31 January 2012
We came to Florida Panther National Wildlife Refuge under an I-75 underpass designed to facilitate the movement of wildlife and water. We began at Picayune Strand State Forest and hiked north to the highway, beyond which is the Panther Refuge.
We’d spent the previous afternoon meeting with Florida Department of Forestry officials discussing a large-scale water restoration project underway at that property. The wildlife underpasses were integrated into Alligator Alley during its conversion to I-75 in the late 1980s and early 1990s. By the end of construction there were 36 wildlife underpasses, 8 feet tall, 70 feet wide and 100 feet long. Ten foot chain link fences bracket the road, funneling wildlife toward the passages. It was a massive project with a $77 million price tag.
The investment appears to be paying off. In 1990, biologists estimated that there were roughly 30 panthers left in the wild. Vehicle traffic on Alligator Alley threatened to reduce panther numbers even further. Since the underpass construction panther roadkill numbers on the Alley have dropped dramatically. In the same span of time, through focused habitat conservation efforts by the state of Florida and federal government (including the creation of the 26,400 acre refuge in 1989), population estimates have increased. There is also good evidence that the introduction of Texas cougars in the mid-1990s provided an influx of genes that benefited panther demographics. Today the panther estimate ranges between 100 and 160 cats. Additional underpasses are now located on SR 29, a north-south road on the refuge’s eastern boundary. Engineers have worked with biologists to design smaller, less costly underpass structures that can be integrated on smaller 2-lane roads, which annually claim the majority of panther roadkill.
Many factors have contributed to the improvement in the panther population. The reduction of panther roadkills may also have to do with increased awareness by motorists and better signage and speed limit enforcement. Just this year the FDOT began placing Roadside Animal Detection Systems, solar powered signs that use flashing LED lights to alert drivers when large animals approach roads. Nevertheless, roads are still responsible for killing panthers. Forty-three cats have been killed on Florida roads since 2009, not including the two cats that have already died in 2012. This challenge notwithstanding, the construction of Alligator Alley underpasses is a successful mitigation effort, allowing the flow of wildlife between large conservation properties across an interstate highway. The construction of a four lane, heavy traffic highways slicing through panther and other species habitat would have had devastating effects on the ecological integrity of adjacent conservation lands, but the numerous and well designed underpasses greatly enhanced species connectivity under the expanded highway. Although panthers were the primary focus for designing the underpasses, many other species have been documented using them including Florida black bear, bobcats, alligators, turkey, and deer. The underpasses also facilitate the flow of water southward to the Picayune and Fakahatchee strands. Continuity with adjoining properties seems to be a theme in this landscape. Multiple agencies must continue to work together to meet these challenges.
For me, the I-75 underpasses are a symbol of the conservation biology movement in the early days. Using what data there were available back in the late 1980s on the panther, scientists and policy makers helped engineer an effective solution. It was not an easy or inexpensive process, but appears to have worked well. I remember one of the first lectures I heard my late graduate school advisor and committed conservation scientist Dr. Dave Maehr give. In it he showed a slide of one of the underpasses and talked about the difficulty of getting the structures paid for, a process he was involved in as the leader of the Florida Game and Freshwater Fish Commission’s (which is now the Florida Fish and Wildlife Conservation Commission or FFWCC) panther research team. Dave matriculated at the University of Florida under Dr. Larry Harris, one of the central figures in the field of conservation biology in the 1980s and 1990s, when it became recognized as a scholarly discipline. Both Dave and Dr. Harris were shrewd negotiators, and both were capable of compromising in order to achieve meaningful conservation goals.
Dr. Harris oversaw the work of many other students who went on to become influential figures in Florida and across the globe, the most prominent of which is Dr. Reed Noss, who in the late 1980s was the first to propose network of connected conservation land in Florida, and has since written many articles and chapters on wildlife corridors and designing conservation land networks to conserve biodiversity. In the last twenty years, other students of Dr. Harris including Dr. Tom Hoctor and Dr. Dan Smith have worked on projects like the Florida Ecological Greenways Network and the prioritization of roadways for future wildlife underpasses to continue the work towards protecting a statewide network of functionally connected public and private conservation lands, aided by a future comprehensive system of wildlife crossing structures across Florida’s large network of highways.
Another of Dr. Harris’ former students was waiting to meet us at the underpass. Darrell Land of FFWCC eventually replaced Dave Maehr as the panther recovery team leader after Dave left the agency to pursue a Ph.D. in conservation biology, and has been in the position now for nearly 20 years. As we approached the underpass in the bright morning we saw Darrell walking toward us, along with Kevin Godsea, the refuge manager for USFWS, and Laurie MacDonald of Defenders of Wildlife. Together the group represented many years of experience in panther biology and policy decisions. As if to remind us of the need to maintain our effort and our focus despite the challenge and high cost of protecting the species and its landscape, a perfectly preserved pair of panther tracks, one male, one female, were waiting in the dried out mud of the underpass.