To date, the virus has not been detected in healthy wild birds, but many dead or dying birds have been found near infection foci. Are they victims or reservoirs? In all likelihood the former, but the latter hypothesis cannot be ruled out. Six healthy ducks carrying the virus - out of a total of 4600 tested and in a particularly severely infected zone - were found in China in January 2005.
Determining the number of stages and where birds stop off during migration
In 2005 and 2006, migrating birds were often under suspicion. However, their migration corridors and periods did not necessarily correspond to the virus spread patterns seen in recent years. To clarify matters, researchers are now plotting comprehensive, accurate flight plans. To this end, with FAO funding, they are fitting birds with small Argos transmitters. This equipment will provide a large number of data and fill the gaps in information on the subject. Migration has already been studied in detail in Europe and Asia, but this is far from the case in Africa, where monitoring is limited to counting the populations in each country or ringing birds, despite the fact that some five million ducks from Eurasia winter in Subsaharan Africa and there are more than four million African ducks that fly between the different regions of the continent.
In particular, the transmitters will provide information on the number of migration stages and where the birds stop off during migration. In fact, they stop off in humid zones propitious to pathogen transmission, where the different species mix with one another. The study should also provide more general information on migration: travelling times and the ecological and manmade factors that determine the stops.
Three species in three African countries
Three species were chosen for the operation: the blue-winged teal, fulvous whistling duck and comb duck, each of which represents a typical migration route. The teal is a Europe-Asia-Africa intercontinental migrator and winters exclusively in Subsaharan Africa, where it is the most common wintering bird. The comb duck restricts its movements to Africa, but covers several regions, while the fulvous whistling duck, the most common African duck, is a nomadic species on a regional level. The researchers' first step was to test the impact of the transmitters on the birds' behaviour in captivity at Montpellier's Lunaret Zoo. They then travelled to Africa, and captured and equipped 45 birds in February. Captures were made at three sites: northern Nigeria, a very humid zone where there have been bird flu foci for more than a year; the inland delta of the Niger River, in Mali, which is the biggest wintering site for Eurasian ducks in Africa; and Malawi, which had the necessary sites for a study of interregional migration. Now that the birds have been released, they can be monitored, and the results, updated twice weekly, are now available on a CIRAD website: http://wildbirds-ai.cirad.fr.
On-line maps for real-time monitoring
The study is a first for Africa. Teams from the FAO and the United States Geological Survey, which work with CIRAD, have also equipped swans in China and Mongolia. For the time being, the researchers do not know how long the transmitters will continue to supply data (this depends on the birds' lifespan).
Each transmitter weighs between 12 and 30 grammes. The 12- and 18-gramme ones are used for teals and fulvous whistling ducks, and the 30-gramme ones for comb ducks, which are larger. They are fitted to the body of each bird, like small backpacks, using teflon straps. The location of each bird is determined using the Argos system. The transmitter emits a signal that is picked up by satellites in polar orbit at a height of 850 km. The satellites then send the signal back to terrestrial reception stations. The data received are subsequently processed by centres specializing in the Argos system. Lastly, once processed, the data are passed on to users.
The maps available on the Wild birds and avian influenza in Africa website can be used to monitor bird movements, virtually in real time. At the moment, the teals from Nigeria are moving towards Lake Chad. They should be heading north in the next few days.
Helen Burford | alfa
Kakao in Monokultur verträgt Trockenheit besser als Kakao in Mischsystemen
18.09.2017 | Georg-August-Universität Göttingen
Ultrasound sensors make forage harvesters more reliable
28.08.2017 | Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren IZFP
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy