Thomas C. Grubb, Jr.

Thomas C. Grubb, Jr., an elective member of the American Ornithologists’ Union (now the American Ornithological Society) since 1968 and a fellow since 1989, passed away on December 17, 2025, at the age of 81. Though a productive scientist across multiple decades, species, and questions, Tom will be best remembered for bringing the term and the concept of ptilochronology to ornithological researchers world-wide. Ptilochronology (“Feather-time”) involves gauging a bird’s nutritional condition by the rate at which a bird can replace a feather. Tom’s innovation grew from a practical frustration: the difficulty of comparing the energetic efforts of individual birds in the field—such as chickadees—at a time when the default tool was doubly labeled water, a difficult and expensive method to measure energetic output that did nothing to account for energetic input. Tom hypothesized that because regrowing lost plumage is a high-priority necessity, a bird should regrow a lost feather as quickly as its current nutritional status permits. Thus, if one were to pluck a single rectrix, the rate at which it was regrown would serve as a reliable index of that individual’s available energy and nutrients over that period. Though the technique requires careful application, it has been useful for comparing nutritional condition between individual birds under specific conditions for many species. He first demonstrated the utility of the technique with captive chickadees (Grubb 1989). In the subsequent three decades, according to Google Scholar, over 800 publications have used the technique, which Tom detailed extensively in his 2006 book Ptilochronology: Feather Time and the Biology of Birds (Grubb 2006). However, Tom’s first major contribution to the world of ornithology was a result of his graduate work at the Bowdoin Scientific Station at Kent Island in the Bay of Fundy. Tom’s major professor for his PhD at U. Wisconsin, John Emlen, had studied gull behavior on Kent Island in the early sixties and introduced Tom to Kent Island. Tom first came to Kent Island during the summer of 1968, not long after graduating from Swarthmore College. Tom and his wife Jill spent the next four years investigating olfactory navigation in procellariiform seabirds generally and Leach’s Storm-Petrels (Hydrobates leucorhous), in particular. Tom’s gift for finding creative ways to answer complex questions resulted in a myriad of investigations. He spent many a days at sea towing rafts reeking of cod liver oil and many nights in the wind and the rain, all to track the paths of incoming storm-petrels relative to the prevailing winds. With a 60’s era night vision scope, he watched storm-petrels find their burrows. He performed homing experiments with anosmic storm-petrels and brought storm-petrels indoors to navigate a Y-maze based on olfactory cues alone. It all added up to the first thorough demonstration of these seabirds’ ability to navigate by smell at multiple spatial scales. His Nature paper on olfactory navigation in Procellariform birds (Grubb 1972) remains an important antecedent for modern research in the field. The entire enterprise was a tour-de-force of Tom’s gift for finding creative ways to answer complex questions, particularly through simple and elegant experimental approaches Tinbergen would be proud of. This was a thread that could be traced directly back to his mentor John Emlen, the originator of the Emlen Funnel, and forward through dozens of graduate students over the subsequent four decades. Tom’s focus shifted to the biology of wintering woodland birds during a two-year faculty stint at Rutgers University. In 1973, Tom moved to the Zoology Department at Ohio State University, where he remained until his retirement in 2005 from what was by then the Department of Evolution and Ecology. Settling in Morrow County, Ohio, he purchased a farm that served as both a home base and a living laboratory. Guided by the “Land Ethic” traditions of Aldo Leopold, Tom designated a portion of his land as a “section of wilderness forever,” planted black walnut trees as a natural inheritance for his grandchildren, and used the farm as the staging area for what became his major research focus for the rest of his career. Soon after arriving at Ohio State, Tom established a long-term study area in Crawford County, Ohio, encompassing more than 15,000 ha of predominantly flat, agricultural land, ∼10% of which was forested and included over 100 discrete woodlots (ranging from 0.07 to 60 ha) as well as two river corridors. Within this heterogeneous mosaic, Tom and his students conducted research on permanent-resident bird species and an assemblage of other flora and fauna. Graduate theses and dissertations originating from this site addressed topics such as the dynamics of the chickadee hybrid zone, winter flock foraging ecology, avian nutritional condition, optimal energy and time allocation, and the demographic and behavioral responses of birds and amphibians to anthropogenic changes associated with woodland fragmentation. This rich study, dubbed the Ohio Woodlot Project, was partially funded by the National Science Foundation and was integral to many of the 125 scientific publications produced by Tom and his graduate students. This vast study area also served as an important training ground for graduate and undergraduate students. Many students were introduced to bird banding and associated field methodologies by Tom. There they discovered that fieldwork required equal parts scientific rigor, stamina, and a sense of humor. Notably, the entire landscape was privately owned by numerous landholders with whom Tom maintained long-standing relationships. He established a long-standing tradition of entering landowners into a lottery for his Ohio State football season tickets. This approach, while unconventional, proved effective and was characteristic of Tom’s personable style of engagement. At heart, Tom Grubb was a field biologist. Though his interests and collaborations spanned every biological level, Tom loved his time out of doors, a passion fueled by his youth among the woods and ponds of Long Island and New Jersey. The Woodlot Project fed this passion. Many a graduate student can recall cold winter days hiking across snow-covered fields to isolated woodlots (“natural aviaries”) to set up feeder-traps, erect mist nets, and band birds—to a soundtrack of Tom’s whistled symphonies—all to test hypotheses in the context of the natural world. As an advisor, Tom did not simply plug graduate students into pre-determined slots. Tom was interested in ideas, not foot soldiers for his own projects. When one of us (P.F.D.) was considering graduate school and contacted him, Tom responded with “If you’re serious, why don’t you drive out here over spring break?” The subsequent “interview” was a morning spent in a small woodlot among the Ohio farmlands, which Paul found by following instructions unaided by GPS. After a morning of bird banding and bright sunshine, both the prospective advisor and the prospective student decided the arrangement might work. Tom encouraged a master’s degree as a trial run. “You can do anything for two years,” said Tom, after which Paul would know if he’d made the right choice. The master’s had nothing to do with woodlots. The subsequent PhD, however, did and was predicated on what Paul found interesting about wintering birds, not by Tom’s fiat. Tom never pushed, but he was always there to discuss, support, and advise. Tom’s mentoring style resulted in members of his lab investigating interesting ideas from Alaska to Florida to the Canadian Maritimes, in addition to the woodlands of Ohio. Tom’s affinity for the scientific method extended far beyond the walls of academia. He authored three books aimed at non-scientific audiences, including a profile of the tufted titmouse (Grubb 1998), but most notably Beyond Birding: Field Projects for Inquisitive Birders (Grubb 1986). This guide empowered birders to apply scientific viewpoints to their hobby, introducing them to the joy of creative experimental designs and simple statistical analyses. In many ways, this was an early and influential expression of “citizen science,” as well as a resource used by one of us (R.A.M.) for teaching animal behavior to undergraduates. Tom’s last book, The Mind of the Trout (Grubb 2003), married Tom’s scientific interests with his most enduring avocation, fly fishing for trout. Tom’s interest in fishing blossomed midway through his academic career. Mauck recalls multiple expeditions to trout streams across Pennsylvania and tributaries of the Great Lakes. Those trips were equal parts casting files on the water and wide-ranging scientific discussions on the long drives to and from the streams. Once retired, he and his wife Jill often travelled to Colorado where son Josh had moved and Tom’s passion for trout was fully unleashed. His favorite streams were in Rocky Mountain National Park. That passion persisted through retirement, as did his talent for woodworking, which resulted in elegant and biologically faithful carvings of cetaceans and birds. In addition, Tom volunteered his time in various ways: cleaning two miles of highway in the Rocky Mountains, serving meals to the homeless, and reading books and newspapers for the blind. Above all else, Tom cherished his family. In addition to his beloved wife Jill, Tom is survived by his sons, Josh Grubb Robinson and Benjamin Robinson Grubb; his daughter, Libby Grubb; his grandchildren, Fiona Robinson, Aidan Robinson, Finnegan Debney, Kai Grubb Enscoe, and Max Robinson Enscoe; his brother, Gary Grubb; and his sister, Linda Woodworth. Thomas C. Grubb, Jr. during his PhD work at Kent Island (photo courtesy of Ed Minot). Memorials Editor: Gregory Nobles, email protected