The early development of forest fragmentation effects on birds

• Published in: Conservation biology Vol. 10; no. 1; pp. 188 - 202
• Main Authors: Hagan, J.M. (Manomet Observatory, Manomet, MA.), Vander Haegen, W.M, McKinley, P.S
• Format: Journal Article
• Language: English
• Published: 238 Main Street, Cambridge, Massachusetts 02142 Blackwell Science Inc 01-02-1996; Blackwell Scientific Publications; Blackwell
• Subjects: Animal and plant ecology; ANIMAL SALVAJE; ANIMAL SAUVAGE; Animal, plant and microbial ecology; Aves; Biological and medical sciences; Bird nesting; BIRDS; BOSQUES; BREEDING PLACES; Commercial forests; Conservation biology; DENSIDAD DE LA POBLACION; DENSITE DE POPULATION; Forest conservation; Forest fragmentation; Forest habitats; FORESTS; FORET; Fundamental and applied biological sciences. Psychology; HABITAT; Habitat conservation; Habitat fragmentation; Habitat loss; HABITATS; INDUSTRIAL FORESTS; MAINE; OISEAU; PAJAROS; POPULATION DENSITY; SPECIES ABUNDANCE; Synecology; TEMPORAL VARIATION; Terrestrial ecosystems; WILD ANIMALS; United States; North America; Maine; America; Vertebrata; Forests; Edge effect; Aves; Mathematical model; Time variation; Population density; Fragmentation; Population productivity
• ISSN: 0888-8892; 1523-1739
• DOI: 10.1046/j.1523-1739.1996.10010188.x

The early development of forest fragmentation effects on forest organisms is poorly understood partly because most fragmentation studies have been done in agricultural or suburban landscapes, long after the onset of fragmentation. We develop a temporal model of forest fragmentation effects on densities of forest-breeding birds and provide data from an active industrial forest landscape to test the model. The model and our empirical data indicate that densities of several forest-dwelling bird species can increase within a forest stand soon after the onset of fragmentation as a result of displaced individuals packing into remaining habitat. Along with higher densities in the newly formed fragments, pairing success in one species, the Ovenbird (Seiurus aurocapillus), was lower in fragments than nonfragments, possibly due to behavioral dysfunction resulting from high densities. Thus, density was inversely related to productivity. The duration and extent of increased densities following onset of fragmentation depends on many factors, including the sensitivity of a species to edge and area effects, the duration and rate of habitat loss and fragmentation, and the proximity of a forest stand to the disturbance. Incipient forest fragmentation may affect populations differently from later stages of fragmentation when the geometry of the landscape has reached a more stable configuration. Our model and data indicate, for reasons unrelated to traditional edge effects, that large tracts of forest can be important because they are relatively free from the variety of plant and animal population dynamics that might take place near new edges, including the encroachment of individuals displaced by habitat loss.