CERULEAN WARBLER (DENDROICA CERULEA) MICROHABITAT AND LANDSCAPE-LEVEL HABITAT CHARACTERISTICS IN SOUTHERN WEST VIRGINIA

The Auk ◽  
2005 ◽  
Vol 122 (2) ◽  
pp. 497 ◽  
Author(s):  
Cathy A. Weakland ◽  
Petra Bohall Wood
The Auk ◽  
2005 ◽  
Vol 122 (2) ◽  
pp. 497-508 ◽  
Author(s):  
Cathy A. Weakland ◽  
Petra Bohall Wood

AbstractThe Cerulean Warbler (Dendroica cerulea) is a species of conservation concern in eastern North America, where declines in its population have been documented over the past several decades. A high proportion of the population occurs in forested areas of southern West Virginia, where it may be threatened by loss and degradation of forested habitat from mountaintop mining and valley fill (MTMVF). We examined, from a landscape perspective, the effects of forest fragmentation (in particular, effects of fragment size and response to edges) on Cerulean Warblers, using territory mapping techniques and geographic information system (GIS) technology in portions of four counties in southwestern West Virginia. We quantified landscape characteristics from digitized aerial photographs and measured microhabitat characteristics on spot-mapping plots. Territory density of Cerulean Warblers was 4.6 territories per 10 ha in intact forest and 0.7 territories per 10 ha in fragmented forest. The best habitat model included both landscape and microhabitat variables and indicated that territory density increased with increasing snag density, percentage of canopy cover >6–12 m and >24 m in height, and distance from mine edge. Models for predicting microhabitat use at the territory level were weak, indicating that microhabitat characteristics of territories were similar to habitat available on spot-mapping plots. The species did not appear to avoid internal edges, such as natural canopy gaps and open-canopy or partially open-canopy roads. Territory placement on ridges was greater than expected, and in bottomlands (ravines) and midslopes less than expected, given availability. Fifty percent of all territories were on ridges. Preference for ridges suggests that MTMVF may have a greater effect on Cerulean Warbler populations than other sources of forest fragmentation, given that ridges are removed in MTMVF. Our data indicate that Cerulean Warblers are negatively affected by mountaintop mining from loss of forested habitat, particularly ridgetops, and from degradation of remaining forests, as evidenced by lower territory density in fragmented forests and lower territory density closer to mine edges.


2007 ◽  
Vol 85 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Yeen Ten Hwang ◽  
Serge Larivière ◽  
François Messier

We examined the seasonal landscape and habitat use patterns of striped skunks ( Mephitis mephitis Schreber, 1776). We tracked 52 male and 72 female skunks from September 1999 to June 2003 in Saskatchewan, Canada. At the local level, den structures differed by sex and season. In autumn/winter, all skunks preferred buildings, whereas in spring/summer females selectively used underground burrows and rock piles for parturition and rearing of young, and males used aboveground retreats. Den sites were closer to crop fields, roads, water sources, and macrohabitat edges than random sites. At the landscape level, den sites were associated positively with weighted mean shape index of crop fields, mean patch size of water bodies, total edge of water bodies, and weighted mean fractal dimensions of grassland, woodland, and farmsteads, suggesting that wetland edges and habitat complexity are important in den selection by skunks. Compositional analysis revealed sex- and season-specific differences at the population level. Both sexes preferred grassland/pastures and farmstead habitats for establishing den sites. In autumn/winter, skunks preferred grassland/pastures for winter dens. However, in spring/summer skunks preferred farmsteads for resting sites. Our results suggest that skunks respond to landscape and habitat features surrounding den sites, and not just specific den or local habitat characteristics.


The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 958-962 ◽  
Author(s):  
Jason Jones ◽  
Paolo Ramoni Perazzi ◽  
Erin H. Carruthers ◽  
Raleigh J. Robertson

Abstract We examined the use of Venezuelan shade-coffee plantations by the Cerulean Warbler (Dendroica cerulea) and other Neotropical migrants. Cerulean Warblers were commonly observed as pairs in mixed-species flocks. Average (± SE) flock size was 13 ± 2 species with 22 ± 3 individuals. Average flock territory size was 2.5 ± 0.2 ha. No differences were detected in foraging behavior (maneuvers, location, or success) among adult males, adult females, and immature birds. Adult males were often observed visiting flowers of canopy trees. The results of this study indicate that shade coffee plantations may provide suitable wintering habitat for Cerulean Warblers although comparisons with other habitats are needed.


The Auk ◽  
1919 ◽  
Vol 36 (4) ◽  
pp. 582-583 ◽  
Author(s):  
S. Harmsted Chubb

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 795-806 ◽  
Author(s):  
Jennifer J. Barg ◽  
Deviah M. Aiama ◽  
Jason Jones ◽  
Raleigh J. Robertson

Abstract Although most habitat characteristics are known to be continuously variable in space, practicality dictates that most habitat-selection studies at the spatial scale of the territory treat within-territory habitat as essentially homogeneous. However, the limitations associated with such a compromise have remained largely unexamined. Male Cerulean Warblers (Dendroica cerulea) exhibit nonrandom space- use patterns within their territories, in that all territories contain areas of intensive use or core areas. In addition to documenting territory-wide habitat and behavioral use patterns in this species, we asked two specific questions about core-area structure and function. (1) Are core-area habitats distinct in their vegetative composition and structure from the rest of the territory? (2) What behavioral mechanisms underlie the nonrandom space-use patterns? On a territory-wide basis, males used trees in proportion to their availability; however, core areas were predominantly composed of bitternut hickory (Carya cordiformis), which was a highly preferred song-post tree. Core areas were not consistently associated with any other habitat feature, including canopy gaps. Core areas were singing centers; song-post densities within core areas were 10× higher than in noncore areas. In our study area, bitternut hickories have significant delayed leaf-out patterns, potentially offering minimal acoustic hindrance to song transmission until late in the breeding season. These singing centers may be strategically placed to simultaneously maintain vigilance over social nests and maximize communication with conspecifics. Core areas are potentially as important to males as nesting habitat is to females, and their provision should be taken into account when implementing conservation or management strategies. Uso de Hábitat en los Territorios y Selección de Microhábitats por los Machos en Dendroica cerulea


The Condor ◽  
2006 ◽  
Vol 108 (1) ◽  
pp. 154-165 ◽  
Author(s):  
Petra Bohall Wood ◽  
Scott B. Bosworth ◽  
Randy Dettmers

AbstractWe examined Cerulean Warbler (Dendroica cerulea) abundance and occurrence in southwestern West Virginia, where the coal-mining technique of mountaintop removal mining–valley fill converts large contiguous tracts of deciduous forest to forest patches surrounded by early successional habitats. Our study objectives were to quantify abundance and occurrence of Cerulean Warblers relative to (1) distance from the edge of extensive reclaimed grasslands and (2) habitat structure and landscape characteristics. Cerulean Warbler abundance increased with distance from the edge and edge effects extended 340 m into the forest. Percent occurrence did not vary with distance from mine edge, suggesting a degree of tolerance to the extensive edge occurring at the interface of forest and reclaimed lands. Abundance and occurrence were greater on ridges and midslopes than in bottomlands; consequently, disturbances such as mountaintop mining in which ridges are removed may have a greater impact on populations compared to other sources of fragmentation where ridges are not disturbed. Models based on the information-theoretic approach indicated that Cerulean Warblers were more likely to be present in productive sites on northwest to southeast facing slopes, upper slope positions (midslope to ridgetop), and forests with low sapling density. Cerulean Warbler abundance was positively associated with more productive sites, higher snag density, large blocks of mature deciduous forest, and low amounts of edge in the landscape. In addition to outright loss of forested habitat, mountaintop mining-valley fill alters the spatial configuration of forested habitats, creating edge and area effects that negatively affect Cerulean Warbler abundance and occurrence in the reclaimed mine landscape.


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