Monday, February 29, 2016

Wacky winter weather confounding plants and animals

The weather this winter in southern New England has been far from typical, and it is having serious implications for wildlife and natural history phenomena. The official temperature at T.F. Green Airport on February 1 reached 66 degrees, a record high for the date, but two weeks later on Valentine’s Day it plunged to minus-9, the coldest temperature in Rhode Island in more than three decades. A week later, it was back in the 60s again. And on February 24, the National Weather Service issued a severe thunderstorm warning, the first time it has ever done so in February. That follows a warmer than usual January and record warmth in December.
            The periods of warm weather in February triggered daffodils, crocuses and other early-blooming flowers to sprout a month or more before they usually do. Wood frogs and spring peepers were observed hopping across roads and chirping loudly in vernal pools in many locations during the last week of February, which is also several weeks earlier than usual. And Keith Killingbeck, a professor of botany at the University of Rhode Island, noticed a red maple tree with flower buds expanding almost two months early on February 25.
Crocuses blooming in Providence (photo by Frank Carini/EcoRI)
If the weather remains warm, these plants and animals shouldn’t experience any ill effects. But what will happen if the deep freeze returns, as it often does in March?
“Early spring plants are pretty tolerant of cold temperatures,” Killingbeck said, “but it depends on how cold it gets and how long those cold temperatures last.  It’s in the realm of possibility that flowers could pop open, bloom and get zapped by a long, cold frost and be toast for the season. A lot of trees are susceptible, too. That’s a lot of energy the plants and trees expend for nothing.”
Killingbeck said that such an event would not affect the survival of the plants, but it eliminates an entire year of reproduction.
Frog and salamander reproduction could be affected, too. In a typical year, evening rains in mid- to late March trigger wood frogs, spring peepers and spotted salamanders to migrate from their wintering locations among the leaf litter and in shallow burrows to temporary pools and small ponds, where they mate and lay their eggs. But the warm weather in late February triggered some to begin their migrations several weeks early. The return of winter conditions in March could jeopardize any eggs that have already been laid.
Lou Perrotti, director of conservation programs at Roger WilliamsPark Zoo and an expert on reptiles and amphibians, said that wood frogs are especially cold hearty and will hunker down until the weather is just right. “The males arrive [in their breeding ponds] first and start calling the girls down, but if it is too cold they will not call and the girls will not move,” he said. “So breeding won’t happen until the temperatures and precipitation are optimal.”
It’s not unusual for a thin layer of ice to form on amphibian breeding ponds after the frogs and salamanders have laid their eggs, according to URI herpetologist Peter Paton. Some eggs may die as a result, he said, but those submerged below the surface should survive. And the adult frogs are usually able to avoid being trapped under the ice by exiting the pond.
Paton does worry, however, about repeated cold and warm spells in March. Wood frogs and spring peepers survive the winter by slowing their metabolism, dropping their body temperature, and allowing the water in their bodies to freeze solid. They survive unharmed thanks to the production of a concentrated sugar solution that acts as an anti-freeze to protect their organs.
“But I don’t know how many times they can withstand freezing and thawing in one season,” he said. “They might not do well if they have to keep doing it.”
Plants and amphibians aren’t the only wildlife that seems to be a bit confused by the weather. On February 25, David Gregg, executive director of the Rhode Island Natural History Survey posted a video on Facebook of a group of bees swarming around his bird feeder. He said it appeared as if the bees were licking the sunflower seeds.
“I understand that one of the concerns about global warming is the mismatch between bees and flowers,” he said. “The bees are active because the weather’s warm, but there aren’t any flowers out yet for them. So maybe that causes them to go after alternative food courses such as my bird seed."
Climate change may well be playing a role in the unusual weather this year, but also playing a role is this year’s strong El Nino, which changes weather patterns in complex and unpredictable ways.
"This overriding element of global warming is impacting everything on our planet,” said Killingbeck, “and then on a little less universal scale, the El Nino year on top of that is messing with certain pockets of the globe as well.”
But he said that all is not lost for this year. At least not yet.
“We’re at a critical time right now,” he said. “It all depends on what happens in the next month. It could still get back to normal. If we get back to more seasonable temperatures in March, the plants should do what they usually do in spring. Or we could have 70 degrees in March and all bets are off.
“But just because we’ve had a wacky winter doesn’t necessarily mean we won’t have a normal spring,” he concluded.

This article first appeared in EcoRI on February 29, 2016.

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