Joseph Merritt

(This column was first published in the August 28, 2000 Buffalo News.)

    Shortly after I began writing these columns I obtained a copy of Joseph Merritt's Guide to the Mammals of Pennsylvania (University of Pittsburgh Press) and the book has served me well over the years as a primary reference. It is a deeply informed text, crammed with information about animals almost all of which we share with our neighboring state.

    And so, when an opportunity to attend a program on mammals directed by Dr. Merritt came my way last month, I jumped at the chance. That was a good decision as I found our instructor not only a thoroughly grounded and experienced mammalogist and an international leader in his field but also a delightful individual with an especially well-tuned sense of humor. He clearly represents a model for youngsters considering his field of study.

    Merritt is resident director of the Powdermill Biological Station located about fifty miles southeast of Pittsburgh in Pennsylvania. This 3 1/2 square mile woodland nature reserve is carved out of a surrounding countryside where multi-million dollar homes are to be seen far beyond fences and broad open fields.

    Powdermill is a beehive of activity. Robert Leberman and Robert Mulvihill have banded over 400,000 birds here and Mulvihill is now studying the effect of stream acidity due to the tailings of abandoned mines on the nesting of Louisiana waterthrushes. Staff members are busy in the Florence Lockhart Nimick Nature Center and other facilities that provide classrooms, labs, exhibit space and an extensive library.

    The station's other focus is on small mammals. Merritt's world-wide reputation is based on his studies of their adaptation to cold. Together with his students he has established the importance of a variety of factors to winter survival, both behavioral and physiological. Many factors are straightforward such as communal nesting and nest construction to reduce loss of warmth, torpor or hibernation to conserve energy. But one anatomical mechanism is not so apparent -- a small area of brown adipose tissue in the animal's mid-back provides internal temperature regulation. This fatty tissue substitutes for the shivering that is used by many insects -- and us -- to warm ourselves. Interestingly, this kind of fat does work for us as well, but only in the womb. Shivering soon takes over this role for the newborn.

    By a remarkable series of experiments on mammals in Colorado and Siberia as well as at Powdermill using radiotelemetry devices implanted in animals and monitored as the animals run free, Merritt has been able to assess seasonal body temperature changes and other physiological factors that have led to our better understanding of these kinds of thermoregulation.

    But what especially impressed me about this scientist was his ability to balance his many administrative and teaching responsibilities with his continuing field research. Several times a month, summer and winter, for over twenty years he and his students have monitored a 2 1/2 acre site with 130 trapping stations.

    That area is only the size of the infield contained inside a quarter mile track yet Merritt's live trapping and release of animals provides a continuing record of an extraordinary number of small mammals – as many as 85 deer mice, 80 white-footed mice, 40 red-backed voles, 50 chipmunks and 25 flying squirrels. On the first day I was there, for example, the 30 traps we set out for flying squirrels produced 12 of these remarkable little animals. Extrapolated, that is equivalent to over 3000 flying squirrels per square mile of forest.

    Most of academic biology today considers nothing large enough to see without use of an electron microscope, but people like Joe Merritt demonstrate that there are still exciting careers to be followed in natural history.-- Gerry Rising