National Park Service U.S. Department of the Interior Acadia Acadia National Park Revisiting MacArthur’s Classic Study of Niche Partitioning of Spruce Wood Warblers Bik D. R. Wheeler, Acadia National Park, Bar Harbor, ME and College of the Atlantic, Bar Harbor, ME

Fig. 5. Depicted is one of Introduction: Distribution: 17 forest structure plots. Each of the four species were The outer circle represents In 1956 and 1957, Robert H. the 20m diameter observed in all quadrats of the boundary. Each tree over MacArthur studied the ecology of five 3m tall was identified, species of the genus Setophaga plot at some time during the measured and mapped. field seasons. Additionally, Each tree is represented as (wood warbler), resulting in a circle where size is each species was seen with proportional to the diameter contributions to the theory of niche at breast height. Fill color partitioning. MacArthur asserted that each other species in the represents species: white is red spruce, green is balsam the five Setophaga are sympatric same tree, at least once during fir, yellow is American larch, the observation period. pink is paper birch, and species that evolved to occupy blue is mountain ash. Large However, there were spatial diameter trees are evenly separate behavioral niches. His spread while small observations were conducted in differences in density of diameter trees have patchy territorial males during the distribution and red spruce Acadia National Park, Maine, USA. are evenly distributed, while In the breeding seasons of 2014 and mapping surveys (Fig.2). other species are patchy. Fig. 2. The study boundaries are shown along with the 50 2015, I repeated MacArthur’s study meter square quadrats labeled with ID numbers. The Forest Structure Assessment: darker blue represents quadrats where singing males in the same location, to reassess were encountered more frequently during surveys and MacArthur (1957) described the plot at Bass warbler niche partitioning and white quadrats represent quadrats where there were zero encounters with the species. Harbor Head as a mature stand of white observe possible changes over time. spruce (Picea glauca) approximately 60-70 Fig. 4. Foraging heights and feet in height. The area today is predominantly substrate measurements. Species Composition: shorter red spruce (Picea rubens). To evaluate The yellow circles represent heights and substrate type availability of size and species of trees in the (in this case branch tips) where a female black- plot, I established 20m diameter plots in which 1956: Cape May warbler throated green warbler trees over 3m were measured and mapped to 2014‐15: Northern parula foraged on June 29, 2014. 2014‐15: Magnolia warbler 1956: Bay‐breasted warbler establish total heights, canopy heights, stem 1956: Blackburnian warbler density, and size class spacing.

1956 and 2014‐15: Myrtle warbler Acknowledgments: Height from lowest portion I would like to thank my advisors and mentors: Dr. John Anderson, Bruce of canopy to top Connery, Ken Cline, Esq., Drs. Abe Miller-Rushing, Nishanta Rajakaruna, Sarah Hall and also the tireless efforts of Anne Hurley, Meaghan Lyon, Bekka Paine, Kristin Dillon, Abby Seymour, Anne Wheeler, Jesse Wheeler, Chris Heilakka,

1956 and 2014‐15: Black‐ and Natasha Krell and Acadia National Park Resource Management Program for throated green warbler Fig 3. This template was used in the original study to illustrate zones of logistical support. This project has been made possible through generous Fig. 1. The newly accepted phylogenic reconstruction for the family foraging. MacArthur (1958) asserted that financial support from the National Park Service, College of the Atlantic, the Parulidae (original figure from Lovette et al., 2010). The relative each warbler preferred a different zone. Height from ground to Garden Club of America, and the Maine Space Grant Consortium. relationships of the study species of both the 1950s study and the The simplification of foraging substrate lowest portion of canopy. current study. Two species of the genus are still present breeders, and stratum habitats are rudimentary but Literature cited: three are no longer present and two additional species are present. are necessary for new methodology to Lovette, I. J., J. L. Pérez-Emán, J. P. Sullivan, R. C. Banks, I. Fiorentino, S. be comparative. Córdoba Córdoba, M. Echeverry-Galvis, F. K. Barker, K. J. Burns, J. Klicka, S. M. Lanyon, E. Bermingham. 2010. A Comprehensive Multilocus Phylogeny For F THE O AT Methodological Comparison and Advancement: The Wood-Warblers And A Revised Classification Of The Parulidae (Aves). E L G A E N Molecular Phylogenetics and Evolution, 57: 753–770. L T The methodology was designed to allow a direct comparison with L I O C C the original study, while utilizing current technology and allowing MacArthur, R.H (1957). Population ecology of some warblers of Northeastern coniferous forests. Ph.D. dissertation, Yale University, New Haven, CT, USA. flexibility in the analysis. My analysis will involve a direct MacArthur, R.H. (1958). Population ecology of some warblers of Northeastern M C I X M L X application of my data to MacArthur’s tree template (Fig. 3) and coniferous forests. Ecology 39:599–619. will also allow me to apply alternative templates (Fig. 4).