Take Part in the Detroit Zoo’s FrogWatch USA Conservation Program

By late winter and early spring, many people are looking forward to warmer weather, longer days and the fun the coming months will bring. I also look forward to this time of year, not only because of the warmer temperatures, but also the rains of spring and the wonderful creatures that will wake from their long, winter hibernation.

I am, of course, referring to frogs and toads! Here in southeast Michigan, most amphibians depend on rain to help them get “in the mood” for the breeding season. Soon after moving from deep winter to early spring, frogs and toads will make their presence known in full chorus, emitting sounds that also help to protect them from predators.

In 2011, the Detroit Zoological Society began hosting a local FrogWatch USA chapter to collect data on the frogs and toads living in the tri-county area. FrogWatch USA is an amphibian conservation and citizen science program managed by the Association of Zoos & Aquariums (AZA). Citizen science programs teach volunteers to collect data using the same protocol and methods, so all data can be can be counted as part of a scientific research project. One scientist working alone could never collect the amount of information a group of citizen scientists can.

There are currently 144 chapters of FrogWatch USA held throughout the U.S. and data has been collected since 1998. Training classes are primarily taught at AZA institutions, but may also be offered at nature centers, museums or colleges. The project focuses on frogs and toads – both amphibians and some of the most sensitive creatures on the planet. They are also indicators of a wetland’s health – if something toxic or lethal invades the wetlands where they live, they will be the first species to become sick, die or disappear.

All monitoring is done outdoors, so it gives volunteers the opportunity to spend time outside in the wetlands and natural areas of their community. Monitoring helps provide important information from each site, such as the diversity, population size and health of the particular frog or toad species that is present; whether or not there are rare or invasive species in the area, and what the overall health of the wetland is. Knowing what species are present at a sight can even help improve the management and protection of a wetland and all species living there.

Four-hour volunteer training sessions are offered at the Detroit Zoo just prior to the frog and toad breeding season, which is just about to begin. Each session includes:

  • An overview of what amphibians are and why they are valuable to the environment
  • Descriptions and key characteristics of the types of wetlands found in Michigan where frogs and toads may be found
  • Information about the locations of monitoring sites and the ability for participants to register
  • An explanation of the monitoring protocols that volunteers will use in the field
  • Information about how to identify the 14 native Michigan frog and toad species by their breeding calls (Identifying a species by its breeding call is by far the best part of the process. Even though it may be a bit challenging at first, surveying by ear is easy on both the surveyor and the frogs and toads, and it can be a lot of fun.)

Once training is complete, a volunteer’s first priority is to find and register for a site to monitor.  While most volunteers come in already knowing where they want to survey, some do not and we help them find locations in the area. Some sites are in backyards where frogs have been heard for years and others are in wetlands seen from afar and believed to be full of amphibians. Once the nighttime temperature is above 35 degrees Fahrenheit, volunteers can monitor at their sites throughout the FrogWatch season, typically February to August, at most twice a week.

Monitoring must take place at least 30 minutes after sunset. Darkness not only brings more amphibians to life but it also puts the noisy daytime animals, such as birds, to sleep. Whether volunteers have hiked into a wetland via a trail full of crunching leaves or are sitting on their back porch as quiet as can be, everyone must allow at least two minutes for the creatures around them to acclimate to their presence. Immediately after two minutes have passed, volunteers will listen for exactly three minutes to identify each species they hear. At the end of three minutes, the monitoring session is complete.

Monitoring the same site year after year is a great way to keep track of the health of frogs, toads and wetlands. If we lose amphibians, we lose a very precious resource and some really amazing creatures.

I hope you can attend one of the FrogWatch USA training sessions coming up at the end of this month, in February and in March. It is a fun and easy amphibian conservation program that anyone can take part in! Click here for more information: https://detroitzoo.org/press-release/leap-conservation-joining-frogwatch/

– Rebecca Johnson is the associate curator of amphibians for the Detroit Zoological Society and works in the National Amphibian Conservation Center.

Veterinary Care: Cutting-edge Technologies in Amphibian Conservation

Last week I was able to attend a very exciting advanced conservation training course to learn assisted reproductive technologies (ART) in amphibians. The meeting was hosted by the Omaha Zoo, and was offered by the Amphibian Taxon Advisory Group (ATAG). I was one of a small group of zoo and conservation scientists invited to learn cutting-edge technologies that have the potential to have a tremendous impact on the conservation of endangered amphibians.

At the Detroit Zoo, we’ve been using hormone treatments to help with reproduction in Wyoming toads and Puerto Rican crested toads for more than 10 years. Recently, Dr. Andy Kouba from Mississippi State University has been able to modify these treatments for use in other species, and to develop techniques for collecting eggs and sperm for in-vitro fertilization (IVF). Two years ago, I traveled to his laboratory to learn these techniques for dusky gopher frogs, and within a few months we became the third zoo to reproduce amphibians via IVF.

The goal of the ART course was to provide in-depth information concerning reproduction in frogs, toads and salamanders. This course was taught by Dr. Kouba and two of his colleagues, and represented the first time that husbandry staff, veterinarians and conservation researchers have come together to discuss assisted reproductive technologies. The attendees brought together a wealth of knowledge, and experiences working with hellbender salamanders, Chinese giant salamanders, Oregon-spotted frogs and others. We talked about the impacts of hibernation, temperature, humidity and social cues on reproduction, and the challenges we have encountered in the past. We learned about the historic use of hormones in amphibians, and how this information can be adapted to new species. We also learned how to gently collect spermic urine from male amphibians, and to stimulate females to lay eggs. We learned how to examine developing tadpoles under a microscope, and cyroperservation techniques for sperm. We also learned how to use ultrasound to monitor egg development in females. During the week, we put these skills to practice, and were able to produce fertilized eggs from Puerto Rican crested toads, American toads, tiger salamanders and Asian black spiny toads (for the first time!).

At the Detroit Zoo, we have number of very endangered species of amphibians, including some that have never or only rarely reproduced outside of the wild. Over the next few months, we will be able to start using cryopreservation to save genetics from these critically endangered species. The skills learned at the ART course will allow us to continue to be leaders in amphibian conservation, and to hopefully successfully breed Japanese giant salamanders, giant waxy tree frogs, and other endangered species at the National Amphibian Conservation Center.

– Dr. Ann Duncan is the director of animal health for the Detroit Zoological Society and oversees the Ruth Roby Glancy Animal Health Complex.

Amphibian Conservation: Saving the Panamanian Golden Frog

The Panamanian golden frog (Atelopus zeteki) is a unique and beautiful amphibian from the highlands of Panama. This yellow or orange and black “frog” is actually a type of toad that walks more than it hops. It resides in areas near fast-moving streams and rivers in the mountainous forests within the country. The International Union for Conservation of Nature (IUCN) lists the Panamanian golden frog as Critically Endangered, which is one step before becoming Extinct.

In the wild they are believed to be in such low numbers that they may no longer be able to sustain as a wild population; in fact, no one has seen a Panamanian golden frog in the wild for quite some time. Massive population decreases are believed to be caused by chytrid fungus, habitat destruction, the exotic animal trade and sedimentation of egg-laying sites in rivers and streams. Now, they exist mostly in captive zoo breeding populations.

One of these breeding populations has been housed in a bio-secure room at the Detroit Zoo’s National Amphibian Conservation Center for 16 years, and has contributed several years of offspring to the Panamanian Golden Frog Species Survival Plan (SSP). SSPs are cooperative management programs through the Association of Zoos & Aquariums (AZA) that aim to reproduce, genetically manage and possibly reintroduce endangered animals into the wild with the assistance of other wildlife management organizations. In addition to its active role in the SSP, the Detroit Zoological Society (DZS) employs several other strategies to conserve the Panamanian golden frog in the wild. At this time, there is nowhere identified in the wilds of Panama to safely release captive-bred tadpole or juvenile golden frogs to the wild.

Breeding the Panamanian golden frog in captivity involves understanding the complex conditions found in their wild habitat. They have an interesting life cycle from courtship to final metamorphosis. In the wild, males of this species will perch on rock outcroppings or on top of large leaves that overhang or are near a flowing stream or river. The males then begin to call, thrusting out the vocal sacs on their throats as they produce a low trill vocalization meant to alert females to their presence as well as warn other males to stay away. Since these animals breed and live in close proximity to the loud sound of rushing water, their low-toned vocalizations can be very difficult to hear. For this reason, golden frogs have evolved a type of sign language they can use to communicate to mates as well as rivals. These amphibians have the ability to execute a “wave” using their front legs to take the place of their hard-to-hear vocalization when conditions around the stream are noisy. This type of communication is known as semaphore behavior.

Once a pair of golden frogs has successfully mated in the wild, the female will deposit up to several thousand small round white eggs underneath a rock in a steam or river and away from direct sunlight. This is done because the white eggs lack pigment entirely and would be adversely harmed by the ultra violet (UV) radiation from the sun. This same issue has to be addressed at the Detroit Zoo. The animals are bred inside aquariums in a specially modified room just for this species. After the breeding pairs are chosen for the year, the animals are placed together in an aquarium. Prior to the onset of the “wet season,” misting cycles within the frogs’ habitat are coordinated to simulate the “dry season,” giving the frogs a sense of seasonality, which helps stimulate them to breed. If eggs are laid in the aquarium, amphibian staff must protect the eggs from the naturalistic UV lighting over the breeding tanks by wrapping black trash bags around the aquarium. This simulates total darkness, which allows the light-sensitive eggs to develop unharmed. Once eggs develop pigment, the trash bags can be removed.

Eventually, the eggs develop and a small black and yellow tadpole emerges from the egg casing. These tadpoles are very well adapted to living in fast, flowing stream environments with strong mouthparts which assist them in clinging to the rocks in turbulent water as they scrape away at algae and the microorganisms they depend on for food. At the Detroit Zoo, we reproduce the golden frog food source by smearing a wet algae mix on small plastic food plates and allowing the mixture to dry. Once the algae is dry, the plates are placed in the water and the tadpoles move over and around the plate, scraping off the food with their specialized mouthpart. After several weeks, the tadpoles metamorphose into fully formed little toadlets, which are turquoise green and black in color, a color phase that camouflages them in while living in a forest habitat. They eventually turn mostly yellow or orange and black upon reaching adulthood.

Along with the extensive breeding program, conserving the Panamanian golden frog involves reaching out to the communities where these animals live and educating the public. In 2015, I assisted the staff at a small conservation center in El Valle, Panama, called the El Valle Amphibian Conservation Center (EVACC). This center is dedicated to breeding, exhibiting and educating the public on Panama’s native amphibians. While in Panama, I assisted EVACC with their amphibian exhibits and breeding programs. The DZS is also becoming involved in developing educational materials to better educate an already sympathetic public about conserving their environment and this important amphibian. Recently, DZS Curator of Education Claire Lannoye-Hall has been appointed as the SSP Education Advisor for the Panamanian Golden Frog SSP. Within this role, the Detroit Zoo will be instrumental in developing educational programs and cultural awareness within Panama.

The Panamanian golden frog holds a special place in the Panamanian culture. Signifying good luck, the golden frog can be seen on lottery tickets and in gift shops all around the country. The history of this little amphibian within Panama can be illustrated by the presence of “rana dorada” or golden frog, in some of the petroglyphs within the country dating back to pre-European contact. Perhaps those ancient artists were hoping for a little luck as they etched images of this mystical amphibian into the rocks of the cloud forest. Hopefully, with a little of that same luck and continued dedication from the Detroit Zoological Society and its conservation partners, the Panamanian golden frog will not disappear from history for good.

– Mark Vassallo is an amphibian department zookeeper for the Detroit Zoological Society, and works in the National Amphibian Conservation Center at the Detroit Zoo.

Amphibian Conservation: Crawfish Frogs in Crisis

What is the best way to repurpose a basement in one of the buildings at the Detroit Zoo? Turn it into an amphibian’s paradise!

Amphibians across the globe are in crisis, with populations declining rapidly due to climate change, habitat destruction and a disease called the chytrid fungus. In an effort to reverse this trend for the crawfish frog (Lithobates areolatus), which is listed as Endangered in the state of Indiana, the Detroit Zoological Society (DZS) partnered with the U.S. Fish and Wildlife Service, the Department of Natural Resources and staff at Indiana University. In 2013 these entities began a repatriation project, which is an effort to return a species to its natural habitat. This involved the collection of egg masses from grasslands in Indiana, which were then transported to the Detroit Zoo, where staff raised them until they were almost froglets before releasing them back into the wild.

The crawfish frog can lay egg masses with as many as 5,000 eggs. That might make one wonder how these animals could be endangered, right? Well, even if all of those eggs hatched into tadpoles, less than one percent of those tadpoles would ever make it out of the water. Tadpoles are an easy prey for a wide variety of animals including birds, fish, mammals, frogs and even larger tadpoles. And even fewer tadpoles would make it far enough into adulthood to breed. This shows how vulnerable the tadpole stage is in a frog’s life, which is why we focused our efforts on this stage.

We knew what we needed to do, but where is there enough room for thousands of tadpoles at the Detroit Zoo? How about right under the noses of Jasiri and Tamba, two Southern white rhinos! Not directly under them, since 12,000 pounds of rhino would be harmful to a tadpole, but rather in the basement of their indoor habitat. It took a lot of hard work from staff, but the space was eventually turned into a fantastic temporary home for crawfish frog tadpoles. Some of their luxury items include manufactured ponds with an automatic rain system, spotlights and temperature control systems – and of course, plenty of food.

In April, the crawfish frog egg mass is transported from Indiana to the Detroit Zoo in a cooler. We take this egg mass right down to the basement where it is placed in water. In a couple of weeks, tadpoles start to emerge, which are then counted and moved into long pond-like pools. We raise these newly hatched tadpoles for about three months, with the amphibian department staff feeding and cleaning them daily. It takes hours to care for the tadpoles each day, but it is all worth it in the end when they are driven back to Indiana and released. The total number of tadpoles varies from year to year, but since this project started in 2013, the DZS has released a total of 10,411 tadpoles back into the wild.

While wild tadpoles have less than a one percent chance of survivability, we were able raise that to an astounding 99 percent in 2014 and 2015 for these “basement” tadpoles. That’s because they don’t need to worry about predators, disease, lack of food or pollution. This lets them get a good head start on life – but we don’t make it too easy for them. Otherwise, they wouldn’t know what to do once they got back to the wild. So before they fully metamorphose – or turn into frogs – they are taken back to Indiana and released into the ponds. Since some frogs lead a “double life” – aquatic and terrestrial – they are able to finish their aquatic life stage in enclosed repatariums, or screened-in containers, that allow protection before they are released as full frogs in the environment in which they will live. This method works well and provides exposure to the environment they will be living in before they become too accustomed to the luxury of the rhino basement.

The DZS crawfish frog conservation project requires long hours, but it is also the best time of the year as a member of the amphibian department staff. Seeing how the DZS can make a positive impact on this species and the ecosystem is very rewarding.

– Michael Andrus is an amphibian department zookeeper for the Detroit Zoological Society and works in the National Amphibian Conservation Center at the Detroit Zoo.

Amphibian Conservation: Wyoming Toads Prepare for Breeding

A pair of small gold eyes peers out from under a mass of sphagnum moss. In a day or two, this warty creature will complete its climb out from the depths of the sandy soil where he has spent the last 30 days sleeping and “chilling” at a cool 38 degrees. Along with seven other individuals of this species, he will awaken due to an increase in temperature and light. By the time the temperature reaches 74 degrees, he will have completely removed himself from the soil and be sitting atop it, hopefully alongside his companion, a slightly larger female. In the week that follows, events these two small cold-blooded creatures will go through could lead to producing thousands of their species in a matter of hours due to their “explosive” nature.

The Wyoming toad (Anaxyrus baxteri) is one of North America’s most endangered species and one of the amphibians we work with as part of a Species Survival Plan (SSP) at the Detroit Zoo’s National Amphibian Conservation Center.  This toad’s wild populations began declining in the 1970s, and by the 1980s was listed as an Endangered Species by the International Union for the Conservation of Nature (IUCN). Possible causes for the population decline are use of aerial pesticides to eliminate mosquitoes, habitat manipulation, and disease in the form of the amphibian chytrid fungus. Realizing a decline was occurring, the last remaining toads were collected and by 1994, all remaining wild-born Wyoming toads were believed to be entirely in captivity. The IUCN now describes the Wyoming toad as extinct in the wild, meaning any toad currently found in the wild has come from captive breeding, in which the Detroit Zoological Society (DZS) has been actively involved.

The Wyoming toad SSP is managed by the Association of Zoos and Aquariums (AZA). The DZS has been a member of this conservation program since 1995 and since 2001 has sent a total of 6,505 tadpoles and toadlets to the wild. All Wyoming toads are the responsibility of the U.S. Fish and Wildlife Service (USFWS), so members of the AZA work closely with them to follow all USFWS permit guidelines for keeping them in captivity. The goal of any captive breeding program is to produce healthy offspring for release into the wild with the goal of rebuilding them into a self-sustaining population. Each toad in captivity is identified and tracked, which helps to pair toads that will produce the most genetically diverse and healthy offspring. Breeding pairs of toads are chosen almost a year in advance so toads have plenty of time to move from one zoo to another to create the breeding pairs.

Although not as well known as Jabari and Kivuli, the giraffe couple at the Detroit Zoo, Wyoming toads Butler and Beverly are a very important couple of toads. They are part of a “bio-secure” population and will never be seen by the public, which ensures they will not accidentally release diseases, known or unknown, into the wild via their offspring. They are held with four other pairs of Wyoming toads in a special room away from all other amphibians, so they will remain free of diseases that could otherwise be found in species not native to the western region of North America.

At the AZA’s recommendation, Butler arrived at the Detroit Zoo last October to be paired with Beverly, who arrived in 2012. Both are now 3 years old, which is about middle aged for a Wyoming toad. In early April, they were placed together into a thermostat-controlled “hibernaculum”, which is used to cool the toads, simulating the hibernation period a wild Wyoming toad would go through during the winter. The toads are kept cooled for about a month to help prepare them for breeding; eggs or sperms may develop and mature as a result of this cooling. The toads are given plenty of sandy soil to bury down into and sleep in just as they would have in the wild, and the Zoo’s animal care staff checks in on them weekly to make sure they are doing well.

At the end of May, the temperature in the hibernaculum will be increased to 70 degrees Fahrenheit and the toads will begin to awaken. Once they have climbed out from the soil, we will place them back into regular husbandry for a few days where they will continue to warm up and eat. Recordings of male toads calling are played during this time to condition toads further for breeding. Within a few days of emerging from hibernation, Butler and Beverly will be placed into a breeding chamber with 2-3 inches of water. The pair will hopefully go into “amplexus” within a few hours, which happens when the male positions himself on top of the female using his front legs and squeezes her, encouraging her to lay eggs. He fertilizes the eggs as she lays them, usually in the dark, overnight. Butler and Beverly should lay thousands of eggs, which is typical of toad species. Described as “explosive breeders”, the more eggs they can lay the better the chance offspring have of surviving the elements, diseases and predators. Since this is a captive breeding, we can help the thousands of eggs that Butler and Beverly produce survive into strong, healthy tadpoles.

Approximately two to three weeks after eggs have hatched into thousands of hungry tadpoles, arrangements are made with the USFWS to ship the tadpoles to Wyoming, where they will be released into protected wetlands. These tadpoles will add to those previously produced in captivity sent yearly by the zoos that participate in this program and the USFWS.

The wetlands are monitored during the spring and summer as part of yearly field surveys done to track the health and population of the toads. This year we hope that Butler, Beverly and the three other pairs of Wyoming toads at the Detroit Zoo are able to contribute thousands of healthy tadpoles to the wild population.

– Rebecca Johnson is the associate curator of amphibians for the Detroit Zoological Society.

Notes from the Field: Surveying Mudpuppies; Rain, Snow or Shine

We battled frigid temperatures as we entered the ice-filled water wearing insulated waders for protection against the elements.

This dramatic introduction sounds like the start of an exciting adventure story in some far-off place, but it actually describes some of the unbelievable conditions right here in Michigan where you can find one of the most fascinating creatures – the common mudpuppy (Necturus maculosus maculosus).

This four-legged, fully aquatic amphibian can be found in rivers, lakes and ponds throughout the midwestern U.S., including the waters of the Detroit River. The Detroit Zoological Society (DZS) is actively engaged in many field conservation projects, including surveying the common mudpuppy around Belle Isle. Our amphibian department has conducted surveys since 2009 as a way to learn more about the overall health and population of the salamanders found in the area. Fieldwork for the project is conducted twice monthly at two different sites, and it is never to be done alone; due to the danger posed by the elements, there must always be two people working on the survey. Depending on the weather conditions, surveys at times are limited to collecting water samples; other times it can involve trapping and processing mudpuppies.

Listed as Least Concern by the International Union of the Conservation of Nature (IUCN), little is known about the true population size of mudpuppies – not just in Michigan but also throughout its entire range. Even though this aquatic salamander has a pair of lungs, it uses blood red, feathery gills located on the sides of its head to gain oxygen from the water. It has a rather flat body and wide head and it uses its tail to move through the water. Mudpuppies prefer to hide under rocks and logs during the day and forage on aquatic insects, crayfish and fish.

Like all amphibians, mudpuppies are valuable indicators of wetland and habitat health. Since water and air move freely in and out of an amphibian’s permeable skin, they will be the first creatures to become sick or even die from the pollutants or toxins found in the habitat, warning us of any impending problems.

Fieldwork and data collection for this project is typically a two-day process. On Day 1, we are in the field collecting water samples and data on the weather, and also setting traps. To capture mudpuppies, we use small collapsible minnow traps that we weigh down to the bottom of the river and bait with frozen smelt. We tie the traps to the shoreline so they won’t be lost in the current of the river. We leave them overnight to allow the mudpuppies plenty of time in their undisturbed habitat to wander in, where they will remain until our return the following day.

The water samples we collect are taken back to our water quality lab where we can conduct more scientific tests. Keeping track of the water quality of the Detroit River is just as important as the data collected on the mudpuppies themselves. A database of this information will help us notice if severe changes have occurred in the water over time.

On Day 2, we return to the field to collect the traps as well as information on any mudpuppies captured overnight.

In the winter, the coast of Belle Isle can be quite treacherous. On one particular day in March, we faced some challenges as ice floes had moved into the shore overnight and were covering the traps we’d placed the day before. I was accompanied by two of the DZS’s most seasoned field researchers: Paul Buzzard, the director of conservation, and Marcy Sieggreen, curator of amphibians. Wearing insulated chest waders and long gauntlet-style gloves for protection against the icy waters, we did some ice stomping and managed to locate and recover all the traps we’d set.

Turned out we had captured one mudpuppy, so we proceeded to gather additional data – information from the animal, weather conditions and the water. We needed to take great care to keep the mudpuppy in the water at all times; in the winter this protects the skin and gills from freezing and in the warmer days of spring, summer and autumn it protects from the heat. We take measurements, weight and pictures of the animal, and if the salamander is healthy and large enough, a small transponder is implanted in the side of the tail to help with identification if recaptured. As quickly as possible, the mudpuppy is returned to the water in the area where we found it.

On Day 2, if conditions are favorable, we also use a digital boroscope to survey the site further. A boroscope, or a “plumber’s camera” as it’s sometimes called, is a camera at the end of a flexible 5-foot-long cable connected to a video screen. We use it to peek under rocks and logs in search of mudpuppies. This tool is a non-invasive way to learn about what else is living in the river.

As we continue with these surveys, we are exploring what other things the data we collect can show us from further analysis. We also plan to return to surveying areas off the coast off the island of Grosse Ile, which are also known to have a population of mudpuppies.

– Rebecca Johnson is the associate curator of amphibians for the Detroit Zoological Society.

Marcy Sieggreen was the curator of amphibians for the Detroit Zoological Society from 2008 until her passing in 2016. The Detroit Zoological Society established the Sieggreen Amphibian Conservation Fund in Marcy’s memory to continue to advance the work she so passionately championed.

Amphibian Conservation: Breeding Puerto Rican Crested Toads

April is an important time for the Detroit Zoological Society’s amphibian conservation programs. Three of the four animals we work with at the National Amphibian Conservation Center (NACC) that are a part of Species Survival Plans (SSP) are preparing to take part in precisely planned and scheduled breeding events. The outcome is the release of captive-born offspring into the wild to aid in the increase of their populations.

First up for the season is the Puerto Rican crested toad, Peltophryne lemur. The PRC toad, as we like to call them, has been part of a well-managed SSP since 1984. Habitat loss and competition from the invasive cane or marine toad (Rhinella marina) are believed to have been primary causes for the toad’s decline. Listed as critically endangered by the International Union of the Conservation of Nature (IUCN), collaborative efforts by the Associations of Zoos and Aquariums, U.S. Fish and Wildlife Service and the Puerto Rico Department of Natural and Environmental Resources have aided the recovery of this toad in the wild. More than 300,000 captive-bred tadpoles produced by 20 zoos have been released to the wild since 1982. Since the year 2000, the Detroit Zoological Society has produced more than 45,000 tadpoles for this program. In 2015, three clutches of eggs laid produced 22,571 tadpoles for release – the largest amount the Detroit Zoo had ever sent. Ongoing research and the creation and protection of pond habitats have also assisted in the recovery of this toad in its natural habitat.

You may be wondering what it takes to produce thousands of tadpoles from toads half the size of the palm of your hand. The breeding season starts with the assignment of four breeding pairs from the SSP. Each toad in captivity is identified and tracked using a studbook. Specialized software chooses pairs of toads that will produce the most genetically diverse offspring. By mid-March, we know who these eight toads are and we can begin preparing them for breeding.

Each toad must be easily identifiable – if you think all toads look alike you’ll be surprised to know that wart patterns and throat markings are very unique, although reading glasses are sometimes needed to make the proper ID. Toads are conditioned by slightly cooling and drying their environments out for a month-long period. A thermostat-controlled refrigeration unit keeps the toads cooled precisely at 66 degrees Fahrenheit. While the toads are “sleeping”, their primary zookeeper works diligently on preparing the breeding tanks where the pairs will breed and the eggs will develop. At this same time, veterinarians prepare a schedule of specialized breeding hormones that will further assist in ensuring that eggs are laid and fertilization happens at the right moment.

Upon their exit from cooling, they return to normal husbandry to warm up and eat for a few days. Breeding calls of male toads are played to encourage breeding behaviors. Males are first to go into the breeding tanks, followed hours later by the females. If all the preparation works, pairs of toads will be in amplexus – which happens when a male is positioned on top of a female and he squeezes her to encourage egg-laying – before we leave for the evening, followed by a morning of tanks full of eggs.

It takes two to three days for eggs to hatch and another couple of days for tadpoles to begin swimming around and actively eating. Tadpoles can be some of the hungriest creatures you will ever encounter. Keepers spend the next 10 days keeping them fully fed by offering them algae pellets, powdered diets and romaine lettuce sometimes three times a day. At the same time, all those foraging tadpoles create a lot of waste, so keepers spend the rest of their time keeping their water clean with frequent water changes.

During all of this, we keep a very important date in the backs of our minds – the last big event in our PRC toad breeding season. Any facility that breeds the PRC toad needs to ship them to Puerto Rico for release on the same date. The release of the tadpoles is timed with the season in which the tads would grow and develop the best in the wild. Tadpoles also need to be shipped at a certain age, before they get too big and begin to develop appendages.

Amphibian staff can spend well over 24 hours collectively counting and packing the tadpoles into Styrofoam-protected shipping boxes. Heavy-duty fish shipping bags are used, doubled up and filled with oxygen to keep tadpoles healthy and safe on their trip to Puerto Rico. Approximately 24 hours later, they will reach their new home in a pond located in a well-protected forest in Puerto Rico. As they develop and grow, they will add to the wild population and one day, hopefully, participate in creating many more thousands of tadpoles!

Rebecca Johnson is the associate curator of amphibians for the Detroit Zoological Society.