[cobirds] Spring Migration is Underway

Spring Migration is Underway

Right this moment spring migration for North American land birds is well underway starting from South and Central America. Some of these migrants will just gradually move north, then use the Panamanian Isthmus follow the topographic features of Central America then entering North America. 

Eastern oriented birds are apt to take a long distance route over the Caribbean Sea before entering North America. At that time of year the prevailing winds are from the southeast, giving those migrants an added boost. Depending upon weather conditions their migration can be very exciting for bird watchers. 

Since there are few visible land features to guide them over the ocean migrating birds will rely on celestial cues, such as the sun and stars. In the northern hemisphere, the sun lies in the south and moves during the day from east to west, and at night the stars rotate counter-clockwise. (In the southern hemisphere, it is all reversed). For course direction they will rely on the degree of geomagnetic pull for re-orienting their course. Some of the over-the-ocean migrants will enter North America via the southeastern states and then move north, but most of the migrants will enter the country via the Gulf Coast states and then branch out in all directions north. Some like the Dickcissels will drift to Colorado for nesting. Many of Colorado's nesting birds winter in Central America so their migration north in spring is shorter and is less dynamic, but equally as welcomed.

Bob Righter

Denver, CO