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Despite mass movements of insects being documented for decades, whether dragonflies migrate in Europe has not yet been experimentally tested. Similarly, little is known about the influence of weather on the movement decisions and intensity of dragonflies. Taking advantage of large movements of dragonflies along the Baltic Sea coast of Latvia, we investigated whether European dragonflies showed directed movements indicative of migratory behaviour and how weather influences their movements. First, we performed orientation tests with individual dragonflies of two commonly captured species,AeshnamixtaandSympetrumvulgatum, to determine whether dragonflies showed directed flight and whether flight direction differed from wind direction. BothA.mixtaandS.vulgatumdisplayed a uniform mean southward orientation, which differed from the prevailing overhead wind direction, indicating migratory behaviour. Second, we investigated the influence of weather conditions on the abundance of dragonflies captured. Differences in flight behaviour in relation to weather conditions were observed betweenA.mixtaand the two smallerSympetrumspecies (S.vulgatumandS.sanguineum). Generally, temperature, cloud cover and wind direction were the most important predictors for dragonfly abundance, with temperature positively, and cloud cover negatively, influencing abundance.Aeshna mixtaappeared to select favourable tail winds (northerlies), whereas abundance ofSympetrumincreased with more easterly winds. Our results provide important information on the influence of local weather conditions on the flight behaviour of dragonflies, as well as evidence of dragonfly migration along the Baltic coast.

Despite mass movements of dragonflies being documented for decades, the influence of weather on the movement decisions and movement intensity of dragonflies has rarely been studied. Here, we investigate the influence of local weather conditions on flight behaviour of dragonflies in Europe, taking advantage of large movements of dragonflies occurring along the Baltic Sea coast of Latvia. Firstly, we performed orientation tests with individual dragonflies of two commonly captured species, Aeshna mixta and Sympetrum vulgatum, in order to determine if dragonflies showed directed flight and whether flight direction was independent from wind direction. Aeshna mixta displayed a uniform mean southward orientation (166.7°), independent from prevailing wind directions, whereas S. vulgatum did not show a uniform orientation. Secondly, we investigated the influence of weather conditions on the abundance of dragonflies captured. Behavioural differences in relation to weather conditions were observed between A. mixta and the two smaller Sympetrum species (S. vulgatum and S. sanguineum). Generally, temperature, cloud cover and wind direction were the most important predictors for migration intensity, with temperature positively influencing abundance and cloud cover negatively influencing abundance. Aeshna mixta appeared to select favourable tailwinds (northerlies), whereas hourly abundance of Sympetrum increased with more easterly winds. Our results provide important information on the influence of local weather conditions on the flight behaviour of dragonflies, as well as evidence of migration for A. mixta and most likely some Sympetrum species along the Baltic coast.

A survey of Odonata in streams on Mount Edough, Algeria, and in Kroumiria, Tunisia, indicated strong faunistic similarities between these two areas, characterized by the presence of lotic dragonfly species with protracted larval development such as Aeshna cyanea, Boyeria irene and Onychogomphus uncatus. Climatic oscillations and marine transgressions have isolated these mountains and their North African populations in the past geological times, which have led to distinct adaptations and stenotopy in various zoological and botanical groups. These mountain forests are also a refuge for aestivating Odonata with postponed reproductive maturation like Lestes numidicus, a species new for Tunisia, Lestes barbarus, Sympecma fusca, Aeshna mixta, Sympetrum meridionale and S. striolatum. In the light of increasing human encroachment, urgent conservation efforts are needed to ensure the perpetuity of these unique habitats in North Africa and their biota.

Migrations of dragonflies in Chokpak Pass of the Western Tien Shan (42.530°N, 70.605°E) were studied using large bird traps of the Rybachy type, which proved to be very efficient for recording these insects. The obligatory southward autumn migrations were proved for Sympetrum fonscolombii and Anax parthenope, and supposed for Hemianax ephippiger, which is a rare species in this region. The autumn movement from the mountains to plains was recorded for the species characterized by seasonal vertical migrations: Sympetrum arenicolor, S. striolatum pallidum, and Aeshna mixta. The cold air fronts increase the intensity of flights.

Anisoptera were monitored or sampled regularly at lowland and nearby upland sites in northeastern Algeria during 1992 and 1993. After emerging in lowlands at about sea level in May and June, adults disappeared from lowlands and were then soon encountered in nearby hills at ca 500-1000 m a.s.l. where they aestivated in woodland for about three and a half months (Sympetrum meridionale) or more than four months (Aeshna mixta, Sympetrum striolatum). During aestivation adults foraged, gradually changed colour and achieved reproductive maturity. Aestivation ended with the onset of heavy rain in late September or early October when mature adults reappeared at lowland sites where they promptly exhibited reproductive behaviour. Although no adults marked in lowlands were recaptured in uplands, the inference that individual adults made two-way flights between lowlands and uplands is compelling. Postponed reproductive maturation in upland refuges maintains continuity of the life cycle in habitats inimical to...

The history of recording and monitoring of Odonata in Britain is briefly described. Results are then presented which suggest that the country’s Odonata fauna is currently in a period of flux, in a manner consistent with the actions of a high-level regulatory factor such as climate change. The ranges of many resident species are shifting. Leucorrhinia dubia has recently been lost from southern England, but many species are presently expanding their ranges to the north and west, some (such as Aeshna mixta and Anax imperator) with considerable speed. In addition to these changes, a number of ‘southern’ species have started to appear in Britain for the very first time. These include Lestes barbarus, Erythromma viridulum (which has now become a locally-common resident in southeast England), Anax parthenope and Crocothemis erythraea. In addition to these distributional changes, some recent trends in flight times are also discussed. Evidence indicates that many species are now emerging significantly earlier than in the past, though trends relating to the end of the flight period are less clear cut.

We present the first detailed study of the diet of Glossy Ibis (Plegadisfakmnt’IIus) in Europe, from an expanding breeding colony in Doñana, southwest Spain. In 2000, fecal samples, mainly from adults, were collected from 15 nests. In 2001, 36 regurgitates were collected, mainly from large chicks. Fecal contents were dominated by aquatic beetles (Coleoptera) and dragonfly (Odonata) larvae, which were present in 100% and 93% of samples re­ spectively. Regurgitates contained mainly aquatic beetles (41% by aggregate percent, mainly Cybisterspp.), dragon­ fly larvae (29%, mainly Sympetrum fonscolombei, Aehna mixta and Anax imperator), Sharp-ribbed Salamanders (Pleurodele, waltZ, 12%) and Carp (Cyprinus carpio, 7%). The absence of vertebrate and other hard remains from fe­ ces was presumably due to their excretion in pellets. Thus fecal analysis is not a suitable method to investigate the food of the Glossy Ibis. The results suggest that there may be no major difference in the diet of breeding adults and their chicks, and that the recent increase in numbers of this ibis in Doñana is not explained by the abundance of introduced Red-swamp Crayfish (Procambarus clarkii) in the breeding area

Previous work has suggested that dragonfly ocelli are specifically adapted to resolve horizontally extended features of the world, such as the horizon. We investigate the optical and anatomical properties of the median ocellus of Hemicordulia tau and Aeshna mixta to determine the extent to which the findings support this conclusion. Dragonfly median ocelli are shown to possess a number of remarkable properties: astigmatism arising from the elliptical shape of the lens is cancelled by the bilobed shape of the inner lens surface, interference microscopy reveals complex gradients of refractive index within the lens, the morphology of the retina results in zones of high acuity, and the eye has an exceedingly high sensitivity for a diurnal terrestrial invertebrate. It is concluded that dragonfly ocelli employ a number of simple, yet elegant, anatomical and optical strategies to ensure high sensitivity, fast transduction speed, wide fields of views and a modicum of spatial resolving power.