Our Work
Through our Northern Leopard Frog Project, Waterton Biosphere Reserve Association (WBRA) aims to raise public awareness about the importance of northern leopard frogs and other amphibians in ecosystems where they function to control insect pests, limit algae growth that contributes to oxygen depletion in wetlands, and help cycle energy and nutrients by providing a link between aquatic and terrestrial habitats.
Join our efforts by learning how you can help improve habitat stewardship for northern leopard frogs to support their expansion from reintroduction sites in WBR.
Dramatic and abrupt declines in northern leopard frog populations starting in the late 1970s resulted in extinction of this species from large portions of its historic range in western North America. This includes much of Waterton Biosphere Region (WBR) where the frog was historically present along major rivers and tributaries, lakes, springs, and irrigation reservoirs. Reintroductions have since occurred at three locations in WBR – in Waterton Lakes National Park, Beauvais Lake Provincial Park, and Town of Magrath – and these are key anchor points for population expansion as we look to see this species once again inhabit our landscape.
- The northern leopard frog is the largest frog found in Alberta. On average, adult frogs can range from 5 to 11 cm (two to five inches) in length, measuring from the tip of the nose to the back end (snout-vent length).
- The background body colour for this long-legged, smooth-skinned frog is either green or brown with a pale white belly.
- Large round or oval spots are bordered by pale rings. These spots can be found dotting the back, sides, and legs of the frog.
- Prominent, white- or cream-coloured ridges (also known as dorsolateral folds) extend along the sides of the back from behind the eyes to the tail.
- The spots and light-coloured ridges are defining characteristics of leopard frogs relative to other frog species in WBR.
During mating season, males call to attract females. The low-pitched call is described as sounding like a door creaking open or a snore, interspersed with clucking or grunting noises. This subdued call does not typically carry long distances and may go unnoticed. Click here to listen to northern leopard frogs calling at a marsh in Manitoba on a May afternoon. Striped chorus frogs are also heard in the background.
Young of the year northern leopard frog. Photo by Parks Canada
Active from April to October in Alberta, you are most likely to encounter northern leopard frogs during warm, wet weather or at dawn or dusk if the weather is not too cool. They may rest during the day in wet areas or shallow pockets in the soil where they can absorb moisture, avoid predators, and bask in the sun to raise their body temperature and speed food digestion. Three distinct habitats are required annually: breeding habitats, summering habitats, and overwintering habitats.
Northern leopard frogs can travel significant distances for their size – young-of-the-year have been captured 5 km from their natal wetland, though annual movements by adults between seasonal habitats are likely less than 2 km. Suitable weather conditions and connecting habitats (e.g., moist corridors along streams through drier environments) will influence frog dispersal and migration movement distances, and these frogs are likely to return to the same breeding and overwintering sites from year to year.
DIET
Northern leopard frog tadpoles primarily graze on algae, phytoplankton, and other plant debris in the waterbody where they hatched from their eggs. Despite their vegetarian tadpole form, juvenile and adult northern leopard frogs are indiscriminate predators eating insects, spiders, worms, crustaceans, and even other small vertebrate prey. Prey availability and temperature will affect growth rate, though adult males will ultimately be smaller than adult females.
HABITAT NEEDS
Northern leopard frogs need a mosaic of three distinct habitats each year for overwintering, breeding, and summer foraging. The next section will describe in detail the importance of each of these three habitats.
BREEDING HABITAT
Northern leopard frogs are typically associated with a wide range of temporary or permanent aquatic habitats during the spring and early summer and can often be found along the edges of ponds, marshes, beaver ponds, streams, rivers, oxbows, and lakes. They prefer clear, clean water in open or lightly wooded areas, rarely occurring in dense forest. Successful breeding sites typically have shallow standing water, a lack of predatory fish, and abundant aquatic and emergent vegetation such as cattails, sedges, rushes, and moisture-tolerant grasses for cover and egg attachment. These breeding habitats are used for mating, egg laying, and tadpole development.
SUMMER FORAGING HABITAT
Summer foraging occurs in moist terrestrial environments near water for escape from predators (e.g., riparian habitats around wetlands or along creeks), but frogs may move farther during wet periods. In general, habitats with short (15-30 cm tall) vegetation are preferred while areas of taller (>1 m) grass are avoided as are wooded areas, open areas, and heavily grazed or mowed areas. The taller vegetation may impede easy movement for the frogs but can offer some protection from the effects of hot sun or hungry predators.
OVERWINTERING HABITAT
Movements to overwintering habitats begin as early as late August and can continue into October. Unlike other local frog and toad species that can withstand partial freezing or burrow into mud to overwinter, northern leopard frogs hibernate under rocks, logs, leaf litter, or vegetation at the bottom of a waterbody. To persist through winter, the frogs need waterbodies with relatively high dissolved oxygen levels in water of sufficient depth that it does not freeze to the bottom, such as that found in creeks, rivers, springs, or large lakes/wetlands. Absence of predaceous fish such as trout or pike is also preferable. Both breeding and overwintering may take place within the same waterbody, but when separate wetlands or waterbodies are used, the habitats are usually within 2 km of one another.
BREEDING
Frog emergence from overwintering sites occurs in April shortly after ice melt from their overwintering site. Males arrive first at a breeding pond to begin calling, primarily at night, with females arriving up to two weeks later. Breeding occurs from late April to early June in Alberta and can last from a few days to a few weeks. This is largely dependent on weather as frog activity is reduced with cooler temperatures (<10⁰C).
Photo by Parks Canada
After mating, females deposit one egg mass each and attach it to submerged vegetation in shallow water in an area exposed to sunlight and with high water temperature relative to the rest of the waterbody. The egg mass is a firm, grapefruit-sized, spherical mass containing 600 to 7000 eggs. Hatching generally occurs after five to nine days but can take almost twice that long depending on the weather and temperature.
Tadpoles linger near the egg mass for two to three days after hatching. Over the next 60 to 90 days, they will feed on plant material and undergo metamorphosis into frogs. The large size of northern leopard frog tadpoles (>10 cm) just prior to metamorphosis is noticeable relative to other frog or toad species in Alberta. Young froglets typically remain within 20 m of shoreline, thus a concentration of young-of-the-year frogs is a good indication of successful breeding within the waterbody.
LIFESPAN
Northern leopard frog tadpoles. Photo by Parks Canada
It ain’t easy being green as all life stages of northern leopard frogs in the wild typically experience high mortality (i.e., ranging from 60% mortality for adults to 93% for young-of-the-year) and lifespans are rarely longer than three to four years. Common predators of eggs and tadpoles include dragonfly nymphs, caddisfly larvae, beetles, belted kingfishers, hooded mergansers, common garter snakes, adult northern leopard frogs, tiger salamanders, and fish. Common predators of juvenile and adult frogs include herons, owls, snakes, waterfowl, raptors, and predatory fish species such as trout.
Irrigation canal that provides little habitat for northern leopard frogs compared to natural vegetation along creeks. Photo by Kim Pearson
HABITAT LOSS, ALTERATION, AND FRAGMENTATION
Northern leopard frogs may be particularly sensitive to influences that disrupt the mosaic of habitats upon which they rely annually. Changes to surface water and groundwater can result from channelling, ditching or draining wetlands and/or converting them to cultivated cropland. Even conversion of wetlands to forage crops can reduce foraging habitat for northern leopard frogs if their movements are hampered by thick, impenetrable cover. Steep-sided canals and ditches can prevent movements of young-of-the-year and adults through the landscape, though creation of irrigation waterbodies can create additional amphibian habitat if appropriate bank sloping is considered.
Livestock grazing can impact northern leopard frogs through removal of upland cover, erosion of riparian areas, increased siltation of wetlands, altered water conditions due to cattle waste, and trampling of egg masses in shallow water. Yet when appropriately timed, light-to-moderate intensity grazing can improve habitat by removing heavy litter and creating areas of shorter cover that allow frog movement and effective hunting for prey as well as increasing openings in emergent vegetation where water temperatures rise and promote development of eggs and tadpoles.
DISEASES
The impacts of disease are particularly detrimental to northern leopard frogs and the effects can be compounded when individuals are stressed by environmental conditions, injury, malnourishment, and other threats.
- Ranavirus is a virus that causes systemic infections and can be transmitted by ingestion, direct contact, or exposure to infected soil or water and can affect amphibians, reptiles, and fish. Mass die-offs are common with mortality rates upwards of 90% when a waterbody is infected.
- Chytridiomycosis (also known as chytrid) is a fungus that attacks keratin, chitin, and cellulose and is now thought to be widespread in many Alberta wetlands. Chytrid fungus causes excessive keratinization and sloughing of skin which impedes water and electrolyte absorption in adult frogs and impacts foraging rates in tadpoles.
- Red leg syndrome is a systemic bacterial infection that is common in amphibians and fish and is almost always fatal.
Landowners and recreationalists can help prevent the spread of these diseases by rinsing off organic material from footwear, tires, etc. when moving between different wetland areas and letting the gear dry at 20⁰C for four days.
ENVIRONMENTAL CONTAMINANTS
Agricultural compounds like pesticides and fertilizers, even at relatively low concentrations, can impact northern leopard frogs and other amphibian populations due to amphibians’ thin and sensitive skin through which they can absorb oxygen. Known impacts vary by chemical but can include deformities, increased mortality from acute toxicity, decreased prey availability, lower survival rates, lower reproductive capacity, reduced growth rates, reduced ability to avoid predators, and increased susceptibility to pathogens. Runoff of livestock waste into wetlands can further upset amphibian populations by increasing algal production which subsequently depletes oxygen.
CLIMATE
As the climate warms, drought concerns extend to permanent drying of northern leopard frog breeding habitats or earlier drying on an annual basis before tadpoles have metamorphized. Previous amphibian and northern leopard frog population declines in the 1930s and late 1970s/1980s corresponded with periods of drought, though this is unlikely to be the sole cause of declines as populations were lost from permanent wetlands too.
Research suggests that increased exposure to ultraviolet (UV) radiation from a thinning ozone layer can result in spinal deformities in amphibians and decreased resistance to disease and pathogens. Since northern leopard frogs lay their egg masses close to the surface of the water, they may be susceptible to UV radiation.
HARVEST/COLLECTIONS
Many people fondly remember catching northern leopard frogs and tadpoles as a child, or perhaps less fondly dissecting one during a high school biology lab. Commercial collections for scientific and educational purposes totalled over a million frogs each year in Manitoba alone. Such harvests dropped off in the 1970s when frog populations declined sharply and collection is now prohibited under the Alberta Wildlife Act. Handling of northern leopard frogs is discouraged where localized populations exist due to their threatened status and sensitivity.
Stewardship example of a landowner restricting cattle access to potential northern leopard frog habitat. Photo by Kim Pearson
WHAT THE WBRA IS DOING TO HELP
In 2015, Waterton Biosphere Reserve Association’s (WBRA) Species at Risk Action Plan identified the need to support northern leopard frog reintroduction efforts conducted by others at Waterton Lakes National Park, Beauvais Lake Provincial Park, and Magrath and to raise awareness among landowners and Waterton Biosphere Region (WBR) residents regarding the reintroduction work and amphibian species at risk in general.
Visual encounter survey. Photo by Kim Pearson
Investigation of historic data sources and public input in response to initial outreach efforts helped identify potential locations at which to survey for northern leopard frogs. Field surveys in 2017 to 2019 confirmed northern leopard frog presence at five previously undocumented locations in WBR within a few kilometres of previous reintroduction sites. Outreach activities increased awareness of this species and how to steward quality habitat for northern leopard frogs as well as other amphibian species.
We are now working on a conservation plan for northern leopard frogs in WBR. This plan will build on results from previous landowner outreach activities and site surveys, review beneficial management practices, compile advice from local and regional experts, and identify the actions WBRA will take going forward to support northern leopard frogs in the area. Please stay tuned for more information.
WHAT YOU CAN DO TO HELP
Maintaining a mosaic of healthy breeding, summering, and overwintering habitats is an important way Waterton Biosphere Region residents can support northern leopard frogs and other amphibians.
Beneficial Management Practices (adapted from MULTISAR Wetland Species guide):
- Avoid draining wetlands or digging them deeper into dugouts, even during dry years, and restore previously drained wetlands. Natural wetlands will help buffer the water table in the surrounding area against fluctuations in precipitation and surface water flow, and the extra acres gained by draining often are less productive.
- Leave a 30 m buffer of native vegetation around all wetlands to help prevent erosion and maintain water quality.
- Adjust timing of grazing around wetlands to avoid sensitive periods for amphibians (i.e., April to mid-July when breeding is occurring and eggs/tadpoles are developing).
- Adjust stocking rates and grazing intensity to ensure adequate carryover and litter (e.g., 40% utilization rate in fescue grasslands, 25-50% utilization rate for riparian areas) and allow periods of rest.
- Use strategic placement of salt blocks to draw cattle away from wetlands and manage utilization of the pasture. A range of vegetation heights usually supports the greatest diversity of wildlife.
- Watch for amphibians when driving on roads and trails near wetlands that are known to be occupied.
- Avoid using pesticides or chemical fertilizers near wetlands hosting species at risk. Amphibians are particularly sensitive to runoff of these compounds and can suffer paralysis, mutations, or even death.
If you are interested in pursuing a cost-shared project to maintain or improve wetland habitat, please reach out to us. We can assist you with access to technical experts and funding opportunities. Examples of stewardship projects include off-stream watering, development of hardened access sites, fencing to support rotational grazing in riparian pastures, controlling run-off from winter pastures, and more.
If you see a northern leopard frog on your land (see identification information under the Sights and Sounds section at the top of this page), please report your sighting to us! Your on-the-ground information will help identify potential dispersal routes and range expansion from the reintroduction sites in WBR. Frog mail is faster than snail mail – send your sightings to nleopardfrog@watertonbiosphere.com
As part of the Species at Risk Action Plan for Waterton Biosphere Region, Waterton Biosphere Reserve Association (WBRA) embarked on a project in 2017 to support northern leopard frog conservation in the area. Extensive public outreach was conducted to engage the community in conversations regarding the importance of amphibians and their habitats in Waterton Biosphere Region (WBR) and solicit information regarding past and present northern leopard frog occurrences. Our outreach included posters, postcards, social media posts, print and online articles, eNewsletters, displays at public events, and workshops. We were able to build on community interest in the project to discuss other amphibian species at risk, associated wetland habitats, and their stewardship in WBR.
Potential northern leopard frog locations were gathered from any public input as well as from historical records to identify areas for survey and future stewardship work. WBR staff, landowners, and volunteers conducted fieldwork at several wetlands on private lands in the summers of 2017 to 2019. To determine whether the wetland was occupied, we used visual surveys for adults, tadpoles, and egg masses in combination with water sampling and subsequent testing for environmental DNA (also known as eDNA sampling). This involved testing for certain species’ DNA in water samples from a given wetland and helped detect amphibian presence even if no visual observations were made.
FIELD SEASON RESULTS
Over the three field seasons of the northern leopard frog project, a total of 47 wetlands managed by 19 unique landowners were sampled for amphibian presence. This map shows the distribution of sampled locations in relation to reintroduction sites. Northern leopard frogs were detected at eight sites; eDNA sampling detected northern leopard frog presence at four sites when they weren’t observed during visual surveys. Overall, these results contributed information for five sites where northern leopard frogs had not previously been recorded. Five other amphibians that call WBR home were also observed, with striped chorus frogs and tiger salamanders most commonly detected.
Northern leopard frog workshop in Magrath (2017) Photo by Kim Pearson
Workshops held at Beaver Mines/Beauvais Lake Provincial Park and Magrath in September 2017 and October 2018, respectively, provided an opportunity for participants to hear from various knowledgeable speakers familiar with northern leopard frog reintroductions and stewardship in the WBR area. The presenters included Lea Randall (Calgary Zoological Society), Kim Pearson (Waterton Lakes National Park), Sarah Downey (Alberta Parks), DeVar Dahl (Town of Magrath), and Mike Verhage and Brad Downey (Alberta Conservation Association).
Thank you to everyone who submitted information on northern leopard frog sightings in the WBR area and to those landowners who allowed us access to your properties. Your support was critical to the success of this project! We are still interested in information on northern leopard frog sightings in the WBR and welcome you to contact us at nleopardfrog@watertonbiosphere.com.
THE WESTERN PRODUCER
Have leopard frogs changed their spots?
“Did the leopard frogs change their spots, the places they used to live? Or did circumstances reduce their numbers?”
In a 2018 article and video by Barb Glen of The Western Producer, these questions and more are discussed. The article covers Waterton Biosphere Region’s Northern Leopard Frog project and its local efforts to improve awareness about amphibians and their habitats within the biosphere.
You can view the article and video here.
PINCHER CREEK ECHO
Waterton Biosphere Reserve to support frog conservation
In an article from May 2018, Andrew Glen McCutcheon of the Pincher Creek Echo features Waterton Biosphere Region’s Northern Leopard Frog project, its main goal, project area, the importance of northern leopard frogs to the ecosystem, and citizen science involvement. It also shares key characteristics to look for when identifying northern leopard frogs.
You can read the feature article here.
CBC NEWS CALGARY
Spot a frog, send an email, save a species?
A CBC News Calgary article from August 2017 featured the Waterton Biosphere Region’s Northern Leopard project and highlighted the importance of land stewardship and maintenance of healthy riparian areas as well as the citizen science component of the project and its necessity given the relative lack of provincial data after 2012.
You can read the article here.
We have compiled a few resources with more in-depth information for you. Click on the images to access the full pdf documents.
We want to acknowledge and send out a huge thank you to the supporters of our Northern Leopard Frog project, Alberta Environment and Parks, Environment and Climate Change Canada, Parks Canada – Waterton Lakes National Park, Alberta Conservation Association, and Land Stewardship Centre.
