Beginning Jan. 18, 2022, the Zoo is open Thursdays, Fridays, Saturdays and Sundays from 8 a.m. to 3 p.m. (last admittance 2:30 p.m.). Select animal buildings remain closed. Entry passes are required for all guests, including infants. All visitors ages 2 and older are required to wear a mask in all indoor spaces at the Zoo, regardless of their vaccination status. Fully vaccinated visitors do not need to wear a mask in outdoor areas.

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Katherine Ralls, Ph.D.

Senior Research Zoologist Emerita
B.A., Stanford University; M.S., Radcliffe College; Ph.D., Harvard University

Katherine Ralls is a mammalogist and conservation biologist emerita at the Smithsonian Conservation Biology Institute's Center for Conservation Genomics. She was one of the first scientists hired at the Smithsonian's National Zoo and was one of the founders of the Society for Conservation Biology. Ralls studies the behavioral ecology, genetics and conservation of terrestrial and marine mammals. She has conducted field studies of sea otters, San Joaquin kit foxes and island foxes.

Ralls' research interests include:

  • Genetic management of small captive and wild populations
  • Behavioral ecology, genetics and conservation of mammals
  • Field studies of sea otters and foxes
  • Sexual dimorphism, mating systems, scent marking and tool-use

Ralls' early papers on scent marking and sexual dimorphism have been widely cited. Her pioneering work on inbreeding problems in zoo animals, along with SCBI’s Jon Ballou, led to the genetic and demographic management of captive populations now practiced in zoos worldwide. Most recently, Ralls and Ballou were among the co-authors of the first textbook on the genetic management of fragmented wild animal and plant populations.

Ralls did her undergraduate work at Stanford University. She earned her master's degree at Radcliffe College and her doctorate in biology at Harvard University. Ralls was the 1996 recipient of the American Society of Mammalogist's C. Hart Merriam Award and the Society for Conservation Biology's Edward T. LaRoe Award. In 2006, she was named an Honorary Fellow of the Zoological Society of London, and in 2015 she was named an Honorary Member of the American Society of Mammalogists.

Recent Publications: 
Larson, Shawn,Gagne, Roderick B.,Bodkin, Jim,Murray, Michael J.,Ralls, Katherine,Bowen, Lizabeth,Leblois, Raphael,Piry, Sylvain,Penedo, Maria Cecilia,Tinker, M. Tim,Ernest, Holly B. 2021. Translocations maintain genetic diversity and increase connectivity in sea otters, Enhydra lutris. Marine Mammal Science, . 10.1111/mms.12841
Powers, Robyn M.,Cypher, Brian L.,Ralls, Katherine,Randall, Jan A.,Kelly, Erica C. 2021. Ecological variation among island foxes relative to reproductive events. California Fish and Game, 400–415. 10.51492/cfwj.cesasi.24
Crooks, Kevin R.,Mills, L. Scott,Sanjayan, M.,Ehrlich, Paul R.,Ogden, John C.,Allendorf, Fred W.,Ralls, Katherine,Noss, Reed F.,Mace, Georgina,Estes, James A.,Doak, Daniel F.,Terborgh, John,Inouye, David W. 2020. Reflections on Michael Soule, a visionary for conservation biology. Conservation Biology, . 10.1111/cobi.13597