Panthers now No. 1 predator of white-tailed deer in Southwest Florida

 

A new study by the University of Georgia found Florida panthers are the No. 1 cause of mortality for white-tailed deer in Southwest Florida.

The researchers set out to get a better picture of what factors most affect the survival of Florida’s white-tailed deer, the most popular game species in the state and a key prey species for the Florida panther.

Published this month in the Journal of Applied Ecology, the publication is part of the South Florida Deer Study, a large-scale white-tailed deer research project funded by the Florida Fish and Wildlife Conservation Commission from 2015 to 2019.

The number of deer killed by Florida panthers was very high compared to previous studies, said Richard Chandler, associate professor in the UGA Warnell School of Forestry and Natural Resources. Of the 241 deer captured and fitted with GPS collars during the study, 96 were killed by Florida panthers. During the 1990s, few deer were killed by panthers and the main sources of mortality came from bobcats and hunter harvest. In the new study, only seven deer were killed by bobcats, and only one deer was harvested by hunters.

“Panther predation went from a very small source of mortality to now being the dominant source of mortality for deer,” Chandler said.

Listed as endangered by the U.S. Fish and Wildlife Service, the Florida panther represents the only population of pumas in the eastern United States. Genetic restoration efforts began in the mid-1990s in response to low population and inbreeding concerns, and the panther population has increased substantially over the last 20 years, from 20 to 30 in the 1990s up to 200 in 2017. 

Population, habitat changes pose challenges for deer

The increase in panther predation on deer comes amid a larger shift taking place across the landscape. The Comprehensive Everglades Restoration Plan now underway will restore natural waterflows and benefit many aspects of the ecosystem, but it may also flood land that was already marginally hospitable to deer. The study found that deep water had a negative effect on female deer survival, although no cases of drowning were recorded.

Amid the landscape changes, Florida wildlife officials strive to maintain sustainable deer hunting opportunities. As in other parts of the country, there is a long, culturally important tradition of deer hunting in South Florida, and hunters provide a large amount of the funding for wildlife conservation in the state. Agencies must balance hunting opportunities with other public interests and panther conservation efforts.

“They have restricted hunter harvest quite a bit for the benefit of the deer population and to make sure there’s plenty of prey for panthers. But it’s a balancing act,” said Chandler. “They don’t want to shut down hunting opportunities, but they don’t want harvest to be so high that it suppresses the prey population and keeps the panthers from recovering. … That’s a big challenge, and it’s not easy. Our results emphasize how difficult that will be. Future work is needed to determine if additional habitat management can bolster the deer population for the benefit of panthers and people.”

The study required teams of experts and technicians working year-round in remote areas of Southwest Florida.

The project’s co-investigators featured renowned deer experts and retired Warnell professors Karl V. Miller and Robert Warren, along with Mike Connor with the Jones Center at Ichauway, Warnell alumnus Mike Cherry, who now leads the deer research program at the Caesar Kleberg Wildlife Research Institute at Texas A&M University, David Shindle with the U.S. Fish and Wildlife Service, and Elina Garrison with the Florida Fish and Wildlife Conservation Commission.

The study’s lead author, UGA postdoctoral researcher Florent Bled, is now a scientist with the Florida Fish and Wildlife Conservation Commission. Graduate students Daniel Crawford, Brian Kelly, Heather Abernathy, Hunter Ellsworth, Lydia Stiffler and Kristin Engebretsen provided key support to the project, which benefited from assistance from the Big Cypress National Preserve, National Parks Service, and the USFWS Florida Panther National Wildlife Refuge.

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JOURNAL

Journal of Applied Ecology

DOI

10.1111/1365-2664.14201 

The answer to keeping moose populations healthy? Wolves

 Predators may keep prey populations healthy by acting as a selective force against genetic diseases. A new study found that wolves select adult moose based on age and osteoarthritis, a chronic disease that can be influenced by genetics. Wolves also showed a strong preference for elderly moose over prime-aged adults. The results indicate that wolves play an important role in keeping prey populations healthy and have considerable implications for the conservation management of predator and prey populations.

Over the last decade, wolves have been at the center stage of conservation news. They were once one of the most widely distributed wild mammals on Earth. But after decades of habitat destruction and human persecution, wolves now only occupy about two thirds of their former range.

Wolves as biodiversity managers

Now, the wolf is making a comeback. The US has seen an increase in their wolf populations across the country, and extensive conservation efforts have led to a comeback across Europe. Yet their return has not been well-received by everyone. Predators may lead to human-wildlife conflicts, as wolves can pose a threat to livestock and pets.

Even so, multiple case studies, such as the reintroduction of wolves in Yellowstone, have shown that the presence of wolves favors ecosystem health. Wolves keep prey populations, such as deer, elk, and moose, in check, which benefits vegetation. Carcasses left behind by wolves provide food for other animals such as scavengers and redistribute nutrients.

A new study published in Frontiers in Ecology and Evolution found another way in which wolves may be beneficial for biodiversity: selective predation. Wolves preyed more on prime-aged adult moose with osteoarthritis than healthy prime-aged individuals. Wolves also showed a strong preference for elderly moose over prime-aged adults.

Selective predation

Selective predation means that a particular type of prey occurs more frequently in a predator's diet than what is expected based on the prey type's frequency in an environment. Predators tend to select individuals that are easier or less risky to hunt.

Selective predation can have important impacts on prey population dynamics. Prey population growth rates are less impacted by predation when predators go for juveniles or elderly adults, as these individuals have lower reproductive values.

Less well understood is the impact of predation of sick individuals on prey population health.

“Wolf biologists have in the past assumed that wolves play an important role in regulating the health of prey populations by selectively removing old or diseased animals,” said Dr Sarah Hoy, of Michigan Technological University. “However, a rigorous assessment of that idea has not been tested until now.”

Healthy moose populations

Hoy and her colleague assessed the extent that wolves select adult moose on the basis of age-class and osteoarthritis.

“Osteoarthritis is a progressively crippling disease caused by deterioration of cartilage on the surfaces of moveable joints (for example, knees and hip joints),” explained Hoy. “As individuals get older, they are more likely to develop osteoarthritis and develop more severe forms of the disease.”

They also examined how temporal variation in kill rates were associated with the subsequent incidence of osteoarthritis in the moose population over a 33-year period.

“When it comes to wolves and moose, it makes a lot of sense that wolves would preferentially target moose that are in poorer condition because adult moose weigh between 800 and 900lbs which is between eight and 10 times as heavy as a wolf,” said Hoy.

They found that wolves showed strong selection for elderly moose and avoided prime-aged adults. The presence of severe osteoarthritis, but not mild or moderate, increased the vulnerability of prime-aged moose to predation.

“But the situation is different for older moose. While older moose are more vulnerable to predation, that vulnerability does not strongly depend on whether an old moose has osteoarthritis,” explained Hoy.

They also found that the incidence of osteoarthritis in the moose population declined following years with higher kill rates.

“The decline in osteoarthritis following years with more predation is – we think – because wolves preferentially removed moose with osteoarthritis from the population,” said Hoy. 

Wolf conservation

The results have important implications for wolf management and conservation. Hoy explained: “The management and conservation of wolves is controversial among the public. Yet our results suggest wolves might be an effective, natural, and more ethical way of regulating the health of deer and moose populations – as opposed to using culls or recreational hunting to reduce the incidence of diseases or parasites of concern.”

“The results are also relevant for policy-related arguments about reasons to refrain from intensively hunting wolf populations,” continued Hoy.

“When deciding whether to hunt wolves it is important to not only consider issues that may be caused by wolves (ie, occasional predation of livestock) but to also consider the important ecological benefits that wolves may provide by removing old and diseased animals from the populations.”

JOURNAL

Frontiers in Ecology and Evolution

DOI

10.3389/fevo.2022.819137 

Caribou herd rebounds as Indigenous stewards lead conservation efforts

 

IMAGE: IN PARTNERSHIP WITH MANY ORGANIZATIONS AND GOVERNMENTS, A NEW INDIGENOUS-LED CONSERVATION INITIATIVE HAS HELPED IMPROVE A KLINSE-ZA CARIBOU POPULATION. view more 

CREDIT: UBC OKANAGAN

Despite recovery efforts from federal and provincial governments, caribou populations across Canada continue to decline, largely due to human activity.

But as a new UBC Okanagan study finds, in central British Columbia there is one herd of mountain caribou, the Klinse-Za, whose numbers are going in the opposite direction—all thanks to a collaborative recovery effort led by West Moberly First Nations and Saulteau First Nations.

In partnership with many organizations and governments, the Indigenous-led conservation initiative paired short-term recovery actions such as predator reduction and caribou guardians at maternal pens, with ongoing work to secure landscape-level protection in an effort to create a self-sustaining caribou population.

Their efforts paid off.

Dr. Clayton Lamb, a Liber Ero Fellow, along with Carmen Richter, a biology master’s student, and Dr. Adam T. Ford, Canada Research Chair in Wildlife Restoration Ecology, conduct research in the Irving K. Barber Faculty of Science. Their latest study shows Klinse-Za caribou numbers have nearly tripled in under a decade.

“We have an Indigenous-led conservation effort to thank for averting the looming extinction of this herd,” says Dr. Lamb. “The population was declining rapidly—a West Moberly Elder once described the herd as a ‘sea of caribou,’ but by 2013 it had declined to only 38 animals.”

Today, the herd count is more than 110 and numbers continue to rise.

“This work provides an innovative, community-led, paradigm shift to conservation in Canada,” Dr. Lamb says. “While Indigenous Peoples have been actively stewarding landscapes for a long time, this approach is new in the level of collaboration among western scientists and Indigenous Peoples to create positive outcomes on the land and put an endangered species on the path to recovery.”

Richter, who is a Saulteau First Nations member, says Indigenous communities have really come together for the good of the caribou.

“We are working hard to recover these caribou. Each year, community members pick bags and bags of lichen to feed the mother caribou in the pen while other members live up at the top of the mountain with the animals. One day, we hope to return the herds to a sustainable size,” she says.

Though the partnership has yielded great success, Dr. Ford is the first to acknowledge that more time and effort will be needed to fully recover the Klinse-Za.

“This work is also an important part of decolonizing the mindset of conservation, which has historically worked to exclude the views of Indigenous Peoples,” he adds.

With caribou declines exceeding 40 per cent in recent decades across Canada, many populations have already been lost. But Dr. Ford insists there is a brighter path forward, and this study proves it.

“This is truly an unprecedented success and signals the critical role that Indigenous Peoples can play in conservation,” he says. “I hope this success opens doors to collaborative stewardship among other communities and agencies. We can accomplish so much more when working together.”

This study was co-produced by western scientists and members of West Moberly First Nations and Saulteau First Nations. The work was recently published in Ecological Applications and is supported by a companion manuscript in Ecological Applications exploring the expeditious population growth.

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JOURNAL

Ecological Applications

DOI

10.1002/eap.2581 

Tree cover helps gray foxes coexist with coyotes in the country

As coyotes have spread outside their native range into the eastern United States, they’ve been known to harass and kill North Carolina’s two native species of fox. A new study finds that preserving tree cover may be essential in helping the gray fox survive with coyotes in rural areas, probably because of the fox’s unusual ability to climb trees.

In the study, researchers used camera traps to find out where gray foxes coexist with coyotes in suburban, rural or wild areas of North Carolina. Surprisingly, they found gray foxes can coexist with coyotes in suburban forest fragments. However, in rural zones, they avoid areas where coyotes live that lack adequate tree cover.

“Coyotes are well known to persecute smaller foxes,” said study co-author Roland Kays, research associate professor at North Carolina State University and director of the NC Museum of Natural Sciences Biodiversity & Earth Observation Lab. “They go out of their way, more than you see in other interactions between species, to really bully, chase and kill the smaller foxes. There is some reason for concern if this species is going to survive. How is that going to happen in an urban environment where you also have people?”

Coyotes have spread across North America from their native range in parts of the western United States, taking advantage of the fact that larger predators – such as cougars and wolves – aren’t found in most of the eastern U.S. anymore.

“The general trend has been a decline in all carnivores, but there are some exceptions, and the coyote is one of the big exceptions,” Kays said.

Researchers wanted to know how coyotes might impact where native species like the gray fox are now found – especially since urbanization could affect how the two species interact by fragmenting their habitats and disrupting food sources.

“Foxes are fairly common in urban areas, perhaps in part because coyote numbers are relatively low,” said the study’s lead author Arielle Parsons, postdoctoral research associate at NC State. “In the Midwest and western United States, there are indications of ‘apparent decline’ in fox populations concurrent with coyote population increases. We don’t know if it’s a true decline yet, but there’s evidence it is.”

The researchers used wildlife photos taken by volunteers to figure out where foxes and coyotes coexist. The photos came from 915 motion-sensitive cameras that volunteers placed in yards, forest fragments and open areas in suburbs, dense suburbs, rural and wild areas. Researchers used the photos to develop a model of whether the two species are likely to be found together, and at what times.

From 347 pictures of coyotes and 943 pictures of gray foxes, they found that the two species are most likely to be found together in areas of high housing density and low forest cover – i.e, the suburbs. Coyotes were generally less likely to live in high density housing areas than the gray fox.

“These two species were more likely to use the same sites in suburban areas, especially small forested wood lots,” Parsons said. “We expected them to use these wood lots at different times to avoid each other, but actually we found that they use these suburban forest fragments at the same time.”

The researchers hypothesized that they could coexist in the suburbs because coyotes are just moving through, not establishing territories, and there are still relatively few of them.

“If they’re just moving through, they may not be as prone to direct competition, or bullying of the gray foxes, or their movements are hard for the gray foxes to predict,” Parsons said. “We also think gray foxes might not have a good way to avoid coyotes consistently in suburbs, since habitat is scarce, or avoidance isn’t necessary given abundant suburban resources.”

In rural areas, the two species were less likely to be seen together. However, gray foxes were more likely to inhabit a site as tree cover increased.

“Gray foxes are very good at climbing trees; they have sharp claws,” Kays said. “They’re one of the only dog relatives that can climb trees. Coyotes can’t. It could be that climbing trees helps them deal with coyotes.”

Researchers also saw a slight shift in the gray foxes’ timing, with the gray foxes more likely to be nocturnal around coyotes. 

Overall, researchers said findings for rural areas suggest gray foxes could be at risk in areas with few houses and little tree cover.

“In rural areas, where we’re seeing gray foxes spatially and temporally avoid the coyotes, that’s where we could see some impact on the gray fox population,” Parsons said. “It could mean the coyote is outcompeting, bullying or even killing gray foxes there. A strong competitive relationship may result in gray foxes not being able to access high quality areas, forcing them to establish themselves elsewhere where resources may not be as abundant. That could be a mechanism behind a decline.”

They found an important benchmark of tree cover is important for gray foxes in rural areas: Tree cover in more than 50% of a 1-kilometer radius resulted in gray foxes being more likely to occupy a site.

“Enhancing and preserving tree cover as much as we can is going to be beneficial for gray foxes,” Parsons said.

Researchers said another takeaway is that humans can impact how species are able to adapt and coexist.

“There are things we can do to change the ways wildlife species are able to adapt to human-dominated environments,” Parsons said. “Reducing habitat fragmentation and preserving forest and green spaces can help enhance the ability for these species to coexist.”

The relationship is evolving over time, they added, and could change. Researchers are continuing to study the populations of the two species over the long term.

The study, “The effect of urbanization on spatiotemporal interactions between gray foxes and coyotes,” was published online in Ecosphere on March 20, 2022. It was authored by Kays, Parsons, Kenneth Keller, Christopher Rota, Stephanie Schuttler and Joshua Millspaugh. The study was funded by the National Science Foundation through grants 1232442 and 1319293 and the North Carolina Museum of Natural Sciences.

-oleniacz-

Note to editors: The abstract follows.

“The effect of urbanization on spatiotemporal interactions between gray foxes and coyotes.”

Authors: Arielle Parsons, Kenneth Keller, Christopher Rota, Stephanie Schuttler, Joshua Millspaugh and Roland Kays.

Published online in Ecosphere on March 20, 2022.

DOI: 10.1002/ecs2.3993

Public conservation voting on restoring gray wolves to Colorado

Author contact: Mark Ditmer (mark.ditmer@gmail.com)

Over 3 million voters in Colorado recently weighed in on Proposition 114, a ballot measure to restore the gray wolf to its former range within the state. Previous public opinion polls suggested widespread support for wolf restoration, but the proposition passed with only a slim margin (50.9% of the total vote), and according to new research from Colorado State University scientists, there was a strong relationship between support for the ballot initiative and political support for the Democratic candidate for president in the 2020 election. Additionally, areas closer to proposed wolf restoration areas showed less support for the ballot initiative. Without considering presidential votes, there was a positive relationship between educational attainment and support for wolf restoration. However, when accounting for presidential votes, the team found that voters for President Biden in precincts with lower levels of education had relatively higher levels of support for wolf restoration than voters in precincts with higher educational attainment.

Previous studies have explored the relationships between demographics, livelihood, and self-reported attitudes and beliefs, but few have examined how these factors correspond to actual public behavior, i.e. voting.  

Read the article: Socio-ecological drivers of public conservation voting: restoring gray wolves to Colorado, USA.

Human disturbance is the most crucial factor for lynx in habitat selection

 Habitat selection in wildlife is a process that occurs at different scales: Balancing advantages, such as high abundance of food, with disadvantages, such as human disturbance. Large predators, with their large spatial requirements, are particularly sensitive to these disturbances. A team led by conservation biologists Prof. Dr. Marco Heurich and Joseph Premier from the Faculty of Environment and Natural Resources at the University of Freiburg has studied this habitat selection process in Eurasian lynx. Their results, published by the researchers in Biological Conservation, provide important information for the conservation of this species in human-dominated landscapes. "Through this study, we can generalize the habitat selection behavior of a large carnivore species on a continental scale fort he first time," explains Heurich.

Large dataset with animals in several European areas

The researchers led by Heurich and Premier used a data set consisting of tracking data on 125 lynx from nine study areas across Europe. They compared the locations available to and actually used by the predators at two scales: the landscape scale, which shows how lynx place their home range in the landscape, and the home range scale, which shows how lynx select the habitats within their home range. For this comparison, the research team used a novel machine learning approach called the random forest. This was extended to include a random effect so that variability within and between study areas could be accounted for.

What the animals avoid and how they orient themselves

On the landscape scale the analysis revealed that lynx avoid roads and human settlements. On the level of their home range, the animals were oriented towards hiding places and the availability of prey. The researchers found only minor differences between female and male lynx in their choice of habitat.

Heurich and Premier found the greatest differences in lynx habitat choice at the landscape level, where there were clear differences between the various study areas, for example between the Swiss Alps and the plains of Estonia. Within the foraging areas, lynx behaved very similarly throughout Europe, preferring heterogeneous forest areas and areas that provided protection from human disturbance.

Fishers facing pressure from wildfires, salvage logging,

 

IMAGE: FISHER, MIDSIZE CARNIVORE OF N. AMERICAN FORESTS. view more 

CREDIT: OREGON DEPARTMENT OF FISH AND WILDLIFE

. – The recovery of the fisher, a charismatic, long-tailed forest carnivore, will likely be hindered by the increasing frequency and intensity of future wildfires, new research by Oregon State University indicates.

A long-term monitoring program along the Oregon-California border showed that fisher abundance declined following three mixed-severity wildfires and that salvage logging also affected fisher populations negatively, said David Green of the OSU Institute for Natural Resources.

“We estimated a 27% reduction in the total number of fishers within our study area following the fires,” added Green, who led the study published today in Ecosphere.

Fierce and secretive, the fisher is an animal of conservation concern whose numbers dwindled in the 19th and 20th centuries due to fur trapping and logging. It’s a member of the Mustelidae family, which also includes wolverines, badgers, otters and minks, and it is native only to Canada and the northern United States.

“The fisher has a limited distribution, and rapid changes to forest structure could threaten its long-term persistence,” Green said.

Despite what they are called, fishers don’t prey on fish. They are so named because early North American settlers noticed a resemblance to the European polecat, which was also called a fitch, fitchet or fitchew.

Roughly the size of a large house cat, fishers not only scale trees but are able to climb down headfirst thanks to hind feet that can rotate almost 180 degrees. That trick helps them carry their offspring in their mouths as they climb up and down trees and may also help them attack prey from above.

The largest fisher population in the western United States is in what scientists refer to as the Klamath-Siskiyou Ecoregion, a 50,000-square-kilometer area straddling the Oregon-California border that has an estimated fisher density of about six per 100 square kilometers.

The researchers monitored fishers and gray foxes on a 465-square-kilometer portion of the ecoregion and examined the impacts of three mixed-severity wildfires – the Beaver, Gap and Happy Camp Complex fires – that burned 26% of the area in the summers of 2014 and 2016.

“A century of fire suppression plus increasingly frequent and long periods of drought are predicted to lead to more frequent and more intense wildfires across the West,” Green said. “Understanding the effects of wildfire on the species that live in forests, and the interactions among species, is important for making the most effective conservation and management decisions. The short- and long-term consequences are unclear for wildlife amid the calls for restoring forests to their natural regimes of frequent, low-severity fires.”

Wildfires, especially high-severity fires, cause vegetation changes that can make an area uninhabitable, he said. Salvage logging and replanting add more layers of complexity and make it harder to understand how wildlife respond to wildfire.

Green and collaborators from OSU, North Carolina State University and the U.S. Forest Service used six years of data from a long-term monitoring program to analyze the effects of fire and salvage logging on a population of fishers as well as a population of gray foxes.

Gray foxes are similar in size to fishers and compete with them for prey. Determining the effects of wildfires on gray fox populations and understanding how gray foxes and fishers interact is important for fisher conservation, Green said.

“Fisher abundance decreased significantly in areas of low-, medium- and high-severity wildfire,” he said. “Gray fox abundance decreased in the years before the wildfires but then rebounded.”

Abundance refers to a species’ relative representation in a particular ecosystem – in this case, how many fishers and foxes there are in the study area compared to other animals who share the area.

The researchers also looked at population density – the number of animals per unit of area. They found that medium-severity wildfires had a negative effect on gray fox density but high-severity fire had a positive effect. Salvage logging negatively affected both fisher and gray fox density, the study showed.

“Our results suggest that increased severity, extent and frequency of wildfires in the western United States will have negative impacts on fisher populations and change community composition for medium-size predators,” Green said. “We found that the wildfires that occurred in the Klamath-Siskiyou Ecoregion affected fisher density negatively regardless of burn severity, while gray fox density decreased in areas that burned at medium severity and increased in areas that burned at high severity.”

The researchers aren’t sure why the different severity levels had differing impacts on the two animals studied. More information on the long-term effects of fire and salvage logging on carnivores is needed, Green said, especially regarding changes in survival or reproduction.