The beautiful demoiselle (Calopteryx virgo) is a species of damselfly belonging to the family Calopterygidae. It is found in Europe, North Africa, and Western Asia. It is often found along fast-flowing waters.
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts with
Beautiful demoiselle are distributed across all of Europe with the exception of the southwestern Iberian Peninsula, the Balearic Islands, and Iceland. In the north, it extends to the Arctic Ocean, much farther north than the banded demoiselle. Its southern populations can be found as far south as Morocco and Algeria. The eastern subspecies of C. v. japonica, found on the Japanese islands, is under debate as to whether it is a separate species. The beautiful demoiselle is mostly found in lowland locations. Regular findings come from areas up to a maximum height of 980 m above sea level; occasionally, they may be found up to 1,200 meters in altitude, such as in the Alps.
The habitat of adults corresponds to the nearby larval habitat. Unlike the adults of the banded demoiselle, beautiful demoiselle may be found in forest clearings, and very rarely on the banks of larger ponds. Trees and shrubs are used as resting places, with the beautiful demoiselle often resting on high herbaceous plants such as the large nettle (Urtica dioica).
The breeding habitats are similar to the larval habitat. They prefer cool, shady waterways, with a more or less strong current, and near-natural vegetation and bank structure. This tends to be meadow and pasture streams in the area, and rarely forest. Riparian vegetation also plays a role as a windbreak. Due to their broad wings, the beautiful demoiselle can be blown away by the wind more easily than other species of damselflies.
Males are territorial, and will perch on bankside plants and trees where they wait for females or chase passing insects, often returning to the same perch. Males can stray well away from water, and females live away from water unless laying eggs or seeking a mate.
Sexually mature beautiful demoiselles display pronounced territorial behavior, occupying territories that they defend against other males. Their defense consists mostly of threatening gestures, spreading their wings and being clearly visible. Optimal territories correspond to optimal nesting places for the females. They are characterized by an increased flow and a suitable oviposition substrate in the potential breeding sites. The size of the territories and their distance apart is dependent on the population density as well as availability of suitable habitat. Males who do not occupy a territory may stay in bankside vegetation and try to fill vacant spots. Especially when only a few males are present, territorial defense is very aggressive. With a higher number of competing males, aggression decreases significantly.
The males will defend their territories from exposed perches in the vegetation which extend over the water, sometimes on vegetation or rocks cushions amid the waters. From here they will survey their territory and perform a behaviour known as "wing lapping", where the wings are quickly flapped down and then slowly lifted. It is believed that this is mainly used for communication, however it may also help ventilate the thorax, possibly playing a role in thermoregulation.
The beautiful demoiselle is considered stenoecious due to their very narrow ecological requirements. The larvae in particular can only thrive in natural bodies of waters that have little human influence. In the largest part of their range, the species is very rare. It is completely absent in major cities and industrial centers, and even in regions with strongly pronounced agricultural use it is found only rarely. Because of this, the Red Data Book (1998) of Germany classifies it as endangered in some states, even in danger of extinction. This is the same in Austria, Switzerland and other Central European countries. The IUCN, however, considers it a species of least concern.
Several factors are known to impact the population of beaufitul damselflies is the necessity of certain aquatic plants. The eutrophication of some waters by household or agricultural wastewater has contributed to the decline of some populations. This causes an increase in algal blooms, decreasing the available oxygen in the affected waters and affecting the type of vegetation present. The new vegetation may not by accepted by the females as oviposition sites. In addition, the larvae have less to hold onto the current, and the algae and dirt particles settle into their gills restricting respiration. The algae is followed by a proliferation of weeds and ultimately a silting of water bodies.
However, natural waters with low water pollution do not guarantee a suitable habitat. Fast growing plants, such as meadowsweet (Filipendula ulmaria), the stinging nettle (Urtica dioica) or Himalayan balsam (Impatiens glandulifera), may cause the area to become overgrown. Additionally if tree growth on the waters edge results in a closed canopy, the damselflies will lack the necessary sunlight. These issues can be counteracted by regular removal of some vegetation, or even a partial thinning of trees and shrubs. In intensively used agricultural areas with regular use of manure fertilizer, a bare strip a few meters wide can prevent eutrophication of riparian areas.
