Collared parakeets grow to around 40 centimeters long, of which the tail makes up about half. At up to 140 grams, they weigh about as much as a blackbird. Adult male collared parakeets have a "collar" that begins in black on the front and changes to a pink to orange-red stripe towards the neck. Young birds and females lack this marking. The plumage of both sexes is predominantly bright green in color. Seen from below, yellow-green tones predominate in the plumage. The upper beak contrasts with the green plumage with a strong shade of red.

The collared parakeet is a very agile flyer and climbs well. It uses its beak as a versatile, powerful tool. Parakeets feed mainly on plant parts and eat ripe fruit as well as seeds, nuts, flowers and buds. When foraging, they can form groups. The appearance in groups can be observed particularly on the flight to and from the roost tree. Several hundred individuals gather on roosting trees in order to be protected from predators at night. Collared parakeets maintain contact with conspecifics through soft and loud calls and powerful cries.

At 48 to 62 centimetres in length, the Alexander's parakeet is considerably larger than the collared parakeet. A definite distinguishing feature is the brown-red shoulder patch that adult Alexander's parakeets have. It is somewhat less pronounced in the female birds.

The first open-air breeding of the collared parakeet was documented here as early as 1975. The first breeding pair of the Alexander's parakeet, which is also found in Wiesbaden today with significantly fewer individuals, followed in 1987.

The original home of the collared parakeet is Africa and southern Asia from India to Vietnam. They have been imported to Central Europe since ancient times and kept in private hands, menageries and zoos. Today's wild European collared parakeets are the descendants of captive refugees that have been released into the wild in several places since the late 1960s and have been able to settle permanently.

The collared parakeets have been observed and counted by volunteer birdwatchers since 1975. Since 2019, collared parakeets and Alexander's parakeets have been recorded by parrot expert Detlev Franz, bird conservation officer Oliver Weirich and the Wiesbaden/Rheingau-Taunus-Kreis working group of the Hessian Society for Ornithology and Nature Conservation (HGON) as part of the Germany-wide parrot monitoring program. This is done when the birds fly into the known communal roosts.

Collared parakeets
The results of the collar-banded parakeet counts fluctuate, but overall show a clear upward trend from around 2,500 individuals in 2019 and 2020 to around 4,800 individuals in 2024 (Fig. 1). While a counting error of no more than +/- 10 % is assumed for the years 2019 to 2022, this could be somewhat greater from 2023 onwards due to new roost trees that are difficult to record.

It is unclear to what extent an increase in numbers at the roost also means an increase in the number of parakeets breeding and foraging in Wiesbaden. Long-term data show that the number of parakeets at communal roosts increases every year until the beginning/mid-July and then falls again. The explanation for this is that some of the parakeets no longer spend the night at communal roosts from mid-July onwards, but spend the night elsewhere, either singly or in small groups. The fluctuating count results from 2019 to 2024 can probably be explained in part by the fact that the ideal time for the most complete count possible was hit at different times. While only roosts in Wiesbaden were known in the entire Rhine-Main region in 2019, roosts in Frankfurt, Hattenheim and Mainz have been added in the meantime. Fluctuations in the number of individuals recorded in Wiesbaden are probably also due to parakeets moving between these roosts. In particular, movements between Wiesbaden and Mainz are likely due to their proximity. Due to different responsibilities, the Mainz roost was only surveyed in 2020 and 2021 and never on the same day as the Wiesbaden roosts. In 2021, around 5,800 parakeets were counted in Mainz and Wiesbaden together, around 1,000 more than in the record year of 2024 in Wiesbaden. The expansion of the collared parakeets from Wiesbaden to other parts of the Rhine-Main region described above could indicate that the capacity in Wiesbaden has almost been reached after 49 years of population growth and that the number of individuals breeding and foraging here is no longer increasing as much as before.

Alexander's parakeets
The number of Alexander's parakeets recorded at the roost increased from around 300 to around 1,000 between 2019 and 2024 (Fig. 2). A counting error of less than +/- 10 % can be assumed for the years 2019 to 2023. In 2024, however, the Alexander's parakeets were scattered across a large number of trees, making a complete count impossible. The numbers of Alexander's parakeets fluctuate because they can turn up at their communal roosts much more incompletely than the collared parakeets. In contrast to the collared parakeets, only the communal roost in Wiesbaden is currently known for the Alexander's parakeets in the Rhine-Main region, so that changes between different large communal roosts should not be an explanation for fluctuating numbers. A sustained upward trend and at least around 1,000 individuals can be assumed for the Alexander's parakeets. This is also supported by the observation that the number of Alexander's parakeets has increased in the optimal habitats and that the collared parakeets have been increasingly displaced here.

The fact that Wiesbaden has become the parakeet capital of the Rhine-Main region is partly due to the fact that they were released here in the 1970s and are loyal to their habitat. With its mild climate and the diverse, sometimes old and exotic tree population in the parks and cemeteries, Wiesbaden offers a good availability of food, roosting places and breeding cavities. German parks are very similar to the urban habitats preferred by parakeets in India in terms of the distribution of trees and the alternation of open areas and trees. There, too, they live in residential and inner-city areas.

The parakeets use all parts of the city that have suitable parks with old trees, cemeteries or suitable gardens. The best observation opportunities can be found in Biebrich Palace Park, the spa gardens and the rear spa facilities. For several decades, the parakeets have also been flying across the city and state borders, following daily flight routes from the roosting tree to the breeding territory, for example to Eltville, Ingelheim or Gustavsburg and back.

Some bird and nature conservationists are critical of the spread of these alien species, as their establishment could at first glance lead to the displacement of native cave-nesting birds such as woodpeckers, nuthatches, jackdaws, stock doves or starlings or bats living in tree caves. However, the data available to date does not show any damage to native animal populations.

One argument against competition with woodpeckers, for example, is that the woodpecker species in question, with the exception of the green woodpecker, generally build their new cavities every year and parakeets have already occupied their breeding cavities at this point. The male parakeets have to present the females with several cavities, one of which they accept in the end. In practice, around a third of the cavities suitable for parakeets remain empty.

As the parakeets feed mainly on plants, there is no competition for the severely depleted insect populations, which have significantly reduced the breeding success of many native bird species. The Federal Agency for Nature Conservation classifies the collared parakeet and the Alexander's parakeet as alien, potentially invasive species in terms of nature conservation and has them on the observation list, i.e. they are specifically monitored in order to improve knowledge about the effects of their spread.

Based on current knowledge, they are therefore not considered invasive species and no measures are currently required to contain either species.

Parakeets reach a climatic limit in Germany. They can only be found where the growing season starts early. In regions that are too cold, there is not enough food available during the breeding season. As a result, parakeets have only been able to settle permanently in the warm river valleys of the Rhine, Main and Neckar. However, these climatic restrictions on their range will become less and less important as global warming progresses.

Settlements are almost exclusively in highly man-made habitats such as city parks, old cemeteries or old tree-rich gardens, in which tree species that do not originally occur here predominate. About half of the food plants of the collared parakeets are alien.

The beech and mixed beech forests around Wiesbaden, for example, are unsuitable for parakeets as they lack a year-round food supply. This also applies to the remnants of alluvial forest along the Rhine, which would be unsuitable for parakeets if they were not close to cultivated landscapes.

The food supply during the breeding season and the availability of nesting cavities are the most likely factors limiting the population density of parakeets in Central European cities. Natural hunters of parakeets are sparrowhawks, goshawks, peregrine falcons, tree falcons, large owls, martens and domestic cats. Parakeets are regularly found in the prey remains of peregrine falcons breeding on the Marktkirche. Other causes of death include pathogens and accidents. The loss of young birds after fledging, for example due to exhaustion, failure to re-fly after landing on the ground or broken wings, is also high among collared parakeets.

To date, there are no known health risks that can be transmitted from parakeets to humans. For example, the risk of free-ranging collared parakeets becoming infected with bird flu (avian influenza) and transmitting the virus to humans can be classified as low according to current knowledge. To date, no case of a collared parakeet infected with avian influenza is known.

It happens that collared parakeets breed not only in tree hollows but also in insulated house walls. They typically use the holes previously chopped into the insulation by great spotted woodpeckers. In Wiesbaden, it can be observed that the foliage on individual trees has been largely "nipped off" by a group of parakeets. Vital trees with no other deficiencies usually compensate for the loss of leaves within the same vegetation period by producing new shoots.

The calls and soiling caused by the birds' droppings can lead to complaints at the parakeets' roosting trees. Disturbances caused by the calls of parakeets are generally limited to the time when the birds arrive at the roost in the evening and depart in the morning. Droppings are mainly deposited in the morning before departure from the roost. In Wiesbaden, a large main roosting site for parakeets has been established on Wilhelmstraße. Spreading it out over several roosts would mean that far more people would be affected by the parakeets' calls and droppings. It therefore makes sense not to restrict the use of this roosting tree.

The legal regulations on animal, nature and species protection must always be observed with regard to parakeets. According to Section 39 (1) of the Federal Nature Conservation Act (BNatSchG), it is prohibited to deliberately disturb wild animals, to kill them without reasonable cause or to impair or destroy their habitats. Section 44 para. 1 no. 1 BNatSchG also applies to the Alexander's parakeet as a specially protected wild bird species, which states that it is prohibited to stalk, capture, injure or kill animals of this species [...].

The guiding principle of nature conservation is that action should only be taken against established neozoa (alien species) in the event of serious damage to the ecosystem. If negative influences on native species are observed, it is examined whether and which population management measures need to be taken to counteract this. The Hessian Ministry for the Environment, Climate Protection, Agriculture and Consumer Protection (HMUKLV) is responsible for this.

In order to prevent the risk of nesting in the thermal insulation of house walls, the installation of suitable nesting boxes has proven successful in several German cities. Heavy soiling of surfaces is counteracted by increased cleaning intervals.

If you intend to close or remove a nest box, please contact the Environmental Agency, Lower Nature Conservation Authority, at an early stage in order to rule out violations of applicable legal standards.