Effects of Forest Fragmentation on Depredation of Artificial Nests

Yahner, Richard H.; Scott, David P.

doi:10.2307/3801078

Cited by 200 publications

(102 citation statements)

References 15 publications

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“…Artificial nest studies can provide an index to depredation pressures, but they cannot accurately measure real depredation as experienced by nesting birds because they lack parental influences, such as nest concealment and defense (e.g., Yahner and Scott 1988, Donovan et al 1997, Keyser et al 1998. Use of large (e.g., quail) eggs may further bias artificial nest studies because they discriminate against small predators (Haskell 1995), but biases can be minimized with use of plasticine eggs, which allow effective sampling of both small and large predators (Donovan et al 1997, Keyser et al 1998.…”

Section: Artificial Nest Experimentsmentioning

confidence: 99%

Nest Predation in an Urbanizing Landscape:the Role of Exotic Shrubs

Borgmann¹,

Rodewald²

2004

Ecological Applications

138

103

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Abstract. Nest predation is considered a primary force shaping avian communities, and landscape-scale features (e.g., amount of fragmentation) are generally recognized as factors mediating nest predation. These same landscape-scale features, however, may promote invasion by exotic plants, which may, in turn, increase risk of nest predation. We examined whether the use of exotic shrubs (Lonicera spp. and Rosa multiflora Thumb.) affected nest predation across 12 riparian forest sites along a rural-urban gradient (Ͻ1-47% urban land cover within 1 km). From 2001to 2003 and American Robin (Turdus migratorius) nests Յ5 m tall were monitored. Nest substrate, nest height, and distance from the forest edge were recorded for each nest, whereas nest placement and nest patch characteristics were measured only for Northern Cardinal nests (n ϭ 68). To further assess relative rates of nest predation in native vs. exotic shrubs while controlling for nest height, distance to edge, and land use, we conducted an artificial nest experiment at two rural sites. Artificial nests (n ϭ 79) were placed at similar heights in honeysuckle, rose, and native nest substrates along a transect 50-75 m from the forest edge. Nest substrate and landscape type alone failed to account for differences in daily mortality rates. Instead, the effect of nest substrate varied with the landscape matrix, such that nests in exotic shrubs in urbanizing landscapes were twice as likely to be depredated than nests in native substrates, irrespective of distance from the edge. Artificial nests placed in exotic shrubs in rural landscapes also suffered higher rates of nest failure than artificial nests in native substrates. Daily mortality rates were greater for nests in exotic shrubs, likely due to reduced nest height and larger shrub volume surrounding the nest. Nests in exotic shrubs were 1.5-2 m lower to the ground and within patches containing 6-9 times more exotic shrub volume. These differences may improve search efficiency of mammalian predators, which appear to be the main predators at our study sites. Based on marks present on recovered clay eggs, 68% of the predation events were attributed to mammals. These findings demonstrate that exotic shrubs can reduce nesting success of forest birds and may cause increased nest failure in urbanizing landscapes. This illustrates another way that exotic plants may diminish habitat quality and limit the capacity of urban forests to contribute to wildlife conservation; therefore, restoring the native shrub community may prove beneficial.

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Section: Artificial Nest Experimentsmentioning

confidence: 99%

Nest Predation in an Urbanizing Landscape:the Role of Exotic Shrubs

Borgmann¹,

Rodewald²

2004

Ecological Applications

138

103

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“…Therefore, a decrease in neotropical migratory species at sites near the city could be expected to occur if the abundance of brown-headed cowbirds increases in the Portland area. Concomitantly, the extent of predation by both avian (e.g., crows and jays) and mammalian (e.g., raccoons, cats and dogs) predators has also been shown to increase with continued fragmentation and urbanization (Askins 1995;DeGraaf 1995;Hoover et al 1995;Rich et al 1994;Robinson et al 1995;Wi1cove 1985;Yahner and Mahan 1996). Many predators of birds have been shown to prefer neotropical bird species, usually because of their habit of nesting near or on the ground (Bollinger and Linder 1994;Linder and Bollinger 1994;Rich et al 1994;Wilcove 1985).…”

Section: Breeding Bird Communitymentioning

confidence: 99%

“…Many predators, such as raccoons, opossums, crows, and jays, are edge associated species. Most of these species are present in higher densities in smaller forest fragments and have been shown to significantly decrease ground nesting success (Angelstam and Andren 1988;Askins 1994;Askins 1995;Blake 1983;Bollinger and Linder 1994;Brown and Robinson 1996;Craig 1997;DeGraaf 1995;Diehl1986;Donovan et al 1995a;Hagan et al 1996;Hoover et al 1995;Leimgruber et al 1994;Linder and Bollinger 1995;Martin and Clobert 1996;Martinet al 1996;McLellan et al 1986;Rich et al 1994;Robinson et al 1995;Rosenberg et al 1987;Terborgh 1989;Whitcomb et al 1981;Wiens 1994;Wilcove 1985;Yahner and Mahan 1996). Wilcove (1985) demonstrated experimentally that in small forest fragments (less than 10 hectares), predation rates on ground nesting birds could reach 100 percent.…”

mentioning

confidence: 99%

“…Brown-headed cowbirds have been shown to cause significant reductions in the nesting success of many avian species, especially those that nest on or near the ground (Bollinger and Linder 1994;DeGraaf 1995;Leimgruber et al 1994;Linder and Bollinger 1995;Robinson et al 1995;Terborgh 1989;Wilcove 1985;Yahner and Mahan 1996). The status of brown-headed cowbirds in Forest Park should be closely monitored in the future.…”

mentioning

confidence: 99%

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The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

Broshot¹

2000

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Forested Area (Forest Park) in Portland, Oregon.The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of plant and avian communities at 25 sites, 24 which were in Forest Park and surrounding areas and one which was in the Ancient Forest Preserve (old-growth stand) northwest of Forest Park. Data were analyzed using multiple regression, ANOV A, and Bonferonni/Dunn. Seven variables were selected representing different urbanization gradients. An additional covariable coded for the old-growth stand, allowing it to be used as a control.Many tree variables, especially those related to shade-tolerant species, were positively correlated with both the distance from downtown Portland and the number of houses in the surrounding area, and negatively correlated with the distance from the nearest forest edge; however, many shrub and herbaceous variables were negatively correlated with the distance from downtown Portland. Species diversity for herbaceous and shrub species was greater at more urban sites, but diversity of trees was lower at more urban sites. There were significantly more non-native species of plants in the city section. I found significantly fewer saplings and small trees, especially shade-tolerant species, in the section of Forest Park closest to downtown Portland, although tree mortality was positively correlated with distance from Portland.Summer bird data revealed significant increases in the abundances of urban and edge species at more urban sites, with concomitant reductions in forest species. There were significantly more ground gleaning birds and short distance migratory species.I also found a significantly greater abundance of birds in the old-growth stand during the winter. This increase was positively correlated with the depth of snow in the nearby Cascade Mountains.My results indicate that Forest Park is apparently progressing in a normal successional pattern with the exception of the city section. The reduction in shade tolerant saplings and small trees in the city section suggest that rate of succession has been slower at more urban sites. Avian data suggest that urbanization affects bird species abundance and guild composition in the more urban areas. ACKNOWLEDGMENTS

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“…Indeed this concept of edge as a positive influence has guided land management practices until recently. Recent studies, however, have suggested that changes in vegetation, invertebrate populations, predation, brood parasitism, and competition along forest edges has resulted in the population declines of several vertebrate species dependent upon forest interior conditions (e.g., Strelke and Dickson 1980, Kroodsma 1982, Brittingham and Temple 1983, Wilcove 1985, Temple 1986, Noss 1988, Yahner and Scott 1988, Robbins et al 1989. Forest interior species, therefore, may be sensitive to patch shape because for a given patch size, the more complex the shape, the larger the edge-tointerior ratio.…”

Section: Edge Metricsmentioning

confidence: 99%

Modelling the susceptibility of pine stands to bark stripping by Chacma baboons (Papio ursinus) in the Mpumalanga Province of South Africa

2017

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PREFACE and 2.0 UPGRADE INFORMATIONAs the authors of FRAGSTATS, we are VERY concerned about the potential for misuse of this program. Like most tools, FRAGSTATS is only as "good" as the user. FRAGSTATS crunches out a lot of numbers about the input landscape. These numbers can easily become "golden" in the hands of uninformed users. Unfortunately, the "garbage in-garbage out" axiom applies here. We have done our best in the documentation to stress the importance of defining landscape, patch, matrix, and landscape context at a scale and in a manner that is relevant and meaningful to the phenomenon under consideration. Moreover, we have stressed the importance of understanding the exact meaning of each metric before it is used. These and other important considerations in any landscape structural analysis are discussed in the documentation. We strongly urge you to read the entire documentation, especially the section on Key Concepts and Terminology, before ever running FRAGSTATS.We wish to remind users that we are not in the commercial software marketing business. We are scientists who recognized the need for a tool like FRAGSTATS to assist us in our research on landscape ecological issues. Therefore, we do not wish to spend a great deal of time consulting on trivial matters concerning the use of FRAGSTATS. However, we do recognize an obligation to provide some level of information support. Of course, we welcome and encourage your criticisms and suggestions about the program at all times. We will welcome questions about how to run FRAGSTATS or interpret the output only after the user has read the entire documentation. This is only fair and will eliminate many trivial questions. Finally, we are always interested in learning about how others have applied FRAGSTATS in ecological investigations and management applications. Therefore, we encourage you to contact us and describe your application after using FRAGSTATS.This release of FRAGSTATS (version 2.0) differs from the previous version in only minor ways. Several "bugs" have been corrected. The most important change is the added option to treat a specified proportion of the landscape boundary and background edge (instead of just all or none) as true edge in the edge metrics (bound_wght option). This fraction also is used as the edge contrast weight for landscape boundary and background edge segments in the calculation of edge contrast metrics. In addition, the convention for naming the output file containing patch ID's in the raster version has been modified to comply with DOS requirements on a PC (id_image option). Similarly, the output file name extensions in the PC raster version have been shortened and renamed to comply with DOS requirements and to avoid conflicts with ERDAS conventions (out_file). The Nearest-neighbor algorithm has been modified slightly to compute actual edge-to-edge distance (previous version used cell midpoints rather than edge).We hope that FRAGSTATS is of great assistance in your work and we look forward to hearing about your applications. A...

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Effects of Forest Fragmentation on Depredation of Artificial Nests

Cited by 200 publications

References 15 publications

Nest Predation in an Urbanizing Landscape:the Role of Exotic Shrubs

Nest Predation in an Urbanizing Landscape:the Role of Exotic Shrubs

The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

Modelling the susceptibility of pine stands to bark stripping by Chacma baboons (Papio ursinus) in the Mpumalanga Province of South Africa

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