An Answer to Vehicle-Caused Turtle Fatalities in Florida

 

Gretchen McLinden – Pre-Veterinary Science

Ryan Keck – BCT

In just a two-mile span of a North Florida highway, 374 turtles lost their lives to collisions with vehicles in one year (Aresco 2005). In Hanson, Kentucky, a car flipped onto its roof, fatally injuring the driver, because it hit a turtle trying to cross the road. In Harrison Township, Michigan, a man nearly killed two men who were helping a turtle get across an intersection (Motor Vehicle Accidents Involving Turtles and Other Wildlife, 2009). While these news articles migrate towards the backs of papers and get overlooked by politics and international conflict, the incidences regarding turtle-roadway damage remain present across the country. Roadways negatively much more than just the turtles that try to cross the street. These roads put the driver, the vehicle, and the turtle at risk. If 374 dead turtles were recorded in one span of a highway in north Florida, how many of those did, or could have caused a secondary accident? How many pedestrians risked their own lives to help the few lucky turtles cross that street safely? While the turtle may be a small creature overlooked by most humans, their importance to ecosystems and the liability that is created by building roads in their habitats makes their livelihood a human issue.

Florida alone has 25 of the 260 turtle species found in the world (Sundquist, Sundquist and Beletsky p. 82). Aresco (2005) states that it has been estimated that many rural roads that turtles could successfully cross have experienced a 100-200% traffic volume increase in the last 20 years, leaving turtles with little chance of surviving the journey (p. 558).With the increase in roadways and the high volume traffic that uses them, there needs to be a solution implemented to help save both the turtle populations as well as eradicate the damages caused by their attempts to cross. Installing small fences and underpasses for roadways intersecting migratory paths of Florida turtles can minimize turtle fatalities, reproductive isolation, and roadway accidents at minimal cost.

In Aresco’s 2005 study, he states, “95% of 343 turtles were killed as they first entered the highway adjacent to the shoulder, while the remaining 5% were killed in the first two traffic lanes” (p. 554). A New Hampshire study by Litvaitis and Tash (2008) estimates that in comparison to non-amphibian species (moose, bobcats), along high volume roads turtles have a 80%-100% probability of being killed, a 30% higher risk than the other species (p. 695). While Litvaitis and Tash did not publish results for after fences were installed, Aresco (2005) stated that with just the installation of fences, the mortality rate of turtles decreased from 11.9 turtles/km/ day to 0.09 turtles/km/day (p. 555). With the addition of underpasses for those that need to cross the road, the number could be decreased even more. In Fuller, J., Hardy, A., Huijser, M., Kociolek, A., McGowen, P. (2008) study, he explains how Boarmen and Sazaki showed the effects of highway fencing on desert tortoises. They discovered that fences significantly reduced mortality for a substantial amount wildlife species, including the desert tortoise. Fuller et al (2008) also cite, “[Boarmen and Sazaki] found 93% fewer tortoise carcasses and 88% fewer vertebrate carcasses along a fenced section compared to an unfenced section of highway” (p. 134).

WVCs, better known as Wildlife-Vehicle Collisions, occur an estimated 300,000 times a year. “However, most researchers believe that WVCs are substantially under-reported for a number of reasons” (Fuller et al, 2008, p. 4). One of the major reasons for this is because “Crash databases typically exclude accidents that have less than $1,000 in property damage [and] not all drivers report collisions with animals” (Fuller et al., 2008, p. 4).  Fuller et al. (2008) also refers to a figure put together by the insurance industry in which they estimate the annual number of Wildlife-Vehicle Collisions to be approximately one million incidents. The very small percentage of these accidents that did occur on roads with fences are almost always a result of no existing crossing structures (Fuller et al, 2008, p. 4). Fuller et al. exclaims how this often results in the animals following their natural instinct to find a way through the fence usually by breaking a hole through it and crossing the road anyways (2008, p. 4).  This emphasizes the importance of implementing both of these structures together to achieve maximum effectiveness.

They then go onto state “Depending on the species concerned, the type of fencing, and whether safe crossing opportunities are provided, wildlife fencing may reduce the number of wildlife-vehicle collisions 80–99 percent” (Fuller et al (2008),p. 135). There have been many studies that prove that as long as the correct fencing and crossing structures are constructed and well maintained they will be almost perfectly effective in preventing wildlife-vehicle collisions.

For a species like turtles that rely on multiple different habitats to live, (a place to nest, a place to breed, a place to lay eggs) migration is a necessary aspect of survival. With roads intersecting such places, these turtles must risk their lives in order to try to survive and continue to reproduce. Situations like that of the turtles in Florida face the issue of reproductive isolation. As defined the Merriam Webster dictionary (1949), reproductive isolation is “ the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences.” Since the turtles are unable to cross roadways safely in order to get to their proper breeding and laying grounds, the turtles remain separated from the rest of their population, unable to further the reproduction of their species. Aresco (2005) discusses Gibbs’ study, when he explains that landscapes fragmented by roads cause a large decrease in amphibian movement that is vital to their survival. If the species becomes separated due to man made roadways, there is very little chance of a turtle successfully reaching the other side in order to broaden their genetic pool through reproducing with different turtles. If part of a species is stuck in one area unable to migrate, not only are they unable to move to find more food, water, and laying ground, but they also are unable to meet new turtles with a different genetic background to increase heterozygosity. With no new introduction of turtles to a population, inbreeding increases and outbreeding becomes less and less possible. Turtle reproduction rates are also reduced due to skewed sex ratios due to high female fatalities from crossing roads.

In areas like Lake Jackson, FL, a road intersects the area where the turtles breed and where the turtles nest. Therefore, female turtles need to be more mobile than males, and many lose their lives seeking nesting areas on the other side of the road. Aresco’s (2005) study stated “6-29% of females are killed annually on the highway during nesting season resulting in male-biased population sex ratios” (p. 558). This affects the population as a whole because turtles, depending on the species, take several years to reach sexual maturity and once they reproduce, they experience high rates of egg and juvenile mortality (Aresco 2005). Roskos (2005) quotes Gibbs in an article where he explains how he found a 95% male turtle population near busy roads, which suggests that the females were killed crossing the street to nesting sites. In a habitat without roads, the long generation time and low survival rates of neonates is balanced by the fact that they have few natural predators. However, vehicles are becoming a major antagonist for these turtles and causing long-term damage to populations.

Low cost construction to save these species will help avoid high cost efforts to save the remaining population in the future. Compared to deer, which according to Conover et al account for, “perhaps $1 billion in automotive repair bills, undetermined damage to agricultural crops… 211 deaths and 29,000 injuries from auto collisions” (1995, p. 412), turtles may seem like less of a priority. This is not true. Turtles are amphibians, meaning their habitats are restricted by water availability, as well as the ability to move from seasonal habitats to food and breeding areas. When considering just turtles, the most effective fences are small enough for an adult human to walk over. This results in a decrease in material prices as well as labor needed for construction. When comparing the low costs of construction and maintenance with the costs in damages from collisions stated earlier it puts it in perspective. It shows that the risk and costs associated with not having fences and crossing structures are much higher than the costs that come with the solution.

Costs can be decreased further through research by scientists, which can determine road kill hot spots. According to Litvaitis and Tash, road kill hotspots are areas where a “disproportionate number of wildlife-vehicle collisions… [occur due to] an obvious response to the availability of life requisites, especially food, water, and sites for reproduction” (2008, p. 689). This means that these ‘hotspots’ can be found not only by the collision rate, but can be predicted with previous knowledge to animal behavior. Scientists know very little about amphibians. According to Stuart et al., say that “[t]he GAA estimates that between 9 and 122 amphibian species have… become extinct since 1980” (2004, p.1784). These species have value in their ecosystems and are already going extinct at a greater rate than other families. This lack of information currently available not only harms the species, but results in efforts to solve the issue of collisions to be much more drawn out and complicated.

One of the major complaints of highway fencing and crossing structures is that they are aesthetically pleasing. Since the fences are a very short and the crossing structures would be in the form of a tunnel, it would barely be noticeable by a driver on the highway. This is a very substantial difference from the fences used to prevent medium and large mammals from crossing highways. Also one of the most aesthetically displeasing common sites on highways are in fact road kill from wildlife vehicle collisions.

Ruediger (2007) claims all successful wildlife crossings are produced through government transportation agencies, public and private landowners and government wildlife agencies working closely and productively together (p. 547).  Implementing fencing and crossing structures in key sections of Florida highways will dramatically change the number of collisions between vehicles and local turtle species. These specific areas will be chosen after field studies and other data is collected to determine which sections are most commonly traveled over by turtles. Fuller et al. (2008) explains, “Several types of fence material are used, but page wire or cyclone fence material is most common” (p. 133). In a study published in the journal Biological Conservation, Woltz, Gibbs and Ducey (2008) ran an experiment to test what characteristics the most effective combination of fencing and crossing structures would have. They discovered that in order for wildlife crossings and fences to be successful in the minimizing of road kill and species isolation for reptiles and amphibians, the crossings must be greater than 0.5m in diameter and lined with soil or gravel, and fencing must be between 0.6-0.9m high. These crossings would be in the form of a tunnel running perpendicular to and under the highway.

There are two situations in which these fences and crossing structures need to be implemented. One of which is with new roads to be built in the future and the second is with older roads currently in use. In the case of future roads, legislature needs to be passed that requires the environmental impact studies for these new roads to include migratory pattern effects. Roads currently in use should be considered for additions of fencing and crossing structures if a significant number of wildlife-vehicle collisions have occurred on them.

Funding is a very vital part of this process and one very easy solution is through tolls. Due to Florida’s extensive road map, and that many of these roads already have tolls on them, instilling a 5% toll cost increase on the toll roads that intersect areas of turtle migration will allow funds to be raised for the building of the fences and underpasses. Since these roads already have tolls, such as U.S 27, the North Florida highway intersecting Lake Jackson, no money will have to go into the building of the tolls. Also, tolls naturally increase their costs every few years. The Pennsylvania Turnpike in 2014 increased tolls by 12% explaining that the extra cost would go to expanding roads, fixing older roads and maximizing the safety of drivers on the road (Pa. Turnpike Reminds Motorists of Toll Increase Starting Sunday Jan. 5^th, 2014, 2014). In a Tallahassee Democrat article by Todd Wright, Leon County Florida’s County Commissioner Dan Winchester agrees with the push to fund fencing and underpasses for turtles, for he states, “This issue isn’t about just spending money to save turtles. This is about environmental safety and motorist safety” (Wright 2005). Turtle-vehicle collisions are a matter of safety not only to the driver, but turtle populations as well and should be considered in the budgets of toll roads.

After one year of toll collections, the initial funds will be used to start the project of building fences and underpasses, and each year they will expand and be properly maintained with some funds going towards research insuring that this infrastructure is as effective as possible.

While small and sometimes overlooked, turtles that try to cross roadways are not only endangering themselves, but also become a liability to people near and on these roads. With the addition of small fences and short paths under highways, the numbers of fatalities, vehicle accidents, and human injury can be reduced greatly, while saving a species that helps Florida ecosystems thrive.

 

 

 

References:

 

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