Walks in my yard have gotten quieter lately. Many of the wild songsters that serenaded my morning routines for the past few months have moved on or are preparing to do so. Fall migration for birds is well underway.
The birds don’t all leave at the same time. In fact, even within a species, the exodus may vary by age and gender. Ruby-throated hummingbirds provide a great example. The mature males start their southbound journey at the end of August and early September. It is thought that because they are stronger and more experienced, they fly further so they get an early start. If food is abundant, staying longer in New Hampshire enables younger birds and females to build up a fat reserve, doubling their body mass. This helps sustain them on a journey which can be more than 1,300 miles.
Hummingbirds from our region spend the winter in southern Mexico and Central America. As the climate has warmed and hummingbird feeders have become more common, a growing number of hummingbirds shorten the trip and overwinter in southern Florida and along the gulf coast. Those that go the longest distance may cross the Gulf of Mexico or travel along the coastal route to their winter range.
Through early September, the tiny jewels were at my feeders regularly. The resident hummers have now left and only an occasional traveler from the north stops to refuel. I send them best wishes for the trip and wonder which one will be my last sighting of the season.
Birds that fly the furthest usually depart the earliest. Some, like tree swallows, left in late July and early August. Tree swallows migrate during the day and often roost in large flocks to rest at night. The ones that nest in the eastern U.S. typically follow the southern coastline from Florida to Central America.
Another summer resident that left before summer was over is the indigo bunting. During much of the warm season, a male perched in the top of my yellow birch tree and sang his song, proclaiming his temporary territory. Hopefully he’s experiencing a safe journey to Cuba or the northern region of South America.
Other songbirds common in our summer woods and fields that spend the winter in the Caribbean include warblers such as the ovenbird, common yellowthroat, and black-throated blue warbler. Yellow warblers, scarlet tanagers, and rose-breasted grosbeaks can be found in Central and South America when the cold and snow make finding food here impossible. Many of these species fly 500 miles across the Gulf of Mexico in a single night!
It seems remarkable that such small creatures can make these arduous and perilous journeys. What is even more incredible is how they do it. Daytime migrants navigate using visual landmarks such as coastlines, rivers and mountain ridges. However, many songbirds migrate at night to avoid predation by hawks, to conserve energy when it’s cooler, and to spend daylight hours eating. It takes a lot of insects to fuel them for their trip! Navigation is accomplished using various methods including the stars. It was once thought that birds had some sort of internal compass that helped direct them. Additional research now indicates that a particular protein in birds’ eyes can detect the orientation of the earth’s magnetic field, enabling them to fly in the proper direction.
Of course, there are plenty of bird species that don’t abandon the north. Those that eat seeds and insects within trees (versus flying insects and caterpillars) trade the migration hazards of tall buildings, coastal storms and habitat loss along the way for northern snow, ice and cold. Either strategy makes living until the next breeding season quite a challenge.
Some ways that we can help are to provide food, shelter and water. The best types of food and shelter are in the form of native plants. Other ways to make birds’ lives easier are reducing outside lighting to help nighttime migrants, avoiding use of pesticides and keeping cats indoors.
Birds provide us with beautiful songs, sights, and inspiration and they decrease insect pests. With all the challenges that they face, at least we can do a few things that make their lives and journeys less difficult.