News Article | August 12, 2016
After an intense recovery program, three groups of California's rare island foxes have been removed from the United States' endangered species list on Thursday, Aug. 11. According to officials from the U.S. Fish and Wildlife Service (USFWS), the population of Channel Island foxes once on the brink of extinction has now rebounded. Meanwhile, a fourth group of island fox was relegated to "threatened." About 12 years ago, wildlife scientists feared that the California island foxes would be completely wiped out. At that time, the population of these cat-like animals, which inhabit a group of islands located off the coast of Southern California, had been reduced by pesticides and non-native predators. The remaining animals had been placed under the endangered species protection. Now, these island foxes have marked the fastest recovery yet for an endangered mammal. Wildlife officials have removed three island fox subspecies on Santa Rosa, Santa Cruz and San Miguel islands from the endangered list. The fourth subspecies, the Santa Catalina Island fox, has been placed on the "threatened" list. Statistics from the USFWS show that the population of these four subspecies has increased from less than 200 animals in the 1990s to nearly 6,000 as of 2015. "We're ecstatic that we've reached this point so quickly," says Steve Henry, USFWS Ventura office field supervisor. The population rebound of the island foxes was hastened by an aggressive recovery program that involved several measures: removal of feral pigs from the Channel Islands, captive breeding of the island foxes and decreasing an influx of golden eagles from the mainland, which have turned into an invasive predator. Furthermore, wildlife officials began injecting the island foxes with vaccine against canine distemper — a contagious and severe viral illness that affects the animal's gastrointestinal, respiratory and central nervous systems. This dangerous virus poses a great threat to animals on Santa Catalina Island, the only island in the archipelago with a significant civilian population. Meanwhile, officials say hunting will not be an issue for the Santa Catalina fox because it remains listed as threatened. The other three subspecies, which are no longer on the endangered list, inhabit three of the five other islands that make up the Channel Islands National Park, where hunting is illegal. The Channel Islands have been home to the tiny island fox for thousands of years but scientists are not certain how the animals arrived at the archipelago. As of 2015, the population of all four island fox groups has been restored to historic levels, officials said. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.
Sonsthagen S.A.,U.S. Geological Survey |
Coonan T.J.,Channel Islands National Park |
Latta B.C.,The Bird Group |
Sage G.K.,U.S. Geological Survey |
Talbot S.L.,U.S. Geological Survey
Biological Conservation | Year: 2012
Gene flow can have profound effects on the genetic diversity of a founding population depending on the number and relationship among colonizers and the duration of the colonization event. Here we used data from nuclear microsatellite and mitochondrial DNA control region loci to assess genetic diversity in golden eagles of the recently colonized Channel Islands, California. Genetic diversity in the Channel Island population was low, similar to signatures observed for other recent colonizing island populations. Differences in levels of genetic diversity and structure observed between mainland California and the islands suggests that few individuals were involved in the initial founding event, and may have comprised a family group. The spatial genetic structure observed between Channel Island and mainland California golden eagle populations across marker types, and genetic signature of population decline observed for the Channel Island population, suggest a single or relatively quick colonization event. Polarity in gene flow estimates based on mtDNA confirm an initial colonization of the Channel Islands by mainland golden eagles, but estimates from microsatellite data suggest that golden eagles on the islands were dispersing more recently to the mainland, possibly after reaching the carrying capacity of the island system. These results illustrate the strength of founding events on the genetic diversity of a population, and confirm that changes to genetic diversity can occur within just a few generations. © 2011.
News Article | September 18, 2016
A well-preserved skull of a mammoth that possibly lived 13,000 years ago was excavated from Santa Rosa Island at Channel Islands National Park, a rare find that scientists said has high scientific importance. The exceptionally intact fossil was first found in 2014 by National Park Service biologist Peter Larramendy. He was conducting stream studies when he noticed an ivory tusk protruding from gravel sediments in a canyon wall in the area he was working in. Charcoal samples adjacent to the fossil that were tested by geologists at the U.S. Geological Survey (USGS) revealed the remains were about 13,000 years old, which means that it lived at about the same time as the Arlington Man, the oldest set of human skeletal remains in North America, which was also discovered in Santa Rosa Island. The skull, however, has been puzzling scientists since its excavation. Paleontologist Justin Wilkins, from The Mammoth Site in South Dakota, who is part of the team that worked to unearth the fossil, said that the fossil does not fit the profile for a pygmy mammoth or the Columbian mammoth. The Columbian mammoths, which could measure up to 4.3 meters or 14 feet, roamed North America a million years after the first mammoths emerged on the continent. The species later moved to the Channel Islands. The descendants of the Columbian mammoths eventually shrank in size, becoming the shorter pygmy mammoths. Pygmy mammoths stood at about 1.8 meters, or 6 feet tall and scientists said that the skull is not small enough to belong to a pygmy mammoth. The skull is neither that big to qualify as a Columbian mammoth. "The discovery of this mammoth skull increases the probability that there were at least two migrations of Columbian mammoths to the island," said geologist Dan Muhs from the USGS. The migrations could have happened 10,000 to 30,000 years ago during the last ice age and the previous glacial period, which happened about 150,000 years ago. The fossil's tusks also baffled scientists. The one on the right measures 1.4 meters (about 4.6 feet) long and coils the same way as that of an older mammoth. The left tusk though is shorter and sloped like those of a juvenile. Scientists hope to find the answer to their questions in the teeth of the animal. The surface thickness, spacing and number of the creature's teeth would give scientists an idea of how old it was when it died. The teeth could also shed light if the mammoth is a pygmy, Columbian or a transitional mammoth species. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
Harvey A.L.,Channel Islands National Park |
Mazurkiewicz D.M.,Sutil Conservation Ecology |
McKown M.W.,Conservation Metrics Inc |
Barnes K.W.,Sutil Conservation Ecology |
And 2 more authors.
Marine Ornithology | Year: 2016
Ashy Storm-Petrels (ASSP) breed in a range restricted to the southern California Current, from Mendocino County in northern California, United States, to the Coronado Islands in northwest Baja California, Mexico. Approximately half the global population nests on the California Channel Islands, but nesting at one of them, Anacapa Island, had not been recorded before this study. In 2011, 10 years af ter rats were eradicated, we conducted a study to determine the breeding status of ASSP on Anacapa Island. We used habitat searches coupled with acoustic sensors to assess potential nesting areas and conducted mist netting to determine general presence. We found one active nest containing a nearly fledged ASSP chick in 2011, representing the first breeding record for the island. © 2016, Marine Ornithology. All rights reserved.
News Article | October 4, 2016
Over 80,000 years ago, somewhere on a southern California beach, a mammoth wandered across the sand. The beast didn't stop at the water’s edge. Step by step, its trunk held high, the towering proboscidean walked into the waves until its feet no longer touched the bottom. One, two, three, kick, the elephant kept paddling, the air-filled sinuses of its great skull helping to keep the mammoth’s head near the surface as it moved further and further out from the coastline. It had a long swim ahead. In the distance, rising from the surface 12 miles to the west, were a small set of islands. That’s where the mammoth emerged onto its new island home. We know that such an event must have happened, and likely happened more than once. The evidence doesn’t come from swim tracks. Those would be nice, but haven’t been found yet (if they were ever preserved in the first place). The clues are in skeletons. On California’s Channel Islands, in sediments left from the last Ice Age, paleontologists have found the remains of mammoths that could have only gotten there thanks to some intrepid pachyderms that made the journey from the mainland. The form that braved the surf were Columbian mammoths – a species only found in North America that ranged over much of the continent, and was presumably less shaggy than its famous woolly relative. These mammoths weren’t just visitors to the Channel Islands, though. They stayed, and, thanks to a phenomenon called insular dwarfism, their population eventually evolved into a smaller species – the pygmy mammoth Mammuthus exilis. These little mammoths stood only about five and a half feet at the shoulder, less than half the stature of their ancestors. Swimming was the only way the mammoths could have arrived. There was no landbridge between the continent and the Channel Islands for them to cross. That’s why other parts of California’s Ice Age fauna – like sloths and sabercats – haven’t been found along the chain. Only aquatically-adept species could make it, and, if the skills of today’s Asian elephants are any indication, Columbian mammoths were likely strong swimmers. And they got a little help from ice. When the world’s glaciers crept over the land, sucking up water to expand their reach, the sea level off the California coast fell and vastly reduced the distance to the Channel Islands. During these times, when the Ice Age was in full effect, the mammoths could swim out to the islands. It was thought that the Columbian mammoths made this trek during the Last Glacial Maximum, sometime around 26,000 years ago or so. Most mammoth remains on the Channel Islands fall within the window of 22,000 to 12,000 years ago. But now there’s an even older date. Thanks to a tusk found along a Channel Islands beach, U.S. Geological Survey researcher Daniel Muhs and colleagues have now pushed back the oldest known mammoth on the islands by tens of thousands of years. Which species the tusk belonged to isn’t clear. It’s small enough that it could either by a pygmy mammoth or a juvenile Columbian mammoth. But dates derived from prehistoric corals from levels beneath the tusk indicate that this mammoth died around 80,000 years ago. This newly-discovered mammoth probably wasn’t the first to stomp across the archipelago. At the time the beast inhabited the Channel Islands, Muhs and coauthors report, the world was in an interglacial. The local sea level was high, and, even if mammoths were accomplished swimmers, the distance was likely too far for them to cross. Therefore, the paleontologists hypothesize, the mammoths must have arrived during even earlier times when glaciers created a shallower sea. The two earlier periods when mammoths could have swum across the channel were 150,000 and 250,000 years ago. With luck, the bones of the earlier arrivals will help refine the date and help fill in this new gap in the mammoth story. It could be that the pygmy mammoths evolved from their Columbian ancestors earlier than thought. Then again, perhaps there were multiple waves of mammoth habitation, flourishing and declining as the seas rose and fell. This isn’t just a story of evolution, though. It’s also one of extinction. No one knows what wiped out California’s mini-mammoths. The traditional Pleistocene culprits have been invoked, and both have their problems. While hunting by humans is often cited as an extinction trigger, especially on islands, there was relatively little overlap in time between the Channel Islands mammoths and humans. Not to mention that no one has yet found unequivocal evidence of hunting or butchery. Extinction by overkill can’t be taken as a default explanation. Swift ecological change is the other popular option. Rising sea levels could have put the squeeze on mammoth populations, and changing vegetation may have limited the beasts’ food supply. But if mammoths arrived on the islands over 80,000 years ago and maintained stable populations from that time on, Muhs and colleagues argue, then they would have previously experienced even more extreme shifts in sea level, climate, and vegetation. If they survived these changes in the past, why not at the end of the last Ice Age? These two explanations aren't mutually exclusive. Perhaps both changing habitat and humans had roles to play. We often confuse the reason the last members of a species died for the singular extinction trigger. The truth may be that multiple causes made populations vulnerable to a particular stress which eventually eradicated any hope of recovery. Extinction is a process, not a singular event. How that process played out amongst California’s lost mammoths, however, is a secret still held tight in tusk and bone. Muhs, D., Simmons, K., Groves, L., McGeehin, J., Schumann, R., Agenbroad, L. 2015. Late Quaternary sea-level history and the antiquity of mammoths (Mammuthus exilis and Mammuthus columbi), Channel Islands National Park, California, USA. Quaternary Research. 83: 502-521. doi: 10.1016/j.yqres.2015.03.001 [This post was originally published at National Geographic.]
News Article | December 10, 2015
New remote sensing techniques, which more closely resemble your smartphone's personal assistant than traditional field sampling, may be able to help. How, for example, do you study an imperiled seabird population when for most of the year the adult birds' stealthy habits keep them out at sea hunting for food – and away from spying scientists – around the clock, except for a brief period in the middle of the night when it's too dark to tell a petrel from a pile of rocks? That was the situation facing researchers who wanted to know if there were any ashy storm petrels on Anacapa Island, about 25 kilometers off the California coast, ten years after invasive rats were eradicated from the island. Ashy storm petrels are small enough to fit in your hand, fog-gray and stern looking, with a prominent brow and slightly hooked beak. It's a look that's belied by their call, which was described in a 1903 scientific paper as a "sing-song twitter, regularly punctuated with a gasp" like a tiny train engine. Their population numbers somewhere between 5,000 and 10,000, all living on craggy coastal islands scattered along the edges of California and Baja California. The International Union for Conservation of Nature lists the species as "endangered," and some scientists worry that ashy storm petrels' limited range and small population make them especially vulnerable to threats like invasive rats. For decades, rats ruled Anacapa Island, a rugged dash of rock in Channel Islands National Park. Introduced rats can decimate island ecosystems by gobbling up seabird eggs, chicks and adults, as well as other native creatures, so 15 years ago state and federal government agencies worked with scientists to get rid of the rats on Anacapa. Seabirds are fundamental to the island ecosystems where they live, according to conservation biologist Rachel Buxton of Colorado State University. They scoop up food from the ocean, then fertilize their home islands with their guano, functioning like a conveyor belt of nutrients. "Their recovery is really important for island restoration," Buxton said. "So it's really central to your whole restoration project to be able to monitor them." But because of the remoteness of coastal islands and the furtive habits of some species, searching for seabirds in person is difficult. Ashy storm petrel adults are rarely at their nesting sites during the day, except when mates are taking turns incubating an egg. Even then, the crevices where they live are so well camouflaged that it's difficult to tell them apart from the rest of a rocky coastline. Researchers scramble up slick rocks and slippery scree slopes, stick scopes down bird burrows, and sometimes even follow their noses in the dark – ashy storm petrels produce a musky odor distinct enough to serve as a signpost marking their homes. "It's one of the most challenging wildlife monitoring situations that I can think of," Buxton said, of searching for nocturnal seabirds. "This is where acoustic recorders have been extremely valuable." After the rat eradication on Anacapa, scientists wanted to see if seabirds were recovering on the island. When they went looking for ashy storm petrels in 2011, they didn't find any. But they left some microphones behind, just in case. They retrieved the recordings every few weeks, and sent them to Conservation Metrics for analysis. Conservation Metrics, a company based in Santa Cruz, California, develops software designed to differentiate between the sounds that scientists want to hear, like the cheeps and chirps of bird chatter, and everything else. It's the same type of voice recognition analysis that smartphones use when they 'listen' and talk back to you – and as with your cellphone, the challenge for the software is the sheer volume of background noise. "It's like Siri constantly trying to figure out what someone's saying, in the middle of Grand Central Station, on speaker phone," said Matthew McKown, CEO of the company. The recordings from Anacapa were, for the most part, devoid of ashy storm petrels' trilling squawk – with one exception. At one site, called Portuguese Rock Cove, microphones picked up the voices of ashy storm petrels on 10 of the 19 nights they were recording. The researchers returned to the island to search for the seabirds once again, and this time, thanks to the recordings, they knew where to look – Portuguese Rock Cove. "They went back and they found the first record ever of an ashy storm petrel breeding on the island," McKown said, proving that remote acoustic sensing has more than potential – it actually works. Acoustic recordings can augment and even improve traditional seabird surveys, McKown said, and Buxton agreed. Still, Buxton, who wasn't involved in the Anacapa study, said she doesn't think the need for traditional, in-person seabird monitoring will ever completely disappear. "There are some things that you just can't tell from acoustic monitoring," she said, like how many chicks survived the breeding season, or what exactly birds have been eating. But, she added, "it's going to be an incredible complement to the way research is done." Ashy storm petrels have more to say, according to McKown, and he and his colleagues will be listening. The National Fish and Wildlife Foundation recently awarded them a grant to set up a wireless network of microphones in the California Coastal National Monument, which spans the entire shoreline of the state. They're going to eavesdrop on Leach's storm petrels, fork-tailed storm petrels and black storm petrels, too, and keep an ear out for other seabirds like puffins and murrelets. "We have a mission to improve conservation through better monitoring," McKown said. By listening in on the conversations of seabirds, he hopes to do just that.
Shears N.T.,University of California at Santa Barbara |
Kushner D.J.,Channel Islands National Park |
Katz S.L.,National Oceanic and Atmospheric Administration |
Gaines S.D.,University of California at Santa Barbara
Environmental Conservation | Year: 2012
No-take marine reserves directly promote the recovery of predatory species, which can have negative indirect effects on prey populations in reserves. When harvesting also occurs on prey species there is potential conflict between the direct and indirect effects of protection, and reserves may not have conservation benefits for prey species. For example, sea urchins are fished in many regions, but may decline in reserves due to increased predation rates. To investigate this potential conflict, this paper compares density, size, biomass and reproductive potential of both a harvested and an unharvested urchin species between a long-term reserve and unprotected sites in California. Consistent with density-mediated indirect interactions, densities of the unharvested species were 3.4-times higher at unprotected sites compared to reserve sites. However, for the harvested species, densities were comparable between reserve and unprotected sites. Both species were consistently larger at reserve sites, and the biomass and reproductive potential of the harvested species was 4.8- and 7.0-times higher, respectively, than at unprotected sites. This is likely due to differences in size-selectivity between harvesting and predators, and potential compensatory effects of predators. While the generality of these effects needs to be tested, these results suggest mechanisms whereby reserves can benefit both predator and prey species. © Copyright Foundation for Environmental Conservation 2012.
News Article | October 13, 2016
Protecting an ecological paradise like the island of Santa Cruz can be challenging for its resource managers who want to maximize visitor experiences while minimizing negative impacts on the park. As the largest of five islands in Channel Islands National Park off the coast of California, Santa Cruz boasts over 2,000 species of plants and animals, some of which are not found anywhere else on earth. But a recent University of Illinois study says the island's rich biodiversity may not be what's valued most by its stakeholders.
News Article | October 13, 2016
Protecting an ecological paradise like the island of Santa Cruz can be challenging for its resource managers who want to maximize visitor experiences while minimizing negative impacts on the park. As the largest of five islands in Channel Islands National Park off the coast of California, Santa Cruz boasts over 2,000 species of plants and animals, some of which are not found anywhere else on earth. But a recent study says the island’s rich biodiversity may not be what’s valued most by its stakeholders.
News Article | September 20, 2016
Scientists have unearthed an exceptionally well preserved fossil of a complete mammoth skull from an eroding stream bank on Santa Rosa Island within Channel Islands National Park.