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Variables affecting the choice of migrating European honey buzzards to fly over a flat highland or to outflank it by flying over steep slopes and deep valleys were tested. Radar located at a Mediterranean bottleneck enabled collection of raptor tracks. Variables included the effects of weather, flock size, time of day, and ground speed of buzzards. It was found that raptors passed over the highland when wind speed (mostly lateral) increased as a result of partial drift, whereas buzzards tended to outflank the highland during midday and afternoon, probably when stronger thermals generated on the valley slopes were available. These results suggest that, in this case study, European honey buzzards modulate the compensation of wind drift at different times of the day, showing a highly plastic behavior during migration. [ABSTRACT FROM AUTHOR]

Transmission of prions between species is limited by the "species barrier," which hampers a full characterization of human prion strains in the mouse model. We report that the efficiency of primary transmission of prions from Creutzfeldt-Jakob disease patients to a wild rodent species, the bank vole (Clethrionomys glareolus), is comparable to that reported in transgenic mice carrying human prion protein, in spite of a low prion protein-sequence homology between man and vole. Voles infected with sporadic and genetic Creutzfeldt-Jakob disease isolates show strain-specific patterns of spongiform degeneration and pathological prion protein-deposition, and accumulate protease-resistant prion protein with biochemical properties similar to the human counterpart. Adaptation of genetic Creutzfeldt-Jakob disease isolates to voles shows little or no evidence of a transmission barrier, in contrast to the striking barriers observed during transmission of mouse, hamster, and sheep prions to voles. Our results imply that in voles there is no clear relationship between the degree of homology of the prion protein of the donor and recipient species and susceptibility, consistent with the view that the prion strain gives a major contribution to the species barrier. The vole is therefore a valuable model to study human prion diversity and, being susceptible to a range of animal prions, represents a unique tool for comparing isolates from different species. [ABSTRACT FROM AUTHOR]

To study the neurophysiology of large-scale spatial cognition, we analyzed the neuronal activity of navigating homing pigeons. This is not possible using conventional radio-telemetry suitable for short distances only. Therefore we developed a miniaturized data logger ("neurologger") that can be carried by a homing pigeon on its back, in conjunction with a micro-global position system (GPS) logger recording the spatial position of the bird. In its present state, the neurologger permits recording from up to eight single-ended or differential electrodes in a walking or flying pigeon. Inputs from eight independent channels are preamplified, band-pass filtered, and directed to an eight-channel, 10-bit analog-digital converter of the microcontroller storing data on a "Multimedia" or "Secure Digital" card. For electroencephalography (EEG), the logger permits simultaneous recordings of up to eight channels during maximally 47 h, depending on memory, while single unit activity from two channels can be stored over 9 h. The logger permits single unit separation from recorded multiunit signals. The neurologger with GPS represents a better alternative to telemetry that will eventually permit to record neuronal activity during cognitive and innate behavior of many species moving freely in their habitats but will also permit automated high-throughput screening of EEG in the laboratory. [ABSTRACT FROM AUTHOR]