. They analysed the results of 103 studies on seven such species. All of these studies had investigated how stands dominated by non-native tree species affected biodiversity or soil condition under the trees compared to stands of native tree species. The organisms studied included plants, mosses, microorganisms and insects from the forest floor to the treetops.

Of the seven alien species studied, only the Douglas fir is currently planted in larger numbers in the Swiss forests. While foresters used to value its fast, straight growth and its versatile wood, today they appreciate its higher drought tolerance compared to spruce. Other species are problematic because they can spread uncontrollably. The North American Robinia, for example, is invasive and can displace native species. It was already introduced in Europe 400 years ago and used in Switzerland, among other things, to stabilise soils.

Robinia can spread rapidly and form stands as here in Valais. Photo by Thomas Reich

Negative effects on biodiversity predominate

Across the 103 studies, the consequences of non-native species for biodiversity were negative. Comparisons from 20 studies show, for example, that on average fewer insect species live on and in Douglas fir than in spruce or beech stands. Robinia also reduces the diversity of insects, eucalyptus that of birds. This is hardly surprising, says Wohlgemuth, head of the WSL Forest Dynamics Research Unit. Because: “These results apply to comparisons between pure stands.” In continuous, uniform plantations, many alien species clearly have worse impacts than native species.

Proportion of cases with increasing (green), decreasing (red) or non-significant (grey) effects of tree species non-native to Europe on diversity attributes (abundance, species richness or diversity) of different taxonomic groups in comparison to native vegetation. Numbers of cases are shown next to the NNTs names, below the diversity attributes and above the bars.

But alien species do not only have negative impacts. Most of them do not affect soil properties. The easily degradable needles of Douglas firs can even make more nutrients available than the poorly degradable spruce needles. “When it comes only to soil properties, the Douglas fir has no negative impact,” Wohlgemuth says. In general, an equal number of studies found positive and negative effects of the seven non-native species on the soil.

Douglas firs are attractive for forestry because of their fast growth, good wood properties and – in regard to climate change – their drought resistance. Photo by Thomas Reich

Furthermore, it makes a difference whether the alien species are more closely or more distantly related to European tree species. “Tree species without closer relatives, such as eucalyptus and acacia from Australia, reduce species diversity more strongly across all studies than closely related species, such as Douglas fir and wild black cherry from North America,” adds Martin Gossner, head of the WSL Forest Entomology Group and second author of the study.

A Douglas fir. Photo by Neptuul under a CC BY-SA 4.0 license

It all depends on the management

Management has a significant influence on whether Douglas fir or other tree species are good or bad for a forest overall. Uniform and dense Douglas fir stands are unsuitable habitats for many organisms. However, the same is true for spruces, which have been planted extensively for timber production in lowland areas of Central Europe over the last 100 years. On the other hand, Douglas firs in stands of native forest trees, individually or in small groups, would hardly disturb the ecosystem, Wohlgemuth says: “We conclude that the impact on native biodiversity is low with mixed-in Douglas firs.”

Should foresters plant non-native tree species or not? Despite certain negative aspects, Wohlgemuth does not recommend total renunciation. “Particularly in the case of Douglas fir, the facts show that moderate admixture in stands has little impact on native biodiversity, while at the same time preserving ecosystem services such as the production of construction timber. This is especially true when other, less drought-resistant conifers are increasingly lacking with regard to unchecked climate change.”

Research article:

Wohlgemuth T, Gossner MM, Campagnaro T, Marchante H, van Loo M, Vacchiano G, Castro-Díez P, Dobrowolska D, Gazda A, Keren S, Keserű Z, Koprowski M, La Porta N, Marozas V, Nygaard PH, Podrázský V, Puchałka R, Reisman-Berman O, Straigytė L, Ylioja T, Pötzelsberger E, Silva JS (2022) Impact of non-native tree species in Europe on soil properties and biodiversity: a review. NeoBiota 78: 45-69. https://doi.org/10.3897/neobiota.78.87022

Web news piece originally published by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. Republished with permission.

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NeoBiota invites risk analysis studies in a new Special Issue on advancements in the screening of freshwater and terrestrial non-native species

The “Recent advancements in the risk screening of freshwater and terrestrial non-native species” Special Issue in the open-access, peer-reviewed scholarly journal NeoBiota is now open for submissions. The deadline for submission is 30 April 2022, with the issue scheduled for publication in August 2022.

The “Recent advancements in the risk screening of freshwater and terrestrial non-native species” Special Issue in the open-access, peer-reviewed scholarly journal NeoBiota is now open for submissions.

The issue is managed by the international team of guest editors of Dr Daniela Giannetto (Mugla Sitki Kocman University, Turkey), Prof. Marina Piria (University of Zagreb, Croatia), Prof. Ali Serhan Tarkan (Mugla Sitki Kocman University, Turkey) and Dr Grzegorz Zięba (University of Lodz, Poland).

Update: The deadline for submission has been extended to 30 April 2022, with the issue expected to be published in August 2022. 

The new special issue is expected to collate prominent contributors from the field of invasive ecology, thereby addressing existing gaps in the knowledge about both freshwater and terrestrial non-native species and their management.

The editors note that despite the current efforts and measures to monitor and tackle the spread of non-native species, and especially those posing imminent threat to local biodiversity and ecosystems, further expansion of such populations has increasingly been recorded in recent years. Of special concern are developing countries, where legislation for controlling non-native species is still lacking.

A major problem is that – as of today – we are still missing on risk screening studies needed to provide evidence for the invasiveness potential of many non-native species across several taxonomic groups, which would then be used to support specific conservation efforts. Unfortunately, this is particularly true for species inhabiting the world’s biodiversity hotspots, point out the editors.

Risk-based identification of non-native species is an essential process to inform policy and actions for conservation and management of biodiversity. Previously published papers on risk screening of aquatic non-native species, and especially those using the most widely-employed ‘-ISK’ decision-support toolkits, have attracted mounting interest from the wider scientific community.

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Visit NeoBiota’s journal website at: https://neobiota.pensoft.net/ 

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Australia’s wish list of exotic pets

In a new study, published in the peer-reviewed open-access scholarly journal Neobiota, scientists estimated the desire of Australians to own non-native and/or illegal alien pets and the major trends in this practice. In addition, the team suggests ways to improve biosecurity awareness in the country.

Juvenile green iguanas for sale at Repticon Trading Convention 2018 in Palm Springs, Florida
Photo by Adam Toomes

Unsustainable trade of species is a major pathway for the introduction of invasive alien species at distant localities and at higher frequencies. It is also a major driver of over-exploitation of wild native populations. In a new study, published in the peer-reviewed open-access scholarly journal Neobiota, scientists estimated the desire of Australians to own non-native and/or illegal alien pets and the major trends in this practice. In addition, the team suggests ways to improve biosecurity awareness in the country.

Over the last two decades, Australia has been experiencing an increased amount of non-native incursions from species prominent in the international pet trade, such as rose-ringed parakeets, corn snakes and red-eared sliders. On many occasions, these animals are smuggled into the country only to escape or be released in the wild.

In general, the Australian regulations on international pet trade are highly stringent, in order to minimise biosecurity and conservation risks. Some highly-desirable species represent an ongoing conservation threat and biosecurity risk via the pet-release invasion pathway. However, lack of consistent surveillance of alien pets held, legally or otherwise, in Australia remains the main challenge. While there are species which are not allowed to be imported, they are legal for domestic trade within the country. Pet keepers have the capacity to legally or illegally acquire desired pets if they are not accessible through importation, and the number of such traders is unquantified.

Since keeping most of the alien pets in Australia is either illegal or not properly regulated, it is really difficult to quantify and assess the public demand for alien wildlife.

A juvenile ball python for sale at Repticon Trading Convention 2018 in Palm Springs, Florida
Photo by Adam Toomes

“We obtained records of anonymous public enquiries to the Australian Commonwealth Department of Agriculture, Water and the Environment relating to the legality of importation of various alien taxa. We aimed to investigate whether species desired in Australia were biased towards being threatened by extinction, as indicated by broader research on pet demand or towards being invasive species elsewhere, which would indicate trade-related biosecurity risks”,

shares the lead author Mr. Adam Toomes from the University of Adelaide.

According to the research team’s analysis, pets desired by Australians are significantly biased towards threatened species, invasive species and species prominent in the U.S. pet trade.

“This novel finding is of great concern for biosecurity agencies because it suggests that a filtering process is occurring where illegally smuggled animals may already be “pre-selected” to have the characteristics that are correlated with invasive species,”

warns Mr. Adam Toomes.

However, the bias towards species already traded within the U.S. suggests that there is potential to use this as a means of predicting future Australian desire, as well as the acquisition of pets driven by desire. Future research from the Invasion Science & Wildlife Ecology Group at The University of Adelaide will investigate whether Australian seizures of illegal pets can be predicted using U.S. trade data.

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Original source:

Toomes A, Stringham OC, Mitchell L, Ross JV, Cassey P (2020) Australia’s wish list of exotic pets: biosecurity and conservation implications of desired alien and illegal pet species. NeoBiota 60: 43-59. https://doi.org/10.3897/neobiota.60.51431

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Invasive parrots have varying impacts on European biodiversity, citizens and economy

The monk parakeet (Myiopsitta monachus), also known as the Quaker parrot, is another South American species, known from the temperate to subtropical regions of Argentina and neighboring countries.
Photo by ParrotNet.

Non-native parrots can cause substantial agricultural damage and threaten native biodiversity, although impacts vary strongly depending on where these parrots have been introduced. Brought to Europe as pets, escaped or released parrots have established numerous wild populations across Europe. Tens of thousands of ring-necked and monk parakeets make up the bulk of Europe’s parrots, but several more species are gaining a foothold too.

A pan-European team of researchers, conservationists, wildlife managers and policy-makers worked together under the umbrella of ParrotNet, an EU COST Action, and have reviewed the available evidence on parrot damage, concluding that measures to prevent parrots from invading new areas are paramount for limiting future harm. Their findings are published in the open-access journal NeoBiota.

The ring-necked parakeet (Psittacula krameri), also known as the rose-ringed parakeet, originates in Africa and South Asia.
Photo by ParrotNet.

Introduced parrots can damage the environment, but severe impacts remain rare and localised. So far, most reports of damage are linked to the widespread and locally abundant ring-necked and monk parakeets. Studies show that in their native ranges, both species can and regularly do inflict large crop losses, but in Europe, expectations of comparable widespread and severe damage to agriculture have so far failed to materialise.

In Europe, competition with native species presents a more serious problem, especially for ring-necked parakeets as they can compete with native species for food and breeding sites. Meanwhile, in the Americas, monk parakeets are notorious for the damage their stick nests cause to power infrastructures by catching fire, yet very little evidence for such problems exist in Europe.

Reported impacts for other parakeet species in Europe are virtually nonexistent, probably because these species have been introduced more recently and currently exist as relatively small and localised populations.

Dr Diederik Strubbe of the Terrestrial Ecology Unit, Ghent University (Belgium) elaborates:

“It was already well known that introduced parakeets can cause damage. There is the oft-cited example of a vineyard in Surrey (UK) where ring-necked parakeets caused a loss of thousands of bottles of wine. In Seville (Spain), the same parakeet species is threatening an endangered native bat population by evicting them from their roosting tree cavities. Our review of all reported impacts however shows that such severe damage is not the norm. In most cases, parakeets introduced to Europe only do limited damage and, for example, about half of the studies focusing on competition between introduced parakeets and native species explicitly report no evidence of impact.”

The study also highlights that differences in the type of damage, and the way they are reported and summarised influences the outcomes of invasive species impact assessments.

The generalised threat level that invasive species pose is often based on their worst known impacts, whilst the capabilities of a species to do damage often requires specific circumstances. While this is relevant information for identifying those invaders that can potentially have major impacts, it is not necessarily representative of the impacts the species is likely to have when introduced to a new area. Similarly, including damage reports from the native range or from other invaded ranges typically results in higher threat level estimates compared to what actually has been observed in Europe.

What can be done to mitigate parakeet impacts?

The Alexandrine parakeet (Psittacula eupatria), also known as the Alexandrine parrot, occupies a natural range that extends from Afghanistan to Vietnam, including all of India, Sri Lanka and the Andaman Islands.
Photo by ParrotNet.

Based on the results of the study, the ParrotNet members also published a ‘policy brief’, summarising and discussing the implications of their findings for policy makers and wildlife managers. Their recommendations include stricter regulation aimed at preventing parakeet introductions, rapid response when emerging populations are detected and better dissemination of information to the public about the impact parakeets can have. For example, using bird feeders that parakeets cannot access may help reduce the abundance of these birds in cities.

Prof. Jim Groombridge of the Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent (UK) comments:

“What should be done to minimise damage by invasive parakeets is ultimately up to policy-makers. But as scientists, we stress that our work again highlights that the best way to combat invasive species is to prevent their introduction and spread. Parakeet populations have already been successfully removed, for example, from islands such as the Seychelles, demonstrating that it is possible to stop them when prompt and decisive action is taken by governments. For the already established and large parakeet populations that can be found across parts of Europe, there is no ‘silver bullet’ solution to the problems they may locally pose. More applied research is needed to find cost-effective and acceptable methods to reduce parakeet impacts in those areas where they do cause damage”.

The nanday parakeet (Aratinga nenday), also known as the black-hooded parakeet, is a species native to South America.
Photo by ParrotNet.

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Original source:

White RL, Strubbe D, Dallimer M, Davies ZG, Davis AJS, Edelaar P, Groombridge J, Jackson HA, Menchetti M, Mori E, Nikolov BP, Pârâu LG, Pečnikar ZF, Pett TJ, Reino L, Tollington S, Turbé A, Shwartz A (2019) Assessing the ecological and societal impacts of alien parrots in Europe using a transparent and inclusive evidence-mapping scheme. NeoBiota 48: 45-69. https://doi.org/10.3897/neobiota.48.34222

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The ParrotNet Policy Brief can be downloaded from: https://www.kent.ac.uk/parrotnet/policybrief/.

Be prepared: Prioritising invasive species for strategic prevention in Durban, South Africa

Durban Harbour, used for both commercial and recreational purposes, is an important hub of human activity. The harbour was found to be an important point of first introduction as well as a site for naturalisation for the three species highlighted in this study.
(Photos by Şerban Procheş /left/ and Carl Munsamy /right/)

While exploring the way alien species invade cities around the world, South African PhD student Ashlyn L. Padayachee (University of KwaZulu-Natal, UKZN) and her supervisors, Serban Proches (UKZN) and John Wilson (SANBI and Stellenbosch University) remember suddenly being stricken.

What they realised was that while cities were gradually starting to prepare for climate change, their responses to invasions were rather reactive. Even though management focused on widespread invasive species, which were currently having the most negative impacts on native biodiversity, the researchers noted that if those decision makers had only targeted the next highly damaging invaders ahead of their arrival, the associated costs would have greatly decreased.

Consequently, the team developed a methodology, based on three key aspects: priority species, points of first introduction and sites of naturalisation, in order to identify the most probable and concerning invasive species for Durban (eThekwini in KwaZulu Natal), a coastal city in South Africa. Furthermore, their work, published in the open-access journal Neobiota provides decision makers from around the world with a new tool, that is easy to use and adjustable to the specificity of different cities.

Firstly, the researchers identified cities with a similar climate to Durban and used existing alien species watch lists, environmental criteria and introduction pathways to identify species, which are not present in South Africa, but are considered of unacceptable risk of invasion. The team continued by figuring out which of those selected species are likely to have pathways facilitating their introduction to the city and developed a climatic suitability model for each. Finally, the scientists linked the climate and pathway information, so that they could identify sites within Durban to be considered as a focus for the contingency planning for particular species.

As a result, the authors identified three alien species as priorities for Durban: Alligator weed (Alternanthera philoxeroides), American bullfrog (Lithobates catesbeianus) and the red imported fire ant (Solenopsis invicta).


River systems are ideal habitats for Alligator weed. River systems adjacent to points of first introduction were identified as important sites of first naturalisation of this species.
(Photo by Şerban Procheş)

In terms of points of introductions, the data highlighted the Durban Harbour, especially for the red imported fire ant. Plant nurseries and garden centres, as well as pet and aquarium shops were also identified as important sites for the three studied species. Additionally, suitable habitats located near the points of introduction, such as river systems and built infrastructure, were found in need of monitoring.


The red imported fire ant is usually found in close proximity to human dwellings, which provide ideal habitats for this species. Built infrastructure, especially those adjacent to the Durban Harbour, was identified as an important site of its naturalisation.
(Photo by Şerban Procheş)

In conclusion, the implementation of prioritisation schemes to consider the three aspects (species, pathways, and sites) allows managers to focus resources on those species which pose a greater risk of invasion and impact.

“This will only ever be one part of a broad range of biosecurity efforts, but it is one where, we believe, we can be prepared,” comment the authors.

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Original source:

Padayachee AL, Proches S, Wilson JRU (2019) Prioritising potential incursions for contingency planning: pathways, species, and sites in Durban (eThekwini), South Africa as an example. NeoBiota 47: 1-21. https://doi.org/10.3897/neobiota.47.31959