| Abstract: | The semipalmated sandpiper Calidris pusilla and the spottedsandpiper Actitis macularia are long- and short-distance migrants,respectively. C. pusilla breeds in the sub-arctic and mid-arctictundra of Canada and Alaska and winters on the north and east coasts of SouthAmerica. A. macularia breeds in a broad distribution across most ofNorth America from the treeline to the southern United States. It winters in thesouthern United States, and Central and South America. The autumn migration route ofC. pusilla includes a non-stop flight over the Atlantic Ocean,whereas autumn route of A. macularia is largely over land. Becauseof this difference in their migratory paths and the visuo-spatial recognition tasksinvolved, we hypothesized that hippocampal volume and neuronal and glial numberswould differ between these two species. A. macularia did not differfrom C. pusilla in the total number of hippocampal neurons, but thespecies had a larger hippocampal formation and more hippocampal microglia. It remainsto be investigated whether these differences indicate interspecies differences orneural specializations associated with different strategies of orientation andnavigation. |
