Stopover ecology and divers migratory strategies use in the Common Sandpiper (Actitis hypoleucos)
Authors: Alfonso BALMORI
Published: Volume 52(2), December 2005. Pages 319-331.
Original Title: Ecología de la sedimentación y utilización de diversas estrategias migratorias en el Andarríos Chico (Actitis hypoleucos)
Aims: Obtain information about the stopover ecology of the Common Sandpiper, to identify the divers estategies used by juvenile and adults and its contribution to the differential migration as well as try to explain the differences in the results of studies realized in the coast and interior.
Location: The study was carried out in the Duero Valley, confluence of Cega and Duero rivers (Valladolid, Spain).
Methods: captures with mist nest, ringing and taking of data in hand.
Results: high variations of body mass were observed in recoveries, with increments of 6.87 grams during the day and losses of 4.94 g. during the night. Body mass of birds captured in the dusk was larger than in the dawn both in adults (average = 9.85) and juvenile (6.65). The index means of fat found for each age and hour was 1.2 at the dawn and 2.2 at dusk for the juvenile, and 1.5 and 2.5 respectively for the adults. It was a high correlation between the body mass and the fat index on the captured birds. The Common sandpiper fattens a daily average of 1.93 grams, increasing their body mass in 5.04 grams among the first and last capture. Some individuals increase until 60% of body mass during their stay. The stragglers birds remain more time at the study area. It seems to exist a higher nutritious efficiency of adults regarding the younger that could explain the progressive delay in the migration of the younger birds.
Conclusions: The species has a very active metabolism, with high variations of body mass along the day and high night losses. The results support the hypothesis that the adults travel quicker than the juvenile in autumn. This can be originated by a higher nutritious efficiency, a smaller energy expense or for the competitive domain of the adults. It is possible that the migration is slower in the coast, where the young birds prevail in the realized studies, than in the interior. Probably in the coast the adults use a similar strategy to the juvenile ones.