Study consolidates nearly 40 years of data to help address concerns for black bear populations as a critical species for overall ecosystem health
Image Credit: John Thomas
In a study recently published in Nature Scientific Reports, researchers with the University of Maryland (UMD) Department of Environmental Science & Technology (ENST) consolidated nearly 40 years of black bear data from across the state of Florida to model habitat throughout the state. While the state has made significant progress in protecting black bears, even removing them from the state’s threatened species list in 2012, the population is still down from over eleven thousand bears to about four thousand currently. Florida has a plethora of diverse ecosystems across the state, and Florida black bears represent pockets of significant genetic diversity. Given their genetic uniqueness and their need for large amounts of habitat, protection of the Florida black bear population is a critical goal. By modeling the habitat across Florida, the state hopes to find ways to best allocate their resources and identify key areas for preservation and conservation while dealing with the overall population growth of bears and humans, future urban sprawl, and sea level rise.
“The state of Florida is one of the most diverse ecologically in the U.S., and it is facing some very distinct challenges,” says Jennifer Mullinax, assistant professor with ENST. “While population growth is slowing in the U.S., Florida is one of the fastest growing states in the country, and they are dealing with growing populations alongside sea level rise and water encroachment as well as increases in storms due to a changing climate. They have very different and unique ecosystems and lots of wildlife we don’t have in other areas, with habitat ranging from the everglades to densely populated cities and highlands, to salt marshes, to citrus farms, and even more flat and dry rolling hardwood forests on top of coastal areas around the Gulf. This gives you a lot of different pockets of bear habitat where bears may or may not be thriving.”
With all of these challenges in mind, the Florida Fish and Wildlife Conservation Commission felt it was important to understand the quality and quantity of black bear habitat across the entire state. While black bear research has been going on in the state since the early 1980s, this data was largely gathered by small groups of researchers in distinct pockets of the Florida black bear population without much thought to how this information all connects across the larger state-wide picture. Understanding habitat issues on a state scale can help direct the allocation of resources and inform conservation efforts.
“I do primarily animal movement and habitat modeling,” explains Mullinax. “I look at how animals move on a landscape, the space they use, and how they use it. For Florida, the task was simple: Can we build a habitat model that tells us where there is good habitat across the entire state where the habitats available to bears are so different? They wanted something that was contiguous. How are all these pockets of black bears separated, and what should we focus on connecting? How do we invest money to preserve land and protect resources that are important to both bears and humans? Statewide questions about things like climate change and urban sprawl as it relates to ecosystem conservation are answered at a much larger scale typically, and so this paper specifically tries to help address those needs and direct places where we need to develop functional corridors for bears to move across the state safely.”
In order to achieve this lofty goal, Mullinax and her postdoctoral researcher, Erin Poor, built two models using decades of data based on several factors to identify bear habitat across the state and find areas to prioritize for management. The first model looked at the entire state, while the second model broke the state into seven bear management units that captured more about the landscape in that area and the available management resources already in that area. Based on thousands of point locations across the state and within bear management units, researchers created variables that are important to bears, such as density of roads and humans, percent deciduous forests, density of water or distance to water, elevation, moisture, canopy cover, and landscape fragmentation. The models also considered agricultural variables that might influence bears, such as the growth of corn, soy beans, and citrus. Based on the value of all of these variables, high quality bear habitat was identified, and consensus between the two models was used to provide deeper insights.
“Looking at where the two models align is important because those areas provide a high level of confidence that those areas are really important for black bears and should be prioritized for conservation going forward,” says Poor. “Carnivores have been heavily persecuted as species. The black bear population across the U.S. as a whole has mostly rebounded, and we see that in the Appalachians and in the Maryland and Virginia area for sure. But some populations haven’t had a chance to rebound as fully, and the Florida population is one of them. The Florida population is not just genetically distinct from the bears in Maryland, but within Florida there are pockets of unique genetic material as well. In order to help maintain the integrity of the species overall across the U.S., we need to maintain these pockets of genetic uniqueness, which makes Florida an important black bear population to protect.”
Even more critical is the role black bears can play as an umbrella species. Because Florida is one of the few states in the U.S. with a rapidly growing human population, development is booming in places in Florida occupied by both bears and humans. Identifying and protecting habitats that are important to bears inherently protects many other vulnerable wildlife populations. Connecting forests and habitats bear use throughout Florida ecosystems makes those systems more stable and resilient for bears and humans.
“Setting aside land for corridors can also help reduce conflict between bears and humans,” says Poor. “If we can identify areas for protection and road crossing structures to help bears get to natural areas, that can all help reduce the pressure of a growing bear population and a growing human population in the same space. Bears are not only raiding trash cans, but they are getting hit on roads and causing property damage, so in this case, conservation work provides a direct service for people as well.”
In fact, there are many direct human benefits to protecting the black bear population according to Mullinax and Poor. “Black bears are a really amazing species,” says Mullinax. “They are a classic umbrella species in ecology, meaning if you can support and protect a black bear population, you are guaranteeing that most of the underlying species and mechanisms in the ecosystem are protected. And they serve many different roles in the ecosystem. They are huge seed dispersers or seed spreaders, and anyone who has ever stepped in a pile of bear scat will quickly see that. They are quick indicators of overall ecosystem health, but they are also very useful for studying human health. Bears sit almost still for months at a time, and so they’ve been studied for osteoporosis and bone loss by understanding how their body functions.”
“The Appalachian region has a huge number of increasing white tail deer, and with that comes Lyme disease from the ticks the deer carry,” adds Poor. “But having a healthy, sustainable carnivore population can help mitigate those risks to humans. Many people may not make that connection to human health, but it is clearly there and shows just one way that ecosystem health affects us all.”
The Florida black bear population is a clear example of the concept of One Health, showcasing how animal, human, and environmental health are all interconnected. However, as Mullinax points out, “Beyond all these benefits, they are just fascinating and charismatic creatures that people love and that need our protection.”
The study, entitled “Multiscale consensus habitat modeling for landscape level conservation prioritization,” is published in Nature Scientific Reports: DOI: 10.1038/s41598-020-74716-3.