The Anthropocene is the best term for the current epoch, with humans the drivers of change today. It may most accurately be defined by loss: the loss of wildlife, the loss of their habitats, and the overall loss of biodiversity. For those of us who work in conservation, this loss can take a heavy toll, but we have hope that we can stop the loss, that we can fix what has been broken. This hope is what drives us to take a holistic, conservation medicine approach that integrates animal, human, and ecosystem health.
While we are rightfully familiar with climate change and other global environmental crises, rarely highlighted in the news is the decline of wetland ecosystems worldwide. And yet, across the planet, wetlands are disappearing at a rate three times faster than forests. Wetlands provide habitat to a multitude of species, flood and erosion control, and water purification. Likewise, they are ecologically and economically valuable when it comes to climate regulation, slowing the change and sequestering carbon from the atmosphere. Between 1970 and 2015, roughly 35 percent of the world’s wetlands disappeared.
The diversity of species within wetland ecosystems is vast, understudied, and disappearing. The Cienaga de Zapata Biosphere Reserve established in 2001 is the largest wetland and protected area in the entire Caribbean, and we are at risk of losing its unique and distinctly Cuban biodiversity.
Home to more than 1,100 known plant and vertebrate species and more than 1,000 known invertebrate species, the Zapata swamp is ecologically, culturally, and economically significant to the Cuban people.
One species in particular, the critically endangered Cuban crocodile (Crocodylus rhombifer), is an emblem of the Zapata swamp and of Cuban pride. Within the swamp ecosystem, crocodiles are top predators and ecosystem engineers, playing a key role in the determination of the health of an environment. They are sentinels of the health of the Zapata swamp, where humans, animals, and the environment are all so connected.
For decades, a team of Cuban scientists have devoted their careers to the conservation of the Cuban crocodile, which has been threatened with extinction due to habitat modification, illegal and uncontrolled hunting, and hybridization with the American crocodile (Crocodylus acutus). Decades of alterations to the swamp landscape have allowed for these two adaptable species to now share habitats where they historically did not co-exist.
Found only in the Zapata Swamp on mainland Cuba, and recently reintroduced to the Lanier swamp on the Isle of Youth, Cuban crocodiles have the most restricted range of any crocodile species on earth. Because of the uncontrolled hybridization, the Cuban crocodiles are quickly losing their genetic identity.
Historically, most of what we know about Cuban crocodiles is from Association of Zoos and Aquariums-accredited facilities and in managed settings in Cuba. Working in Cuba has its share of challenges, but many have succeeded in building relationships and allowed for shared information between experts in Cuba and those abroad. The Wildlife Conservation Society (WCS) and the American Museum of Natural History have contributed to the crocodile breeding and genetic work being done in Cuba since the early 1990s.
More recently, a team from the Saint Louis Zoo in St. Louis, Mo.; WCS Bronx Zoo in the Bronx, N.Y.; Smithsonian Institute’s National Zoological Park in Washington, D.C.; and Cameron Park Zoo in Waco, Texas, have come together to study the Cuban crocodile in Cuba. AZA zoos manage an important genetic reservoir of Cuban crocodiles, but in Cuba, the Zapata Crocodile Farm (ZCF) manages up to 4,000 genetically pure Cuban crocodiles at any one time, bred in part for repatriation.
In August 2018, this multi-institutional team traveled to the Zapata Crocodile Farm to perform the first ever health assessments of adult Cuban crocodiles in Cuba. The information obtained during this pilot study, and from a second sample season in 2019, is useful not only for the management of crocodiles in managed care slated for reintroduction into the swamp, but for the health of the free-living crocodiles as well.
A grant from the AZA Conservation Grants Fund provided the means to perform this work and donated equipment to the Zapata Crocodile Farm for both the pilot work and future health studies at the farm. Because crocodiles are sentinels of ecosystem health, we are compiling a dataset that includes managed care and free-living health reference ranges, to include baseline blood parameters and infectious pathogen identification. Since they are known to bioaccumulate environmental toxins, we will also test for heavy metal and pesticides.
These data will complement the information we have in AZA zoos on this species and be used more broadly beyond Cuba. If successful, this work will expand to free-living Cuban crocodiles and to other species within the Zapata swamp to provide much needed information on the health of the ecosystem, including the health of the wildlife and the people who call this region home.
The limiting factor for conservationists in Cuba is access to resources. On our first trip to Cuba, we arrived right after hatching season at the farm. The Zapata Crocodile Farm has perfected the art of breeding Cuban crocodiles. Anyone familiar with the reproduction of crocodilians knows the importance of temperature, not only its effects on embryo development but also its ability to determine the sex of hatchlings.
The incubation temperature needed for male crocodiles is 32-34 °C, and cooler or warmer than that will produce females. Young crocodiles born at the Zapata Crocodile Farm are not accurately identified as male or female until the age of three. During past annual censuses, staff at the Zapata Crocodile Farm have documented an over-abundance of female hatchlings, with very few males (1 male per 50 female). Their main challenge is to how to maintain consistent incubation temperatures at the farm. The solution: a simple change in incubation.
In 2019, the Cuban/U.S. team received a grant from the Aquarium and Zoo Facilities Association Clark Waldram Conservation Fund to make improvements to the Zapata Crocodile Farm incubation room. This funding allows us to study and set goals on improving more balanced hatchling sex ratios. And now, two years later, with some good planning and lots of work by staff on both ends, we will soon be able to definitively confirm that this work will result in male hatchlings.
As we slowly move forward, our goal is to provide data-driven recommendations for how we can protect the Cuban crocodile and its ecosystem. We are investigating several facets of animal care at the farm, including behavior and nutrition. With some data on the nutritional status of Cuban crocodiles in the U.S., thanks to the St. Augustine Alligator Farm, WCS Bronx Zoo, and the Saint Louis Zoo, we have data for comparison with future nutritional studies with Zapata Crocodile Farm crocodiles.
Additionally, together with our Cuban partners, we plan to expand our messaging through outreach both in Cuba and the U.S. Funding for this continued work is provided by the Saint Louis Zoo WildCare Institute Program for Crocodile Conservation in Cuba, the Saint Louis Zoo Institute for Conservation Medicine, and the WCS Bronx Zoo Herpetology department.
The environmental and economic value of the Zapata swamp ecosystem is immense, but only if it is protected. However, it is not possible to protect something we don’t yet understand. A conservation medicine approach keeps us grounded to the fact that we are all connected—humans, animals, and environments. Enormous pride and cultural significance surrounds crocodiles in Cuba, making this an easy sell for why protecting this incredibly unique species also improves the lives of the people who call the Zapata swamp region home.
Hero Photo Credit: ©WCS
Kelvin Alvarez is a wild animal keeper in the Herpetology department at the Bronx Zoo.
Jamie Palmer is a technician at the Saint Louis Zoo Institute for Conservation Medicine.
Lauren Augustine is the curator of herpetology at the Saint Louis Zoo.