The Effect of Forest Fragmentation on Forest Interior Species (page 3)
In this study I was trying to find how big a forest has to be to contain certain forest interior species? To do this I collected data on different interior species in different sized forest on the Eastern Shore of Maryland. I would see which species are absent or present as forest sizes ranged. Then I analyzed and drew conclusions about which interior species are area sensitive and how big a forest should be to contain certain species. I found that the most area sensitive species were two of the rarer warblers, Black and White Warbler and Worm-Eating Warbler. This is consistent with the background information. These two warblers were listed as having the highest minimum area needed at 304 ha (see table 6). The least area sensitive species were mostly species that were not truly interior birds and were not listed as interior species in my background information. These species included such edge birds as the Carolina Wren (see discussion for more details).
Why were some species more area sensitive than others? The Worm-Eating Warbler and the Black and White Warbler were said to be found in larger forest in the background information. It was also said that they were both ground nesters and feeders (see tables 4 and 5) which would make them subject to predators and therefore sensitive to forest fragmentation. Therefore it makes sense that they would only be found in large forest with a great amount of interior were they would be less vulnerable to predators. That is why they are the most area sensitive birds. The birds such as the Carolina Wren, Great Crested Flycatcher, and many others are the least area sensitive species of the forest birds. In the background Information none of the least sensitive species were listed as key interior species. Most of these species are found on the edge of the forest and would not be sensitive to forest fragmentation. They do not need a forest with interior and therefore are found in the smallest forests tested.
The forests on the eastern shore are usually too small or fragmented for the key interior species. Some key interior species listed by my background information were not found at all during the study and most of them were species that require a large amount of interior. All of these species required a minimum or optimum size over 100 hectares (ha). Most key interior species tested, such as the Scarlet Tanager, were always found in forests over 100 ha. For example, the red-eyed vireo was always found above 102 ha., which is consistent with the background information that says its optimum area is >101 ha. We would have a greater Biodiversity of forest interior birds if most eastern shore forests were greater than 100 ha. Then we would find more of the most area sensitive birds. What are needed are some solutions which can make Eastern Shore forests larger; these include bio-corridors connecting forests, squaring or rounding off forests to create more interior, and tree farming.
One way we could extend this study is by zooming in on one interior species or group, such as warblers. Also, I did not look at how the quality of different types of forests affects the species in them. For instance, some interior species were found in smaller forest but the quality of the forest was what counted. For example, a Prothonotary Warbler can be found in a smaller forest if there is a large swampy habitat available. That's one thing that could affect the data. Another thing is that I was only checking for absence or presence not nesting success. A species may be in a forest but that does not mean its nesting is not being affected by predators. Some questions that arose during this study were:
- were some of the interior species being found in smaller forest because of habitat?
- how can we make Eastern Shore forests larger? All of these questions can be answered in further studies.
Anderson, S.H. and Robbins, C.S. "Habitat Size and Bird Community Management." Transcript, North American Wildlife and Natural Resources Conference, Vol. 46, 1981, pages 511 - 520.
Bent, A.C. Life Histories of North American Wood Warblers. Smithsonian Institution. U.S. Natl. Mus. Bulletin 203, 1953.
Bushman, Ellen S. and Therres, Glenn D. "Habitat Management Guidelines for Forest Interior Breeding Birds of Coastal Maryland." MD Dept. of Natural Resources, Wildlife Technical Publication 88-1, 1988.
Campbell, Mark and Johns, Mark. "Habitat Fragmentation and Birds." North Carolina Wildlife Resources Commission, 2005.
Connecticut Department of Environmental Protection. "Brown-headed Cowbird." Wildlife in Connecticut Informational Series, 1997.
Connor, R.N. and Adkisson, C.S. "Effects of Clearcutting on the Diversity of Breeding Birds." Journal of Forestry, Vol. 73, no. 12, 1975, pp. 781-785.
DeGraaf, R.M. et al. Forest Habitat for Birds of the Northeast. U.S. Forest Service, Northeast Forest Experimental Station, 1980.
Griscomb, L. and Sprunt, A. The Warblers of America. Devin-Adair Co., New York, N.Y., 1957.
Hoover, Jeffrey P. et al, "Effects of Forest Patch Size on Nesting Success of Wood Thrushes", The Auk, Vol. 10, no. 1, 1995, pp. 146 - 155.
Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Co., Boston, 1996.
Kroodsma, R.L. "Effect of Edge on Breeding Forest Bird Species." Wilson Bulletin, Vol. 96, no. 3, 1984, pp. 426-436.
MacArthur, Robert H. and Wilson, Edward O. The Theory of Island Biogeography. Princeton University Press, Princeton, NJ, 1967
Ortega, Yvette K. and Capen, David E. "Effects of Forest Roads on Habitat Quality for Ovenbirds in a Forested Landscape." The Auk, Vol. 116, no. 4, 1999, pages 937 - 946.
Robbins, C.S. "Determining Habitat Requirements of Nongame Species." Transcript, North American Wildlife and Natural Resources Conference, Vol. 43, 1978, pages 57 - 68.
Robbins, C.S. "Effect of Forest Fragmentation on Bird Populations." in DeGraaf, R.M. and Evans, K.E., eds. Management of North Central and Northeastern Forests for Gamebirds, U.S. Forest Service Gen. Tech. Rep. NC-51, 1979.
Robbins, C.S. "Effect of Forest Fragmentation on Breeding Bird Populations in the Piedmont of the Mid-Atlantic Region." Atlantic Naturalist, Vol. 33, no.1, 1980, pp. 31-36.
Roberts, Christopher and Norment, Christopher J., "Effects of Plot Size and Habitat Characteristics on Breeding Success of Scarlet Tanagers", The Auk, Vol. 10, no. 1, 1995, pp. 146 - 155.
Robinson, Scott K., Thompson III, Frank R., Donovan, Therese M., Whitehead, Donald, R., and Faaborg, John. "Regional Forest Fragmentation and the Nesting Success of Migratory Birds." Science, Vol. 267, March 31, 1995, pp. 1987 -1990.
Rosenberg, Kenneth V. et al, A Land Manager's Guide to Improving Habitat for Forest Thrushes, Cornell Lab of Ornithology, 2003.
Smith, K.G. "Distribution of Summer Birds Along a Forest Moisture Gradient in an Ozark Watershed." Ecology, Vol. 58, no. 4, 1977, pp. 810-819.
Stewart, R.E. and Robbins, C.S. Birds of Maryland and the District of Columbia. North Am. Fauna 62, 1958.
Whitcomb, R.F. et al. "Effects of Forest Fragmentation on Avifauna of the Eastern Deciduous Forest." Ecological Studies, Vol. 41, 1981, pp. 125 - 206.
Wilcove, D.S. "Nest Predation in Forest Tracts and the Decline of Migratory Songbirds." Ecology, Vol. 66, no. 4, 1985, pp. 1211 - 1214.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.