In three consecutive years (1998 to 2000), 20 adult grayling Thymallus thymallus (L.) (FL ± SD: 326 ± 43 mm) were radio-tracked during circum reproduction period (February to May) in the River Aisne, Belgium. Before the spawning period, grayling remained consistently in the pool-riffle sequence in which they had been captured. Pre-spawning migration time extended from 7 to 29 March. Distances travelled during the spawning migration ranged from 70 to 4980 m (mean ± S.E.: 1234 ± 328 m). Spawning migrations started under conditions of decreasing water level and increasing water temperature in a thermal range (daily mean T°) from 5 to 8 °C. Spawners remained from 1 to 31 days (mean ± S.D.: 10.4 ± 9.8 days) at the spawning grounds and performed a post-spawning homing from 28 March to 18 April in decreasing water flow and in a thermal range (daily mean T°) from 7 to 11 °C. This study demonstrates that migration patterns of grayling are similar between years, but with a timing adjusted as a response to annual variations of the hydroclimatic conditions.
This is a report on a post-lactating female soprano pipistrelle, Pipistrellus pygmaeus, which in autumn exploited habitats from sea level to the transition zone between alpine and sub-alpine areas. It travelled more than 12.3 kilometres from its roost and returned to its roost at sea level on all four nights when it was tracked. In addition to the telemetry bat, several soprano pipistrelles utilized high altitudes during the days of tracking as heard on ultrasound detector.