The landscape of North Carolina has changed dramatically since the first European settlers arrived over 400 years ago. Thousands of acres of bottomland hardwoods along major river systems, vast longleaf savannas, shrub-like pocosins, open oak-hickory forests, cove, northern hardwood, open pine and spruce-fir systems in the mountains and even large prairies greeted early explorers. All of these areas held a great diversity of birds and other wildlife. Natural fires and frequent burning by Native Americans helped create a mosaic of open areas of all types and sizes interspersed within large tracts of woodlands throughout the state.
As Europeans settled the state in the 17th and 18th centuries, the natural landscape began to change drastically. Vast tracts of land were cleared to provide lumber for homes and ships, start farming operations or create livestock grazing ranges. This broke up the continuity of many of our natural systems. As the population of North Carolina grew and expanded, more habitats were permanently cleared or altered. Extensive logging operations that were not done in a sustainable manner cleared huge amounts of cypress-gum swamps, bottomland hardwoods and longleaf pine savannas. Fire suppression in the 20th century greatly reduced and altered many other natural communities. Many wetland systems were drained and filled to support farming, pine plantations, new towns and other development.
As a result of all these land-altering events, many habitats in North Carolina today are highly fragmented. This means they have become isolated into smaller pieces and often no longer function in an ecologically sound manner for many species of birds. Forests, shrubland and grasslands are now often broken up into distinct, smaller units that no longer meet the needs of many migratory or even resident birds. They are separated by large agricultural operations, sprawling towns and cities, roads, housing developments and shopping malls. Some species of wildlife thrive in these situations. Many do not. Neotropical migratory birds in particular seem sensitive to these smaller patches of habitat in which they are forced to nest and raise young. These are the birds that nest in North America, but spend our winter in Mexico, the Caribbean, and Central and South America.
Habitat fragmentation reduces the size of patches of forest, shrubland, wetlands and grasslands. This reduces the total area of contiguous habitat available to birds and increases the isolation of the habitat. It also leads to an increase in edge habitat that is successfully exploited by a variety of predators that eat bird eggs and young. An edge is basically where two different habitat types meet, and in agricultural, suburban and even rural areas this edge is often very abrupt. Opportunistic and adaptable animals operate well in fragmented habitats such as raccoons, foxes, skunks, opossums, squirrels, rat snakes, crows, bluejays, grackles and feral and pet dogs and cats. They all impact bird populations by eating eggs, young birds and even adults. Other non-native birds like European Starlings common in urban and suburban areas compete with native cavity nesting birds for nest sites. Brown-headed Cowbirds parasitize some birds in fragmented habitats by laying their own eggs in the nests of other birds (see the fact sheet on cowbirds for more information). Non-native invasive plants like Japanese honeysuckle (Lonicera japonica), Chinese privet (Ligustrum sinense) and Japanese grass (Microstegium vimineum) encroach into smaller habitat fragments, limiting the growth of native plants, disrupting natural succession and limiting vegetative and structural diversity. This in turn impacts bird populations.
All of these problems together along with direct loss of habitat can put considerable pressure on landbird populations in our state and throughout the region. Overall in the southeast, predation seems to be the primary cause of bird nest failure, especially among neotropical migrants. Birds forced to compete for nesting sites in smaller and smaller fragments of habitat cause some to raise young in undesirable locations with reduced food supplies or even abandon nesting efforts altogether. These same problems are also occurring not only in breeding habitats, but also in migration stopover sites and wintering areas throughout the Americas for migratory landbirds. Characteristics of the surrounding landscape often influence affects of habitat fragmentation on bird populations.
Following is a list of scientific papers to help you learn more about fragmentation of forests, shrubland, grasslands or other habitat types and the associated impacts on birds:
Annand, E.M., and F.R.Thompson III. 1997. Forest bird response to regeneration practices in central hardwood forests. Journal of Wildlife Management 61: 159-171.
Askins, R.A. 1994. Open corridors in a heavily forested landscape: Impact on shrubland and forest-interior birds. Wildlife Society Bulletin22: 339-347.
Askins, R.A. 2001. Sustaining biological diversity in early successional communities: the challenge of managing unpopular habitats. Wildlife Society Bulletin 29: 407-412.
Bayne, E.M., and K.A. Hobson. 1997. Comparing the effects of landscape fragmentation by forestry and agriculture on predation of artificial nests. Conservation Biology 11:1418-1429.
Bayne, E.M., and K.A. Hobson. 2001.Effects of habitat fragmentation on pairing success of ovenbirds: Importance of male age and floater behavior. Auk 118(2):380-388.
Blake, J.G. and W.C. Hoppes. 1986. Influence of resource abundance on use of tree-fall gaps by birds in an isolated woodlot. Auk 103: 328-340.
Blake, J.G., and J.R. Karr. 1987. Breeding birds of isolated woodlots: Area and habitat relationships. Ecology 68: 1724-1734.
Blake, J.G., and B.A. Loiselle. 2001. Bird assemblages in second-growth and old-growth forests, Costa Rica: Perspectives from mist nets and point counts. Auk 118: 304-326.
Burke, D.M., and E. Nol. 1998. Influence of food abundance, nest-site habitat and forest fragmentation on breeding Ovenbirds. Auk 115:96-104.
Bollinger, E.K., B.D. Peer, and R. W. Jansen. 1997. Status of Neotropical migrants in three forest fragments in Illinois. Wilson Bulletin 109:521-526.
Brawn, J.D., and S.K. Robinson. 1996. Source-sink population dynamics may complicate the interpretation of long-term census data. Ecology 77:3-12.
Buehler, D.M., D.R. Norris, B.J.M. Stutchbury and N.C. Kopysh. 2002. Food supply and parental feeding rates of hooded warblers in forest fragments. Wilson Bulletin 114: 122-127.
Burhans, D.E. and F.R. Thompson III. 1999. Habitat patch size and nesting success of Yellow-breasted Chats. Wilson Bulletin 111: 210-215.
Darveau, M., P.Beauchesne, L. Belanger, J. Hout, and P.LaRue. 1995. Riparian forest strips as habitat for breeding birds in the boreal forest. Journal of Wildlife Management 59: 67-78.
De La Zerda Lerner, S., and D.F. Stauffer. 1998. Habitat selection by Blackburnian Warblers wintering in Columbia. Journal of Field Ornithology 69: 457-465.
Dessecker, D.R.,and D.G. McAuley. 2001. Importance of early successional habitat to ruffed grouse and American woodcock. Wildlife Society Bulletin 29: 456-465.
Doherty, P.F., and T.C. Grubb. 2000. Habitat and landscape correlates of presence, density and species richness of birds wintering in forest fragments in Ohio. Wilson Bulletin 112: 388-394.
Donovan, T.M., F.R. Thompson III, J. Faaborg, and J.R. Probst. 1995. Reproductive success of migratory birds in habitat sources and sinks. Conservation Biology 9:1380-1395.
Donovan, T.M., P.W. Jones, E.M. Annand, and F.R. Thompson III. 1997. Variation in local-scale edge effects: Mechanisms and landscape context. Ecology 78:2064-2075.
Dos Anjos, L. and R. Bocon. 1999. Bird communities in natural forest patches in southern Brazil. Wilson Bulletin 111: 397-414.
Fauth, P.T. 2000. Reproductive success of Wood Thrushes in forest fragments in Northern Indiana. Auk 117 (1): 194-204.
Ford, T.B., D.E. Winslow, D.R. Whitehead and M.A. Koukol. 2001. Reproductive success of forest-dependent songbirds near an agricultural corridor in south-central Indiana. Auk 118: 864-873.
Frederickson, T.S. 1998. Impacts of logging and development on central Appalachian forests. Natural Areas Journal 18: 175-178.
Friesen, L.E., V.E. Wyatt and M.D. Cadman. 1999. Pairing success of Wood Thrushes in a fragmented agricultural landscape. Wilson Bulletin 111: 279-281.
Gale, G.A., L.A. Hanners, and S.R. Patton. 1997. Reproductive success of Worm-eating Warblers in a forested landscape. Conservation Biology 11:246-250.
Gibbs, J.P., and J. Faaborg. 1990. Estimating the viability of Ovenbird and Kentucky Warbler populations in forest fragments. Conservation Biology 4:193-196.
Graves, G.R. 2001. Factors governing the distribution of Swainsons Warbler along a hydrological gradient in Great Dismal Swamp. Auk 118: 650-664.
Hagan, J.M., P.S. McKinley, A.L. Meehan and S.L. Grove. 1997. Diversity and abundance of landbirds in a northeastern industrial forest. Journal of Wildlife Management 61:718-735.
Hanski, I.K., T.J. Fenske, and G.J. Niemi. 1996. Lack of edge effect in nesting success of breeding birds in managed forest landscapes. Auk 113:578-585.
Harris, R.J., and J.M. Reed. 2001. Territorial movements of Black-throated Blue Warblers in a landscape fragmented by forestry. Auk 118: 544-549.
Hobson, K.A., and E.M. Bayne.2000. Effects of forest fragmentation by agriculture on avian communities in the southern boreal mixedwoods of western Canada. Wilson Bulletin 112:373-387.
Holmes, R.T., T.W. Sherry, P.P. Marra, and K.E. Petit. 1992. Multiple brooding and productivity of a Neotropical migrant, the Black-throated Blue Warbler (Dendroica caerulescens), in an unfragmented temperate forest. Auk 109:321-333.
Holmes, R.T., and T.W. Sherry. 2001. Thirty-year bird population trends in an unfragmented temperate deciduous forest: Importance of habitat change. Auk 118:589-609.
Hoover, J.P., M.C. Brittingham, and L.J. Goodrich. 1995. Effects of forest patch size on nesting success of Wood Thrush. Auk 112:146-155.
Hunt, P.D.1996. Habitat selection by American Redstarts along a successional gradient in northern hardwood forest: Evaluation of habitat quality. Auk 113:875-888.
Johnson, D.H. and L.D. Igl. 2001. Area requirements of grassland birds: A regional perspective. Auk: 24-34.
Jones, J. and R.J. Robertson. 2001. Territory and nest-site selection of Cerulean Warblers in eastern Ontario. Auk 118: 727-735.
King, D.I., C.R. Griffen, and R.M. DeGraaf. 1996. Effects of clearcutting on habitat use and reproductive success of the Ovenbird in forested landscapes. Conservation Biology 10:1380-1386.
King, D.I., C.R. Griffen, and R.M. DeGraaf. 1997. Effect of clearcut borders on distribution and abundance of forest birds in northern New Hampshire. Wilson Bulletin 109:239-245.
Krementz, D.G. and J.S. Christie. 1999. Scrub-successional bird community dynamics in young and mature longleaf pine-wiregrass savannahs. Journal of Wildlife Management 63: 803-814.
Kuehl, A.K., and W.C. Clark. 2002. Predator activity related to landscape features in northern Iowa. Journal of Wildlife Management 66: 1224-1234.
Lambert, J.D., and S.J. Hannon. 2000. Short-term effects of timber harvest on abundance, territory characteristics, and pairing success of Ovenbirds in riparian buffer strips. Auk 117(3): 687-698.
Lent, R.A., and C.E. Capen. 1995. Effects of small-scale habitat disturbance on the ecology of breeding birds in a Vermont (USA) hardwood forest. Ecography 18:97-108.
Manolis, J.C., D.E. Anderson and F.J. Cuthbert. 2002. Edge effect on nesting success of ground nesting birds near regenerating clearcuts in a forest-dominated landscape. Sauk 119: 955-970.
Marzluff, J.M. and K. Ewing. 2001. Restoration of fragmented landscapes for the conservation of birds: A general framework and specific recommendations for urbanizing landscapes. Restoration Ecology 9:280-292.
Matlock, G.R. 1993. Microenvironment variation within and among forest edge sites in the eastern United States. Biological Conservation 66:185-194.
Moorman, C.E. and D.C. Guynn. 2001. Effects of group selection opening size on breeding bird habitat use in a bottomland forest. Ecological Applications 11: 1680-1691.
Moorman, C.E., D.C. Guynn and J.C. Kilgo. 2002. Hooded Warbler nesting success adjacent to group-selection and clearcut edges in a southeastern bottomland forest. Condor 104: 366-377.
Norment, C. 2002. On grassland bird conservation in the northeast. Auk 119: 271-279.
Ortega,Y.K., and D.A. Capen.1999. Effects of forest roads on habitat quality for Ovenbirds in a forested landscape. Auk 116:937-946.
Paton, P.W.C. 1994. The effect of edge on avian nest success: How strong is the evidence? Conservation Biology 8:17-26.
Pearson, S.M. 1993. The spatial extent and relative influence of landscape-level factors on wintering bird populations. Landscape Ecology 8:3-18.
Petit, L.J., and D.R. Petit.1996. Factors governing habitat selection by Prothonotary Warblers: Field tests of the Fretwell-Lucus models. Ecological Monographs 66:367-387.
Peterjohn, B.G. 2003. Agricultural landscapes: Can they support healthy bird populations as well as farm products? Auk 120: 14-19.
Porneluzi, P., J.C. Bednarz, L.J. Goodrich, N.Zawada, and J. Hoover.1993 Reproductive performance of territorial Ovenbirds occupying forest fragments and a contiguous forest in Pennsylannia. Conservation Biology. 7:618-622.
Porneluzi, P., and J. Faaborg. 1999. Season-long fecundity, survival and viability on Ovenbirds on fragmented and unfragmented landscapes. Conservation Biology 13:1151-1161.
Probst, J.R., and J.P. Hayes. 1987. Pairing success of Kirtlands Warblers in marginal vs. suitable habitat. Auk 104:234-241.
Pulliam, H.R., and B.J. Danielson. 1991. Sources, sinks and population regulation. American Naturalist 137:550-566.
Rappole, J.H., and M.V. McDonald. 1994. Cause and effect in population declines of migratory birds. Auk 111:652-660.
Ricketts, M.S., and G. Ritchison. 2000. Nesting success of Yellow-breasted Chats: Effects of nest site and territory vegetation structure. Wilson Bulletin 112: 510-516.
Roberts, C., and C.J. Norment. 1999. Effects of plot size and habitat characteristics on breeding success of Scarlet Tanagers. Auk 116: 73-82.
Robinson, S.K., F.R. Thompson III, T.M. Donovan, D.R. Whitehead, and J.Faaborg. 1995. Regional forest fragmentation and the nesting success of migratory birds. Science 267: 1987-1990.
Robinson, S.K. 1998. Another threat posed by forest fragmentation: Reduced food supply. Auk 115: 1-3.
Rodewald, A.D., and R.H. Yahner. 2000. Bird communities associated with harvested hardwood stands containing residual trees. Journal of Wildlife Management 64:924-932.
Rodewald, A.D. 2002. Nest predation in forested regions: Landscape and edge effects. Journal of Wildlife Management 66: 634-640.
Roth, R.R., and R.K. Johnson. 1993. Long-term dynamics of a Wood Thrush population breeding in a forest fragment. Auk 110:37-48.
Rudnicky, T.C., and M.L. Hunter. 1993. Avian nest predation in clearcuts, forest and edges in a forest-dominated landscape. Journal of Wildlife Management 57:358-364.
Sabine, D.L., A.H. Boer, and B. Ballard. 1996. Impacts of habitat fragmentation on pairing success of male Ovenbirds, Seiurus aurocappillus, in southern New Brunswick. Canadian Field-Naturalist 110:688-693.
Sieving, K.E., M.F. Wilson and Toni L. DeSanto. 1996. Habitat barriers to movement of understory birds in fragmented south-temperate rainforest. Auk 113:944-949.
Sodhi. N.S., and C.A. Paskowski. 1997. The pairing success of male Black-and-white Warbler, Mniotilta varia, in forest fragments and a continuous forest. Canadian Field-Naturalist 111: 457-458.
Sherry, T.W., and R.T. Holmes. 1989. Age-specific social dominance affects habitat use by breeding American Redstarts (Setophaga ruticilla): A removal experiment. Behavioral Ecology and Sociobiology 25:327-333.
Simons, T.R., and G. Farnsworth.1995. Evaluating Great Smoky Mountains National Park as a source of regional biodiversity. 1994 Annual Report to the National Park Service. Gatlinburg, Tennesseee.
Smith, T.M., and H.H. Shugart.1987. Territory size variation in the Ovenbird: The role of habitat structure. Ecology 68: 695-704.
Song, S.J. and S.J. Hannon, 2000. Predation in heterogeneous forests: A comparison at natural and anthropogenic edges. Ecoscience 6: 521-530.
Thompson, F.R.,III, and R.M. DeGraaf. 2001. Conservation approaches for woody, early successional communities in the eastern United States. Wilson Society Bulletin 29: 483-494.
Tilghman, N.G. 1987. Characteristics of urban woodlands affecting breeding bird diversity and abundance. Landscape and Urban Planning 14:481-495.
Triquet, A.M., G.A. McPeek, and W.C. McComb. 1990. Songbird diversity in clearcuts with and without a riparian buffer strip. Journal of Soil and Water Conservation 45: 500-503.
Van Horn, M.A., R.M. Gentry, and J. Faaborg. 1995. Patterns of Ovenbird (Seiurus aurocapillus) pairing success in Missouri forest tracks. Auk 112:98-106.
Van Horne, B. 1983. Density as a misleading indicator of habitat quality. Journal of Wildlife Management 47:89-101.
Vickery, P.D., and S.C. Melvin. 1994. Effects of habitat area on the distribution of grassland birds in Maine. Conservation Biology *: 1087-1097.
Vickery, P.D. and J.R. Herkert. 2001. Recent advances in grassland bird research: Where do we go from here? Auk 118: 11-15.
Villard, M.A., P.R. Martin, and C.G. Drummond. 1993. Habitat fragmentation and pairing success in the Ovenbird (Seiurus aurocapillus). Auk 110:759-768.
Wenny, D.G., R.L. Clawson, J.Faaborg, and S.L. Sheriff. 1993. Population density, habitat selection and minimum area requirements of three forest-interior warblers in central Missouri. Condor 95:968-979.
Wesolowski, T. 1981. Population restoration after removal of wrens (Troglodytes troglodytes) breeding in primaeval forest. Journal of Animal Ecology 50:809-814.
Wilcove, D.S. 1985. Nest predation in forest tracts and the decline of migratory songbirds. Ecology 66:1211-1214.
Winter, M. 1999. Nesting biology of Dickcissels and Henslows Sparrows in southwestern Missouri prairie fragments. Wilson Bulletin 111: 515-527.
Woodward, A.A., A.D. Fink and F> R. Thompson III. 2001. Edge effects and ecological traps: Effects on shrubland birds in Missouri. Journal of Wildlife Management 65: 668-675.
Yahner, R.H. 1997. Long-term dynamics of bird communities in a managed forested landscape. Wilson Bulletin 109: 595-613.