The monk parakeet (Myiopsitta monachus) as a potential pest for agriculture in the Mediterranean basin

The monk parakeet (Myiopsitta monachus) has been introduced in the last decades to many cities in many parts of the world. For most of this time it has been restricted primarily to urban areas, but it is starting to spread to rural habitats. In its native range, the monk parakeet is considered a pest for agriculture, consuming a wide variety of crops such as grains, fruits, and vegetables. However, there is very little information about its potential role as a pest for agriculture in the areas where it is exotic. Here we conducted an experimental survey of the impact of the monk parakeet on corn in SE Spain using camera traps. The monk parakeet was the animal that produced the highest damage, being responsible for 98.6% of the time employed by all animals consuming corn. The percentage of cobs damaged ranged from 36.8 to 100% depending on the cultivar, whereas the crop loss (measured as the length of the cob consumed with respect to the total length of the cob) ranged from 17.7 to 71.1%. The results suggest that the monk parakeet may be a serious pest for agriculture in the Mediterranean basin if their populations continue growing.

Sex and Age Effects on Monk Parakeet Home-Range Variation in the Urban Habitat

Home-range size is a key aspect of space-use, and variation in home-range size and structure may have profound consequences for the potential impact of damage and control strategies for invasive species. However, knowledge on home-range structure of naturalized parrot species is very limited. The aim of this study was to quantify patterns of home-range variation according to sex and age of the monk parakeet Myiopsitta monachus, an invasive parakeet in Europe. Mean kernel home-range size was 12.4 ± 1.22 ha (range 1.7–74.1 ha; N = 73 birds). Juveniles had a larger home-range size than adults, but sexes did not differ in kernel home-range size. The mean maximum distance moved by monk parakeets was 727 ± 37.0 m (range: 150–1581 m), and it was not dependent on either the sex or age of the birds. Having a small home range is one of the conditions for the feasible eradication of an invasive species; hence, the small home range of urban monk parakeets that we report here is good news for pest managers. However, this small home-range size can limit the effectiveness of culling operations with traps or feeders with contraceptives or poison, and other alternatives, such as funnel nets or traps, should be used.

Dietary plasticity in an invasive species and implications for management: the case of the monk parakeet in a Mediterranean city

Behavioural flexibility may play a relevant role during invasion of a new habitat. A typical example of behavioural flexibility favouring invasion success refers to changes in foraging behaviour. Here we provide data on changes in the foraging strategies of monk parakeets Myiopsitta monachus over a period of 17 years (2001–2017) in Barcelona city. During this time, consumption of food on the ground increased by more than 25 % and the consumption of anthropogenic food increased by 8 %. Detailed information about the food consumed is provided. Feeding on the ground and consumption of low plants allow parakeets to reach not only anthropogenic food but also crops, thereby increasing the risk of crop damage as the invasion evolves. Early detection of damage to crops is crucial in order to prevent further harm, and makes the precautionary principle highly relevant.

Nesting innovations allow population growth in an invasive population of rose-ringed parakeets

Certain traits of recipient environments, such as the availability of limiting resources, strongly determine the establishment success and spread of non-native species. These limitations may be overcome through behavioral plasticity, allowing them to exploit alternative resources. Here, we show how a secondary cavity nester bird, the rose-ringed parakeet Psittacula krameri, innovates its nesting behavior as a response to the shortage of tree cavities for nesting in its invasive range in Tenerife (Canary Islands). We observed that some breeding pairs excavated their own nest cavities in palms, thus becoming primary cavity nester, whereas others occupied nests built with wood sticks by another invasive species, the monk parakeet Myiopsitta monachus. The use of these novel nesting strategies increased the number of breeding pairs by up to 52% over 6 years, contributing to a 128.8% increase of the whole population. Innovative nests were located at greater heights above ground and were more aggregated around conspecifics but did not result in greater breeding success than natural cavities. Occupation of monk parakeet colonies by rose-ringed parakeets also benefited the former species through a protective-nesting association against nest predators. Our results show how an invasive species innovate nesting behaviors and increase nest-site availability in the recipient environment, thus facilitating its population growth and invasion process. Potential behavioral innovations in other invasive rose-ringed parakeet populations may be overlooked, and should be considered for effective management plans.

A fine-grained analysis of a Monk parakeet (Myiopsitta monachus) nest suggests a nonhomogeneous internal structure

We report first data on the fine-grained structure (branch diameter, length and diversity) in three different sectors [core (central side), buffer (peripheral side), and nest chamber)] of a nest of Monk Parakeets (Myiopsitta monachus) from a non-native breeding site located in an urban park (Rome, central Italy). The central core sector was characterized by longer and thicker branches capable of supporting the nest. The peripheral part (buffer) was characterized by less long and less thick branches with the function of completing the structure. Branches building the nest chamber were shorter and less thick but very diversified in size, because they included both small branches supplied inside the chamber and longer branches covering it. This diversification of the internal chamber (nest chamber) could be functional to maintain stable temperatures of incubator chambers compared to large fluctuations outside the nest. The presence of leaves of herbaceous species (Hordeum leporinum) could play a bactericidal role for the nest plant material.

The Number and Distribution of Introduced and Naturalized Parrots

Parrots have been transported and traded by humans for at least the last 2000 years and this trade continues unabated today. This transport of species has involved the majority of recognized parrot species (300+ of 382 species). Inevitably, some alien species either escape captivity or are released and may establish breeding populations in the novel area. With respect to parrots, established but alien populations are becoming common in many parts of the world. In this review, we attempt to estimate the total number of parrot species introduced into the wild in non-native areas and assess how many of these have self-sustaining breeding populations. Based the public databases GAVIA, eBird, and iNaturalist, 166 species of Psittaciformes have been introduced (seen in the wild) into 120 countries or territories outside of the native range. Of these, 60 species are naturalized, and an additional 11 species are breeding in at least one country outside of their native range (86 countries or territories total). The Rose-ringed Parakeet (Psittacula krameri) and Monk Parakeet (Myiopsitta monachus) are the most widely distributed and successful of the introduced parrots, being naturalized in 47 and 26 countries or territories, respectively. Far and away, the United States and its territories support the greatest number of naturalized parrots, with 28 different species found in either the continental US, or Hawaii or Puerto Rico. Naturalized species as well as urbanized native species of parrots are likely to continue increasing in numbers and geographical range, and detailed studies are needed to both confirm species richness in each area as well mitigate potential ecological impacts and conflicts with humans.

The Role of Monk Parakeets as Nest-Site Facilitators in Their Native and Invaded Areas

While most of the knowledge on invasive species focuses on their impacts, little is known about their potential positive effects on other species. Invasive ecosystem engineers can disrupt recipient environments; however, they may also facilitate access to novel resources for native species. The monk parakeet (Myiopsitta monachus) is a worldwide invader and the only parrot that builds its own communal nests, which can be used by other species. However, the ecological effects of these interspecific interactions are barely known. We compared the role of the monk parakeet as a nest-site facilitator in different rural and urban areas, both invaded and native, across three continents and eight breeding seasons. A total of 2690 nests from 42 tenant species, mostly cavity-nesting birds, were recorded in 26% of 2595 monk parakeet nests. Rural and invaded areas showed the highest abundance and richness of tenant species. Multispecies communal nests triggered interspecific aggression between the monk parakeet host and its tenants, but also a cooperative defense against predators. Despite the positive effects for native species, monk parakeets also facilitate nesting opportunities to other non-native species and may also transmit diseases to tenants, highlighting the complexity of biotic interactions in biological invasions.

The Monk Parakeet (Myiopsitta Monachus) as a Potential Pest for Agriculture in the Mediterranean Basin

The monk parakeet (Myiopsitta monachus) has been introduced in the last decades to many cities of the Mediterranean basin. For most of this time it has been restricted primarily to urban areas, but it is starting to spread to rural habitats. It is considered a pest for agriculture in its native range, consuming a wide variety of crops such as grains, fruits, and vegetables. However, there is very little information about its potential role as a pest for agriculture in the areas where it is exotic. Here we conducted an experimental survey of the impact of the monk parakeet on corn in SE Spain using camera traps. The monk parakeet was the animal that produced the highest damage, being responsible for 98.6% of the time employed by all animals consuming kernels. The percentage of cobs damaged ranged from 36.8–100% depending on the cultivar, whereas the crop loss (measured as the length of the cob consumed with respect to the total length of the cob) ranged from 17.7–71.1%. The results suggest that the monk parakeet may be a serious pest for agriculture in the Mediterranean basin if their populations continue growing.

Leaf bathing in ring-necked parakeets Psittacula krameri

Bathing is one of the main actions birds perform as part of their preening. They may bathe in water, snow, dust, and even ants. Leaf bathing, where birds make use of water droplets on leaves to bathe, is less common. Here we describe four observations between 2017 and 2021 of ring-necked parakeets Psittacula krameri bathing on water droplets on leaves during rain.Over the past twenty years we have often seen monk parakeets Myiopsitta monachus bathing in puddles but never on leaves. The monk parakeet often forages on the ground, but ring-necked parakeets are reluctant to do so. We therefore interpret that the leaf bathing we observed in the ring-necked parakeet could be an anti-predatory strategy to avoid going down to the ground.