This time we went to Sierra de Béjar mountains for a study on the wintering area of the bluethroat Luscinia svecica with the use of light-level loggers. The area, at ca. 2000 m.a.s.l., constitutes one important breeding site for the subspecies azuricollis. There are ten subspecies that breed across different places in Eurasia and winter in Africa, Mediterranean basin, and probably in the Indian subcontinent. With the use of light-level loggers we aim to describe the spatio-temporal distribution of the Spanish bluethroat population and point out where they winter.
The use of light-level loggers requires the recapture of the tagged individuals in subsequent seasons to get the data recorded from the loggers. Therefore, it is useful to previously study the returning rates of the population breeding in specific sites. Since we already have insight of relatively high returning rates of bluethroats breeding in Sierra de Béjar area from 2009, we chose this as study site. Future plans are to come back next breeding seasons to recapture the tagged birds. With the devices back in the lab, we will calculate the positions where the birds were and ultimately delineate their annual range.
This research is a collaborative project between the University of Copenhagen and Aranzadi Society, Spain. The field work was organized at the outset of the breeding season (May 1st – 3rd) with three members of the group. We worked in two nearby field sites in the area where the bluethroat activity was moderate. We captured fifteen males and four females, fitting with loggers only the males since we believe that they may have higher returning rates. Two of the males were recaptures ringed in 2012 which were good news.
The main capturing method was with mesh traps baited with mealworms. Some mist nets were also set. Playback was used for attracting the birds at both traps and nets. Between 9 and 12 mesh traps were constantly set along the day changing locations every 20-30 minutes.
The highest breeding site in the area (1990 m.a.s.l.), which is considered the optimal site in terms of density of bluethroat breeding pairs, is next to a skiing resort.
Other birds seen in the area were water pipit Anthus spinoletta, common whitethroat Sylvia communis, northern wheatear Oenanthe oenanthe, ortolan bunting Emberiza hortulana, stonechat Saxicola torquata, dunnock Prunela modularis, skylark Alauda arvensis, common raven Corvus corax, and blackbird Turdus merula. Among the raptors, griffon vulture Gyps fulvus, short-toed eagle Circaetus Gallicus, booted eagle Aquila pennata, black kite Milvus migrans, and common kestrel Falco tinnunculus were spotted over the site.