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Can birds outfly climate change?

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As global temperatures continue to rise and ecosystems shift, animals are left with limited options. They must either adjust to the changing conditions in their habitats or relocate to cooler environments. For many species, neither choice is easy – or sometimes even possible.

Ecologists had long assumed birds were among the most adaptable species in a warming world simply because they can fly to higher altitudes or towards global poles. But a new study by researchers from Yale University found that even birds are struggling to stay ahead of rising global temperatures.

The study, which was recently published in the journal Nature Ecology and Evolution, analyzed 20 years of data from 406 bird species across North America. They found that while most birds did shift their ranges northward – by about 40 to 50 miles on average during the summer – the changes weren’t enough to keep up with the rapid pace of climate change.

Birds still experienced significant warming in their new areas when compared with temperatures in their original home range.  In fact, warming was about 1.35 degrees Celsius more in summer, and a striking 3.7 degrees more in winter. And some species, especially those with limited flight ranges or specific habitat needs, like the cactus wren, didn’t move at all.

Highly mobile birds like the blue-winged warbler did better, avoiding nearly two degrees of warming by traveling more than 100 miles north. But even they couldn’t completely dodge the heat.

The findings raise serious concerns about whether less mobile species can survive in a warming world, and underscores the urgent need to better understand and manage those most vulnerable to climate-driven extinction.

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Even birds can’t outfly climate change

Photo, posted March 1, 2023, courtesy of Henry via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Parks for bugs

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Urban areas can have a variety of green spaces:  gardens, parks, and roadside and median plantings.  It turns out that these spaces can serve as pollinator refuges.

A study by researchers at the University of British Columbia found that reducing lawn mowing and creating pollinator meadows – essentially parks for bugs – significantly boosts pollinator diversity and creates healthier and more resilient ecosystems.

The 3-year study surveyed pollinators in 18 urban parks across the city of Vancouver.  It compared parks where meadows were planted and mowing was restricted with parks that were kept as standard turfgrass lawns.

Parks with meadows saw an immediate increase in pollinator species – from 21 to 47 more wild bee and hoverfly species – compared to parks without meadows.  These increases continued over the entire three-year study period.

The researchers identified more than 100 species of wild bees and hoverflies and 35 of them were only found in parks with meadows.

People think of urban landscapes as poor environments for biodiversity, but this study demonstrated that even relatively small changes can have significant impacts.  Even a patchwork of small habitats can allow species to move freely and settle into multiple areas quickly.

The researchers had advice for urban residents as well.  They suggest that people reduce mowing, plant native flowering shrubs and trees, create diverse habitats that incorporate a variety of plants that bloom at different times, avoid pesticide use, and leave natural nesting sites for pollinators.

Preserving pollinators is an important task and having a few parks for bugs can really help.

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How ‘parks for bugs’ boost pollinators in Vancouver

Photo, posted September 19, 2011, courtesy of Eric Bridiers / U.S. Mission Geneva via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Amphibians and climate change

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Amphibians are a group of vertebrate animals that include frogs, toads, and salamanders. They are unique for their ability to live both in water and on land during different stages of life. Amphibians play a crucial role in ecosystems, often serving as both predators and prey in food webs.

Amphibians are the world’s most at-risk vertebrates, with more than 40% of species listed as threatened.  They are cold-blooded creatures and rely on external sources to regulate their body temperature.  But needing to regulate their body heat this way makes amphibians particularly vulnerable to temperature change in their habitats. 

Researchers from the University of New South Wales in Australia can now predict the heat tolerance of 60% of the world’s amphibian species.  This new tool will allow scientists to better identify which amphibian species and habitats will be most impacted by climate change.  

The study’s landmark findings, which were recently published in the journal Nature, found that 2% of amphibian species are already exposed to overheating in shaded terrestrial conditions.  According to the research team, a 4°C global temperature increase could push 7.5% of amphibian species beyond their physiological limits. 

Local amphibian extinctions can trigger ecological repercussions, including reshuffling community compositions, eroding genetic diversity, and impacting the food chain and overall ecosystem health.

The researchers highlight the importance of vegetation and water bodies in protecting amphibians during heat waves, and emphasize the need to provide adequate water and shade during future conservation efforts. 

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The pot is already boiling for 2% of the world’s amphibians: new study

Photo, posted October 8, 2011, courtesy of Dave Huth via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The importance of shallow water

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Vacationers love beaches with shallow water.  They are great for families with small kids and for less confident swimmers.  Such beaches often attract intense coastal development.  However, they are also fragile habitats that are disappearing around the world.

A new study led by the University of South Florida highlights the need to protect these marine ecosystems.  Shallow coastal waters are known as tidal flats, and they are critical to global seafood supplies, local economies, and overall marine health.  Shallow water ecosystems are interlinked with other marine habitats and are vital for the lifecycle of marine species far from shore.

Shallow water ecosystems are at risk not only from coastal development, but from harmful algal blooms triggered by human activity, from marine heatwaves, and from boats operating in sensitive habitats such as seagrass meadows. These habitats contribute millions of dollars to local economies such as those in Florida but there is not much direct habitat managements in place to protect these ecosystems.

The University of South Florida study, published in the journal Fisheries, enumerated ten core strategies that boaters, anglers, wildlife managers, and policymakers can adopt to prioritize and preserve shallow marine ecosystems from humans and from increasingly powerful weather events.  Foremost among these efforts are the protection of key fish species, such as tarpon, whose protection would benefit additional species that use the same habitats.

Habitat management and restoration should be essential concerns for coastal communities to provide long-term benefits for both themselves and for the marine life that depends on shallow-water habitats.

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Why shallow water at the beach is more important than you might realize

Photo, posted February 14, 2018, courtesy of Marcelo Campi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Sea turtles and climate change

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Life is a struggle for survival from the moment a sea turtle hatches.  In fact, only one sea turtle out of every 1,000 typically reaches adulthood as a result of natural predators and other challenges.  Those fortunate enough to make it to adulthood face serious threats from humans. For example, sea turtles are hunted for their meat, eggs, and shells in some regions. Their beach habitats get developed. Harmful marine debris and oil spills pollute their waters and beaches.

Now, climate change is exposing sea turtles to even greater threats.  Rising sea levels and stronger storms threaten to erode and destroy their nesting beaches. Warming oceans disrupt currents, potentially exposing sea turtles to new predators, and damaging the coral reefs that some depend on to survive.

As these environmental challenges intensify, sea turtles are beginning to adapt in surprising ways.  According to a new study by researchers from the University of Exeter in England and the Society for the Protection of Turtles in Cyprus, sea turtles are responding to climate change by nesting earlier.  Researchers monitoring nesting green and loggerhead turtles in Cyprus have discovered they are returning to their regular nesting spots earlier each year to compensate for rising temperatures.

Temperature plays a crucial role in determining the biological sex of sea turtles.  Warmer nest temperatures produce more female hatchlings than males.

But at least for now, sea turtles seem to be doing enough to ensure their eggs continue to hatch by nesting earlier in more ideal temperatures.  While this is good news, there’s no guarantee that it will continue. 

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Turtles change nesting patterns in response to climate change

Photo, posted December 20, 2021, courtesy of Cape Hatteras National Seashore via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Restoring English hedgerows

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Hedgerows are lines of different types of bushes and small trees growing very close together typically placed between fields or along the sides of roads in the countryside.  The network of hedges throughout rural England dates back to the Bronze Age, or even possibly Neolithic times.  As the first farmers began clearing areas of land for cultivation, they left strips of trees as boundaries.  Hedgerows act as field boundaries but also protect livestock, support biodiversity, and help mitigate climate change.

There are currently about 250,000 miles of hedgerows in England. However, about half of these important habitats were lost in the post-WWII years due to agricultural intensification.  Furthermore, a 2007 survey found that fewer than half of remaining hedgerows were judged to be in good structural condition.

The UK Centre for Ecology and Hydrology has set a target to create or restore 45,000 miles of hedgerow by 2050.  While the overall length of managed hedgerows in England has not changed much since 2007, the proportion in good structural condition has improved significantly and hedgerow height has increased.

England’s Department for Environment, Food & Rural Affairs aims to create or restore 30,000 miles of hedgerow by 2037.  However, the Climate Change Committee recommends that the national hedgerow network be increased by 40% by 2050 and the organization Natural England’s long-term aspiration is a 60% increase in hedgerow extent to support thriving plants and wildlife. 

For more information on this topic and other environmental news visit us at: earthwiseradio.org or Find us on Facebook.

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​​​​​​​Urgent need to enable more farmers and contractors to revive England’s network of hedgerows

Photo, posted May 27, 2016, courtesy of Dave S. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Regrowing forests naturally

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Deforestation is one of the major causes of climate change and restoring and enhancing forests is a major activity around the world as a way to mitigate its effects.  There are high-profile initiatives to plant millions of trees, but these projects are often ill-conceived and poorly managed.

One of the most dramatic failures was the planting of over a million mangrove seedlings on the Filipino island of Luzon back in 2012.  A study 8 years later found that fewer than 2 percent of the trees had survived.  The rest died or were washed away.

The causes of failure in tree planting programs include planting of trees that become vulnerable to disease, competing demands for land, changing climate, planting in areas not previously forested, and a lack of aftercare including watering seedlings.

A multinational study recently published in Nature has found that forests could regrow naturally on more than 800,000 square miles of land around the tropics without the need for planting trees by hand.  This is an area larger than Mexico.

The researchers mapped areas where forests would be likely to regrow – areas where soils are healthy and where there is already forest nearby to supply seeds.  In some places, lands are so degraded that it is necessary to plant trees by hand, but this is costly and prone to failure.  Forests that regrow naturally tend to fare better and make better habitats for wildlife.

The effect of regrown forests on the climate would be very substantial.  If these forests were allowed to grow for three decades, they would absorb enough carbon to offset 50 years of emissions by Australia, the home of the lead researcher of the study. 

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Tropical Forests Could Regrow Naturally on Area the Size of Mexico

Photo, posted February 16, 2018, courtesy of Jason Houston / USAID via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Flower power in agriculture

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Agriculture is the world’s largest industry.  When managed sustainably, agricultural operations can provide many environmental benefits, such as protecting watersheds and habitats, and improving soil health and water quality.  Sustainable agriculture also embraces biodiversity by minimizing its impact on wild ecosystems and incorporating numerous plant and animal varieties into farm ecosystems.

A new study of farms in India has demonstrated the power of incorporating flowers into farming practices.  According to the research by ecologists from the University of Reading in the U.K. and the M.S. Swaminathan Research Foundation in India, planting flowers beside food crops attracts bees, boosts pollination, and improves both the yield and quality of crops.

 The study, which was recently published in the Journal of Applied Ecology, is the first of its kind in India.  The researchers focused on moringa – which is a nutrient-packed superfood native to South India, and bees – the plants’ essential pollinators. 

Working alongside farmers, the researchers planted marigold and red gram crops alongside moringa trees across 12 moringa orchards.  They found that flower-visiting insect numbers and diversity were 50% and 33% higher, respectively, in orchards with floral interventions compared to those without them.  Floral interventions also led to larger moringa pods and a 30% increase in harvestable fruits.

India has many crops of high economic and nutritional value.  The study highlights how farmers can significantly improve crop pollination services and boost yields, while also managing their lands in a more sustainable manner.

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Flower power on Indian farms helps bees, boosts livelihoods

Floral interventions on farms boost pollinators and crop yields

Photo, posted June 24, 2008, courtesy of Jim via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wind turbines and bats

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Collisions with wind turbines are one of the leading causes of bat mortality in North America and Europe.  Most bat fatalities are caused by bats colliding with the rotating blades of wind turbines.  Fatalities are highest during autumn migration and on nights with low wind speeds.

According to a recent study, land-based wind turbines kill as many as 880,000 bats a year and are wiping out so many threatened bats that some species may become endangered unless preventative action is taken.

The big challenge is that bat conservation experts and scientists don’t know how to stop or reduce turbine collisions.  They don’t really know why bats are interacting with turbines to the extent that they are.  Do turbines attract bats?  Do turbines’ bright lights or just their silhouettes stimulate an attraction response?

The U.S. Department of Energy has awarded $8 million to five research centers to develop strategies for deterring bats from wind turbines. 

One of these is Bat Conservation International, which is an organization whose mission is to accelerate research to address knowledge gaps in bat ecology and behavior and develop technologies and industry methods to reduce fatality of bats at wind farms.  Among the approaches to be tested is limiting the use of nighttime lighting on wind farms to make migrating bats less likely to fly through blades. 

Another team at Boise State University is designing ultrasonic noisemakers to scare off bats. 

In announcing the new program, the Department of Energy states that wind energy must be appropriately and responsibly sited, which includes the protection of wildlife and their habitats.

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Experts Seek to Spare Bats From Wind Turbine Collisions

Photo, posted January 10, 2013, courtesy of Tom Shockey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Chasing The Ivory-Billed Woodpecker | Earth Wise

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The ivory-billed woodpecker is or was the largest woodpecker in the United States. The last unassailable sighting of the bird was in 1944.  Since then, there have various reports of glimpses of the bird or of hearing its distinctive sounds.  But there has not been anything resembling proof that the bird still exists.

Despite this, the ivory-billed woodpecker has been legally protected under the Endangered Species Act.  There has been a proposal to end that protection and formally declare the species extinct.  Because of the controversy surrounding the bird, a final ruling on its status has been repeatedly delayed by the US Fish and Wildlife Service.

Very recently, a peer-reviewed study in the journal Ecology and Evolution makes the case that the ivory-billed woodpecker still exists and that it is premature to declare it extinct.  The study cites visual encounters by expert observers, audio recordings, tree-damage, and rather grainy video evidence.  The authors claim that there is intermittent but repeated presence of birds that at least look and behave like ivory-billed woodpeckers.

One might ask:  why does it matter whether this bird is declared extinct or not?  The answer is that there are limited federal funds for conservation efforts, and they should be spent on saving genuinely endangered species and habitats.  The authors of the new study say that removing federal protection would be bad for any remaining ivory bills, which may be living in some swampy old-growth forests in Louisiana.  Other scientists consider conservation resources expended on the ivory-billed woodpecker to be chasing a ghost.

As is the case for several other notorious objects, one really clear photograph of an ivory-billed woodpecker could solve a long-standing mystery.

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A Vanished Bird Might Live On, or Not. The Video Is Grainy

Photo, posted October 19, 2014, courtesy of James St. John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Vanishing Arctic Lakes | Earth Wise

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In recent decades, the warming in the Arctic has been much faster than in the rest of the world.  The phenomenon is known as Arctic amplification.  A study by the Finnish Meteorological Institute published in August in Communications Earth & Environment determined that during the past 43 years, the Arctic has been warming nearly four times faster than the rest of the globe.  The result of this amplified warming has been that glaciers are collapsing, wildlife is struggling, and habitats continue to disappear at a record pace.

Research published by the University of Florida has identified a new threat associated with Arctic amplification: lakes in the Arctic are drying up.

Over the past 20 years, many Arctic lakes have shrunk or dried up completely across the entire pan-Arctic region, which spans the northern parts of Canada, Russia, Greenland, Scandinavia, and Alaska.

Arctic lakes are essential elements of the Arctic ecosystem and for the indigenous communities that live in the region.  They provide a critical source of fresh water for those communities and local industries. 

The rapid decline of Arctic lakes is unexpected.  Earlier predictions were that climate change would first actually expand lakes in the region as ground ice melted.  Lakes drying out was not expected until much later in this century or even in the 22nd century.  Instead, it appears that thawing permafrost may drain lakes and overwhelm the expansion effect caused by melting ice.  The theory is that thawing permafrost decreases lake area by creating drainage channels and increasing soil erosion.

The finding suggest that permafrost thawing is occurring faster than anticipated, which presents many additional problems.

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As the climate crisis intensifies, lakes across the Arctic are vanishing

Photo, posted June 20, 2014, courtesy of Bob Wick / Bureau of Land Management via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Beavers Are Flooding The Warming Arctic | Earth Wise

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The accelerating warming in the Arctic has transformed the region into a warmer, wetter, and more diverse environment.  Warming temperatures have encouraged the increasing growth of vegetation, particularly shrubs that provide beavers with bark to eat and branches to build with.  Warming temperatures also mean that lakes and streams freeze solid for shorter periods of time or not at all, allowing beavers to pursue their construction projects for longer periods during the year.

Prior to the mid-1970s, residents of the Alaskan Arctic encountered few beaver ponds.  In 2018, researchers using satellite imagery mapped 12,000 beaver ponds in Alaskan tundra.

Beavers are causing major changes in the streams and floodplains that many small Alaskan villages depend upon for food, water, and navigation.  As the rodents transform lowland tundra ecosystems, they are eliminating food sources, deteriorating water quality, and making it difficult to navigate waterways.

The migration of beavers across the Arctic landscape is largely a result of climate change.  But it is also becoming one of the factors amplifying climate change.  Scientists are trying to figure out the degree of permafrost thawing that beaver dam-and-den building is causing and how fast these defrosted organic soils will degrade and release trapped carbon and methane.

Beaver dams alter the hydrology of streams by slowing the flow, storing and spreading water to create wetlands, raising the water table, and lowering the oxygen content of the water. 

Climate-driven changes in species distributions affect human well-being as entire ecosystems continue to change.  Shifts in animal habitat stimulated by climate change could have profound consequences across the globe.

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Beavers Are Flooding the Warming Alaskan Arctic, Threatening Fish, Water and Indigenous Traditions

Photo, posted June 12, 2018, courtesy of Peter Pearsall/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Plastic-Eating Bugs | Earth Wise

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27-year-old Miley Cyrus and 30-year-old Liam Hemsworth divorced exactly one year ago, but still continue to remember each other quite often in conversations with reporters. Recently, Miley indulged in nostalgia once again. During a recording Miley Cyrus boyfriend list of the podcast Barstool Call Her Daddy, the singer said that her ex-husband was her first man. It happened almost 10 years before they got married. I didn’t have that with men until I was 16, but I ended up marrying this guy,

According to a new study, microbes in oceans and soils around the world are evolving to eat plastic.  The study by Chalmers University in Sweden was published recently in the journal Microbial Ecology.

The study is the first large-scale assessment of the plastic-degrading potential of bacteria.  There are 95 microbial enzymes already known to degrade plastic. 

The researchers looked for similar enzymes in environmental DNA samples taken from bacteria from 236 different locations around the world. They found that one in four of the organisms analyzed carried suitable enzymes.  Overall, they found many thousands of new enzymes.

The explosion of plastic production in the past 70 years has given microbes time to evolve to make use of plastic.  About 12,000 new enzymes were found in ocean samples and 18,000 in soil samples.  Nearly 60% of the new enzymes did not fit into any known enzyme classes, suggesting that these molecules degrade plastics in ways that were previously unknown.  The large number of enzymes in such a wide range of habitats is an indication of the scale of the problem of plastics in the environment.

The first bacterium that eats plastic was discovered in a Japanese waste dump in 2016.  Scientists tweaked that microbe in 2018 and managed to create an enzyme that was even better at breaking down plastic bottles.

The next step in research is to test the most promising enzyme candidates in the laboratory to investigate their properties and see how effective they can be in plastic degradation.  The hope is to be able to engineer microbial communities with targeted degrading functions for specific polymer types.

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Bugs across globe are evolving to eat plastic, study finds

Photo, posted June 19, 2013, courtesy of Alan Levine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Importance Of Urban Green Spaces | Earth Wise

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Projections are that 68% of the global population will be living in cities by 2050.  It is therefore not surprising that urban green spaces are critically important for promoting mental and physical well-being.

An international study, published in Science Advances, took soil samples from different types of urban green spaces and comparable neighboring natural ecosystems in 56 cities from 17 countries across six continents.

The study concluded that even roadside plantings contribute a range of important microbial communities that are critical for sustaining productive ecosystems services, such as filtering pollutants and sequestering carbon dioxide.

Parks and gardens constitute most of the open spaces available for recreational activities in cities and play important roles in curbing pollution, reducing noise, and lowering air temperatures.

In addition, human exposure to soil microbes has been shown to be beneficial to human health by promoting effective immunoregulation functions and reducing allergies. The study found that city parks and even roadside plantings support a great variety of different microbes that are different from natural ecosystems. 

We think of roadsides as being barren but the vegetation along footpaths and roadsides are important microbial habitats.  Some European cities, such as Bern in Switzerland, have instituted policies to protect the natural vegetation along footpaths and roadsides.

The new study is a part of a series of research efforts looking at the important of green spaces for ecosystem health.  As the world becomes increasingly urbanized, every bit of greenery in cities and highways is important and is needed for sustaining a healthy environment.

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Every spot of urban green space counts

Photo, posted June 3, 2013, courtesy of Manuel MV via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Plastic Pollution And The Galapagos Islands | Earth Wise

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The proliferation of plastics remains one of the world’s most challenging environmental problems.  Plastic pollution can be found in some of the most remote regions of the planet, including atop the world’s tallest mountains and in the deepest depths of the ocean.  Even the Galapagos Islands, a volcanic archipelago in the Pacific Ocean, are no exception.

According to a new study by researchers from the University of Exeter, the Galapagos Conservation Trust, and the Galapagos Science Center, plastic pollution has been found in seawater, on beaches, and inside marine animals at the Galapagos Islands. 

In the most polluted hotspots, more than 400 plastic particles were found per square metre of beach. The researchers found that only 2% of macroplastic pollution – plastic fragments larger than five millimeters – was identified as coming from the Galapagos islands. All seven of the marine invertebrate species examined – 52% of individuals tested – were found to contain microplastics.

Significant accumulations of plastic were also found in key habitats, including rocky lava shores and mangroves. In fact, plastics were found in all marine habitats at the island of San Cristobal, which is where Charles Darwin first landed in Galapagos.

Most of the plastic pollution in the Galapagos appears to arrive via ocean currents. According  to the research team, the highest levels of plastic pollution were found on east-facing beaches, which are exposed to pollution carried across the ocean on the Humboldt Current. 

The pristine images of the Galapagos, a world-famous biodiversity haven, might give the impression that the region is protected from plastic pollution.  But clearly that is not the case.

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Plastic in Galapagos seawater, beaches and animals

Photo, posted April 12, 2012, courtesy of Ben Tavener via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Assisted Colonization | Earth Wise

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As the pace of climate change continues to quicken, many species seem to be unable to keep up and could face extinction as a result.   There is a potential strategy for people to help species reach places with more suitable physical and biological conditions.  People could carry endangered animals to habitats cut off by mountains, rivers, or human-made barriers.  They could plant endangered trees higher up mountain slopes or to locations further north.  Such actions have been termed assisted colonization.

People have been moving species around the world throughout human history for various reasons either intentionally or inadvertently.  But as a conservation strategy, assisted colonization is quite controversial.

The argument is whether the risk of moving species to more favorable conditions outweighs the risk of inaction.  The salvation of one species could mean the destruction of another.   A species that seems perfectly innocuous when moved to one place can become a rampant invader in another.

An upcoming international conference on Biological Diversity to be held this fall in China may take up the issue of creating a set of guidelines on assisted colonization.   Such guidelines would help people assess which species to focus on; where, when, and how to move them; how to weigh the risks of action and inaction; and how to conduct such actions across international borders.  Assisted colonization may be useful in some instances and not in others.  There needs to be a way for the world to decide whether it is warranted or not.  With climate change posing a growing threat to many of the world’s species, this is an issue that should be addressed.

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Amid Climate Pressures, a Call for a Plan to Move Endangered Species

Photo, posted July 16, 2014, courtesy of Mark Spangler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Living On Trash | Earth Wise

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Litter is persistent and widespread in rivers worldwide.  The world’s major rivers and estuaries are hotspots for plastic waste.  Trash and microparticles wash down tributaries and build up before rivers enter oceans.

New research published in the journal Freshwater Biology has found that as this waste accumulates, aquatic river species like insects and snails are increasingly choosing to settle on plastic rather than on natural features like rocks and fallen branches.

Researchers from the University of Nottingham in the UK collected plastic waste from three rivers in eastern Britain along with rocks from the same rivers.  Their analysis of all the macroinvertebrates on the items’ surfaces found that the surfaces of plastic waste items had nearly four times the diversity of the small animals as did the rocks.  In addition, the more complex the plastic’s surface was, the higher the diversity.

The growing abundance of plastic waste coincides with a decline in natural habitat features in urban rivers.  This is a result of increasing amounts of sedimentation from development that blankets riverbeds in silt and sand, restricting the supply and movement of rocks, fallen tree branches, and aquatic plants.

Clearly litter can serve as a place for various species to colonize, but trash is not a good environment for them.  Trash can release toxic chemicals and entangle animals.  Microplastics pose risks for the animals if ingested.

Estimates are that between 1.15 and 2.41 million tons of plastic waste enter the ocean every year from rivers around the world.  Natural habitats have become rare in urban rivers.  River ecosystems built around piles of trash are not a good thing.

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As Plastic Pollution in Rivers Gets Worse, Species Are Increasingly Living on Litter

Photo, posted August 17, 2010, courtesy of Renee_McGurk via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carnivores Eating Human Food | Earth Wise

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A recent study by ecologists at the University of Wisconsin-Madison has found that carnivores living near people often get more than half of their diets from human food sources rather than from their traditional prey.  This represents a major lifestyle disruption that puts North America’s carnivore-dominated ecosystems at risk.

The researchers studied the diets of seven predator species across the Great Lakes region using bone and fur samples taken from animals from areas as remote as national parks to metropolitan areas including Albany, New York.  What they found – unsurprisingly – is that the closer carnivores lived to cities and farms, the more human food they ate.  Dietary contributions of human food varied with species, but on average was more than 25% in most human-altered habitats.

The researchers studied the diets of carnivores like bobcats, coyotes, red and gray foxes, fishers, and American martens by chemical analysis of samples from Minnesota, Wisconsin, upstate New York, and the Upper Peninsula of Michigan.  The diets of the animals could be analyzed on the basis of the carbon content of bone and fur samples.  Human food, heavy in corn and sugar, lends these samples a distinctive carbon isotope signature.  In contrast, prey species confer their own carbon signatures.  The ratio of these isotope fingerprints provides information on the proportion of an animal’s diet that came from human sources.

Relying upon human food increases how much carnivores overlap one another in their competition for food.  Compared to when these predators vie for distinct prey, there can be more conflicts between animals.  Changing how a species gets their food can have far-ranging effects on ecosystems.

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Carnivores living near people feast on human food, threatening ecosystems

Photo, posted August 18, 2007, courtesy of Jitze Couperus via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Native Bees In A Honeybee World | Earth Wise

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There is a great deal of attention on the plight of bees and other pollinators.  Much of that focuses on the problems plaguing the large, domesticated honeybee colonies that are trucked from region to region to pollinate everything from almonds to fruit trees.  Managed bee colonies have recently been losing more than 40% of their population over the course of a year.  But overall, honeybees are still relatively safe. They are a globally distributed, domesticated species and are not remotely threatened with extinction.

But another group of bees – native bees – faces a different range of threats, most linked to habitat loss.   Worldwide, roughly 20,000 native bee species have evolved over millions of years to thrive in countless habitats, where they have specialized in pollinating specific flowers and plants – in some cases just a single plant.

Scientists have estimated that, globally, 1 in 6 bee species is regionally extinct. In the United States there are about 4,000 native bee species, most of which are solitary bees that nest in the ground or cavities, with many that require just one or a few plant species for sustenance. At least 23 percent of U.S. native bees have declined, with bees in areas with heavy commodity-crop production particularly hard hit due to habitat loss and pesticide use. Other threats to native bees include climate-driven sea-level rise and increased temperatures, loss of host plants, and competition and disease from non-native honeybees. 50% of Midwestern native bee species disappeared from their historic ranges in the last 100 years.   Four of our bumblebee species declined 96% in the last 20 years, and three species are believed to already be extinct. 

Native bees are in big trouble.

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Backyard Battle: Helping Native Bees Thrive in a Honeybee World

Photo, posted December 2, 2017, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Beavers And The Warming Arctic | Earth Wise

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Beavers have a remarkable ability to transform landscapes.  Using their sharp teeth, they fell trees and shrubs and build dams, which cause small valleys to fill with water and form new lakes.  Some of these lakes measure five or ten acres in size, or even more.  And beavers are very efficient builders; they often build their dams at precisely those points where can they have the greatest effect with the least effort.

Scientists studying beaver activity in the Arctic regions of Alaska have found that the changing climate is leading to a substantial increase in beaver populations and their effect on the landscape.

In 2018, researchers found that the beavers living in a 7,000 square-mile area in northwest Alaska had created 56 new lakes in just five years.  Thanks to rising temperatures, more and more habitats offer the shrubs that beavers need for food and building material.  In addition, the lakes, which used to freeze solid, now offer beaver-friendlier conditions.  Also, beavers are not hunted as intensively as in the past.

The scientists were surprised that beavers have seized the opportunity so intensively.  There is basically an exponential growth in beaver dams.  This is actually a worrisome situation.  Forming all these new lakes degrades ice-rich permafrost in the area.  In the Kotzebue region of Alaska, the overall water area has increased by more than 8% over the past 17 years, and roughly two-thirds of that is due to beavers.

The degradation of the Arctic’s permafrost is a dangerous situation and it appears that anyone who wants to predict its future has to keep the activity of beavers in mind.

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Beavers gnawing away at the permafrost

Photo, posted June 23, 2018, courtesy of Becky Matsubara via Flickr.

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