Environment-Biodiversity-Effects

Mass die-off of birds in south-western US 'caused by starvation'

The Guardian Phoebe Weston 12/26/20

The mass die-off of thousands of songbirds in south-western US was caused by long-term starvation, made worse by unseasonably cold weather probably linked to the climate crisis, scientists have said.

Flycatchers, swallows and warblers were among the migratory birds “falling out of the sky” in September, with carcasses found in New Mexico, Colorado, Texas, Arizona and Nebraska. A USGS National Wildlife Health Center necropsy has found 80% of specimens showed typical signs of starvation.

Muscles controlling the birds’ wings were severely shrunken, blood was found in their intestinal tract and they had kidney failure as well as an overall loss of body fat. The remaining 20% were not in good enough condition to carry out proper tests. Nearly 10,000 dead birds were reported to the wildlife mortality database by citizens, and previous estimates suggest hundreds of thousands may have died.

Loss of bees causes shortage of key food crops, study finds

<embed> https://www.theguardian.com/environment/2020/jul/29/bees-food-crops-shortage-study </embed> the Guardian Oliver Milman Wed 29 Jul 2020 00.01 EDTLast modified on Wed 29 Jul 2020 12.35 EDT

Of seven studied crops grown in 13 states across America, five showed evidence that a lack of bees is hampering the amount of food that can be grown, including apples, blueberries and cherries. A total of 131 crop fields were surveyed for bee activity and crop abundance by a coalition of scientists from the US, Canada and Sweden.

“The crops that got more bees got significantly more crop production,” said Rachael Winfree, an ecologist and pollination expert at Rutgers University who was a senior author of the paper, published by the Royal Society. “I was surprised, I didn’t expect they would be limited to this extent.”

'Landscape of fear': what a mass of rotting reindeer carcasses taught scientists

<embed> https://www.theguardian.com/environment/2020/jul/08/landscape-of-fear-what-the-rotting-carcasses-of-reindeer-taught-scientists-aoe </embed>

When 323 reindeer were killed by lightning on a remote Norwegian plateau, their bodies were left for nature to take its course.
Scavenger birds such as ravens, crows and eagles visited the highest density of carcasses in 2017 and then were nearly absent in 2018. The reverse was true of rodents (such as root vole, lemming, bank vole and field vole), which were absent from the site in 2017 and then were everywhere in 2018. Scientists believe rodents were too fearful to go to the site while these larger birds were around. Carcasses are interaction hotspots, but not all interactions are positive: “It’s kind of like, here’s a buffet, you’ve got a lot of hungry folks coming in to eat, and maybe they don’t like one another very much,” says Frank.

The Rabbit Outbreak A highly contagious, often lethal animal virus arrives in the United States

The New Yorker June 2020

One of the lagoviruses of the family Caliciviridae causes a highly contagious illness called rabbit hemorrhagic disease. RHD is vexingly hard to diagnose. An infected rabbit might experience vague lethargy, or a high fever and difficulty breathing, or it might exhibit no symptoms at all. Regardless of the symptoms, though, the mortality rate for RHD can reach a gloomy hundred per cent. There is no treatment for it. The virus’s ability to survive and spread is uncanny. It can persist on dry cloth with no host for more than a hundred days; it can withstand freezing and thawing; it can thrive in a dead rabbit for months, and on rabbit pelts, and in the wool made from Angora-rabbit fur, and in the rare rabbit that gets infected but survives. It can travel on birds’ claws and flies’ feet and coyotes’ fur. Its spread has been so merciless and so devastating that some pet owners have begun referring to it as “rabbit Ebola.”

Long-term predator–prey cycles finally achieved in the lab

Nature 12-18-2019

A key question in ecology is what allows species to persist over time — particularly when there are pairs of species in which one is an exploiter and the other its victim. A long-standing theory attempts to answer this question by explaining how relative numbers of predators and their prey can cycle continuously1. First, prey numbers would increase, giving the predator more food. The subsequent increase in predators would lead to a decline in prey. Predator numbers would then decline owing to a lack of food, restarting the cycle. However, it has proved unexpectedly challenging to demonstrate this type of persistent predator–prey cycle in simple controlled systems in the laboratory. Writing in Nature, Blasius et al.2 report just such a demonstration, succeeding where almost 90 years of experimental work has failed.

The challenge posed by such a demonstration was exemplified in 1934 by the ecologist Georgii Gause4, who studied the dynamics of two unicellular organisms — the predator Didinium nasutum and its prey, Paramecium caudatum. Gause found that, on the one hand, if the predator was efficient, it ate up all the prey and then starved. On the other hand, if part of the environment helped to conceal the prey, the predator was less efficient — and so starved (Fig. 1a). Coexistence and long-term cycles could be achieved only through artificial means — namely, by adding prey at regular intervals.

Light pollution is key 'bringer of insect apocalypse'

The Guardian 11/22/19

Artificial light at night can affect every aspect of insects’ lives, the researchers said, from luring moths to their deaths around bulbs, to spotlighting insect prey for rats and toads, to obscuring the mating signals of fireflies.

Brett Seymoure, a behavioural ecologist at Washington University in St Louis and senior author of the review, said: “Artificial light at night is human-caused lighting – ranging from streetlights to gas flares from oil extraction. It can affect insects in pretty much every imaginable part of their lives.”

‘Insect apocalypse’ poses risk to all life on Earth, conservationists warn

The Guardian 11/13//2019

A new report suggested half of all insects may have been lost since 1970 as a result of the destruction of nature and heavy use of pesticides. The report said 40% of the 1million known species of insect are facing extinction.
The analysis, written by one of the UK’s leading ecologists, has a particular focus on the UK, whose insects are the most studied in the world. It said 23 bee and wasp species have become extinct in the last century, while the number of pesticide applications has approximately doubled in the last 25 years.

Worldwide decline of the entomofauna: A review of its drivers

Science Direct 4/2019

• Over 40% of insect species are threatened with extinction.

• Lepidoptera, Hymenoptera and dung beetles (Coleoptera) are the taxa most affected.

• Four aquatic taxa are imperiled and have already lost a large proportion of species.

• Habitat loss by conversion to intensive agriculture is the main driver of the declines.

• Agro-chemical pollutants, invasive species and climate change are additional causes.

The Bugs We Can’t Live Without

WSJ 7/17/2019 Paywall

Insect populations are in dramatic decline, and the consequences could be serious for everything from waste management to agriculture 

DailyKos 7/17/2019 No Paywall

"Nearly half of all insect species worldwide are in rapid decline and a third could disappear altogether, according to a study warning of dire consequences for crop pollination and natural food chains.
The recent decline in bugs that fly, crawl, burrow and skitter across still water is part of a gathering "mass extinction," only the sixth in the last half-billion years.
"We are witnessing the largest extinction event on Earth since the late Permian and Cretaceous periods," the authors noted.

Biodiversity crisis is about to put humanity at risk, UN scientists to warn

The Guardian Biodiversity Crisis UN report 503 2019

The world’s leading scientists will warn the planet’s life-support systems are approaching a danger zone for humanity when they release the results of the most comprehensive study of life on Earth ever undertaken.

Up to 1m species are at risk of annihilation, many within decades, according to a leaked draft of the global assessment report, which has been compiled over three years by the UN’s leading research body on nature.

The 1,800-page study will show people living today, as well as wildlife and future generations, are at risk unless urgent action is taken to reverse the loss of plants, insects and other creatures on which humanity depends for food, pollination, clean water and a stable climate.

The final wording of the summary for policymakers is being finalised in Paris by a gathering of experts and government representatives before the launch on Monday, but the overall message is already clear, according to Robert Watson, the chair of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).

The Guardian Loss of Natural World 5/06/2019