Earth Wise

A look at our changing environment.

You are here: Home / Archives for predators

predators

Harnessing The Smell Of Fear | Earth Wise

By Leave a Comment

Plant-eating insects present a major problem for farmers and home gardeners.  Aphids, for example, are a highly destructive pest to many crops.  Their large numbers and ability to transmit plant pathogens make them a persistent problem for growers.

Pesticides are chemical substances that are commonly used to prevent, destroy, repel or mitigate pests.  They include insecticides for insects, rodenticides for rodents, herbicides for weeds, and fungicides for microorganisms.  According to the U.S. Geological Survey, approximately one billion pounds of these chemicals are used in the United States every year.     

But pesticides can also contaminate soil, water, and other vegetation, as well as kill many non-target species.  Exposure to these chemicals is dangerous for human health. 

According to a new study, researchers from Pennsylvania State University have developed a way to bottle the “smell of fear” produced by predators in order to repel and disrupt pests naturally without the need for these harsh substances.  The researchers recently presented their findings at the American Chemical Society meeting.  

Aphids happen to be a favorite food of ladybugs. Aphids and other herbivorous insects will steer clear of fields and gardens if they smell predators nearby.  The researchers identified and extracted the volatile odor profile from ladybugs.  The researchers used the compounds to create a special odor blend that can be used in an essential oil diffuser to spread the scent across a garden or field. 

The research team plans to conduct field tests to see if the effects outside are similar to what was observed in the lab.  A natural and effective pest repellent would be a big win for people and the planet.  

**********

Web Links

Protecting gardens and crops from insects using the ‘smell of fear’

Protecting gardens and crops from insects using the ‘smell of fear’ (YouTube)

Photo, posted May 10, 2011, courtesy of DM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Collapse of Northern California Kelp Forests | Earth Wise

By Leave a Comment

For thousands of years, thick canopies of kelp formed an underwater forest spanning the coast of Northern California.  Kelp is the cornerstone of a rich subtidal community, providing food and habitat for all sorts of marine creatures.  But in recent years, a shocking transformation has occurred.  Satellite imagery reveals that the area covered by kelp forests off the coast of Northern California has declined by more than 95%.  Only a few small, isolated patches remain.  

In a new study, researchers at the University of California Santa Cruz found that the kelp forest decline was an abrupt collapse as opposed to a gradual decline. 

According to the study, which was recently published in the journal Communications Biology, kelp forests north of San Francisco were resilient to warming events in the past, like El Niños and marine heatwaves. But the decline of a key sea urchin predator – the sunflower sea star – from sea star wasting disease caused the kelp forests’ resiliency to plummet.  Sea urchins are voracious consumers of kelp.     

But it was a series of events – not just the sea urchins – that combined to decimate the Northern California kelp forest.   A marine heatwave that became known as “the blob” developed in 2014 and moved down the West Coast in 2015.  Around the same time, a strong El Niño event developed and brought warmer water up the coast from the south.  The warming ocean waters combined with the ravenous sea urchin population resulted in the dramatic decline of kelp. 

According to researchers, the prospects for a Northern California kelp forest recovery remain poor unless sea urchin predators return to the ecosystem. 

********** 

Web Links

The collapse of Northern California kelp forests will be hard to reverse

Photo, posted August 13, 2019, courtesy of Sara Hamilton of OSU College of Science via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Assisting Evolution | Earth Wise

By Leave a Comment

As plants and animals around the world grapple with climate change, invasive species, disease, and other threats, conservationists grapple with the issue of what it means to protect what is natural and how far to go to prevent extinctions.

Australia is where many of these issues have risen to the forefront.  Imported mammals – particularly cats and foxes – have decimated many of Australia’s indigenous marsupials.  Much of the focus for decades has been on killing off the invaders and cordoning off protected animals.  In recent years, however, there have been efforts to expose prey animals to limited numbers of predators to develop prey populations that are better equipped to survive among predators.  Getting rid of all the predators is not realistic.  Saving species may require helping them to adapt.

On the Great Barrier Reef, where half its coral populations have perished because of rising water temperatures, scientists are breeding corals that are more heat tolerant.  They are even considering the use of gene editing technology to “assist evolution” in developing corals that can survive in a changing world.

At SUNY College of Environmental Science and Forestry in Syracuse, New York, researchers have produced a genetically modified American chestnut tree that is resistant to chestnut blight, the fungal pathogen that killed off nearly every chestnut tree in North America in the early 20th century.

The idea of conservation is to protect what is natural in our world.  However, at a time when there are unprecedented threats to so many species, the distinction between what is natural and what is artificial may no longer provide a sound guide to what should be done to protect life on earth.

**********

Web Links

Assisting Evolution: How Far Should We Go to Help Species Adapt?

Photo, posted November, 2000, courtesy of Bernard Dupont via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

What’s Killing Orcas? | Earth Wise

By Leave a Comment

With their characteristic tall dorsal fins and black and white color patterns, orcas are one of the ocean’s most iconic species.  Measuring up to 32 feet long and weighing as much as 6 tons, orcas have one of the largest geographic distributions of any species.  They live in all latitudes, in all oceans, from the Arctic to Antarctica.    

While they are often referred to as killer whales, orcas are actually not whales at all.  Orcas are the largest dolphin species and one of the most powerful predators on the planet. 

But human interference has made life significantly more difficult for orcas in recent years.  According to pathology reports on more than 50 orcas stranded over nearly a decade in the northeast Pacific and around Hawaii, the predators face a myriad of mortal threats.  Many of those threats stem from human interactions. 

Researchers from the British Columbia Ministry of Agriculture analyzed these orca pathology reports in a new study, which was recently published in the journal PLOS ONE,.  Of 52 orcas stranded between 2004 and 2013, causes of death were determined for 42%. For example, one orca died after receiving a halibut hook injury. Two orcas died from the blunt force trauma of vessel strikes. While there was no singular common cause of death, the study found a common theme:  human-caused deaths occurred in every age class – from juveniles to adults.

The researchers also note that humans aren’t just indirectly hurting orcas with things like lack of salmon or legacy toxins.  Humans are also directly killing killer whales with boat strikes and fishing gear.   

These findings will help establish a baseline of information to assess future orca conservation efforts. 

**********

Web Links

What’s killing killer whales?

Photo, posted July 5, 2009, courtesy of Rennett Stowe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Global Decline In Wildlife | Earth Wise

By Leave a Comment

According to a new report released by the World Wildlife Fund, global populations of mammals, birds, amphibians, reptiles, and fish have declined by 68% in less than half a century. 

The report presents a comprehensive overview of the state of the natural world based on the tracking of almost 21,000 populations of more than 4,000 vertebrate species between 1970 and 2016. 

The report shows that the main cause of the dramatic decline in species populations on land is habitat loss and degradation, which includes deforestation driven by food production.  Additional factors include land-use change and the use and trade of wildlife.

Wildlife populations found in freshwater habitats have suffered a decline of 84%, which is the steepest decline in any biome.

Insect populations have declined rapidly in many places, but most of the information about insects comes from a small number of countries in the northern hemisphere.  There is very little information from large parts of the world, such as Africa, South America, and Asia, where land-use change and agricultural expansion are happening fast.  What happens to insects matters a lot to humanity.  Insects play central roles in the world’s ecosystems as waste processors, pollinators, predators, and prey. 

The report is clear evidence of the damage human activity is doing to the natural world.  Threats to the integrity of ecosystems endanger humans and all of nature.  This is especially apparent in the midst of a global pandemic.  It is now more important than ever to take coordinated global action to halt and reverse the loss of biodiversity and wildlife populations across the globe.

**********

Web Links

Living Planet Report reveals 68% decline in global wildlife populations since 1970

Photo, posted May 7, 2020, courtesy of Bernard Spragg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Too Many Bison | Earth Wise

By Leave a Comment

The population of large herbivores in Yellowstone National Park has undergone many dramatic changes over the course of time.  The numbers of both the iconic Rocky Mountain elk and bison have gone up and down as a result of human interactions.

Bison, of course, once were a dominant species from east of the Appalachians to west of the Rocky Mountains, with most of an estimated 30 million living on the Great Plains.  As the west was settled, bison populations plummeted and by the late 1800s, they were nearly extinct.

When Yellowstone was established, there were exactly 22 bison in the park.  By 1925, there were more than 750 in the park and culling of the herd in the park’s Lamar Valley was practiced for the next four decades.

The elimination of predators like grey wolves and cougars in the early 1900s caused both elk and bison populations to mushroom and both underwent culling.  When culling was ended in 1968, there were 4,000 elk and 100 bison.  Within 20 years, those numbers were 20,000 and 1,000.   Reintroducing wolves and cougars reduced the elk population to about 5,000, but bison numbers have continued to grow, now reaching about 4,000.

While the long-term recovery of the Yellowstone bison herd is a major conservation success story, the fact is that bison are powerful ecosystem engineers.  Large numbers of them disrupt species distribution across scrub steppe and grasslands because of what they eat, trample, and rub their horns and bodies on.  They have a tremendous capacity to limit the structure and composition of ecosystems.

Park administrators have complicated management decisions to make to take into account the often wide range of ecological effects that abundant large herbivores can have on ecosystems.

**********

Web Links

Bison in northern Yellowstone proving to be too much of a good thing

Photo, posted August 10, 2016, courtesy of Brian Gratwicke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Beavers And Biodiversity

By Leave a Comment

Beavers are large, semi-aquatic rodents known best for their ability to construct dams, canals, and lodges (their homes).  They are among the largest rodents in the world.  With powerful jaws and strong teeth, beavers fell trees to use as building materials, often changing their environment in ways few other animals can. But in a good way.  As it turns out, beavers are important for biodiversity. 

According to new research from the Faculty of Natural Sciences at the University of Stirling in Scotland, reintroducing beavers to their native habitats is an important step towards solving the freshwater biodiversity crisis. 

Researchers surveyed water plants and beetles in 20 wetlands in Sweden – 10 created by beavers and 10 that were not – in order to understand what impact beavers might have on the variety of plant and animal life around them. 

The research team’s findings build on previous work that has shown that beavers have an important impact on biodiversity.  This latest study discovered that the number of species found only in beaver-built ponds was 50% higher than in other non beaver-built wetlands in the same region. 

Beavers are known to be profound engineers of the environment. They use wood to build dams across rivers in order to form ponds behind them.  They do this to raise the water level in order to avoid predators, like bears and wolves. But it turns out many other plants and animals, like water plants and beetles, also benefit from their work.

According to the research team, reintroducing beavers to their native habitats should benefit the wider biodiversity and be seen as an important step towards solving the freshwater biodiversity crisis. 

**********

Web Links

Beaver reintroduction key to solving freshwater biodiversity crisis

Photo, posted October 2, 2014, courtesy of USFWS Midwest Region via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fish And Ships

By Leave a Comment

Solutions to overfishing of certain tuna and shark populations have been hindered by some significant unknowns:  where the fishing is happening, and where the fish are.  But researchers from Stanford University have recently shed some light on this mystery. 

According to a paper recently published in the journal Science Advances, the researchers have developed a map of shark, tuna, and ship movements that could help ocean managers identify regions of the sea where vulnerable species may be at risk. 

The researchers’ work builds on a 2018 study in which four years of satellite vessel movement data was used to develop a machine learning algorithm that mapped the footprint of 70,000 different fishing vessels around the world.  In their paper, the researchers zeroed in on the activities of 900 vessels from 12 countries in the northeast Pacific Ocean to figure out to what degree fishing fleets, sharks, and tunas overlapped. 

The researchers combined the vessel data with the ocean habitat preferences of sharks and tunas obtained from a decade-long tracking program called Tagging of Pacific Predators (or TOPP).  According to the IUCN, most of the 876 individuals tagged in TOPP belong to species that are either threatened or near-threatened.

By synthesizing this data, researchers were able to map where sharks and tunas would have the highest overlap with commercial fishing vessels.  Increasing the transparency of where fish meets fleets will allow ocean managers to determine where international protections may be needed. 

The United Nations is currently developing the world’s first legally binding treaty to protect international waters.  The Stanford University researchers hope their findings can help with this treaty’s formulation. 

**********

Web Links

Tunas, sharks and ships at sea

Photo, posted June 20, 2011, courtesy of Mike Baird via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Reviled Animals Can Be Beneficial

By Leave a Comment

Predators and scavengers are widely persecuted by people because they are often harmful to property, livestock, and human beings.  Nonetheless, research has shown that many of these animals play important roles in ecosystems and their removal can be quite harmful.

[Read more…] about Reviled Animals Can Be Beneficial

Trouble For Vultures

By

When we think of vultures, we picture big, ugly birds circling over a carcass in the desert.  They are a stereotypical harbinger of death.  But in many parts of the world, vultures are in danger of disappearing.  Our knee-jerk reaction might well be “good riddance”, but as is the case for pretty much all participants in ecosystems, vultures have an important role to play.  And when they aren’t around to play that role, bad things can happen.

[Read more…] about Trouble For Vultures

Ecotourism And Endangered Species

By

Ecotourism is increasing on a global scale.   Ecotourism is generally defined as responsible travel to natural areas that conserves the environment, sustains the well-being of the local people, and involves interpretation and education.  Visitor numbers to many protected areas around the world are expanding every year.  Ecotourism provides rich experiences for the traveler and often has great benefits to local communities fighting poverty and seeking sustainable development.

[Read more…] about Ecotourism And Endangered Species

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)