A reader writes: We usually have a number of hummers at our feeders and the nearby trumpet vine, but this year have seen only a couple around. In the past there have several vying for the feeders. Any thoughts on this?
Yes, I can offer a specific reason that might have impacted your hummingbirds, one of several I could mention. Broadly speaking, however, it's the changing climate.
The speed of change is surprising for some of us, totally unexpected by many of us and unacknowledged by others. We're now actually living with the changes we've heard and read about. It's not our future. It's our now.
Here's a reason that might explain your missing hummers: Bird behavior and their environments are becoming mismatched. The website NatureCanada (naturecanada.ca) puts it this way:
"Much of a bird's life cycle and behavior is closely linked to cues from the environment, like changing seasons. A mismatch occurs when birds cannot shift their behavior, such as breeding times, to coincide with changes in environment, such as when prey is available."
For your hummingbirds this could mean a mismatch with the flowers they need for nectar or the tiny insects they eat for protein. The insects are particularly important if chicks are being fed. Maybe the hummers you expected to see didn't nest at all. Birds can forgo nesting if they sense poor survival chances.
In particular, long-distance migration based on changes in the length of day can create risk of a mismatch, the Canadian website says. Ruby-throated hummingbirds beginning migration in Mexico, for example, can have no idea of drought conditions in Minnesota.
Warblers in North America aren't migrating earlier from their neotropical wintering grounds, despite earlier springs in their northern breeding ranges. This risks arrival after spring food sources on breeding grounds are gone, the Canadian site says.
"A growing body of research on climate change and migratory birds shows that although birds are shifting their spring migrations sooner, they're not doing this fast enough to keep up with the pace of change," according to Rebecca Heisman, a science writer in Washington state, writing for the American Birding Conservancy.
"Many of these birds initiate their northward flight based on day length, not temperature," she explains. This means their migration occurs at the same time each year. It does not shift to accommodate change in climate conditions at the migration destination.
"The seasonal resources they rely on such as caterpillars may already be past their peak for the year, reducing their breeding success," Heisman writes.
An Audubon report on birds and climate, a comprehensive study that analyzed decades of data, showed a shift in the ranges of more than half of North America's bird species.
Unanswered is the question of whether the new ranges meet the needs of the birds making the change. Then, what can we do to help keep birds in our yards and parks?
We can work to reduce threats presented by outdoor cats, pesticides and windows. Save every life we can.
Help cut carbon emissions by making smart decisions about how we live and travel. Restore bird habitat. Planting trees is a great way to improve bird habitat and safely store carbon.
For certain, don't expect the climate to improve. Act accordingly.
Lifelong birder Jim Williams can be reached at email@example.com.
Early arrival not necessarily better
Certain species are by nature early spring migrants. The NatureCanada website reports that tree swallows are nesting up to nine days earlier than they did 30 years ago. This corresponds to a rise in average spring temperatures, factor of a warming climate. Early also can mean a timing misalignment. The swallows eat insects. If the birds arrive before insects hatch, the birds are in trouble.