KINGSTON, R.I. – April 11, 2025 – Spring is in the air: the days are longer, the weather is warmer, and you might be noticing more rabbits hopping through your backyard. While adorable, the wild ones we see most frequently in New England are invasive Eastern cottontails, which were introduced to the area in the 1930s primarily to benefit hunters. The native species, New England cottontails, are considered vulnerable because of their decreasing population.

Alex Rebelo and Alannah Lee, both animal science and technology majors, are working on conservation efforts alongside Justin Richard, assistant professor in the Department of Fisheries, Animal and Veterinary Science, to ensure more New England cottontails are born and released into the wild every year to support declining populations and establish new ones. “Increasing the population of the only cottontail species of cottontail native to New England is important for biodiversity,” says Rebelo, noting their importance for a healthy and balanced ecosystem. 

URI goes to the Zoo

Because the two cottontail species are incredibly difficult to distinguish in the wild, the New England cottontail is easiest to study in human care. “One of the aspects of this research that is so fascinating to me is that this is a species that could literally be living in our backyards, yet we know so little about them,” says Richard. “In collaboration with Roger Williams Park Zoo in Providence, we conducted the first formal research on social or reproductive behavior in this species, and continue to learn new things with each observation.”

Lee is developing methods to non-invasively study hormones in the animal’s fecal samples as part of the conservation breeding program at the zoo, which works to restore native populations by breeding them there and releasing them into their natural habitats.

“This program takes a tremendous amount of effort—from animal care professionals to veterinarians to a variety of researchers and wildlife managers,” Richard says. “The experienced staff at the zoo is what makes this conservation program possible, and the hard work of talented undergraduates like Alannah and Alex allow us to dig deeper into cottontail biology to increase its conservation impact.”

Analyzing different hormone concentrations in female rabbits ensures the efficiency of the zoo program, and Lee says it’s been rewarding to feel like she actively helps make a difference in the rabbits’ chances of success in the wild. “It’s been interesting to learn just how cool hormones are,” she adds. “Looking at cortisol concentrations, for example, can tell you how stressed an animal is. Hormones tell us so much about what’s going on in the body that you would never be able to tell just by looking at an individual.”

Lee was awarded an undergraduate research grant by URI’s Office of Undergraduate Research and Innovation to conduct the research. “The funding allows me to study a specific hormone precursor, dehydroepiandrosterone sulfate (DHEA-S),” she says. “Validating DHEA-S as a useful steroid in conjunction with other hormones as a useful pregnancy detection tool would provide higher confidence in our predictions and a more efficient breeding program at the zoo, so I’m hoping this funding will allow me to meet that goal.”

Breeding wildlife is not always easy and often met with more questions than answers, resulting in varying degrees of success, said Louis Perrotti, the Zoo’s director of conservation programs, which emphasizes the value of the research being done by Richard and his students.

“This research has helped us work through many of the questions we had in the beginning years of the project,” Perrotti said. “The information from these research projects and the data collected by Dr. Richard and his students have answered these questions and guided the zoo to make changes to our breeding protocols that have resulted in a significant increase in rabbit production. This is a great example of partnerships in action for the conservation of threatened and endangered species.”

Behavioral research

On campus, Rebelo is working on a different aspect of research with the same goal as Lee: to get more New England cottontails in the wild every year. His first task involved counting urination spots of each rabbit to see if there was a correlation between how often the female urinated in a particular area and how often she visited a particular male to see if there was something researchers could do to increase breeding.

Previous research by Richard has shown that the rabbits are selective and particular when it comes to their breeding and environment, with only about half of male-female pairings resulting in kits, or baby rabbits. Based on these findings, a mate choice trial is conducted before the breeding season starts to observe female rabbits’ behaviors and optimize their chances of reproducing. Rebelo analyzes data from those trials.

He also works on thermal imaging for pregnancy detection — an ideal method because it’s non-invasive and quick. “Thermal imaging pregnancy detection allows us to optimize breeding pairings by not pairing already pregnant females, which puts less stress on the mother and should therefore help her produce healthy kits,” Rebelo says. “Based on the findings from that study, we change how we manage their environments to hopefully mitigate stress and encourage them to produce more babies.”

Both students say that pursuing majors in animal science has been rewarding — even when it’s challenging. Rebelo, who is heading to veterinary school in Glasgow, Scotland, in May, notes that organic chemistry, while an infamously tough subject to tackle, helped expand his worldview. “Now I see how wonderful it is that everything is here because it is so complex,” he says. “Even with something as small as a blade of grass, there is so much going on to drive its life and growth.”

Lee highlights learning about the importance of research to conservation efforts. “Before starting on this project, I thought that conservation was just about getting animals to breed and waiting for babies, but it’s so much more than that,” Lee adds. “Seeing how things work has shown me how much goes into making sure these animals get to continue calling this area home.”

As for what the general public can do to aid conservation efforts? “Drive slower,” Rebelo says. “And put your phone away while driving so you can pay attention.”

This story was written by Anna Gray in the College of the Environment and Life Sciences.