For Birds, Animals – Climate Change Means Migration, Mating Mismatch

April 6, 2018

New York Times:

Every year, as the seasons change, a complex ballet unfolds around the world. Trees in the Northern Hemisphere leaf out in the spring as frost recedes. Caterpillars hatch to gorge on leaves. Bees and butterflies emerge to pollinate flowers. Birds leave the Southern Hemisphere and fly thousands of miles to lay eggs and feast on insects in the north.

All of these species stay in sync with each other by relying on environmental cues, much as ballet dancers move to orchestral music.

But global warming is changing the music, with spring now arriving several weeks earlier in parts of the world than it did a few decades ago. Not all species are adjusting to this warming at the same rate, and, as a result, some are falling out of step.

Scientists who study the changes in plants and animals triggered by seasons have a term for this: phenological mismatch. And they’re still trying to understand exactly how such mismatches — like the blooming of a flower before its pollinator emerges — might affect ecosystems.

In some cases, species might simply adapt by shifting their ranges, or eating different foods. But if species can’t adapt quickly enough, these mismatches could have “significant negative impacts,” said Madeleine Rubenstein, a biologist at the United States Geological Survey’s National Climate Change and Wildlife Science Center.

“If you look at the past history of climate on earth, there has never been such a dramatic, rapid, change in the climate,” said Andrea Santangeli, a postdoctoral researcher at the Finnish Museum of Natural History. “Species have to respond really fast,” he said, “that’s really unprecedented.”

Here are examples of mismatch, just one of the many threats that species face from global warming, that scientists have discovered so far:

An orchid’s sex life turns bleak

The early spider orchid relies on deception to reproduce. Each spring, the orchid, whose bulbous crimson body looks like an insect, releases a pheromone that tricks solitary male bees into thinking the plant is a mating partner — a key step for pollination.

This ruse, which scientists call pseudocopulation, works because the orchid tends to bloom during a specific window each spring — shortly after lonely male bees emerge from hibernation but before female bees appear.

Yet with spring coming earlier, female bees are now emerging sooner and luring the male bees away from the lovelorn orchid, according to a 2014 study from Britain.

By examining data collected in herbariums and in the field over a century, the researchers found that the gap between the times when male bees and female bees emerge shrinks by about 6.6 days for each degree Celsius of warming, giving the orchid less opportunity to reproduce.

“The main finding is that things are getting increasingly bad for orchid pollination,” said Anthony Davy, a professor of biological science at the University of East Anglia, and the lead author of the paper. For this orchid — which is already rare — the future looks bleak, he said.

Spring comes early, but the flycatcher doesn’t

The European pied flycatcher runs on a tight schedule each spring.

From its wintering grounds in Africa, the bird flies thousands of miles north to Europe to lay eggs in time for the emergence of winter moth caterpillars, which appear for a few weeks each spring to munch on young oak leaves.

By timing this just right, the flycatchers ensure there’s enough food around when their hungry chicks hatch. In a series of studies in the 2000s, however, scientists in the Netherlands showed that many flycatchers were starting to miss this narrow window.

As spring temperatures warmed, oak trees were leafing out earlier and peak caterpillar season was arriving up to two weeks sooner in some places. But many flycatchers, which appear to schedule their departure from Africa based on the length of day there, were not getting to Europe early enough for their spring meals.

In the parts of the Netherlands where peak caterpillar season had advanced the fastest, the scientists later found, flycatcher populations dwindled sharply. “That was the big discovery that suggested this mismatch could have real consequences for populations,” said Christiaan Both, an ecologist at the University of Groningen.


2 Responses to “For Birds, Animals – Climate Change Means Migration, Mating Mismatch”

  1. J4Zonian Says:

    The window for donating to primary campaigns seems to get earlier every year, and many progressives, still relying on photoperiod (the increase in photo ops as media begins its yearly cycle of covering the wrong candidates and telling the wrong stories), fail to wake up from winter slumber enough to contribute meaningfully.

  2. rabiddoomsayer Says:

    Finally you are getting why the rate of change is so very important and not just the final magnitude. Had the change been slow enough then species would adapt, but now the speed of change is too fast. Unfortunately the pace of change will only increase.

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