Wildlife Conservation: Lending Amphibian “Sexpertise” to Other Accredited Zoos

I recently participated in a partnership to save an incredible species of amphibian: the blue spotted salamander (Ambystoma laterale). This animal is regionally endangered in parts of the Midwest and about 10 years ago, the Iowa Department of Natural Resources started a partnership with Omaha’s Henry Doorly Zoo. They wanted to breed these salamanders for release at locations where they once thrived but have now disappeared. Having had little success in doing so thus far, the organizations reached out and requested my amphibian “sexpertise”. I travelled to Omaha to deploy some of my special reproductive techniques with the blue spotted salamander assurance colony living there.

It comes as no surprise that these salamanders proved very difficult to breed. Blue spotted salamanders need an extraordinary amount of “salamander romance” in order to breed naturally. These animals undergo winter brumation (a hibernation-like state). In the spring, they will emerge from brumation when it begins to rain and when the temperature rises in order to migrate to breeding ponds. Their migrations can be over several miles, and most salamanders return to the same pond every breeding season. In captive breeding situations, we attempt to recreate the cues that the salamanders take from the wild in order to get them “in the mood” for breeding. We cool them down and offer them the opportunity to undergo brumation. We place them in rain chambers so they can experience an “indoor storm”. We also attempt to create a naturalistic pond for them to breed in with proper vegetation and leaf litter.

Sometimes, despite our best efforts, the natural cues we provide artificially are not enough to trigger breeding. Many amphibians are having difficulty breeding in the wild, due to changes in the climate and their habitat. Given that the natural environment is not currently providing ideal cues for breeding, it is especially difficult to perfectly recreate environmental breeding cues for animals in human care. When captive animals do not breed in response to the cues we provide, we often use hormone treatments to give them a little boost. These hormone protocols are meant to trigger breeding behaviors as well as the release of sperm and eggs. In the best-case scenario, the application of hormones will result in the animals breeding on their own. In the worst-case scenario, the animals will not breed on their own after the application of hormones and an in vitro fertilization (an artificial fertilization of the eggs with the sperm in a petri dish) will take place.

We used a combination of natural cues and hormones to stimulate breeding in the blue spotted salamanders. The amount of hormones I gave to the female blue spotted salamanders was determined by how developed their eggs looked on ultrasound. While giving the animals hormones resulted in many interesting behaviors, the salamanders did not breed on their own. After giving them time to breed on their own without success, I attempted in vitro fertilization. In order to perform this technique, I needed to collect eggs from the females and sperm from the males. There was one big problem with attempting this technique – the male blue spotted salamanders were not producing sperm. Fortunately, I had a back-up plan!

The blue spotted salamander is no ordinary salamander. In the wild, many female blue spotted salamanders breed through a special adaptation called kleptogenesis, meaning that they steal sperm. You read that correctly: sperm thieves. Most salamanders undergo internal fertilization. This occurs when the male deposits the sperm in a ball – called a spermatophore – into the environment. Through a courtship dance, the spermatophore is collected by the female. These special female blue spotted salamanders will find and collect spermatophores deposited by males from other, closely related, species (including Jefferson’s salamanders, tiger salamanders, and small-mouth salamanders). This is the part where it becomes complicated. Rather than using the sperm to fertilize their eggs and have hybrid offspring, an enzyme in the sperm activates the egg which begins to grow into an embryo. The rest of the sperm is discarded, and the offspring which develop are essentially clones of the mother. Knowing that blue spotted salamander females are often sperm thieves, I had the Omaha Zoo’s resident male tiger salamanders (Ambystoma tigrinum) on standby. I was able to collect sperm from the tiger salamanders in order to use in the in vitro fertilization of the blue spotted salamander eggs.

Unfortunately, the eggs did not fertilize with the tiger salamander sperm. While we did not achieve offspring, we learned what we need to do differently next time around. We certainly will not give up on these amazing animals. We will try to breed the blue spotted salamanders again later this year, using slightly different techniques.

Thank you to our partners at Omaha’s Henry Doorly Zoo and the Iowa DNR.

– Dr. Ruth Marcec is the director of the National Amphibian Conservation Center at the Detroit Zoo.

Animal Welfare – Understanding the Needs of Amphibians

The penguins living at the Polk Penguin Conservation Center are not the only water-dependent species being studied by the Detroit Zoological Society’s Center for Zoo Animal Welfare (CZAW). We are conducting research to uncover indicators of welfare in frogs, toads and salamanders living at the Detroit Zoo’s National Amphibian Conservation Center.

Welfare indicators in amphibian species have largely consisted of body condition scoring and measures of reproductive success, neither of which provide comprehensive understanding of how individual animals are faring. Identifying additional indicators can help us to better understand the needs of amphibians living in zoos.

Due to the catastrophic declines in amphibian populations around the world in recent years, amphibian conservation has become a priority for zoos and other conservation organizations. While many institutions prioritize the management of captive populations of amphibians as one strategy in the preservation of these species, virtually no literature exists today regarding how the captive representatives of rapidly vanishing amphibians are faring. The Detroit Zoological Society created the National Amphibian Conservation Center nearly two decades ago, and it is still the largest facility dedicated to amphibian conservation and care in the world. CZAW is now conducting studies to help understand the individual preferences and behavioral and physiological responses of these animals to captive environments and husbandry practices, as well as individual capacities for coping with stressors of captive environments.

Housing animals in multi-species habitats is a common practice in zoos and aquariums. Some amphibians however, such as poison dart frog species, may be housed together due to their shared environmental requirements and their conspicuous aesthetics. Little research has been conducted on the impact that mixed-species living has on the welfare of the individuals. At CZAW, we have examined how different species partition their habitat and how their behavior may be impacted by one another. This helps us ensure that the needs of each animal are being met.

While much emphasis has been placed on the impacts of captivity on the welfare of large mammals, little attention has been granted to large amphibians living in the care of humans. Japanese giant salamanders are currently listed as Near Threatened by the International Union of Conservation of Nature and their wild numbers are decreasing due to habitat loss and hunting.

These salamanders present a unique challenge when it comes to habitat design, given their potential to grow up to 1.5 meters in length and their nocturnal activity patterns. Traditional ways of housing amphibians may not be as successful for giant salamanders and in turn may impact their welfare. The Immersion Gallery at the amphibian center is being renovated as a new habitat for the Japanese giant salamanders, with the goal of giving the animals increased physical and social choices. We are also developing a project to assess the ways in which this increase in choice can improve the welfare of the individual salamanders.

As we continue to study how amphibians can thrive in zoos, we not only help the individuals, but we can also contribute to the efforts being made to conserve them. Greater understanding of how individual captive amphibians are faring is critical to ensuring their well-being and to meeting ethical obligations of keeping animals in captivity.

Stephanie Allard, Ph.D., is the director of animal welfare for the Detroit Zoological Society and oversees the Center for Zoo Animal Welfare.

Notes from the Field – Peru

Hola amigas y amigos!

Alas, my work this season is almost completed, today is my last day in the rainforest. Since my last post, I ran into staff from the Detroit Zoological Society education department, who were in Peru for the Adopt-a-School program, and who assisted in an overnight adventure with the amphibian club. We all spent the night at a research station where we were able to enjoy an evening walk through the jungle looking for amphibians, the canopy walkway and the next day a morning walk back to the boats. We saw salamanders, several species of frogs and they have been very busy with their observations while I was back in the states.

Marcy - rainforest     Marcy - canopy rainforest

During November, the season begins where the rain becomes heavier and frequent, almost daily. This is when the rivers start to rise. Since I landed in Peru the river has already had a noticeable increase. However, one of the many lakes we visit in high water was still dry enough we could walk to it.

Last night, we traveled by boat to the edge of the narrow stream to hike to the place called Lorenzo Lake. This is one area that we monitor twice a year and expect to see hundreds of amphibians and calls that are nearly deafening. We were not expecting to see so many of the giant hunting ants (locals call bullet ants for the pain they inflict when they bite), we had to be especially careful passing brush from the narrow path carved out by our machete. Many scorpions and beautiful moths plagued the long hike to lake, but the calls we could hear before we docked could even dock the boat. It was a beautiful night!

– Detroit Zoological Society Curator of Amphibians Marcy Sieggreen is doing fieldwork in Peru, studying amphibians in the lower elevations of the Amazon River to see how they are faring with increased human populations and impacts in their habitats.

Editor’s note: 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.