The month of August brings the official start of fall migration through our wetlands. Although most of the colorful songbirds that are favorites among birders will not be migrating through in number until September and October, shorebird species like sandpipers and plovers start leading the way as early Late July into August. The start of shorebird migration can easily be overlooked by birders because August is the peak of summer heat and humidity in the RGV and because shorebirds can often be challenging to find (especially inland) and identify. But for those that make the effort, it can be very rewarding and enjoyable. We are incredibly lucky at the SPIBNC&GS because we have the perfect habitat to see and study a great diversity of shorebird species during migration. Our 50-acres of coastal wetlands are an immensely valuable pit stop for these migratory birds, some of which have some of the longest and most arduous migration journeys of North American birds. Most migratory shorebirds’ lives and migration journeys start in the extreme north. Numerous species have summer nesting ranges in latitudes as far north as Northern Canada, Alaska, and the Arctic Tundra! Although short-lived, the summers in those latitudes provide a great abundance of nesting sites, food, as well as daylight. Because of the Earth’s tilt, shorebirds nesting in the Arctic Circle during the spring and summer benefit from almost 24-hour daylight, which helps them raise their young at a faster rate. Breeding birds arriving in the spring have just a couple of months to raise young before extreme cold begins to set in again and the insect surplus that nourishes the birds starts to dwindle. Birds that failed to nest early in the season will recognize their lack of new opportunity and will forego giving nesting another shot and will instead start to leave nesting sites and begin migrating south as early as June. They are closely followed in July by adults just finished with nesting, and lastly the young of the summer begin their journey south as soon as they get a good handle of flight sometime around late July and August.
Because of bird banding operations, it is also known that shorebirds can exhibit high site-fidelity. Meaning that they somehow return to the same nesting and non-breeding (wintering) sites every year! It is incredible to think that the Sanderlings that we are so accustomed to seeing chasing the waves on the beach take such a long flight to the Arctic in the spring, breed and nest there, and are back on SPI beaches by late summer and early fall before we even notice they were gone!
While SPI is a perfect non-breeding site for many species, some will keep on flying south and cross the equator into South America, where because of the opposite seasons between northern and southern hemispheres, it is summer! It is interesting to think that some of these birds live in a perpetual summer as they move from nesting sites in the northern end of the northern hemisphere to non-breeding sites in the southern hemisphere! Talk about globetrotting! We at the birding center are excited about shorebird migration this month and hope that you get to see some of these birds along their journey on your peaceful morning walk on our boardwalk or on the beach.