Thesis
MIGRACIÓN E INVERNACIÓN DEL PLAYERO ROJIZO DEL PACÍFICO (Calidris canutus roselaari) EN GUERRERO NEGRO, BAJA CALIFORNIA SUR, MÉXICO
Autor
ARCE VILLAVICENCIO, NALLELY
Institución
Resumen
ABSTRACT
The Guerrero Negro wetland complex (GN) is one of the most important places for shorebirds in Mexico and the most important wintering place registered for the Pacific population of the Red Knot (Calidris canutus roselaari). This subspecies have the smaller population and also is the less studied, and because of the importance of the GN complex it seems important to monitor the population and the utilization pattern in this site. This study has the objective determining the use patterns of the Red Knot in the GN complex during the migration and wintering period. Using monthly surveys the abundance was determined during two years (2007-08 y 2008-09). In 2007-08 a total of 38,470 registers were realized and in 2008-09 a total of 14,766 registers with a maximum of 6,736 and 7,956 in November in the two years respectively. The maximum number observed represented 39% of the total population of this subspecies. The observed differences between the two years, probably may have been related with the variation in temperature between these years, because in the year with the greater temperature the smaller abundances were registered. The Red Knot abundance was highest during the winter (4,757 birds), moderate in autumn and spring (1,317 and 1,742 birds, respective) and lowest in summer (152 birds). In total, 547 individuals of Red Knot (C. canutus roselaari) were captured (2.7% of the total population), of which 87.6% were adults, suggesting that GN it’s an optimal wintering site for this subspecies. The lower weights and stables between fall and winter, and the molt chronology of the fraction of adults suggest also that GN is a wintering place for this population. The resightings corroborate the taxonomic identity of the subspecies and provide the first evidence of migratory connectivity between the Red Knots between Wrangel Island, Alaska, Washington and GN, and also probe that the C. canutus roselaari subspecies migrate for the Pacific coast. The return rate to the study area (20%) show that the Red Knot present fidelity to the wintering site GN.