Papers by Christoph Willigalla
European Journal of Entomology, Apr 5, 2012
Urbanisation is an important cause of species extinctions. Although urban water systems are also ... more Urbanisation is an important cause of species extinctions. Although urban water systems are also highly modified, studies on aquatic or semi-aquatic organisms are rare. The aim of this study is to identify the factors that determine species richness of Odonata in 22 Central European cities and along an urban-rural gradient within six of them. With 64 indigenous species in total and an average of 33 species per city, the species richness of Odonata in Central European cities is comparatively high. A generalised linear model indicates that species richness is positively related to city area. Additional predictors are climatic variables (temperature amplitude, sunshine duration and July temperature) and the year last studied. Since most cities are usually located in areas with naturally high habitat heterogeneity, we assume that cities should be naturally rich in dragonflies. The role of city area as a surrogate for habitat and structural richness most likely explains why it is strongly associated with Odonata species richness. The relationship between species richness and the climatic variables probably reflects that Odonata species richness in Central Europe is limited by warm and sunny conditions more than by availability of water. The temporal effect (the year last studied) on species richness is likely to be a consequence of the recent increase in Mediterranean species associated with global warming. Urbanisation clearly has an adverse effect on the species diversity of Odonata. Species richness increases along a gradient from the centre of a city to the rural area and is significantly highest in rural areas. This pattern probably reflects a gradient of increasing habitat quality from the centre of cities to rural areas. Moreover, the number of water bodies is generally very low in the city centres. Based on our results, we make recommendations for increasing the abundance and number of species of dragonflies in cities.
Movement Ecology
Background Migratory insects are important for the provision of ecosystem services both at the or... more Background Migratory insects are important for the provision of ecosystem services both at the origin and destination sites but – apart from some iconic species – the migration routes of many insect species have not been assessed. Coastlines serve as a funnel where migrating animals including insects accumulate. Migratory behaviour and captures of dragonflies in bird traps suggest autumn migration of dragonflies along coastlines while the origin and regularity of this migration remain unclear. Methods Dragonfly species were caught at the bird observatory Kabli at the Baltic coast in Estonia in 2009, 2010 and 2015. For the 2015 data set, we used a stable hydrogen (H) approach to trace the potential natal origin of the migrant hawker (Aeshna mixta). Results 1079 (2009), 701 (2010) and 88 (2015) A. mixta individuals were caught during the study periods (35, 37 and 11 days in 2009, 2010 and 2015, respectively). The migration period lasted from end of August to end of September. Based on...
Aim: Recent studies suggest insect declines in parts of Europe; however, the generality of these ... more Aim: Recent studies suggest insect declines in parts of Europe; however, the generality of these trends across different taxa and regions remains unclear. Standardized data are not available to assess large-scale, long-term changes for most insect groups but opportunistic citizen science data is widespread for some. Here, we took advantage of citizen science data to investigate distributional changes of Odonata. Location: Germany Methods: We compiled over 1 million occurrence records from different regional databases. We used occupancy-detection models to account for imperfect detection and estimate annual distributions for each species during 1980–2016 within 5 x 5 km quadrants. We also compiled data on species attributes that were hypothesized to affect species' sensitivity to different drivers and related them to the changes in species' distributions. We further developed a novel approach to cluster groups of species with similar patterns of distributional change to repre...
Recent studies suggest insect declines in parts of Europe; however, the generality of these trend... more Recent studies suggest insect declines in parts of Europe; however, the generality of these trends across different taxa and regions remains unclear. Standardized data are not available to assess large-scale, long-term changes for most insect groups but opportunistic citizen science data is widespread for some taxa. We compiled over 1 million occurrence records of Odonata (dragonflies and damselflies) from different regional databases across Germany. We used occupancy-detection models to estimate annual distributional changes between 1980 and 2016 for each species. We related species attributes to changes in the species’ distributions and inferred possible drivers of change. Species showing increases were generally warm-adapted species and/or running water species while species showing decreases were cold-adapted species using standing water habitats such as bogs. We developed a novel approach using time-series clustering to identify groups of species with similar patterns of tempor...
Inhaltsübersicht Kurzfassung Abstract 1. Einleitung 2. Untersuchungsgebiet 3. Methode 4. Ergebnis... more Inhaltsübersicht Kurzfassung Abstract 1. Einleitung 2. Untersuchungsgebiet 3. Methode 4. Ergebnisse 5. Diskussion 5.1 Änderungen der Libellenzönose 5.2 Bemerkungen zu ausgewählten Arten 6. Dank 7. Literatur Kurzfassung In Jahr 2006 haben die Mitarbeiter des NABU-Projektes Biomonitoring die Libellenfauna aller Still-und Fließgewässer der Stadt Mainz untersucht. An den 18 Untersuchungsgewässern gelang der Nachweis von 36 Libellenarten. Bisher waren erst 23 Arten in Mainz bekannt. Die Mehrzahl der neu nachgewiesenen Arten kann der Gruppe der Mittelmeerarten zugeordnet werden. 2006 gelang der Nachweis von Aeshna affinis, Crocothemis erythraea, Orthetrum brunneum, Sympetrum fonscolombii und Sympetrum meridionale. Während Vorkommen der ersten vier Arten auch aus anderen Regionen Rheinland-Pfalz bekannt sind, handelt es sich beim Nachweis der Südlichen Heidelibelle um die erste Sichtbeobachtung dieser Art in Rheinland-Pfalz seit 1993. Insgesamt setzt sich die Libellenzönose der Stadt Mainz nun zu fast 60% aus mediterranen Arten zusammen. An einigen Gewässern erreichten Aeshna affinis und Crocothemis erythraea die höchsten Abundanzen unter den angetroffenen Arten. Neben den mediterranen Arten stieg auch die Anzahl der Arten der Fließgewässer. So zählen mitt-lerweile Gomphus flavipes, Gomphus vulgatissimus und Onychogomphus forcipatus zur Libellenfauna des Untersuchungsgebiets. Als Ursache für den starken Artenanstieg werden verbesserte Gewässer-und Strukturqualität des Rheins, Klimawandel und eine höhere Erfassungsintensität angenommen.
Libellen zählen wegen ihrer Farbenpracht, ihrer Flugkünste und ihrer Größe neben den Tagfaltern z... more Libellen zählen wegen ihrer Farbenpracht, ihrer Flugkünste und ihrer Größe neben den Tagfaltern zu den attraktivsten einheimischen Insekten. Durch die Bundesartenschutzverordnung sind alle Libellenarten gesetzlich geschützt. Neben Ubiquisten gibt es unter den Libellen auch ausgesprochene Spezialisten, stenöke Arten, die sehr hohe Biotopansprüche stellen und nur ausgewählte Lebensräume besiedeln. Für ihre gesamte Entwicklung benötigen Libellen sowohl aquatische als auch terrestrische Lebensräume. So wird das Larvalstadium, welches bei einzelnen Arten bis zu drei Jahren betragen kann, ausschließlich im Gewässer verbracht. Dabei sind die Larven auf gleichbleibende Umweltqualitäten, auf geeignete Nahrung, auf Versteckmöglichkeiten und sichere Schlupfhabitate angewiesen. Als adulte flugfähige Insekten sind Libellen mobil und benötigen ein größeres Biotopangebot, wobei einzelne Biotope als Jagd-, Reifungs-, Reproduktions-oder auch Schlafhabitat fungieren.
Kurzfassung In den Jahren 2008-2013 wurden an 13 ausgewählten Gewässern innerhalb des Stadtgebiet... more Kurzfassung In den Jahren 2008-2013 wurden an 13 ausgewählten Gewässern innerhalb des Stadtgebietes von Mainz Libellen kartiert. Es konnten 44 Libellenarten nachgewiesen werden, was einem Anteil von 66 % der in Rheinland-Pfalz vorkommenden 67 Arten entspricht. Chalcolestes viridis, Coenagrion puella, und Sympetrum striolatum erreichten eine Stetigkeit von über 90 %, S. sanguineum sogar von 100 %. Im Vergleich zu publizierten Daten aus 2006/07 kamen im Stadtgebiet von Mainz vier bodenständige Arten hinzu: Coenagrion scitulum, Erythromma lindenii, Lestes virens und Brachytron pratense. Als weitere Gäste konnten E. najas, Anax parthenope und Leucorrhinia pectoralis beobachtet werden. Aktuell konnten Orthetrum brunneum und Ophiogomphus cecilia nicht nachgewiesen werden. Die Zunahme der Artenzahl steht vermutlich mit aktuell klimabedingt stattfindenden Arealverschiebungen der Libellenfauna im Zusammenhang. Bemerkenswert ist jedoch, dass sowohl höhere Artenzahlen als auch höhere Stetigkei...
The Odonata fauna of the rain-storage ponds in the city of Mainz, Rhineland-Palatinate, Germany -... more The Odonata fauna of the rain-storage ponds in the city of Mainz, Rhineland-Palatinate, Germany -Between 2006 and 2008, 32 species of Odonata were recorded at twelve rain-storage ponds (RSP) in Mainz. This is 84 % of the total Odonata fauna of the city area of Mainz, which comprises 38 species in total. Twenty-two of the observed species were classified as indigenous. On average, we found between six and nine species per RSP. Therefore, beside park ponds, RSP serve as a second important habitat for dragonflies and damselflies in urban areas.
European Journal of Entomology, 2012
Urbanisation is an important cause of species extinctions. Although urban water systems are also ... more Urbanisation is an important cause of species extinctions. Although urban water systems are also highly modified, studies on aquatic or semi-aquatic organisms are rare. The aim of this study is to identify the factors that determine species richness of Odonata in 22 Central European cities and along an urban-rural gradient within six of them. With 64 indigenous species in total and an average of 33 species per city, the species richness of Odonata in Central European cities is comparatively high. A generalised linear model indicates that species richness is positively related to city area. Additional predictors are climatic variables (temperature amplitude, sunshine duration and July temperature) and the year last studied. Since most cities are usually located in areas with naturally high habitat heterogeneity, we assume that cities should be naturally rich in dragonflies. The role of city area as a surrogate for habitat and structural richness most likely explains why it is strongly associated with Odonata species richness. The relationship between species richness and the climatic variables probably reflects that Odonata species richness in Central Europe is limited by warm and sunny conditions more than by availability of water. The temporal effect (the year last studied) on species richness is likely to be a consequence of the recent increase in Mediterranean species associated with global warming. Urbanisation clearly has an adverse effect on the species diversity of Odonata. Species richness increases along a gradient from the centre of a city to the rural area and is significantly highest in rural areas. This pattern probably reflects a gradient of increasing habitat quality from the centre of cities to rural areas. Moreover, the number of water bodies is generally very low in the city centres. Based on our results, we make recommendations for increasing the abundance and number of species of dragonflies in cities.
Naturschutz und Landschaftsplanung
In the city of Münster rain storage ponds have been constructed since 1980 to temporarily store p... more In the city of Münster rain storage ponds have been constructed since 1980 to temporarily store peak flow discharge and large amounts of surface effluents. A dragonfly inventory of all rain storage ponds identified 27 species (61 % of a total of 44 species occurring in the city area of Münster), with 22 classified as (potentially) permanent settlers and five species as guests. Beside species frequently occurring at all types of water habitats of the city area a number of specialized species could be found. The earlier comprise Cercion lindenii, Erythromma najas (Red-eyed damselfly), Ischnura pumilio (scare blue-tailed damselfly) and Aeshna grandis (brown aeshna), more specialised species are Lestes dryas (scare emerald damselfly), Somatochlora metallica (brilliant emerald) and Orthetrum brunneum (southern European skimmer). The colonization depends on the one hand on light conditions and vegetation structure of the ponds, on the other side on the spatial relationship to other import...
Abstract Roosting habitats of Odonata, in particular of Ischnura elegans and Coenagrion pulchellu... more Abstract Roosting habitats of Odonata, in particular of Ischnura elegans and Coenagrion pulchellum (Odonata) – Odonates use different habitats for maturing, mating, foraging, and roosting. There is not much knowledge about the odonates’ choice of habitat for roosting at night. In our study we investigated two potential nocturnal roosting sites. We investigated whether individuals were clustering for roosting and whether there existed any preferences in the choice of the roosting site depending on the odonates’ gender. Locations of our study were an assemblage of artificial ponds at the Johannes Gutenberg-University Mainz and a lake in the nature reserve “Eich-Gimbsheimer Altrhein”, situated between Mainz and Worms. The investigation took place in June and July 2013. In the night, we found remarkably less species of Anisoptera and Zygoptera than during the day. Compared to Anisoptera, Zygoptera preferred to roost in lower positions. At both studied sites we mainly found a lot of indi...
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Papers by Christoph Willigalla