False Springs & the Impact on Bird Populations

Have you ever had the experience of suffering through long, wintry, 20 degree days; then, suddenly, there’s several days in the 70’s before winter comes roaring back? Scientists call this sudden warm period a “False Spring”, and it’s as confusing for plants and animals as it is for humans.

“False spring” is becoming increasingly common as climate changes. And when warm temperatures awaken dormant plants and animals prematurely, they can throw off kilter the timing of seasonal events crucial to an entire ecological food web.

While occasional false springs are not new, what is new in recent years is the combination of increasingly warmer springs and extreme temperature swings. This phenomenon increases the likelihood that plants will emerge from dormancy prematurely, producing young leaves, buds and blooms. When unusually mild temperatures and subsequent plant growth are followed by freezing temperatures, early buds and blooms killed by a hard frost can mean failure to flower and fruit for the rest of that year.

False spring can harm not only the plants that put forth early sprouts, leaves or blooms, but other species and entire ecosystems. The timing of leaf and flower development has effects that ripple throughout an ecosystem because these changes prompt the flow of sap, nectar and nutrients within plants and so affect the availability of shelter and food. This can have profound consequences, particularly during bird migration.

Different species of migratory birds depend on different clues to know when to begin their spring migration — usually changes in daylight or weather. If a bird species depends on changes in daylight to know when to migrate — something that, obviously, remains constant even as climate changes  —  they may take off for their spring habitat at the usual time. But if that spring habitat experienced an early or false spring, they may arrive to in their breeding ground to find that the insects have already hatched and plant resources that they require are already gone.

Along with the other effects of Climate Change, false spring is a concern to the Bucks County Audubon Society. Within the Delaware River Watershed, forests, parks, and open space provide critical habitat for birds. According to a recent study by the National Audubon Society, birds in Bucks County that are highly vulnerable to just a 2°C rise in temperature include the Red-headed Woodpecker, the Brown Thrasher, the Eastern Towhee, and the Yellow-Throated Warbler.

Find out what you can do to reduce the effects of Climate Change, both at home and in the wider community. It will take all of us to save the planet. There is no Planet B.

-Written by guest blogger + Bucks Audubon Advocacy Committee Member, Jim Mansfield

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