Concerns over declining songbird populations have led to investigations of the effects of various silvicultural practices on breeding songbirds. Few studies published, however, have examined both songbird populations and avian nest success among harvesting treatments, particularly in forested landscapes. We conducted a study in the Monongahela National Forest of West Virginia during the summers of 1993 to 1996 to compare breeding-bird abundance and daily nest survival rates among different sivicultural treatments: a two-age treatment (a type of deferred removal in which 37-49 mature trees/ha remain after a harvest until the next rotation), clearcutting treatments 15 years after harvest, unharvested forest surrounding the harvested stands, and unharvested stands not adjacent to cuts. Abundance and daily nest-survival rates did not differ among treatments ( p Ͼ 0.05) for four of the five species for which the most nests were found: Wood Thrush ( Hylocichla mustelina ), Rose-breasted Grosbeak ( Pheucticus ludovicianus ), Acadian Flycatcher ( Empidonax virescens ), Veery ( Catharus fuscescens ), Red-eyed Vireo ( Vireo olivaceus ). Parasitism rates were low (6%), and most parasitized nests were associated with the two-age harvest treatment. A source-sink model for the Wood Thrush revealed that all treatments were likely population sources for this species. Thus, it appears that 15 years after harvest, cuts placed within otherwise extensively forested areas do not result in the type of edge effects (population sinks) observed in areas fragmented by agriculture in the midwestern United States. Further, because neither nest success nor avian abundance was lower in the two-age than clearcut harvests, we conclude that two-age management is a viable conservation alternative to clearcutting in large forested landscapes where Brown-headed Cowbird ( Molothrus ater ) parasitism is not a concern.Abundancia de Aves Canoras y Tasas de Supervivencia de Nidos de Aves en Bosques Fragmentados por Diferentes Tratamientos Silviculturales Resumen: La preocupación sobre la declinación de poblaciones de aves canoras ha conducido a investigaciones sobre los efectos de varias prácticas silviculturales sobre la reproducción de aves canoras. Sin embargo, pocos estudios han examinado tanto las poblaciones de aves como el éxito de nidos de aves entre tratamientos de cosecha, particularmente en paisajes boscosos. Realizamos un estudio en el Parque Nacional Monongahela en Virginia Occidental durante los veranos de 1993 a 1996 para comparar la abundancia de aves reproductoras y las tasas diarias de supervivencia de nidos entre diferentes tratamientos silviculturales (tratamiento de dos edades [un tipo de remoción diferida en el que permanecen 37-49 árboles maduros/ha después de una cosecha hasta la siguiente rotación] y tratamientos de tala total 15 años después de la cosecha, bosque no cosechado alrededor de los áreas cosechadas y áreas sin cosechar no adyacentes a áreas con cortes). La abundancia y las tasas diarias de supervivencia de nidos no d...
Management indicator species (MIS) often are selected because their life history and demographics are thought to reflect a suite of ecosystem conditions that are too difficult or costly to measure directly. The northern flying squirrel (Glaucomys sabrinus) has been proposed as an MIS of temperate rain forest of southeastern Alaska based on previous studies in the Pacific Northwest that demonstrated its habitat is multi‐factorial, i.e., an emergent property of old‐growth forest. We evaluated the suitability of flying squirrels as MIS in temperate rain forests of Alaska by modeling seasonal (spring, autumn) microhabitat use with stepwise logistic regression (SLR) using either individual habitat variables (n = 26) or multivariate habitat “factors,” which were linear combinations of individual habitat variables generated from factor analysis. We compared the efficacy of single variable vs. multivariate factor models in explaining variation in microhabitat use to test the hypothesis that the habitat of flying squirrels in southeastern Alaska was an emergent property of old‐growth rain forest. The underlying premise was that if factors were more thorough in explaining microhabitat use, the habitat of flying squirrels was multifactorial; that is, it consisted of multiple late‐seral forest attributes occurring coincidentally at usable spatial scales (e.g., home range). SLR models with multivariate factors performed poorer in predicting capture sites than models of individual habitat variables. Two variables, density of large (>74 cm dbh) trees and understory cover of Vaccinium, explained much of the variation in microhabitat use. We conclude that the habitat of G. sabrinus in southeastern Alaska does not reflect emergent properties of old‐growth forest in southeastern Alaska and hypothesize that this pattern may be related to regional ecological differences that facilitate a more general lifestyle than populations in the Pacific Northwest. Furthermore, the effectiveness of Glaucomys sabrinus as an MIS in north temperate rain forest is suspect, illustrating that regional differences in ecology of a species warrant caution when considering the suitability of MIS among geographic areas.
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