Richard T. Holmes

• Professor Ronald and Deborah Harris Professor Environmental Biology Emeritus, and Research Professor of Biology
• Ph.D., University of California, Berkeley, 1964
• Richard.T.Holmes@Dartmouth.edu

Research Interests

My interests are in behavioral, population, and community ecology, particularly the ecological factors and processes that determine or influence population size, habitat selection, social organization and life history patterns. Most of my research concerns birds — their reproductive ecology, territoriality, site fidelity and dispersal, survivorship, habitat selection, foraging behavior, and related population attributes.

For the last 20+ years, my research has focused on the ecology and behavior of migratory passerine birds in their north temperate breeding areas in New England and in their neotropical wintering quarters in the Caribbean and Central America. Long-term studies of bird populations in the Hubbard Brook Experimental Forest in central New Hampshire have led to a pluralistic model of population regulation and community structure for such neotropical migrant species. This model emphasizes the operation of diverse density-dependent and density-independent factors, including climatic events, vegetation structure, food abundance and availability, intraspecific territoriality, site (habitat) selection, and the presence and impact of other species (particularly predators), that affect populations in both breeding and winter quarters and probably also during migration.

Current Project

Building on our long term studies of birds in northern hardwoods forests, our current research examines the impact of climate (weather) on bird distribution, abundance, and demography.We are testing hypotheses concerning the effects of abiotic conditions (e.g., weather) and biotic factors (e.g., bird density, food, predators) on bird populations distributed across an environmental (altitudinal) gradient) at Hubbard Brook. The results are expected to elucidate ecological mechanisms generating changes in bird distribution, abundance and productivity as they may be affected by climate change. The research will also continue to contribute to our understanding of the factors affecting neotropical migrant bird populations, some of which are currently declining.

Selected Publications

• Sillett, T.S., R.T. Holmes, and T.W. Sherry. 2000.  Impacts of a global climaate cycle on population dynamics of a migratory songbird.  Science 288: 2040-2042
• Holmes, R.T., and T.W. Sherry. 2001. Thirty-year bird population trends in an unfragmented temperate deciduous forest: importance of habitat change. Auk 118:589-610.
• McPeek, M.A., N.L. Rodenhouse, T.W. Sherry, and R.T. Holmes. 2001. Site dependent population regulation: population-level regulation without individual-level interactions. Oikos 94:417-424.
• Sillett, T.S., and R.T. Holmes. 2002.Variation in survivorship of a migratory songbird throughout its annual cycle.Journal of Animal Ecology 71:296-308.
• Rubenstein, D.R., C. P. Chamberlain, R.T. Holmes, et al. 2002. Linking breeding and wintering ranges of a Neotropical migrant songbird using stable isotopes. Science 295:591-593.
• Jones, J., P. J. Doran and R.T. Holmes.  2003. Climate and food synchronize regional forest bird abundances. Ecology 84: 3024-3032.
• Rodenhouse, N.L., T.S. Sillett, P.J. Doran, and R.T. Holmes. 2003. Multiple density-dependent mechanisms regulate a migratory bird population during the breeding season. Proc. Royal Society London B 270:2105-2110.
• Sillett, T.S., N.L. Rodenhouse, and R.T. Holmes. 2004. Experimentally reducing neighbor density affects reproduction and behavior of a migratory songbird. Ecology 85: 2467-2477.
• Nagy, L.R., and R.T. Holmes. 2005. Food limits annual fecundity of a migratory songbird: an experimental study.  Ecology 86: 675-681.
• Johnson, M.D., T.W. Sherry, R.T. Holmes, and P.P. Marra. 2006. Assessing habitat quality for a migratory songbird wintering in natural and agricultural habitats.  Conservation Biology 20: 1433-1444.
• Holmes, R.T. 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (S2): 2-13.
• Betts, M.G., N.L. Rodenhouse, T.S. Sillett, P.J. Doran, and R.T. Holmes. 2008. Dynamic occiupancy models reveal within-breeding season movement up a habitat quality gradient by a migrant songbird.  Ecography 31: 592-600.
• Rodenhouse N.L., S.N. Matthews, K.P. McFarland, J.D. Lambert, L.R. Iverson, A. Prasad, T.S. Sillett, and R.T. Holmes. 2008. Potential effects of climate change on birds of the Northeast.  Mitig. Adapt. Strat. Global Change 13: 517-540.
• Faaborg, J., R.T. Holmes, et al. 2010. Recent advances in understanding migration systems of New World landbirds.  Ecological Monographs, in press.