THE EDGE EFFECT AND ECOTONAL SPECIES: BIRD COMMUNITIES ACROSS A NATURAL EDGE IN SOUTHEASTERN AUSTRALIA

Ecotones have been considered as unique environments, and the concepts of edge effect and ecotonal species have been widely used, especially in avian community ecology. We studied the patterns of bird densities across heath-wood edges at replicated sites in three locations in southeastern Australia. Multivariate analysis showed that the bird community in the ecotone was intermediate between the heath and wood communities, indicating that the ecotone contained a mixing of species rather than a unique bird com- munity. ANOVA showed a modest increase in bird density at the wood side of the ecotone, which may be partly due to sampling biases rather than to some inherent habitat value in the ecotone. The outstanding pattern was that bird density and species richness in the wood habitat were twice as high as in the heath habitat. Of a total of 86 species, 31 occurred in sufficient numbers to categorize according to their habitat association (generalist, or heath or wood specialist) and their density at the ecotone (ecotone neutral, ecotone shy, or ecotone conspicuous). Three of these were habitat-generalist-ecotone-neutral. Fourteen species were ecotone neutral but were habitat specialists on either the wood (13 spp.) or the heath (1 sp.). Three species were ecotone shy. Although 11 species were ecotone conspicuous, they also occurred in either heath or wood or both. Thus, no species could be categorized as entirely ecotonal. We conclude that there is little evidence from this or other studies of avian communities to support an edge effect of increased density and species richness, and no evidence of entirely ecotonal species.

[1]  M. C. Newman,et al.  Fundamentals of Ecotoxicology, Second Edition , 2002 .

[2]  P. Risser,et al.  The Role of Landscape Boundaries in the Management and Restoration of Changing Environments: Introduction , 1991 .

[3]  Jack Baker.  The Eastern Bristlebird: Cover-dependent and Fire-sensitive , 2000 .

[4]  S. Jacobs,et al.  Native Trees and Shrubs of South-Eastern Australia , 1983 .

[5]  Jack L. Griggs.  All the Birds of North America : American Bird Conservancy's Field Guide , 1997 .

[6]  G. Pyke,et al.  Habitat Use by Eastern Bristlebirds in Barren Grounds Nature Reserve , 1992 .

[7]  A. J. Underwood,et al.  Experiments in Ecology. , 1997 .

[8]  R. Balda,et al.  Breeding Bird Use of a Pinyon Juniper Ponderosa Pine Ecotone , 1976 .

[9]  H. Possingham,et al.  Bird Responses at Inherent and Induced Edges in the Murray Mallee, South Australia. 1. Differences in Abundance and Diversity , 1999 .

[10]  R. Macarthur,et al.  On Bird Species Diversity , 1961 .

[11]  Paul G. Risser,et al.  The Status of the Science Examining EcotonesA dynamic aspect of landscape is the area of steep gradients between more homogeneous vegetation associations , 1995 .

[12]  C. Murcia.  Edge effects in fragmented forests: implications for conservation. , 1995, Trends in ecology & evolution.

[13]  S. Robinson,et al.  Edge effects on nest predation in the Shawnee National Forest, southern Illinois , 1995 .

[14]  Richard H. Yahner,et al.  Changes in Wildlife Communities Near Edges , 1988 .

[15]  J. Terborgh,et al.  Structure and Organization of an Amazonian Forest Bird Community , 1990 .

[16]  E. Odum,et al.  Breeding Bird Populations in Relation to Plant Succession on the Piedmont of Georgia , 1956 .

[17]  L. W. Gysel,et al.  Avian Nest Dispersion and Fledging Success in Field‐Forest Ecotones , 1978 .

[18]  Richard Brewer.  The science of ecology , 1988 .

[19]  V. Johnston.  Breeding Birds of the Forest Edge in Illinois , 1947 .

[20]  M. Schilthuizen,et al.  Ecotone: speciation-prone. , 2000, Trends in ecology & evolution.

[21]  E. Odum.  Fundamentals of ecology , 1972 .

[22]  L. Harris.  Edge Effects and Conservation of Biotic Diversity , 1988 .

[23]  P. Paton,et al.  The Effect of Edge on Avian Nest Success : How Strong Is the Evidence ? , 2001 .

[24]  B. Noon,et al.  Avian community structure along elevational gradients in the northeastern United States , 1976, Oecologia.

[25]  H. Odum,et al.  Fundamentals of ecology , 1954 .

[26]  K. P. Reese,et al.  Preliminary Test of the Ecological Trap Hypothesis , 1988 .

[27]  J. Baker.  The decline, response to fire, status and management of the Eastern Bristlebird , 1997 .

[28]  P. Risser,et al.  Ecotones at Local to Regional Scales from Around the World. , 1993, Ecological applications : a publication of the Ecological Society of America.

[29]  M. Lawes,et al.  Edge effects at an induced forest-grassland boundary: forest birds in the Ongoye Forest Reserve, KwaZulu-Natal , 1997 .

[30]  T. Johns,et al.  Succession in Bird Assemblages over a Seven-year Period in Regrowth Dry Sclerophyll Forest in South-east Tasmania , 1997 .

[31]  Laurance,et al.  Do edge effects occur over large spatial scales? , 2000, Trends in ecology & evolution.

[32]  Jack J. Lennon,et al.  A metapopulation model of species boundaries , 1997 .

[33]  R. M. Nally.  Short Communication: Population Densities in a Bird Community of a Wet Sclerophyllous Victorian Forest , 1997 .

[34]  J. Terborgh.  The Role of Ecotones in the Distribution of Andean Birds , 1985 .

[35]  A. Plumptre,et al.  Edge Effects on the Understory Bird Community in a Logged Forest in Uganda , 2000 .