Bedingungen für den Fortpflanzungserfolg: Zur Öko-Ethologie des Graukranichs Grus grus während der Jungenaufzucht

Im Rahmen eines internationalen Projektes von Kranichschutz Deutschland (NABU, WWF, Lufthansa) wurden in den Jahren 1995 bis 2000 in Mecklenburg Vorpommern Untersuchungen zu Verhalten und Lebensraumansprüchen reproduzierender Graukraniche durchgeführt. Die zentrale Hypothese der Arbeit lautet: Eine gute Nahrungsverfügbarkeit, eine geringe Vegetationshöhe und ein geringer Vegetationswiderstand sollten zur Bevorzugung bestimmter Revierbereiche führen und somit die Reviergröße beeinflussen. Im Fokus standen außerdem die Wirkungen anthropogener Einflüsse. Da sich Kraniche während der Jungenaufzucht äußerst unauffällig verhalten, waren Grundlagen für effiziente Schutz- und Managementkonzepte kaum verfügbar. Erstmalig wurden die Habitatnutzung und die Reviergröße von Kranichfamilien mit Hilfe der Radiotelemetrie ermittelt (Null-Peak-Peilung). Zur Abschätzung des Vegetationswiderstandes wurde ein neues Verfahren entwickelt. Innerhalb der Reviere beeinflussten der Feldanbau mit Raps, landwirtschaftliche Störreize, die Nahrungsverfügbarkeit und die Jagdausübung die Habitatnutzungsintensität (HNI) am stärksten. Der Nahrungserwerb erfolgte in fast allen Habitattypen. Naturnahe bzw. extensiv genutzte Habitate wurden signifikant häufiger frequentiert als intensiv bewirtschaftete Nutzflächen. Die HNI der Kranichfamilien korrelierte signifikant mit der Verfügbarkeit der Nahrung. Straßen und Straßenverkehr beeinflussten die HNI ebenfalls. Der Mindestabstand zu Kreisstraßen war signifikant größer (mittlerer Abstand 308m) als zu Bundesstraßen (141m). Die Einflüsse der Vegetationshöhe und des Vegetationswiderstandes auf die HNI waren meist von geringer Bedeutung (keine Korrelation bzgl. der HNI). Habitate wurden erst gemieden, wenn bestimmte Schwellenwerte überschritten wurden (Veg.-höhe > 1m, Veg.-widerstand auf einen definierten Dummy >8N). Kranichreviere waren durchschnittlich 69,7ha (max.=131,8ha) groß.Ein Ausblick präsentiert künftige und bereits begonnene Projektvorhaben

Migration and wintering patterns of a central European population of Common Cranes Grus grus

7 paginas, 1 figura y 1 tableAims To describe migration routes and phenology, and the interannual fidelity to staging and wintering sites. Methods A total of 93 cranes were colour-banded, and 67 of them radiotagged, at their breeding territories in northern Germany and later located at their wintering areas in Spain. Results After a migratory trip lasting 3–28 days, most cranes arrived at Gallocanta in northeastern Spain, where they staged for 1–44 days. Some families stayed there the whole winter, but most continued to southwestern Iberia, where they dispersed over at least 13 wintering areas. Site fidelity was more marked in adult pairs than immatures, half of which used different areas in their second and third winters from those used by their parents. Conclusions Most German cranes wintered in southwestern Spain, with smaller numbers in France. Some immatures remained in France as second- or third-year birds, after having spent their first winter in Spain with their parents, whereas none of them shifted southwards. This suggests that immatures have probably contributed more than adult pairs to the northward shift in the winter range observed during the last decadesWe thank H. Dirks, T. Fichtner, V. Günter, S. Röper and W. Mewes for their help during crane capture and radiotagging, and K. Peter for preparing the figure. Funds for transmitters and fieldwork were provided by Kranichschutz Deutschland (Naturschutzbund Deutschland, Umweltstiftung WWF Deutschland, Lufthansa Umweltförderung) and Umweltministerium Mecklenburg-Vorpommern (Abt. Naturschutz). Facilities for travelling between Spain and Germany were kindly provided by Lufthansa. Aerial location of Common Cranes was possible thanks to the generous collaboration of the Spanish Air Forces and the staff of the Getafe Air Base. We thank 42 Group and its pilots, as well as the maintenance staff, who installed the antennae on the aircraft.Peer reviewe

Population, flocking behaviour and habitat selection of the Grey Crowned Crane Balearica regulorum at Lake Ol’ Bolossat basin, Kenya

Lake Ol’ Bolossat is an inland wetland located in Nyandarua County, Kenya that provides critical year-round habitat for the Globally Endangered Grey Crowned Crane Balearica regulorum gibbericeps. This study aimed at establishing the population size and density of cranes in the basin, ratio of young to adults (as a measure of productivity), and habitat selection and use during the breeding and non-breeding seasons. Using complete ground counts, five censuses were conducted between 2017 and 2020 with between 521 and 1115 cranes recorded, and we estimate the local population size to be 250–350 individuals. Population density ranged from 0.99–2.18 cranes/km2 during the breeding and non-breeding seasons respectively. From all 219 observations made during the study period, the  mean flock size was 28.21 with a maximum flock size of 332 and a modal flock size of 2–25 individuals. The average proportion of young cranes across all counts was 11.65% indicating a population which is breeding successfully. Although cranes occupied both wetlands and terrestrial habitats in almost equal proportions across the year cumulatively, the difference in choice of habitat between the breeding and the non-breeding seasons was significant (χ2=489, df=1, p=0.0001), whereby more cranes (mostly paired individuals) were observed in marshes during breeding months. Wheat fields were the most often used of terrestrial habitats among fields of different crop types sampled. Holding 14% and 5% of Kenya’s and the global population of Grey Crowned Cranes, respectively, Lake Ol’Bolossat is undoubtedly an important site for this species’ conservation and survival. Keywords: Lake Ol’ Bolossat, Balearica regulorum gibbericeps, habitat selection, population size, flock characteristic

Distribution and population estimates of four crane species in Ethiopia: A global crane hotspot facing increasing threats

Four species of crane occur in Ethiopia, making the country the most important in Africa for cranes. Black-crowned Balearica pavonina and Wattled Cranes Bugeranus carunculatus, both listed as Vulnerable, are resident species, while Common Grus grus and Demoiselle Cranes Anthropoides virgo, both listed as Least Concern, are migrants. We assessed the distribution and minimum population size of four crane species at the most important and main crane sites during 2007–2019. Some potentially important sites, particularly for Black-crowned Cranes, were not able to be surveyed. Breeding areas of resident cranes were also surveyed. Results showed that Black-crowned Cranes were mainly distributed in the Gambela and Lake Tana areas and the minimum population estimate was 3319 individuals. Wattled Cranes were distributed in Bale Mountains National Park, Lake Tana, Jimma wetlands, Bonga and central Rift Valley areas and the minimum population estimate was 366. Migratory Common Cranes were found in Lake Tana, central Ethiopia, south-central Rift Valley, and some places in southern Ethiopia with the highest populations recorded at Lake Tana and secondly at Debre-Zeit. The minimum population estimate for Common Cranes was 70 000. Migratory Demoiselle Cranes were restricted to the northwestern corner of Ethiopia and the minimum population estimate of 21 500 was based on previously published data. Wetlands are the main habitats for cranes and in Ethiopia these habitats are being degraded and are under increasing threat from overgrazing, water extraction for irrigation, siltation, and habitat loss from farming. Key wetland sites that should be protected or sustainably managed include those at Gambela, Lake Tana (Chimba and Yiganda, in particular), and the Boyo and Jimma areas. Cheleleka at Debre-Zeit, Sululta plain around Addis Ababa, and Shesher floodplain in Lake Tana are important roosting sites for Common Cranes. Keywords: Black-crowned Crane, Common Crane, Demoiselle Crane, threats, Wattled Crane, breeding sites, wetland