Animal attraction: San Diego’s mammals get their own atlas
Scott Tremor’s dad introduced him to the outdoors, creating a love of nature and research that later led him to study biology at San Diego State University. It was while he was studying mammalogy there that he noticed there weren’t very many resources on mammals in San Diego County. Fast forward 30 years to his current role as lead author and organizer of a new atlas on the county’s mammals.
“The San Diego County Mammal Atlas is a natural history of the mammals of San Diego County, the biodiversity of which is one of the greatest in the United States … this book covers the biology of all 91 terrestrial and 31 inshore marine visitors known to have occurred here during recorded history, since 1796,” he says. “(As a student at SDSU) I felt like there were few resources on the mammals of the county beyond a list, and that there wasn’t a lot of information on the natural history of the species. I think that’s when I got the inspiration (for the book).”
Tremor, 53, is a mammalogist with the San Diego Natural History Museum and lives in Pacific Beach. The atlas has been more than 10 years in the making, with maps, original photographs, illustrations of skulls, criteria for identification (including the echolocation calls of bats), and information on habitat, diet, reproduction, predators, behavior and conservation challenges. He took some time to talk about his work on the book, his passion for natural history and why conservation is so important to him.
Q: Tell us about the new atlas on the county’s mammals.
A: Many mammals of San Diego County face serious consequences from the continued growth of the human population and the expansion of terrestrial development, as well as increased marine harvesting. In a time of changing climate, with fires increasing and droughts intensifying, we are also seeing changes in the distribution of many mammals, including non-native species that may displace, depredate, compete with, or indirectly affect native ecosystems and species. These factors give rise to management concerns at every scale; land managers increasingly need better information to sustain wildlife.
This book is designed for use by land managers, wildlife biologists, scholars, and students from high school level and up. It is complementary to the San Diego County Bird Atlas, the San Diego Natural History Museum’s online San Diego County Plant Atlas, and the online Amphibian and Reptile Atlas of Peninsular California. Thanks to these scholarly works, San Diego County is now biologically one of the best-documented regions in the world.
Q: Why did San Diego’s mammals need their own atlas?
A: Given the complexity of our habitat and the onslaught of urbanization, San Diego County is home to many rare and endangered species. Facing threats such as climate change, fire, marine harvesting and land development, it is important that land managers have the necessary information to sustain a wild and healthy ecosystem.
Q: How do we know that “the diversity of mammals in San Diego County is greater than any other county in the United States …”?
A: Well, that’s a good question. Not all counties in the United States have been quantified for their mammalian diversity and it is possible that another county could take the lead one day, but to our knowledge, San Diego is currently the county with the highest documented number of mammals in the U.S.
Q: And why is this diversity in San Diego so much greater than other places in the U.S.? What is it about San Diego that lends to this level of diversity?
A: Being a coastal county, San Diego boasts a wealth of marine mammals as well as terrestrial mammals. The California bight (curved Southern California coastline from Point Conception to San Diego) draws many marine species in close to the coast, including a fascinating array of occasional visitors like the killer whale. On the terrestrial front, the amazing topography of our county has created both Mediterranean and desert environments, with a large number of habitats, which support species of many families. We also have a surprisingly high number of volant (flying) mammals, our bats, and we’re fortunate to have a dedicated bat biologist at the museum.
What I love about Pacific Beach ...
Access to the bay and the beach and living in a very walkable community where there is always plenty to do.
Q: What is it about mammalogy that you enjoy?
A: I love the exploration of the natural world. Traveling to different parts of our diverse region and learning more about the animals that inhabit, and are unique to, our region is amazing to me. I love seeing so many different animals in the course of my work, and I really enjoy collaborating with the experts — so many incredible scientists who have dedicated their lives to one or more of these fascinating creatures. I am particularly passionate about natural history collections and the scientific documentation of our time. These collections are so integral to documenting and understanding our region, and contemporary collections are necessary to compare to historical data, but also to provide legacy data for future generations of mammalogists. I feel that in our collections, so many things are recorded that will undoubtedly tell the story of our time in a way that we cannot fully comprehend.
Q: What did you learn as a result of working on this book that you didn’t know before?
A: Although our county is better studied than most, I learned that there is a serious lack of information on many species. Although many remain, filling some of these knowledge gaps was fascinating. For example, I learned that the role of rabbits in the ecosystem is very important, and that the waxing and waning of grasslands is strongly affected by their foraging habits. Also, I learned that the ringtail (a member of the raccoon family) is more elusive than rare. The atlas inspired people to share data and report sightings of unusual mammals. Thanks to their efforts, we now know that this species is likely more abundant than previously believed.
Q: What were some of the fascinating discoveries you made in the course of working on this book that stood out for you?
A: The historical perspectives in the atlas are fascinating. Pronghorn, which look similar to antelopes, were numerous on the San Diego coast, foraging on planted fields in Point Loma in the 1800s. The last San Diego grizzly bear was also one of the largest in California and it was killed on Camp Pendleton in 1901. Some of the most fascinating contemporary data came from citizen science and the public. For example, for marine mammals, data from the San Diego Whale Watch gave us incredible insights into the seasonality and frequency of inshore cetaceans.
Q: What do you want people to understand about conservation?
A: San Diego species face many threats, and conservation of these species is an active and adaptive process as we learn more about the world around us. San Diego is a testing-ground for many kinds of conservation — including the Multiple Species Conservation Plans, the Habitat Conservation Plans, and Natural Communities Conservation Plans — which are all strategic ways to address the multiple threats to our region.
Q: Why is conservation important to you?
A: I think we are truly fortunate to have such great biodiversity in our county, and I feel it is our obligation to protect it.
Q: What does it mean to you to have completed a book like this?
A: I feel I have made a contribution to society, which provides a biological baseline for future generations.
Q: What’s been challenging about your work with this project, specifically?
A: Time. Having to sacrifice time with family and friends to complete this has been personally challenging.
Q: What’s been rewarding about that work?
A: I have grown as a scientist and as a member of the San Diego community.
Q: What has it taught you about yourself?
A: That with time and perseverance, I can bring a group of people together to accomplish an enormous task.
Q: What is the best advice you’ve ever received?
A: Keep it simple.
Q: What is one thing people would be surprised to find out about you?
A: Even though I’m a terrestrial biologist, I love the ocean.
Q: Describe your ideal San Diego weekend.
A: A good Mexican meal, a bike ride along a quiet road, and a swim in the ocean!
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