Pollinators threatened by climate change

By Laura Fitzgerald
Posted 6/19/19

Beekeeper Richard Sullivan pried the gate guarding the Orange County Arboretum’s two bee hives open, snow and ice crunching against the wood.

Resembling stacked wooden boxes, the bees were …

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Pollinators threatened by climate change

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Beekeeper Richard Sullivan pried the gate guarding the Orange County Arboretum’s two bee hives open, snow and ice crunching against the wood.


Resembling stacked wooden boxes, the bees were snuggled safely inside their hives. Sullivan pressed his ear to the hive and tapped the other side.


“They’re alive,” Sullivan said, slightly surprised.


He has a reason to be surprised: while never an easy task, beekeeping is becoming more difficult in the Hudson Valley as a changing climate affects their food source and the bees themselves.


Tom Sotridity, owner of Mountain View Apiary, said while beekeepers always expect a certain number of bees to die in the winter, beekeepers in recent years have been experiencing larger percentages of their bees dying.
A winter colony loss survey from the Bee Informed Partnership shows the average bee die-off percent increasing from 2007-08 to 2017-18 in New York state.


“People are having a harder time keeping their bees alive,” Sotridity said. “Bees are having a harder time making their living, having enough honey to live through the winter, getting enough pollen to be able to create the necessary population for the winter.”


Sullivan said warmer winter weather causes bees to be more active and use their winter food stores more quickly.


The Mohonk Preserve climate data, gathered from a weather station at Mohonk Lake that collected weather data daily from 1896 to 2006, shows a warming trend consistent with the southern Hudson Valley of between 1 and 2 degrees Celsius over the century.


The number of freeze days, or days in which the minimum temperature reached or fell below 0 degrees Celsius, increased.


Variable temperatures, especially during winter, wreak havoc because bees will venture outside the hive and away from their food source during the day when it’s warm. To stay warm in the winter, bees form a tight ball within the hive, sharing their body heat. When it gets cold at night, bees die off away from their warmth and food source.


The Mohonk data also shows a 100-millimeter precipitation increase over the twentieth century, driven largely by an increase in precipitation in September, October and November. The data also shows a marginal tendency towards extreme precipitation events after the 1960s Northeast drought.


Variable weather patterns also affect the bees’ food source. An excess of moisture, such as the past year, and changing temperatures, affects the bloom time of flowers and pollen content. Called a phenological mismatch, bees collect their food at the same time each year, so a movement in times disrupts bees’ foraging and damages hive health.


Sotridity said an increase in carbon dioxide in the atmosphere and a decrease in oxygen also affects pollen in the plants in which honey bees storage, causing poor nutritional value.


The impacts from climate change are also compounded by the varroa mite, a common parasite that feeds on bee blood and fat stores, weakening honeybee colonies and transmitting deadly viruses across the colony. The mite originated in Asia, and was introduced to the U.S. in the 1980s. Bees who are already stressed by climate change are more susceptible to the diseases these mites bring.


There are many factors that affect bee health and cause colonies to collapse or die; climate change is just one of them.


“It’s a perfect storm. It’s not one thing; it’s a whole pile of things,” Sotridity said.


Phenological mismatches caused by a changing climate also affect another tiny pollinator: birds.


Mohonk Preserve Research Ecologist Megan Napoli said migrating birds must time their arrival perfectly to coincide with their food source availability. When birds arrive at different dates than usual, their food source may not be available.


While Napoli said Mohonk has not conducted species-specific studies examining these mismatches, the preserve has recorded a change in migration patterns.


The ruby-throated hummingbird, red-winged blackbird, eastern towhee and chipping sparrow started arriving earlier from the period of 1996-2017 versus when study began in 1934, varying from six to 20 days earlier than their original migration pattern.


The Mohonk Preserve also reported some species that were once migratory are now year-round residents. The American robin, turkey vulture, song sparrow, Carolina wren and brown-headed cowbird have ceased migrating.


The National Audubon Society’s Birds and Climate Change Report shows that approximately 100 bird species are at risk of losing range or will migrate.


Senior Climate Scientist Brooke Bateman said as birds lose range due to changes in climate, they might also gain range further north. Some species might benefit by gaining new range.


However, just because a species might be suited to the climate of a new area, that habitat might not have other necessary elements needed to survive, such as food or shelter; some species will be threatened by range shifts.


“It’s going to be a mixed bag,” Bateman said.


An earlier arrival date might also make birds susceptible to cold snaps, which kill insects birds depend on and has negative physiological impacts on birds’ bodies.


Bateman said birds play an essential role in the environment by pollinating plants, disbursing seeds, and regulating insects. The elimination of birds from a location can have unforeseen cascading effects that affect the entire ecosystem, such as an increase in insects, which destroy crops and other plants.


Honeybees also play a vital role in the ecosystem, playing a vital role in much of the world’s food supply.
Honeybees are the largest crop pollinator in the country, contributing nearly $20 billion to the value of U.S. crop production, according to the American Bee Keeping Federation. As honeybees travel from flower to flower to gather pollen and nectar, they pollinate crops such as apples, cherries, melons, broccoli and more.

climate change, birds, bees, pollinators