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Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change., Financial and logistic support were provided by GREFA, IREC, UCLM (Universidad de Castilla-La Mancha), CSIC and MITECO.

In the 19th century, Red kite (Milvus milvus) was very common and widespread in Sardinia, but in the mid-900 an important decline occurred. Since the 1970s the species has been studied more continuously, but in recent years the published data seem contradictory. In 2018-2020, authors carried out specific research to collect data on the population of the Red kite in Sardinia exploring both the historical range of the species and areas where the species was reported in the past. In 2018-2020, we estimated 10-13 breeding pairs in an area of about 3,440 km2 located in the north west of Sardinia. As regard wintering, we estimated 30-40 birds in winters 2018-2019 and 2019-2020, whereas 90-110 birds were counted in winter 2020-2021.

As the whole Palearctic steppe system, its iconic bird, the Great Bustard has also suffered from the expansion of intensive agriculture. The species now typically has stable or growing populations only in protected areas, but negative processes are still prevalent even there. In this study, we present a recent change in a part of the Natura 2000 site designated for the isolated West Pannonian population. In recent years, a total of 2.3 km Center-pivot and laterally moving linear irrigation systems have been built and 4.7 km of underground pipelines have been laid, with which more than 52% of the 1245,5 ha study area was irrigated by 2020. In comparison to 2009, when the study period has started, the sown area of autumn cereals, one of the main breeding habitats, was roughly halved and the proportion of crops unsuitable for breeding was increased. New crops requiring irrigation have emerged with a rate of 30.6% in the last year. Despite the available support, the area of alfalfa, which is the most significant breeding habitat, and is grown almost exclusively in the agri-environmental scheme, has decreased. As a result of habitat degradation, the number of Great Bustard females observed in the area in spring decreased to a small fraction of the beginning. Irrigation farming is expected to increase, as a response to the climate change, but in order to save agro-steppe habitats and their species, the adverse effects of agricultural intensification need to be urgently addressed at both local and European levels.

From 2014 to 2020, 32 black kites from various European countries were tagged with telemetry devices and tracked to study their spatiotemporal behaviour. Eleven birds which crossed the Mediterranean Sea and the Black Sea directly over large water bodies out of traditional migration routes over the Strait of Gibraltar, the Dardanelles/the Bosporus area and the east coast of the Black Sea were selected for this study. Ten birds attempted to cross the Mediterranean Sea and one attempted to cross the Black Sea. All black kites crossed the sea successfully but in one case the bird failed. The maximum water crossing length was recorded at 542 km. The average speed of the birds crossing the sea included a broad range from 27.7 to 97 kph. There was a correlation between average speed and tail-wind speed during the crossing. We conclude that the most favourable conditions for black kites when crossing large water bodies such as the Mediterranean and Black seas were sunny to partly cloudy weather with temperatures over 20 °C, the speed of the tailwind of 1.1–10.8 m/s and the air pressure over the standard value of 1013 hPa.

The European population of Black Kites of the nominate subspecies Milvus migrans migrans (Boddaert, 1783) is estimated at 81,200–109,000 pairs. The birds winter in Africa but their natal dispersal remains largely unstudied. Here, we analyze the behavior of 25 GPS-tracked Black Kites tagged from 2014 until 2018 using GPS/GSM telemetry devices from 16 nests in Bulgaria, Czech Republic, Germany and Slovakia. We calculated juvenile Black Kite post-fledging areas (PFA) using Kernel density estimations 95% (KDE95) and minimum convex polygons 95% (MCP95). Our results revealed that the average occupied PFA for juvenile birds was 2.8 km2 (range 0.006–20.1 km2) as KDE95 and 0.3 km2 (range 0.07–1.35 km2) as MCP95. Birds left PFA from 29 July to 30 August (median 12 August). Two main migration routes were used by tagged birds, namely a southwestern European route crossing the Strait of Gibraltar and a southeastern European route to Turkey and the Middle East. Migration routes which directly crossed the Mediterranean Sea to Africa from Italy and Greece were rarely used. Winter quarters were located in sub-Saharan Africa throughout the belt from Senegal and Gambia to Ethiopia. Four Black Kites remained to stay in tropical Africa during their first summer, seven birds moved north but to substantially lower altitudes (in Morocco, Spain and Turkey) then those in their natal areas. During the second year, Black Kites wintered again in the tropical part of sub-Saharan Africa, summer quarters were located north from the winter quarters, three birds stayed throughout the summer in Africa, three in south to central Europe, one in Turkey and one in northwestern Russia. One 3-year-old bird (fourth calendar year) attempted to nest but it was unsuccessful and occurred 15.6 km from the natal nest. Temporary settlement areas (TSA) were commonly used by Black Kites during migratory routes, winter and summer quarters. The average home range size of TSA was 233.8 km2 (range 0.99–852 km2) as KDE95 and 140.2 km2 (range 0.1–1054 km2) as MCP95. As usual, siblings used the same migratory routes and also shared the same winter and summer quarters. Our findings suggest that the genetic background of the migration behavior of Black Kites is strong.

Some birds of the central European population of Red Kite Milvus milvus are non-migratory and winter within their natal area, whereas others migrate to southern Europe or even to northern Africa. To determine what factors affect the area use and communal roost use by Red Kites wintering in their natal area. We studied spatiotemporal activity and factors affecting area use by Red Kites wintering in their natal area in the tripoint border area of Austria, the Czech Republic, and Slovakia, using GPS/GSM telemetry devices. We characterized home ranges used by wintering Red Kites in natal areas. Birds wintered for an average of 146 days and spent 88% of the time within temporary settlement areas (TSAs). The number of TSAs used by one Red Kite during the winter varied from 1–4 (mean ± sd = 2 ± 1); the mean (± sd) size of the home range of TSAs was 190 ± 144 km2 as a 95% minimum convex polygon, 136 ± 82 km2 as a 95% kernel density estimate, and 41 ± 34 km2 as a 50% kernel density estimate (core activity area). Age, breeding status, and percentage of forest habitat were the main factors negatively related to home range size. Winter duration and the number of TSAs were positively related to the size of the home range. Young birds (before first breeding) and males explored larger areas and used more TSAs during winter. Wintering of Red Kites in their natal area may relate to the social refuge–territory prospecting hypothesis, breeding site fidelity, wintering site fidelity, and/or mate loyalty, and this understanding could lead to better conservation of Red Kites in central Europe.

Four red kites (Milvus milvus), (siblings, RK1, RK2, RK3 and RK4) from the same nest in north-eastern Austria were tagged with telemetry (GPS/GSM/UHF) loggers on 23 June 2018 during the pulli growth stage and tracked until 5 April 2019. RK1 (female), RK2 (male), RK3 (female) and RK4 (female) occupied post-fledging areas until 1 August 2018 when they then began to migrate following a south-eastern direction. RK1 wintered in central Italy and used three temporary settlement areas (TSA). RK2 and RK3 migrated to the Croatian coast of the Adriatic Sea and returned back to winter in their natal area. They used three and two TSA, respectively. RK4 reached the Italian coast of the Tyrrhenian Sea, crossing the sea in 12 h with an average flight speed of 58.6 km·h−1). The bird flew at an average altitude of 429 m above sea level before arriving in Algeria. RK4 then crossed the neighbouring border and wintered in Tunisia. It used two TSA (one in the Czech Republic and one in Tunisia). The migration behaviour and wintering locations among these floaters with the same genetic background during natal dispersal was substantially different and supposedly influenced by various environmental factors rather than by genetics.

Predator behaviour and population numbers can be determined by many factors such as prey availability, individual and habitat characteristics, and intraspecific or interspecific factors. Using satellite telemetry, we measured home range size in 3 individuals of Red Kites (Milvus milvus) in three consecutive winters to document the pattern of spatial responses to increasing availability of its dominant prey, the Common Vole (Microtus arvalis), in the Břeclav District, Czech Republic. Starting with winter 2017/2018, we found that the home range sizes decreased in winter 2018/2019 when the index of vole population density increased from 678 burrow entrances in autumn 2017 to 1414 burrow entrances per hectare in autumn 2018. Home range sizes did not change in winter 2019/2020 in spite of the further increase in vole population density up to 6673 entrances per hectare in autumn 2019. Based on censuses at 5 communal roosts in January 2018, 2019, and 2020, we documented the pattern of numerical responses to increasing availability of voles. Numbers of wintering Red Kites did not respond to growing vole densities until they reached the highest level in autumn 2019, suggesting that the response of wintering numbers was delayed by 1 year compared to that in home range. Our study thus provides empirical support for the spatial and numerical responses of Red Kites to prey availability and suggest that these responses may differ in sensitivity to increases in vole density, being triggered at different periods of the vole population cycle.

Red Kite shows a great variability in its migration strategies: most individuals in north-eastern Europe are migrants, but there is also a growing number of sedentary individuals. Here, we tagged 49 Red Kites wintering in Spain with GPS/satellite transmitters between 2013 and 2020 to study the autumn and spring migration between the breeding or summering areas in Central Europe and the wintering quarters in Spain. In first place, differences between immatures and adults were found for spring migration. Adults began the spring migration towards the northeast in February–March while the immature individuals began to migrate significantly later and showing a wider date range (February-June). Adults also takes significantly less days to arrive at their destinations (12 ± 5 days) and cover more distance per day (134.2 ± 37.1 km/day) than immatures (19 ± 11 days and 98.9 ± 21.2 km/day). In second place, we also found differences between spring and autumn migration (excluding immatures). Spring migrations were clearly faster and with less stopovers days than autumn migrations. Autumn migration began between mid-October and late November and two different behaviours were observed: most birds made a quick migration direct to the wintering areas with only some days of stopovers, but others prolonged the migration with long stops along the route. These results highlight a great variation in the migratory movements of Red Kite, not only according to age but also between individuals and seasons. Funding for the tagging was provided by Fundación Iberdrola España, Gobierno del País Vasco, Fundación Biodiversidad, Grupo Ornitológico SEO-Monticola, FAB and Binaced townhall. NorthStar donated two GPS-GSM prototype units to deploy on Kites. J. Vidal-Mateo is supported by a FPU grant of Spanish Ministry of Education (reference FPU014/04671).

We characterized the spatiotemporal activities in winter grounds of Red Kites originated from central Europe and wintering in south-eastern Europe. We found not only Red Kites at these places but often also Black Kites Milvus migrans. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161 ± 43 SD, n = 14 cases). We usually found a number of Red Kites wintering together at winter grounds, although some Red Kites wintered alone. We found Black Kites wintering together with Red Kites at the same winter grounds in 6 out of 14 cases. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the numbers of Black Kites were lower than the numbers of Red Kites or Black Kites were wholly absent. If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for birds staying at one place through the entire winter was from 10 to 108 km2 (median 72, mean 60 ± 36 SD, n = 12 cases) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km2 (median 434, mean 466 ± 115 SD, n = 3 cases) which is substantially larger than the size of home ranges published to date for Red Kites wintering in central and south-western Europe.

Dispersal is a key process affecting the dynamic and genetic structure of populations. To increase our knowledge on first-year dispersal in the white-tailed eagle (WTE), 35 nestlings in the Czech Republic, Hungary, and Austria were equipped with GPS/GSM loggers while on the nest between 2016 and 2019. Twenty-nine individuals surviving until March 31 were used to assess post-fledging areas, first-year dispersal distance and direction, temporary settlement areas, and habitat selection. The first flight from the nest was observed between May 19 and July 8. Start of dispersal from post-fledging areas occurred between July 1 and November 14. Post-fledging areas were significantly larger in males (p = 0.001, median 1236 km2, n = 15) than females (median 139 km2, n = 12). Maximal dispersal distance ranged from 93 to 433 km from the native nest (median = 187 km) and did not correlate with Simpson’s Diversity Index computed for habitats in individual 100% minimum convex polygons (MCP). Median sizes of minimum convex polygons were 26,888 km2 for 100% MCP and 13,376 km2 for 95% MCP (n = 29). Median sizes of kernel density estimates (KDE) were 3393 km2 for 80% KDE and 1137 km2 for 50% KDE. After start of dispersal, young WTEs returned to the proximity of the parental nest for night roosting sporadically. No sex-specific differences in dispersal distance were recorded. While young individuals from the three subpopulations are likely to occur in the same area during the first year of life, future nesting site identification will enable us to assess real gene flow and the connectivity level among them. As this study has illustrated, future conservation efforts to protect young WTEs will require cross-border cooperation.

A total of 13 Red Kites Milvus milvus fitted with GPS/GSM telemetry loggers in central Europe were tracked in Serbia from 10 July 2014 until 31 March 2018. These birds remained in Serbia for 138 days (counted as number of one bird/one day stays). Red Kites occurred mostly in the Vojvodina Province (NW Serbia). They were registered most often in April and October, which corresponded to their spring and autumn migrations. It is possible that Red Kites occur in Serbia more often than formerly, and this could in future result in this threatened European raptor’s more frequently wintering and breeding within the country.

The gene mcr-1 conferring resistance to last-line antibiotic colistin has been reported globally. Here, we describe the first detection of plasmid-mediated colistin resistance in Russian wildlife, an isolate of Escherichia coli sequence type 2280 from a black kite (Milvus migrans) scavenging raptor. Whole-genome sequencing and plasmid transferability experiments revealed that mcr-1.1 was located on conjugative IncI2 plasmid pDR164 (59891 bp). Migratory black kites may contribute to the global spread of mobile colistin resistance.

The whole area of the River Danube in Vienna, with its three more or less parallel river stretches Donau, Neue Donau and Alte Donau is an important hibernating area for waterbirds. The “Alte Donau” is an intensely used recreation area. Here especially, people take an interest in birds and feed them in winter. For the inhabitants of a city, this close contact with birds has a highly social aspect, notably for children and elderly people. Nevertheless, the high number of birds has a negative impact on water quality. In the years 1997/1998 to 2000/2001 a total of 391.313 individuals were observed in the Viennese Danube area, consisting of 44 species of water birds, 6 gulls and 8 hybrid species. Most frequent during the whole investigation was the Black-Headed Gull (Larus ridibundus) with a maximum of 15.579 individuals on a single day; Mallard (Anas platyrhynchos) and Eurasian Coot (Fulica atra) dominate among the waterbirds (not counting gulls). Out of these 44 species 23 species of waterbirds, 3 gulls and one hybrid species and a total of 71.913 individuals were observed on the waterbody of the Alte Donau by regular countings during the winters from 1997/1998 to 2000/2001. The three most frequent species on the Alte Donau were the Black-headed Gull with a maximum of 5.965 individuals on a single day, followed by the Mallard and the Mute Swan.

SummaryWinter oilseed rape represents an important food source for Great Bustards. Great Bustard surveys during four consecutive winters (2005/2006–2008/2009) were used to identify characteristics of oilseed rape fields, which increase their attractiveness for the species in its West Pannonian wintering area. The study was conducted in study areas in Eastern Austria, around the Austrian–Slovakian–Hungarian border and in the Hungarian Moson Plain. To test for effects of field size and isolation of fields from other rape fields, and the distance to the nearest paved road on occurrence and abundance of Great Bustards (maximum number of birds counted in individual rape fields per winter), we calculated generalized linear mixed models (GLMMs) including all three predictor variables as fixed effects and winter as random effect for each of the three study areas. Field size most strongly affected occurrence and abundance of Great Bustards. The availability of large (>>15 ha) winter rape fields far from paved roads is recommended as a prime conservation measure to improve the quality of rape fields as foraging habitat for Great Bustards during the winter months (November–March).

At the turn of the 19-20th centuries, the Great Bustard population of the Kisalföld (Little Hungarian Plain) numbered 4000 specimens. By 1990, only about 100 individuals remained in the Hungarian and Austrian territories. Of the many possible negative factors of current times, the greatest pressure on the Great Bustard population stems from unfavorable crop structures, extensive use of intensive agricultural technologies and predation. During the past decades, we have seen a shift in nesting place locations from natural-like habitats to agrar-type habitats. This change may be explained by the more favorable structure and microclimate of this latter habitat type paralleled with greater food source availability. In order to escape this ecological trap, we have to engage in active conflict resolution that provides protection the region's Bustard population. For this very reason, the MOSON Project was founded in 1992 at the northern part of the Mosoni-Plain in the territory of Lajta-Hanság Co. Later, several Austrian regions joined the project. On these territories, out of the above mentioned 100 specimens, only 20 birds lived at the time. As the result of active habitat management of Great Bustards and coexisting small game species (mostly due to the influence of set-aside areas) as well as effective predator control (especially the Red Fox) resulted in an increase of the Great Bustard population. By the end of the 1990's, the population grew to 120-130 individuals which number was limited by the carrying capacity of this territory. Consequently, the species continued to reoccupy new regions in the Hungarian and Austrian territories. These days, the number of Great Bustards in these protected regions is estimated to be 400 individuals. In 1998, the Mosoni-plain was given IBA (HU-001) status, and in 2004, the region was protected under the Natura 2000 EU nature conservation network.

The genetic diversity, population structure and gene flow of the Great Bustards (Otis tarda) living in Austria-Slovakia-West Hungary (West-Pannonian region), one of the few populations of this globally threatened species that survives across the Palaearctic, has been assessed for the first time in this study. Fourteen recently developed microsatellite loci identified one single population in the study area, with high values of genetic diversity and gene flow between two different genetic subunits. One of these subunits (Heideboden) was recognized as a priority for conservation, as it could be crucial to maintain connectivity with the central Hungarian population and thus contribute to keeping contemporary genetic diversity. Current conservation efforts have been successful in saving this threatened population from extinction two decades ago, and should continue to guarantee its future survival., Partial funding was provided by project CGL2012/36345 from the Spanish Directorate General for Scientific Research.

SummaryCollisions with power lines represent an important mortality factor for Great Bustards Otis tarda throughout the distribution range of the species. This study evaluates the success of two conservation measures implemented in the West-Pannonian distribution range to reduce the number of power line collision casualties: (1) extensive underground cabling of 43.1 km power lines, and (2) marking of 89.7 km power lines starting in 2005 and 2006, respectively. The mortality rate of Great Bustards in our study area (covering 686.5 km2) decreased significantly between 2002 and 2011, predominantly caused by reduced mortality due to power line collisions. Univariate tests indicate that underground cabling and power line marking significantly decreased power line collision casualties. Generalised linear models (GLMs) highlighted the prominent effect of underground cabling. Our results indicate that five years after underground cabling and marking of power lines within core areas of the West-Pannonian distribution range of the Great Bustard, the population already benefited through a significantly decreased mortality rate. Both conservation measures most likely contributed strongly to the rapid recovery of the West-Pannonian Great Bustard population observed within the last decade.

SummaryFlight directions of Great Bustards Otis tarda after take-off were used to analyse effects of power lines on spatial movements of this highly endangered bird species. Data on flight directions came from Great Bustard observations conducted in eastern Austria (northern and eastern parts of Lower Austria, northern part of Burgenland), western Slovakia and western Hungary. Flight directions were determined by a constructed line connecting take-off site and the bird’s position after a flown distance of 100 m. Up to a distance of 800 m from the nearest power line, mean flight direction of Great Bustards after take-off deviated significantly from a random distribution. The mean flight direction angles clearly indicate that take-off flight routes point away from power lines at an angle of approximately 180°. Furthermore, flight directions of bustards still deviated from a random distribution in two 200-m distance bands much further away from power lines (> 1,200–1,400 m, > 1,400–1,600 m), possibly suggesting that even at larger distances from power lines flight directions might still be affected by such artificial linear landscape structures. With increasing distance to nearest power lines, mean vector length r values of flight paths decrease significantly, while circular standard deviations S values increase significantly. Very similar results were achieved independently if all data were pooled or analysed separately for individual study areas for which the number of flight observations was large enough to conduct reliable analyses. Our study reports a strong effect of power lines on the flight behaviour of Great Bustards, at least up to a distance of 800 m, perhaps even up to 1,600 m. Although this may significantly reduce the risk of collision with power lines it most likely has severe consequences for the spatial movements of birds within the entire landscape and between potentially suitable breeding and foraging habitats.

The Lobau, a former floodplain area of the Danube River situated within the city limits of Vienna (Austria), was strongly affected by the river regulation in 1875. The reduced hydrological connectivity led to an increasing loss of aquatic habitats. A water enhancement scheme with a maximum water input of 0.5 m3 s−1 was initiated in 2001. The present study assesses the effect of this scheme on biodiversity using three target species groups – aquatic molluscs, dragonflies and fish – following a common Before–After Control-Impact design (BACI). Dragonflies and molluscs were positively affected, reflecting the habitat alterations in the system. For fish, no significant impact was observed. The aim of the scheme has been achieved: increased habitat diversity and improved habitat conditions for the system's initial community and further rheophilic/rheotolerant species. Water enhancement schemes can be effective remediation measures and deserve further attention in the management of urban wetlands.

Diazodiphenylmethane (DDM) undergoes cycloadditions to 1-substituted buta-1,3-dienes exclusively at the C(3)C(4) bond. At room temperature, the N2 loss from the initially formed 4,5-dihydro-3H-pyrazoles 2 is faster than the cycloaddition and furnishes the vinylcyclopropane derivatives 7 and 9 with structural retention at the C(1)C(2) bond. 2-Substituted butadienes react with DDM at the C(3)C(4) bond to give 12; isoprene, however, affords 3,4/1,2 products in the ratio of 86 : 14. DDM is a nucleophilic 1,3-dipole: 1-Cyanobutadiene reacts 400 times faster than 1-methoxybuta-1,3-diene (DMF, 40°). The log k2 for the additions to six 1-substituted butadienes show a linear correlation with σp (Hammett) and ϱ=+2.9; the log k2 of five 2-substituted butadienes are linearly related to Taft's σI (ϱ=+1.7). The structures of the vinylcyclopropanes 7, 9, and 12 are established by NMR spectra and oxidation. A cyclopropyl carbinyl cation is made responsible for the isomerization of 12, R=Ph, Me, by acetic acid to 4-substituted 1,1-diphenylpenta-1,3-dienes 25 and 29; TsOH at 200° converts 25 further to 9,10-dihydro-9-methyl-10-phenyl-9,10-ethanoanthracene (27). Thermal rearrangement of 7, 9, and 12 at 200–300° produces the 3- or 1-substituted 4,4-diphenylcyclopentenes 30 and 31. These give the same mass spectra as the vinylcyclopropanes, and an open-chain distonic radical cation is suggested as common intermediate. Besides spectroscopic evidence for the cyclopentene structures, hydrogenation and epoxidation are described; NMR data support the trans-attack by perbenzoic acid.

1. The ecological status of floodplain areas along the Austrian section of the Danube was assessed by an approach based on dragonfly surveys. Although this river section contains a relatively high portion of the river-type-specific alluvial floodplain areas, most of them are influenced by river regulation and damming. 2. A key element of the assessment procedure, which is oriented towards the new EC Water Framework Directive, is the Odonate Habitat Index. 3. Classification of ecological status is based on the comparison between the status quo and reference conditions derived from a historical situation minimally influenced by human activities. 4. Data from 408 sites from 14 investigation areas were used. Ten of the 14 areas were ranked in class II (‘good ecological status’) within the five-tiered system, which is the level of ecological status targeted in the directive. One area corresponds to the reference condition (class I, ‘high ecological status’), and three areas do not meet the quality objective (class III, ‘moderate ecological status’). A total of 49 species were found along the whole section, which represents 82% of the river-type-specific reference list. Copyright © 2003 John Wiley & Sons, Ltd.

Benzonitril-[4-nitro-benzylid] und 4-Nitro-benzonitril-benzylid, die aus den Imidoylchloriden 1 und 11 durch 1.3-Eliminierung von HCl mit Triathylamin freigesetzt werden, vereinigen sich leicht mit Benzaldehyd oder Mesoxalsaure-diathylester, die aktive Dipolarophile sind. Die Einstellung des Tautomeriegleichgewichts 1 ⇋ 11 wird dabei unterdruckt. Aus der Cycloaddition mit Benzaldehyd gehen Paare stereoisomerer Δ3-Oxazoline hervor, einer einheitlichen Additionsrichtung entsprechend. An Mesoxalsaureester lagern sich dagegen die Nitril-ylide in beiden moglichen Richtungen an, wobei Δ2- und Δ3-Oxazoline entstehen. Die Bildung zweier Oxazol-Derivate aus den Nitril-yliden und Benzoylchlorid kann durch Cycloaddition uber Chlor-dihydrooxazole oder uber Benzoyl-nitril-ylide durch 1.5-Dipolare Cyclisierung stattfinden. 1.3-Dipolar Cycloadditions, 63. The Addition of Aromatic Nitrile Ylides to Carbonyl Compounds Benzonitrile 4-nitrobenzylide and 4-nitrobenzonitrile benzylide, generated from the imidoyl chlorides 1 and 11 by 1.3-elimination of HCl with triethylamine, combine smoothly with benzaldehyde or diethyl mesoxalate, which are active dipolarophiles. The tautomerization 1 ⇋ 11 is suppressed. The regiospecific cycloaddition to benzaldehyde results in pairs of stereoisomeric 3-oxazolines. In contrast, the nitrile ylides add to mesoxalic ester in both possible directions to furnish 2- and 3-oxazolines. The formation of two oxazole derivatives from the afore-mentioned nitrile ylides and benzoyl chloride is explainable by cycloaddition via chloro-dihydrooxazoles, but can also be explained by 1.5-dipolar cyclization of benzoylated nitrile ylides.

Die Cycloaddukte des Benzonitril-[4-nitro-benzylids] (2) an die CN-Dreifachbindung (Cyanameisensaureester, Aryl-cyanat), die CN-Doppelbindung (N-Benzyliden-methylamin) und die CS-Doppelbindung (Dithiobenzoesaureester, Thionbenzoesaureester, Trithiokohlensaureester, Thionkohlensaureester) werden strukturell gesichert. Der Anlagerung an Nitrosobenzol folgt eine Cycloreversion zu Nitron – Nitril. Die bei den Nitril-ylid-Cycloadditionen beobachteten Orientierungen werden mit denen des Diphenylnitrilimins und der Diazoalkane verglichen. 1.3-Dipolar Cycloadditions, 64. Further Reactions of Nitrile Ylides with Hetero-multiple Bonds The products from cycloaddition of benzonitrile 4-nitrobenzylide (2) to the CN triple bond (ethyl cyanoformate, aryl cyanate), the CN double bond (benzylidenemethylamine) and the CS double bond (methyl dithiobenzoate and thionbenzoate, trithiocarbonic and thioncarbonicester) were structurally elucidated. The addition to nitrosobenzene is followed by a cycloreversion to give nitrone – nitrile. Nitrile ylides, nitrile imines and diazoalkanes are compared in their directions of cycloaddition.

N-[4-Nitro-benzyl]-benzimidoylchlorid (2) und 4-Nitro-N-benzyl-benzimidoylchlorid (4) bilden in Gegenwart von Triathylamin in Benzol ein 92 : 8-Tautomerie-Gleichgewicht. Bei tiefer Temperatur im dipolar-aprotischen Solvens werden 2 und 4 mit Triathylamin zu blauen Carbanionen deprotoniert. Die Tautomerie 2 ⇋ 4 wird uber α-Chloralkyl-azomethine vermittelt, die im Gleichgewicht zu 8–10% auftreten und bei Hydrolyse Benzaldehyd und 4-Nitro-benzaldehyd liefern. Die triathylamin-katalysierte Tautomerisierung 2 ⇋ 4 last sich in Gegenwart von 2.4-Dinitro-phenylhydrazin unterdrucken; die erwahnten Zwischenstufen werden abgefangen und in Benzaldehyd- und 4-Nitro-benzaldehyd-[2.4-dinitro-phenylhydrazon] ubergefuhrt. Tautomerism in Imidoyl Chlorides N-[4-Nitrobenzyl]-benzimidoyl chloride (2) and 4-nitro-N-benzyl-benzimidoyl chloride in the presence of triethylamine in benzene establish a 92 : 8 equilibrium. Triethylamine deprotonates 2 and 4 in dipolar aprotic solvents at low temperature to produce blue carbanions. The tautomerization 2 ⇋ 4 takes place via α-chloroalkylazomethines, which occur in the tautomeric mixture to the extent of 8–10% and can be hydrolyzed to benzaldehyde and 4-nitro-benzaldehyde. The base-catalyzed tautomerization 2 ⇋ 4 is suppressed in the presence of 2.4-dinitrophenylhydrazine, which converts the afore-mentioned intermediates into an equimolar mixture of benzaldehyde- and 4-nitrobenzaldehyde-[2.4-dinitrophenylhydrazone].