Science Spotlight

Researchers built 90 hair-snare stations designed to pull a small hair sample from black bears that cross the snares.


The Warner Mountains Black Bear Project study area (blue boundary) and layout of hair-snare grids (yellow squares) in northeastern California. The upper-left inset shows the southernmost hair snare grid and layout of hair-snare locations (red circles). Density estimates and information on habitat from within the 10 grids will help researchers estimate overall black bear abundance across the entire study area.

California’s black bear population is healthy and growing, with an estimated 35,000 animals, up from an estimated 10,000 to 15,000 in 1982. But how do wildlife biologists determine these figures – and why are they important?

Deep in the Warner Mountains in Lassen and Modoc counties CDFW is just completing the first year of a study of black bears. The lead scientist, Steffen Peterson, explained that anecdotal evidence in recent years – including increased bear sightings by both field scientists and everyday citizens, as well as an increased number of requests for depredation permits due to bear-human conflicts – seemed to indicate that the population of black bears in the Warner Mountains was booming and this area would be ideal for scientific research.

According to Peterson, the two primary objectives of the Warner Mountains Black Bear Project are to estimate black bear abundance in the study area and to determine how black bears use the landscape. This kind of information on black bear demography and space use is essential for wildlife managers to make scientifically sound bear management decisions for this region of California.

CDFW is using a genetic capture-recapture method to estimate the population size. Usually, this involves physically capturing an animal, marking it in some way and releasing it. But this particular study achieves the same goal with non-invasive techniques – specifically by using hair snares, which cause relatively little stress or harm to the animals. Hair snares have been used on many furbearing species to determine presence, to calculate a minimum absolute count of individuals present, or to estimate total population size by collecting a DNA sample from individuals without physically capturing the animal. Unique repetitive sequences, known as microsatellites, within the DNA sample serve as individual identifiers, making it possible to know when and where each unique animal was present.

In addition, because the DNA located within roots of mammalian hair can identify species, sex, and individuality, this genetic technique is ideal for researchers to estimate abundance as well as obtain information on demographics and genetic diversity.

Peterson, a CDFW scientific aid and a Humboldt State University graduate student, and other researchers built 90 hair-snare stations distributed across 10 sampling grids that that are designed to pull a small hair sample from bears that cross the snares.

The contraption consists of two parallel strands of barbed wire stretched around a cluster of three or more trees, one about eight inches off the ground and the other about 20 inches off the ground. This forms a barbed-wire “corral” in which researchers place a pile of logs drizzled with fish oil. The oil acts as an attractant to black bears, who have both a finely attuned sense of smell and a profound love of fish. At two thirds of the hair-snare stations, researchers placed a trail-camera to help verify the effectiveness of the snares at capturing hair samples when a bear is present. The trail photos also provide demographic (cub-adult ratio) information on bears within the study area.

“The use of hair-snares to collect genetic data for abundance and density estimates has become the gold standard for American black bear,” said Peterson. “The hope is for the bear to cross between the two strands of barbed wire, although some of our video footage from the trail cameras shows bears crossing – even jumping, in some cases –  over the wire. Because bears are big, robust animals, for the most part they pay little mind to the barbs and typically cross them, leaving us a nice big clump of hair. Bears are the ideal critter for hair-snares in this way.”

Although Peterson stressed that it is much too soon in the study process to draw conclusions about the number of black bears living on the grid, initial results indicate that, at a bare minimum, black bears are certainly roaming throughout the study area.

During a 50-day hair collection period that took place this summer, black bears were detected in all of the grids created in the study area that encompasses roughly 600 square miles of high desert terrain; researchers collected 469 samples of hair in all at 57 of the 90 hair-snare locations.

“Long story short, we are pleased by the amount of detections observed during our data collection,” Peterson said. “Good detections will strengthen our ability to estimate density within each grid which will allow us to more reliably estimate abundance off the grid – i.e., the Warner Mountain study area as a whole.”

Peterson is now set to begin the DNA analysis phase on the samples collected. This will allow him to determine precisely how many individual bears left hair behind (bears often leave more than one sample at a snare location and some individuals are repeat visitors), as well as information on gender and habitat use, including the movement of bears across the study area.

Next summer, project staff will capture and collar 12 adult black bear with research collars, which will record hourly GPS locations of the bears as they move across the landscape, providing information on how they use the landscape, including seasonal habitat preferences and, during the winter hibernation period, where bears den.

“This information will greatly improve our knowledge of how bears use these high desert ecosystems, characteristic of the Great Basin, and guide future land management in this region,” Peterson said.

The project is expected to continue for another two to three years. ###

CDFW Photos. Top Photo: Emily Monfort, a CDFW scientific aid, carefully removes black bear hair from barbed wire at a hair-snare location. The DNA from this clump of hair will be examined in the laboratory to determine the sex and genetic identity of the black bear that crossed this wire.  Photo credit Korrina Domingo (CDFW).

Panorama of Summer Lake


USGS employee holding goose


Summer Lake


Summer Lake


Melanie in the water retrieving geese


Melanie in sideview mirror


Fitting the collar


A finger nibble

Every September, California Department of Fish and Wildlife waterfowl biologist Melanie Weaver sets off on an unusual business trip. She packs up a trailer with huge nets, wire, rockets, crates and a number of VHF collars. She makes the seven-hour drive to Summer Lake, in southern Oregon’s high desert country, and settles in for a waterfowl capture project of indeterminate length. Her quarry is Anser alibifrons elgasi — the Tule white-fronted goose. Her goal is to capture, collar and release these huge, cackling birds until she runs out of collars.

Tule geese are one of two sub-species of white-fronted goose — also known colloquially as specklebelly geese, or “specs,” by hunters. The other sub-species of white-fronted goose, Pacific white-fronted, are plentiful, numbering about 700,000 in the Pacific flyway. But the Tule goose is far less common. Weaver estimates there are only 15,000 to 16,000 Tules.

Monitoring goose populations — particularly Tules — is a high priority for CDFW, as regulations are tied to the less numerous species. Currently, California regulations dictate that the hunting season for white-fronts on the west side of the Sacramento Valley closes on Dec. 21. This is to minimize harvest on Tule geese.

“They are right in the middle of a popular hunting area for Pacifics, so we have to be proactive,” Weaver explained. “If we saw the population decline significantly, we’d have to consider closing the season for all white-fronted geese. We want to avoid that.”

But why would the California Department of Fish and Wildlife be trapping geese north of the state line? One reason is logistics —Tule geese begin their southward trek from Alaska in mid-August or thereabouts. They’re heading for the Sacramento Valley, and Summer Lake Wildlife Area is a major stop over along the migration route. As they move further south into California, Tule geese mix with their more common cousins, the Pacifics. “We’ve tried to capture them in and around the Sacramento National Wildlife Refuge Complex before, and we end up expending a lot of effort just for a handful of Tules caught,” Weaver explained. “So the Oregon Department of Fish and Wildlife suggested moving our capture effort to the Summer Lake Wildlife Area. It’s largely only Tule geese coming through this time of year.”

And that’s the other reason — this partnership between the waterfowl programs from neighboring states illustrates the importance and strength of the Pacific Flyway. Alaska, Canada, Washington, Oregon and California all have a stake in ensuring the conservation of the species that traverse their lands and use their waters. ODFW doesn’t just offer up their land as a banding site. They also provide lodging for Weaver, typically split the cost of the radio collars, and supply labor for the duration of the project, no matter how long it takes.

Weaver’s ODFW counterpart, waterfowl biologist Brandon Reishus, was in it for the long haul right alongside Weaver. On a chilly Monday morning in mid-September, only just a week after they laid out the nets, they hit the jackpot. On that particular day, Reishus was crouched in the blind, using a scope to scan for incoming flocks, while Weaver sat nearby in a pickup truck. They waited and watched for a few hours, keeping in touch by radio, before Reishus spotted his opportunity. After a quick heads up to his Californian counterpart, the Oregon biologist pressed the detonation button, launching the pre-set rockets a quarter mile away. In the blink of an eye, the 60-foot-long net sailed over the unsuspecting birds as they blissfully churned up grit from the water. Both biologists then jumped into the truck and raced to the site, where they untangled the geese and put them into crates for transport to the Summer Lake Wildlife Area shop. The final count on this particular morning was 14 birds; a small number was all that was needed to complete the marking effort for this year as an earlier capture resulted in 44 birds.

The geese were given a little time to settle down before the processing began. Each bird was sexed and the bills measured. Although Weaver and Reishus can typically identify their catch just by the size and color (Tules are larger and darker than Pacifics), scientific measurements are essential for definitive identification.

The birds were also weighed before they were banded and collared. The collars will enable the biologists to obtain a population estimate on the wintering grounds, using a mark resight method. This and other data obtained from the bands will be used to make future management recommendations.

In the early afternoon, Weaver and Reishus drove back to the exact spot where the net was deployed just hours earlier. On the count of three, all the crates were opened at the same time, and the geese noisily rushed out, spreading their wings and re-forming their flock as they raced away.

As Weaver and Reishus affixed the last of the VHF collars on this particular Monday, they marveled at the unusually early conclusion of this years’ trapping effort. Sometimes it takes a full two weeks to use up their supply of collars. Once again, the team effort paid off. And even as they packed up their equipment from the Summer Lake Wildlife Area and prepared to head their separate ways, they were making plans to meet up again in a week, for a Pacific Flyway Study Committee meeting in Arizona.

“It’s such a valuable partnership,” Weaver said. “We look at the big picture, and we all work on solutions together.”
 
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CDFW Photos. Top Photo: weighing a goose.

A newly collected female wild white abalone releases eggs during the captive breeding program’s annual spawning event. This was the first new genetic input in the captive population for 14 years. Photo taken for CDFW by M. Ready

At nearly 130 feet underwater, CDFW abalone researcher Dr. Laura Rogers-Bennett didn’t have much time. Her dive computer told her it was time to ascend, which meant that she would have to stop searching for the endangered white abalone hiding in the waving fields of red and gold gorgonians.

Reluctantly, she watched the beautiful scene drop away below her as she kicked slowly upwards. She moved through the towering elk kelp towards her safety stop, a precious white abalone kept solidly in her grasp. On that trip, back in 2004, Rogers-Bennett and Ian Taniguchi, another CDFW abalone expert, and a team of other scientist divers collected 21 critically endangered white abalone off the deep reefs in the Channel Islands. This collection trip was conducted in an effort to save the species before they disappeared from the wild, and to create a captive breeding program that could bring this important and iconic species back from the brink of extinction.

Fourteen years later, the white abalone Captive Breeding Program is a thriving reality, thanks to the vision and hard work of a committed team of scientists from the White Abalone Consortium (WARC). Those 21 animals that Rogers-Bennett helped to collect in the Channel Islands have now produced thousands of descendants in captivity. The program is so successful, in fact, that it is now producing more animals than it has space to raise. Now, the next step is for WARC and CDFW scientists to perfect methods to release these captive bred animals back into the wild.

A huge challenge for CDFW and the WARC is to ensure that the captive-bred animals stand the best chance for survival in the wild – and one of the greatest obstacles could lie within the abalones’ own DNA. Because the entire captive-bred population stems from only 21 animals, the genetic diversity of the captive program is limited. One of the main factors that influence how a population of animals will react to stress is how genetically diverse the individuals are from one another. 

In the past, wild, healthy white abalone populations had large numbers of individuals to reproduce with. This created a vast number of family lineages and resulted in an expansive genetic pool. A population with diverse genetic parentage strengthens the overall population by ensuring that there will be a diversity of responses among the individuals. For example, some stresses, like disease or environmental change, may affect certain individuals while others maybe be more genetically suited to defend against those threats. If the population faces a major disease outbreak, some individuals will likely survive, enabling the populations to restore itself over time. But if a population lacks this genetic diversity due to limited parentage, the entire population could succumb to the disease.

The solution is to introduce new animals into the captive breeding population in order to diversify the gene pool and create animals vigorous enough to thrive in the wild. Yet that’s a trickier proposition than one might think, because of their endangered status. Even when evidence strongly suggests that there has been zero reproduction, researchers follow very strict guidelines so as not to disrupt potentially viable populations. For this reason, WARC and CDFW spent years monitoring reproduction of wild white abalone populations, until they were absolutely certain that the animals were not reproducing in the wild.

In 2017, the WARC was given a permit by NOAA to collect wild animals for the captive breeding program. The following May, when conditions were right, Rogers-Bennett and the WARC team of scientists returned to the Channel Islands on the first white abalone collecting trip in more than a decade. WARC divers gathered in the spring sun on the deck of the research vessel Garibaldi to discuss the day’s dives, which would be to nearly 120 feet. Everyone was focused, but a cautious optimism hung in the air. Encountering the incredibly rare white abalone was a long shot, but two individuals had been spotted in the area within the last year.

Alongside her team, Rogers-Bennett descended through the water column, watching as the ocean floor came into focus below her. As she got closer, she could just make out the familiar shape of an abalone. She assumed it was another, more common species of abalone, but as she got lower she recognized the unmistakable markings of a white abalone. She had landed directly on top of one!

Since the beginning of 2017, 10 animals have been collected by WARC scientists and transported to their facility in Bodega Bay. This is the first time in 14 years that scientists will be able to add new genetics to the captive breeding program. Dr. Kristin Aquilino, Director of the UC Davis Captive Breeding Program for the WARC, was able to include a newly collected female white abalone into the 2017 annual captive breeding spawn. It takes time before wild animals are able to integrate into the program, but researchers hope that the newly collected animals will participate in the next white abalone broodstock spawn.

With the new genetics from the wild abalone being introduced to the captive breeding program, and restorative stocking studies underway, the future for this species is looking brighter all the time. Through the dedication of a brilliant team of scientists, policymakers and an engaged public, the WARC is hopeful that one day the white abalone will resume its ecological role in the deep reef ecosystems of the beautiful Southern California kelp forests.

Please stay tuned for more updates about the white abalone and our other abalone restoration work in California!

CDFW Photos. Top Photo: CDFW diver Ian Tanigucci takes notes before collecting a wild white abalone (in the foreground) in 2017. This is one of 10 white abalone collected from the wild to be integrated into the captive breeding program at Bodega Marine Lab. These newly collected animals will provide a new and much needed source of genetics for the captive bred white abalone populations.

Ready for release.


Heading back out to the open water.

CDFW Senior Environmental Scientist Mike Harris is credited with the rescue of a green sea turtle that was unintentionally caught from a pier in Morro Bay.

Harris and the Morro Bay Harbor Patrol responded to a report of the hooked turtle on Aug. 17, after Harris was alerted by a friend in the area.

He arrived to find the angler had carefully secured the turtle and was waiting for help. He noticed the fishing line with a swivel was sticking out of the turtle’s mouth and determined the hook could not be easily removed.

Harris shares work space in Morro Bay with The Marine Mammal Center (TMMC) triage facility, positioning himself well for marine wildlife response. Coincidentally, the TMMC Morro Bay veterinarian is Heather Harris, Mike’s wife, who happens to be an expert on sea turtles.

“She was the first person I called,” he said.

Veterinarian Harris stabilized the turtle and determined it needed surgery since the hook was lodged deep in its throat. Not having the proper equipment and supplies for this type of surgery at the triage site, Heather reached out to colleagues at the Aquarium of the Pacific in Long Beach to arrange for the required care.

The green sea turtle was transported that afternoon and underwent surgery for the hook removal the same day. The hook was successfully removed, the turtle was provided antibiotic treatment and, after several weeks of rehabilitation, was released back into the wild on September 18th.

Harris said the rescue was made possible by the great working relationship between CDFW, TMMC, other agencies and the public.

“Over the past 20 years, I’ve built a connection with the community,” said Harris. “Whether it’s whales, dolphins or sea otters, the public and local agencies often call me to report these types of wildlife events.”

Harris has worked in the Morro Bay area for more than 27 years and is one of two sea otter biologists that work for CDFW’s Office of Spill Prevention and Response (CDFW-OSPR) Marine Wildlife Veterinary Care and Research Center (MWVCRC).

The MWVCRC is a one-of-a-kind lab built in 1997 and focuses on the rescue, rehabilitation and research of oiled marine wildlife, with emphasis on sea otters. California lawmakers created OSPR in 1991 due to several major spills including the Exxon Valdez in 1989. The lab is funded by a fee on petroleum entering California refineries.

Photos Copyright Aquarium of The Pacific. Top Photo: Rescued green sea turtle.

Northern watersnakes are native to the eastern United States. A breeding population was discovered in Placer County in 2007 and a second population confirmed in 2014. Photo courtesy of Todd Pierson.


Coqui frogs have appeared periodically in Southern California. The first coqui was collected from a private residence in Orange County in 2012 and arrived on a tropical house plant.


Nutria have been confirmed in six central California counties, including Tuolumne County where this nutria was photographed near Don Pedro Reservoir in 2017. Photo courtesy of Peggy Sells.


Southern watersnakes are native to the southeastern United States and can reach lengths of 5 feet. They have been found in Yolo, Sacramento and Los Angeles counties. Photo courtesy of Todd Pierson.

Six months after announcing the discovery of a breeding population of invasive nutria in the San Joaquin Valley, CDFW’s Invasive Species “hotline” continues to receive multiple reports each week of nutria sightings from the public.

The reports come in on the toll-free line – (866) 440-9530 – or its e-mail counterpart – Invasives@wildlife.ca.gov – and numbers have reached as many as 30 e-mails and nine calls in a day.

The hotline accounts are checked each weekday – and often multiple times a day. CDFW attempts to respond to every individual submission. To date, about 95 percent of the nutria reports have turned out to be false – either sightings of other wildlife mistaken for nutria or reports that lack enough information to confirm one way or another.

“If it’s on your roof or chewing up the wires in your car, it’s not a nutria,” said Helen Benson, an environmental scientist with CDFW’s Invasive Species Program.

The misidentification of nutria is understandable. Nutria closely resemble several species of native and non-native wildlife, including muskrats, beavers, and rats, which adds to the challenge of a positive identification. Nutria are semi-aquatic rodents native to South America that haven’t been seen in California for 40 years until the spring of 2017 when a pregnant female turned up in a beaver trap.

Still, CDFW welcomes and encourages all reported sightings, preferably accompanied by a photo or video to help verify the identity.

In April, the hotline received one of its most important tips when an Animal Services officer with the City of Lathrop called to report catching and releasing a nutria – without realizing what it was at the time. The officer took photos of the animal, however, which became the second nutria confirmed in San Joaquin County on the edge of the Delta.&

CDFW has focused its early eradication efforts on keeping nutria out of the Delta, where their destructive burrowing into levees, ditches, canals and other water infrastructure could jeopardize the Delta’s flood control and water conveyance systems. CDFW has since launched nutria surveillance and eradication operations in the Delta to mirror those occurring farther south in the San Joaquin Valley.

While CDFW’s Benson estimates that about 80 percent of the Invasive Species hotline’s reports involve nutria these days, the hotline itself predates the nutria infestation by more than a decade. It was created in 2007 to help combat another invasive species crisis: the discovery of quagga and zebra mussels in California.

“Most people don’t realize that invasive species are the second-greatest threat to native species after habitat loss,” Benson said.

It’s easier to combat and possibly eliminate invasive species early before populations become entrenched, which explains CDFW’s aggressive nutria eradication response.

Coqui frogs are another invasive species dealt with quickly when reports come into the hotline. The voracious, tiny tree frogs native to Puerto Rico, Central and South America emit a deafening raucous that belies their small size. The call from one of these tiny amphibians can reach noise levels of 80 to 90 decibels – the same as a running lawnmower. Colonies of coqui frogs have been blamed for lowering property values on Hawaii’s Big Island.

Coqui frogs have turned up in Southern California, arriving in nursery plant shipments from Hawaii and other exotic locales. CDFW asks those contacting the hotline to record the frogs’ calls for confirmation, at which point CDFW will dispatch biologists to catch and remove the frogs.

The Invasive Species hotline has also proved helpful in combatting two invasive aquatic snakes that have turned up in Northern California – the northern watersnake and southern watersnake – likely released into the environment by disenchanted owners who acquired them as pets. Their ill temperament and unpleasant odor make them poor pets – along with the fact they are illegal to possess in California without a permit. CDFW has launched trapping efforts in the suburban Sacramento communities of Roseville and Folsom, where breeding populations of the snakes have been confirmed. It’s possible these snakes could find their way to backyard ponds and swimming pools, and reports to the hotline would help CDFW’s efforts to eradicate them.

Invasive species are a persistent threat to California, and the public plays an important role in helping CDFW identify and respond to new threats. Whether in their backyard or hiking their favorite trail, everyday citizens across the state are partners in protecting their natural resources by reporting unfamiliar plants and animals they don’t recognize.

CDFW Photos. Top Photo: Juvenile Coqui frog.