Use of Riparian Corridors and Vineyards by Mammalian Predators in Northern California

Abstract

To address increasing fragmentation, conservation biologists have focused on protecting core habitat areas and maintaining connectivity among protected areas. Wildlife corridors, strips of relatively intact habitat designed to connect habitat fragments, may enhance connectivity, but little empirical evidence supports the idea that large mammals prefer to use corridors rather than the surrounding developed landscape. In Sonoma County, a premium wine-grape-growing region in California, we examined mammalian predator use of 21 riparian corridors classified as denuded, narrow, or wide according to the width of the remaining natural vegetation adjacent to the creek. We used unbaited, remotely triggered cameras to determine occurrence of predator species. We also monitored predator use of six vineyards, three close to core habitat and three far from core habitat, with unbaited cameras. Mammalian predator detection rates were 11-fold higher in riparian study areas than in vineyards. More native mammalian predator species were found in wide corridors than in narrow or denuded creek corridors. The number and activity level of native predators was higher in vineyards adjacent to core habitat than in vineyards farther away, where the number and activity level of non-native predators was higher. Maintaining wide and well-vegetated riparian corridors may be important in maintaining the connectivity of native predator populations to ensure their long-term survival. Utilización de Corredores Riparios y Viñedos por Mamíferos Depredadores en el Norte de CaliforniaResumen: Para tratar con el incremento en la fragmentación, los biólogos de la conservación han enfocado en la protección deáreas de hábitat núcleo y el mantenimiento de la conectividad entreáreas protegidas. Los corredores, franjas de hábitat relativamente intacto diseñadas para conectar fragmentos de hábitat, pueden incrementar la conectividad, pero existe poca evidencia empírica que sustente la idea de que mamíferos mayores utilizan preferentemente corredores en comparación con el paisaje desarrollado circundante. En el Condado de Sonoma, una región de primera calidad para el cultivo de la vid en California, examinamos el uso por mamíferos depredadores de 21 corredores riparios clasificados como denudados, angostos o amplios, de acuerdo con la amplitud de la vegetación natural remanente adyacente al arroyo. Utilizamos cámaras de disparo remoto, no cebadas, para determinar la ocurrencia de especies de depredadores. También monitoreamos, con cámaras no cebadas, el uso de seis viñedos por depredadores, tres cercanos al hábitat núcleo y tres alejados del hábitat núcleo. Las tasas de detección de mamíferos depredadores fueron 11 veces mayores enáreas riparias que en corredores angostos o denudados. El número y nivel de actividad de depredadores nativos fue mayor en viñedos adyacentes al hábitat núcleo en comparación con los viñedos alejados, donde el número y el nivel de actividad de los mamíferos depredadores fue mayor. El mantenimiento de corredores riparios anchos y con...

Climate change, wine, and conservation

“…Similar housing growth in the Napa Valley of California has been associated with extensive development of small-estate vineyards. Large-lot housing may be compatible with movements of animals such as pronghorn and wolves, but vineyards almost certainly would not (18,19). Vineyards currently in these areas are routinely fenced to exclude herbivores such as deer and elk and omnivores such as bear (35).…”

“…Vineyard establishment involves removal of native vegetation, typically followed by deep plowing, fumigation with methyl bromide or other soilsterilizing chemicals, and the application of fertilizers and fungicides (16,17). Mature, producing vineyards have low habitat value for native vertebrates and invertebrates, and are visited more often by nonnative species (18,19). Thus, where vineyards are established, how they are managed, and the extent to which they replace native habitats have large implications for conservation (20,21).…”

Testing mechanistic explanations for mammalian predator responses to habitat edges

“…First, predation risk and/or the presence of predators often were not found throughout the entire edge gradient (i.e., in the habitat edge and both adjacent habitats; Albrecht 2004;Chalfoun et al 2002;Heske 1995), which means that it was not possible to determine if the edge effect arose as a consequence of predator penetration into the adjacent habitat or due to specifically enhanced activity of edge specialist predator species along the habitat edge. Second, since most studies did not collect data on prey distribution (e.g., Dijak and Thompson 2000;Donovan et al 1997;Hilty and Merenlender 2004), habitat qualities could not be sufficiently evaluated. Third, most studies failed to reliably determine particular predator species (e.g., Huhta et al 1998;Pasitschniak-Arts and Messier 1995;Storch et al 2005).…”

LiDAR derived ecological integrity indicators for riparian zones: Application to the Houille river in Southern Belgium/Northern France

“…As ecotones located at the intersection of land and water, riparian zones are exceptionally rich in biodiversity (Naiman and Décamps, 1990;Naiman et al, 1993). They represent ecological corridors (Rodriguez-Iturbe et al, 2009) and provide a crucial habitat for terrestrial animals and for migrating birds (Hilty and Merenlender, 2004;Machtans et al, 1996;Skagen et al, 1998Skagen et al, , 2005. The width of a zone can range from a few metres to several kilometres.…”