The Southern sea otter population is healthy at the core of its range along the California coast, but the aquatic mammals are still struggling to expand north and south, probably because of predation by sharks, scientists said as they released the results of the latest annual otter survey.
“The population index has exceeded 3,090 for the first time, and that’s encouraging,” said Lilian Carswell, Southern Sea Otter Recovery Coordinator for USFWS, referring to a threshold number for recovery. If the population stays above that number for three years in a row, the U.S. Fish and Wildlife Service could consider a delisting proposal.Sea otters were presumed to be extinct in California in the early 1900s, but a remnant population of 30 animals was discovered and protected in the 1930s near Bixby Bay, north of Big Sur. They were listed as a threatened species in 1977, deemed at risk from oil spills. Continue reading “California sea otter population growing steadily”→
‘Reducing immediate impacts is essential to tackling the biodiversity crisis’
About 75 percent of the world’s threatened species are at risk because of human impacts to their environment and unsustainable harvesting, according to a new study in the journal Nature.
“Addressing these old foes of overharvesting and agricultural activities are key to turning around the biodiversity extinction crisis” said lead author Sean Maxwell of the University of Queensland, “This must be at the forefront of the conservation agenda.”
Scientists from the University of Queensland, the Wildlife Conservation Society and the International Union for Conservation of Nature studied 8,688 species on the IUCN Red List. They found that 72 percent of species are imperiled by unsustainable harvesting. The production of food, fodder, fiber and fuel crops; livestock farming; aquaculture; and the cultivation of trees imperils another 62 percent. By comparison, 19 percent are considered threatened by climate change. Continue reading “New report IDs biggest global threats to wildlife”→
Researchers call for balance between mining and ecosystem protection
New research shows that proposed mining on the seafloor of the Pacific Ocean would likely have a huge impact on marine biodiversity. A study published in the journal Scientific Reports, documents an “impressive abundance and diversity among the creatures” on the seafloor in the Clarion-Clipperton Zone — an area in the equatorial Pacific Ocean being targeted for deep-sea mining.
“We found that this exploration claim area harbors one of the most diverse communities of megafauna (animals over 2 cm in size) to be recorded at abyssal depths in the deep sea,” lead author Diva Amon said in a press release.
The researchers explained that a combination of biological, chemical and geological processes formed a high concentrations of polymetallic “manganese” nodules on the deep seafloor in the CCZ–an area nearly the size of the contiguous United States. These nodules are potentially valuable sources of copper, nickel, cobalt and manganese, among other metals, which has led to an interest in mining this region. Continue reading “New study documents biodiversity in proposed deep sea mining zone”→
Migration changes could affect competition for nesting sites
As global warming speeds up the springtime northward migration of swallows, it could spell trouble for mountain bluebirds.
Both species are cavity nesters; at times they compete for the same habitat. Historically, mountain bluebirds have arrived in the breeding territories earlier than the swallows, giving them a chance to defend their nests. But if the swallows arrive first, the bluebirds may have a harder time finding a safe spot to lay eggs, according to new research published in The Auk: Ornithological Advances.
The scientists from the University of Saskatchewan acknowledged that the outcomes of interspecies battles for nest sites depend on a number of factors, but wanted to study what happens when tree swallows and mountain bluebirds compete for nest sites. So they set up side-by-side pairs of nest boxes in grassland habitat in central British Columbia.
When bluebird and swallow pairs moved in next door to each other, they would either block the entrance to one box and let the two pairs of birds compete for the one that remained, or remove both boxes and replace them with a fresh one.
“I became interested in this topic after watching many competitive interactions over natural tree holes during a long-term study of Northern Flickers in central British Columbia,” said researchers Karen Wiebe. “In early spring when the birds are trying to claim a nest site, these disputes can be intense and really grab your attention. Because bluebirds and swallows readily use nest boxes, I was motivated to try some experiments in a system where I could have more control over the spacing of nests and settlement patterns of the birds.”
Wiebe found that when Tree Swallows were defending their previously owned box or when the two species were competing over a new box, Tree Swallows won 65-70 percent of the time. Bluebirds got a boost when they defended a box they already occupied, however, fending off swallows 77 percent of the time.
Climate change may bring the two species into direct competition more often and reduce bluebirds’ ability to claim and defend nest sites.
“This is a nice set of clever and simple experiments that show that species are not the same when it comes to the importance of being the first one to occupy a nest site,” according to ecologist Hanna Kokko of the University of Zurich, an expert on interspecies competition in birds. “The one that currently tends to arrive first, the bluebird, relies more on this, which could easily cause problems if the arrival order changes on a changing planet.”
Scientists say Nile crocs may be thriving in Sunshine State swamps
The latest non-native species to invade Florida’s subtropical clime is a man-eater, according to University of Florida researchers who say they’ve genetically identified Nile crocodiles living in the swamps of the Sunshine State.
The aquatic reptiles can grow as long as 18 feet and weigh as much as a small car, and in their native habitat eat everything from hippos and zebras to humans. In Florida, they could eat native birds, fish and mammals, as well as the state’s native crocodile and alligators, said the researchers, have confirmed the capture of multiple Nile crocodiles in the wild, using DNA analysis.
Researchers track chytrid in mountains of Cameroon
Africa’s frogs may also be succumbing to the chyrid fungus that has wiped out species around the world, researchers reported this week in the journal PLOS ONE.
Tracking frogs on Cameroon’s Mount Oku and Mount Manengouba over a span of more than 12 years, University of Florida herpetologist David Blackburn and colleagues at the Museum für Naturkunde in Berlin have linked declines of at least five frog species linked with chytrid — possibly exacerbated by habitat destruction, pollution and climate change. Continue reading “Biodiversity: Frog-killing fungus turns up in Africa”→
Using a vast sample of data collected in a citizen science project, researchers say they’ve been able to discern how hydropeaking affects aquatic insects that form the base of river food chains. The information could help resource managers develop alternative hydropower practices that aren’t as harmful to ecosystems, according to a new study published in the journal BioScience.
Hydropeaking refers to the practice of increasing river flows at times of peak demand, generally during the day. This study shows how abrupt water level changes affect aquatic insects in every stage of life. The research was done by scientists with the U.S. Geological Survey, Oregon State University, Utah State University and Idaho State University. Continue reading “Environment: Can dams be operated without killing rivers?”→