The information on this page summarizes our SARSP funded research project (2018-2020).
The Fowler’s toad (Anaxyrus fowleri) is a provincially and federally listed endangered species in Ontario, where the only remaining populations are in Rondeau, Long Point and the Niagara-Haldimand area (COSEWIC, 2010). Since Niagara houses the highest density of these toads along with the highest density of people (Green and Middleton, 2013), there is cause for concern on how human activity impacts toad survival (Green et al., 2011). Nickel Beach in Port Colborne, Ontario is one of the few remaining locations in the Niagara region with decent refuge and breeding habitat for the Fowler’s toad. Because of its large natural sand dunes and shallow rocky pools at the east and west ends of the beach, the habitat at Nickel Beach supports one of Niagara’s largest subpopulations of Fowler’s toads (Green and Middleton, 2010; Yagi and Tervo, 2006).
The west half of Nickel Beach is owned by Vale Canada Inc. and leased to the City of Port Colborne who manages the property as a daytime use public beach (Planck and Blot, 2006; Yagi and Tervo, 2006). The eastern half of Nickel Beach is privately owned. One of the main human impacts to Fowler’s Toad at Nickel Beach is vehicular access, parking on the beach and associated grading to create beach parking.
Due to the relaxed regulation of vehicle access on the public-use beach over the past several years, Nickel Beach has become a popular place for human socializing. With such popularity, there is increased pressure on the landowners to keep the beach free of debris and algae to maximize visual appeal and minimize unpleasant odors. Therefore, tractors used to rake the sand, has become a popular method for grading, clearing debris, algae, and compacting the sand for vehicle use. Unfortunately, at certain times of the year the Fowler’s toads use the beach in such a way that heavy machinery or vehicles driving on the beach would directly harm these animals.
The City of Port Colborne and Vale Inc. for many years have been supportive partners for Fowler’s Toad recovery and followed earlier Ministry advice to;
in order to minimize negative impacts to the population (Planck and Blott, 2006). Nickel Beach was an example of management in response to seasonal biological indicators and an example of compromising human use to improve ecological functions.
However, in recent years the entire beach and some dune areas have been converted for human use, including vehicular parking, by redistributing and compacting sand with heavy machinery (i.e., grading). Although both the City and Vale staff are eager to help the Fowler’s toad where they can, they are not willing to again restrict vehicle use to the first section of beach and leave the remaining areas to the toads and people accessing the beach on foot. Because there are new limitations in the amount of beach and dune space available due to unprecedented, elevated Lake Erie water levels (2018-2020), restricting vehicular access to the beach would diminish revenue potential from those paying to park on the beach.
The purpose of this study was to quantify the impact of human activity on the population of Fowler’s toads at Nickel Beach, and to inform ongoing management practices to promote long-term survival of this toad population.
Our objectives were to:
This data was used to inform a population viability model, in order to predict the long term trajectory of the population under current and updated management scenarios. Further recommendations will be communicated to landowners, to aid in development of best toad habitat conservation practices.
Nickel Beach is located on the northern shore of Lake Erie in Port Colborne, Ontario (42.8758° N, 79.2391° W). The beach runs west-southeast in a curved-shape, historically leaving the two main breeding locations at flat limestone outcrops on the west and east ends of the shallow bay (red circles). The public beach stretches 1 km from the west end eastward to the center of the bay, while the remaining 1.2 km is sectioned off as private land. In the public section, natural sand dunes can reach over 3 meters tall, with native dune grasses, shrubs and young trees growing on the foredune, and large trees with thick undergrowth behind the dunes. The Common hop tree (Ptelea trifoliata), a threatened species, is also found throughout the mid dune areas. The private section has a hardened shoreline (i.e. no sand dunes), with a continuous break-wall constructed out of a range of materials; rocks, metal and poured cement (Fig. 1).
To assess human impact on Fowler’s toads, we conducted pressure surveys on foot 2 to 3 times weekly over three active seasons (2018, 2019 and 2020). Duration of the seasonal surveys started from the May long weekend through Labour Day weekend in September, when vehicle access to the beach ends. We counted the total number of vehicles and people on the beach, from the westernmost point of the public beach to the center of the bay, where a large yellow gate separates the public and private beach. We also recorded other impacts caused by beach activity throughout the summer, including timing of beach grading and grooming, patrons parking on beach dunes, and evening beach activities.
Fowler's toads are nocturnal animals. They are active at night and can be found sitting along the water's edge, foraging for insects on the beaches of Lake Erie. During the breeding season (May-June) adult toads can be found gathering around shallow pools of water along the shoreline or in backshore wetlands to call and lay eggs.
Their daytime habitat is the soft sand of the upper beaches and natural sand dunes. Fowler's toads normally bury down into the sand (less than 5 cm deep), and remain there during the day to escape the sun and hot temperatures, and digest their meal from the night before. Sometimes the toads make use of cover objects and can bury under woody debris on beaches.
You can find Fowler's toads emerging from their daytime refuge at night, just after the sunsets and temperatures cool down.
The study area was extensively surveyed for Fowler’s toads from the end of May/early June to the end of September every year (2018-2020). We conducted visual encounter surveys and mark-recapture surveys from the westernmost point of the public beach to the easternmost point of the privately-owned beach, weather permitting. On several occasions over the course of the 3-year study, conditions were too dangerous for surveyors to cross "pinch-points" on the beach. In these circumstances, surveys were conducted to the extent possible.
Visual encounter surveys conducted during the day focused on searching for and counting eggs masses, toads in amplexus, tadpoles and toadlets. Evening toad surveys targeted juveniles and adults and included toadlets once they transitioned to nighttime activity patterns. We ‘marked’ toads by taking photos of each toad's dorsal spot pattern, and using an image-recognition software called Fotospottr (Matlab, Schoen et al. 2015), to determine recapture status.
The first step for assessing population viability is to determine the population growth rate. We accomplished this by building a Leslie matrix for Fowler’s toad life stages; tadpole, metamorph, toadlet,
juvenile, subadult and adult (Crowder et al., 1994). We calculated the survival rates for the toadlet, juvenile, subadult, and adult stage using our full dataset from 2018-2020. Fecundity was calculated using average egg mass sizes from Yagi and Green (2016), for both sub adult and adult toads.
To determine which stage class held the most significance in the population, a sensitivity analysis was conducted, following methods given in Crowder et al. (1994).
Pressure surveys yielded 3633 of cars on the beach over the course of 3 field seasons (1103, 820, 1710 in 2018, 2019, and 2020, respectively). A total of 3773, 2940 and 12,456 people were counted in 2018,
2019, and 2020. The mean number of cars on the beach in 2018, 2019 and 2020 were 46, 45 and 46, respectively, however the beach frequently reached capacity on weekends (250-300 cars in 2018-
2019, 150 cars in 2020). The mean number of people for each year was 157, 165, and 593, respectively.
Due to the COVID-19 pandemic, Nickel beach was not open to the public (in vehicles or on foot) until July 7th 2020, and unlike previous years, remained open until September 26th 2020. Interestingly, despite pandemic restrictions, the mean number of people at Nickel Beach was greater in 2020 than in previous years. In all years, cars parked illegally along the guard rail just outside the gate when Nickel Beach was at capacity, or as a “free” alternative to paying to park on the beach. Frequently, surveyors observed cars parked along the guardrail being fined.
Over the course of the three-year study, 56 whole population surveys were conducted, with over 648 hours of search effort logged. Toad population size was calculated using the Chapman-Peterson method with adult toads. The population estimate for 2018, 2019 and 2020 was 547 ± 18 (SE), 660 ± 34 (SE), and 398 ± 18 (SE), respectively. Historical data collected by MNRF (2003 to 2016) was used to help create the above figure. Data collected from 2012 to 2016 has not yet been fully processed for calculations to date.
The sensitivity analysis revealed that the sub-adult life stage holds the most potential in the population for recovery if survival increased in this group. We found that a 41% increase in survival of sub adults was required to increase overall population growth rate.
We compared PVAs from four different management scenarios in order to assess the potential change in extinction risk depending on population growth rate and dispersal rates.
Scenario A (top panel, grey) represents the current conditions for toads at Nickel Beach, where population growth rate is low, and dispersal rates are low due to presence of barriers along the shoreline (caused by high water levels along break walls).
Scenario B (bottom panel, grey) represents the population with the same low growth rate but with higher dispersal rates, assuming management has occurred to alleviate dispersal restrictions.
Scenario C (top panel, pink) represents the population with increased growth rate, as a result of management protection of the sub-adult life stage, but with reduced dispersal rates, or no management action to address dispersal barriers.
Scenario D (bottom panel, pink) represents the population with both increased growth rate and increased dispersal rates.
Both Scenarios C and D predict a very low extinction risk over a 100 year time frame.
The Fowler’s toad population at Nickel Beach in Niagara was thought to be one of the few remaining viable populations due to the relatively high abundance, ideal overwintering habitat (large natural dunes), proximity of good quality breeding sites (rocky pool headlands), shoreline connectivity to the east and good quality daytime refuge habitat (Green et al., 2011).
Even with a high amount of human use during the day, mitigation measures such as the seasonal timing of beach grooming, addition of grading setbacks from breeding sites, storage of graded sand at the west end into an artificial dune and controlled car access to the first fence, helped sustain the population. However, these mitigation measures were developed when Lake Erie water levels were much lower and are outdated (see Fig. 15, left).
The Fowler’s toad is adapted to Lake Erie cycles provided they have access to these habitat features across a range of water levels. Populations tend to cycle with changes in lake levels and since this species is short lived, population viability requires a large number of breeding sub-adults and adults to sustain the population. Toads need to be able to move annually from their wintering site in the dunes to breeding sites and then back to summer refugia and shorelines for nightly re-hydration and feeding. Toadlets need to disperse from breeding sites along shorelines where they feed and hydrate all summer, using daytime refugia, once they can maintain their
water balance like older toads. They also must find good hibernation sites to survive their first winter.
In this study we found that vehicle parking occupied the majority of available beach space during the toad active season, and the toads responded by moving away from this area for that time.
Since the toads normal refugia habitat are the natural sand dunes found on Nickel Beach (Vale property), the toads must eventually return to this area to find appropriate hibernation habitat.
In 2018, toads were better able to transverse the beach and move away from the disturbances. In 2019 and 2020 we observed higher lake levels which eliminated usual breeding habitat and created "pinch points" along the shoreline where the lake water reached the constructed break walls, leaving no dry beach space for toads to traverse. Toads were observed attempting to climb over the rocky break walls to reach breeding sites (see image to left).
Additionally, in 2020 the lake activity was so dynamic that zero recruitment was recorded at this site.
The population viability analysis revealed overall that the Fowler’s toad population at Nickel beach, in its current state, is in decline and will continue to be in decline without recovery actions that improve survival of the sub-adult life stage and dispersal to and from breeding sites along the shoreline.
During high lake levels there is no room to use the beach as a parking lot and to maintain endangered species habitat. The human impacts on the toad population during high lake levels are more egregious and they are cumulative. Managers must use alternative parking solutions, and re-implement beach management conditions that are sensitive to the toad’s life cycle. Many people would be able to enjoy the public beach for daytime use but not for driving. In addition to habitat impacts on the public beach, the private beach- which could have been used by toads as refugia during intense public beach use- was not - due to high water levels and hardened shoreline. The human impacts on the toads would be lessened with proper beach management and mitigation of dispersal barriers to the east.
Beach nourishment is a technique involving the addition of natural rock and sand mixtures to
the shoreline at the base of the shore wall barriers and areas with high erosion rates (expressed at high lake levels). The material used will eventually get moved about by wave action but will remain at least annually and provide dispersal opportunities for adult toads to get back and forth from breeding sites (creek mouths during high lake level periods) and hibernation sites (natural dunes at Nickel Beach); and allow toadlets to disperse from breeding sites to suitable daytime refuge and hibernation habitat available at Nickel Beach. Adding natural rock can be done annually. It is a low-cost solution (materials and labor) and can have positive impacts to fish habitat because the rock will move about and provide more structure to support fish spawning habitat function. The beach nourishment can continue until the collapsed shore walls are fixed according to coastal engineering specifications.
Our solution regarding restoring connectivity so toads can access the creek mouth areas in the next bay for breeding is truly innovative. Creek mouths near beaches offer an opportunity for toads to breed because they are entry points into back dune areas with shallow protected waters on sand. This means more targeted outreach and education to landowners with shore walls with significant erosion are needed to address the dispersal barriers along the shoreline.
There is an immediate concern that this population will crash in very a short time frame (<10 yr) because the population is now confined preventing natural dispersal and rescue effects. Furthermore, since the high lake level cycle is about 10 years to get back to lower levels- it is realistic to assume time will run out and an emergency response is needed over the next 5 years. Collaborations will be required with municipal drainage engineers and regulatory agencies regarding approval of “beach nourishment” as an emergency measure to build beaches at the base of eroding shore walls. In the long-term, removing or redesigning shore wall protection can be accomplished by consulting a coastal engineer. Designing outreach materials to inform the community and landowners about shoreline processes and solutions to erosion will also help address this impact.