Four-year satellite tracking of a White Stork Ciconia ciconia since independence : description of an odyssey

Ein nestjunger Weißstorch aus der Gegend von Kaliningrad, Russland, wurde im Juli 2000 in der Biologischen Station Rybatschij aufgezogen und im September verspätet freigelassen. Im Rahmen eines Projektes zur Untersuchung des Orientierungsvermögens wurde er mit einem Satellitensender (14554) ausgestattet. Obwohl die Weißstörche aus dem Kaliningrader Gebiet normalerweise nach SO ziehen, wanderte der besenderte Vogel nach SW ab, überquerte das Mittelmeer von Frankreich nach Tunesien, verbrachte seinen ersten Winter und zweiten Sommer in Nordafrika und seinen zweiten Winter im Tschad-See-Gebiet im Norden von Nigeria und Kamerun. Im Sommer 2002 hielt er sich auf der Iberischen Halbinsel auf, im Winter 2002/2003 im äußersten Süden Spaniens. Im Sommer 2003 kehrte der Storch im Alter von 3 Jahren in das Verbreitungsgebiet osteuropäischer Weißstörche zurück – nach Nordpolen, nur 220 km südwestlich von seinem Geburtsort, wo er möglicherweise brütete. Der Wegzug 2003 verlief über die für osteuropäische Weißstörche typische Ostroute. In Afrika zog der Storch weit nach Westen – bis in den West-Tschad – sodass sich sein Winterquartier nur 175 km von dem Gebiet entfernt befand, das er 2002 über die Westroute erreicht hatte.A White Stork from the Kaliningrad region of Russia was taken into captivity as a nestling in 2000, raised at the Biological Station Rybachy and released after a retention experiment in September. The bird was tagged with a satellite transmitter 14554 as part of an investigation of the orientation abilities of juvenile White Storks. In the first autumn, the bird moved towards the SW, even though the normal migratory direction for the storks from Kaliningrad is SE. The bird crossed the Mediterranean from France to Tunisia, and spent its first winter and second summer in North Africa. It spent its second winter in the Lake Chad area, in northern Nigeria and Cameroon. In summer 2002 it was in the Iberian peninsula, in winter 2002/2003 in the southernmost part of Spain. At the age of 3 years this bird returned to the distribution area of East European White Storks. It spent the summer (possibly bred) in northern Poland, 220 km SSW of its natal site. Autumn migration 2003 followed the eastern flyway typical of East European White Storks. When in Africa, the bird moved far to the W, to western Chad, so that its wintering area 2003 was only 175 km away from the area that had been reached in 2002 via the western flyway

Migratory Eurasian reed warblers can use magnetic declination to solve the longitude problem

The longitude problem (determining east-west position) is a classical problem in human sea navigation. Prior to the use of GPS satellites, extraordinarily accurate clocks measuring the difference between local time and a fixed reference (e.g., GMT) [1] were needed to determine longitude. Birds do not appear to possess a time-difference clock sense [2]. Nevertheless, experienced night-migratory songbirds can correct for east-west displacements to unknown locations [3-9]. Consequently, migratory birds must solve the longitude problem in a different way, but how they do so has remained a scientific mystery [10]. We suggest that experienced adult Eurasian reed warblers (Acrocephalus scirpaceus) can use magnetic declination to solve the longitude problem at least under some circumstances under clear skies. Experienced migrants tested during autumn migration in Rybachy, Russia, were exposed to an 8.5° change in declination while all other cues remained unchanged. This corresponds to a virtual magnetic displacement to Scotland if and only if magnetic declination is a part of their map. The adult migrants responded by changing their heading by 151° from WSW to ESE, consistent with compensation for the virtual magnetic displacement. Juvenile migrants that had not yet established a navigational map also oriented WSW at the capture site but became randomly oriented when the magnetic declination was shifted 8.5°. In combination with latitudinal cues, which birds are known to detect and use [10-12], magnetic declination could provide the mostly east-west component for a true bi-coordinate navigation system under clear skies for experienced migratory birds in some areas of the globe

Navigation by extrapolation of geomagnetic cues in a migratory songbird

Displacement experiments have demonstrated that experienced migratory birds translocated thousands of kilometers away from their migratory corridor to unfamiliar areas can orient towards and ultimately reach their intended destinations. This implies that they are capable of “true navigation”, commonly defined as the ability to return to a known goal after displacement to a completely unknown location without relying on familiar surroundings, cues that emanate from the destination, or information collected during the outward journey. In birds, true navigation appears to require previous migratory experience, and it is generally assumed that, to correct for displacements outside the familiar area, birds initially have to gather information within their year-round distribution range, learn predictable spatial gradients of some environmental cues within it and extrapolate from those to cues of unfamiliar magnitude ̶ the gradient hypothesis. However, the nature of the cues used, and evidence for actual extrapolation remains elusive. Geomagnetic cues (inclination, declination and total intensity) provide predictable spatial gradients across large parts of the globe and could serve for navigation. We tested the orientation of long-distance migrants, Eurasian reed warblers (Acrocephalus scirpaceus), exposing them to geomagnetic cues of unfamiliar magnitude only encountered beyond their natural distribution range. The birds demonstrated re-orientation towards their natural migratory corridor as if they were translocated to the corresponding geographic location but only when all naturally occurring magnetic cues were presented, not when declination was changed alone. This result represents direct evidence for migratory birds’ ability to navigate using geomagnetic cues extrapolated beyond the range of magnitude they previously experienced

Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Stopover ecology of migratory Sedge Warblers (Acrocephalus schoenobaenus) at Eilat, Israel

Migrating Sedge Warblers Acrocephalus schoenobaenus were captured in Eilat, Israel, during their spring and autumn migration. Data on spring and autumn body masses, their interannual variation and the pattern of fuel accumulation were analysed. Body mass and body condition index significantly varied between the years of study in spring but not in autumn. This may be due to birds over-flying the area, but loop migration might also be involved. Sedge Warblers gain mass in Eilat, both in spring and in autumn. Birds in poor initial condition and those stopping over for a longer period gained more body mass faster. In spring, but not in autumn, the progress of the season was another important factor: late birds gained more body mass. The average rate of body mass gain was 0.179g day–1 ± SE = 0.026. This suggests that Eilat is an important staging area for Sedge Warblers in spring and to a smaller extent in autumn.Ostrich 2004, 75(1&2): 52–5