Cheerful daffodils, bright forsythia, and delicate pink-and-white cherry blossoms are blooming unseasonably early in the southeastern United States and mid-Atlantic. Some have already peaked, with bright petals turning wilted brown, but it’s still mid-March. Migratory birds, such as the Nashville warbler, landed weeks ahead of schedule, with ticks landing on blades of grass in New York state and elsewhere, looking to catch their first victims of the season since February.
These premature signs of spring have spurred a mild winter in much of the eastern half of the country. It was in the top 10 in 18 states. Some locations, including New York City and Nantucket, had the earliest signs of spring on record, including unfolding leaves and blooming flowers, according to data from the U.S. National Phenology Network.
Humans may welcome the opportunity to put their coats away early. But an unscheduled spring can have devastating effects on ecosystems. Shorter hibernation can lead to increased conflict between humans and animals from the loss of flowers that pollinators normally visit. “A really early spring can lead to all kinds of unforeseen problems,” says Morgan Tingley, an ornithologist at the University of California, Los Angeles. “The problem is that early spring is not the exception. say. “The extreme has become typical. That’s when we start to see stronger, really negative effects.”
The study of how species behave in line with the Earth’s cycles is called phenology. For example, birds migrate as the days get shorter and longer. The leaves turn golden or red when the temperature drops. When ecologically intertwined species do not match seasonal cues, it is called a phenological mismatch.
Flowers that bloom early in cool weather run the risk of being mismatched with key pollinators, such as hummingbirds and bees, who can follow climate-independent cues such as day length. This means pollinators miss the nectar they need for energy and the flowers also stop fertilizing at their normal rate. These plants produce fewer seeds and, in the case of crops, produce fewer fruits. Botanist Susan Pell, executive director of the U.S. Botanic Gardens in Washington, DC, is particularly concerned about this year’s fruit tree harvest. “Almost everything is flowering much earlier than usual,” she says. Fruit trees are at risk from flowering early, as sudden frosts can destroy the delicate buds that eventually bear fruit if the weather changes.
Early flowering also means early pollen release, which can prolong the usual seasonal woes for those with allergies. trees released pollen, a major allergen. At the beginning of March, Atlanta and Raleigh, North Carolina saw record pollen count increases.
Not all flowers bloom early on the other end of the spectrum. Some attribute efflorescence to the amount and quality of sunlight they receive. If the primary flowers that are present do not bloom, they will have nothing to eat. “I’ve heard some anecdotal stories…that dead bees have been sighted on the ground,” says Teresa Crimmins, director of the National Biological Network. Some biologists speculate that the warm temperatures lured the bees out of their winter hibernation, causing them to starve without proper blooms.
An early spring coupled with a warm winter increases the likelihood that some pests will eat plants and, in the case of mites, humans. Without flash freezing, these arachnids and various pests don’t die en masse, says Pell. This can also lead to population growth in the spring and summer.
If the emergence of insects is hastened by warming, their numbers could peak before the arrival of the insect-eating birds or the hatching of the bird chicks. Tingley’s research suggests that some birds are migrating more as the climate warms, but only about half the current rate at which plants emerge in the spring. have been found to keep pace with plant progress. According to Deja Perkins, an avid birder and urban ecologist at North Carolina State University Raleigh, several bird species appeared earlier this year in Raleigh. “It makes me happy, but it also worries me,” she says.
Seasonal mismatches aside, early spring opens the door to another problem. Recent studies have found that climate change can exacerbate human-wildlife conflicts by altering animal habitats and behaviors. One example is bear hibernation. Mild winters and early spring lengthen the bear’s active season, allowing them to come into more frequent contact with humans to forage.
Ultimately, scientists still don’t fully understand the extent to which early springs and warm winters affect ecosystems (and our daily lives). Further long-term studies are needed to elucidate how relationships between species are affected. Citizen science projects that track events in nature can help researchers understand the effects of these seasonal changes, Perkins says. For example, Nature’s Notebook from the USA National Phenology Network The app, the California Academy of Sciences’ iNaturalist social network, and the Cornell Institute for Ornithology’s eBird app allow anyone to report seasonal changes they notice in their area.—Leaf buds, emergence of insects, observation of wild birds, etc.—and compare what they see with observations from previous years.
“For people who don’t always think about climate change on a daily basis, it really puts the focus on how things are really changing,” Crimmins says. “We could see some pretty significant effects.”
