MEDN Deer Mouse Monitoring

Little, Annie; Baker, Stacy; Schamel, Juliann

Like other nearshore island groups, California’s Channel Islands have a depauperate vertebrate fauna when compared to that of the nearby mainland. For example, on most of the 8 islands in the archipelago the only rodent is the deer mouse (Peromyscus maniculatus), which is recognized as a separate subspecies on each of the islands. They are the only native small mammal species on Santa Barbara and Anacapa islands. Because it is one of only several vertebrate species occurring on the islands, the deer mouse has considerable ecological influence. Deer mice are a preferred food item for the endemic island fox (Urocyon littoralis) (Coonan et al. 2010), and as seed and flower predators they influence the dynamics of both native and non-native vegetation (Schwemm 2008). Deer mice are egg predators for landbirds (Peluc et al. 2008) and for some crevice-nesting seabirds (Schwemm and Martin 2005). Island mice are also important in terms of zoonotic disease. Deer mice on the Channel Islands are a reservoir for the virulent Sin Nombre strain of hantavirus, with seroprevalence being higher on islands with greater area, higher precipitation, and fewer predators (Orrock et al. 2011). Because of their ecological importance, as well as their status as endemic subspecies, deer mice were chosen for monitoring as part of the park’s long-term ecological monitoring program (Fellers et al. 1988). Only the populations on Santa Barbara, Anacapa, and San Miguel Islands (the islands originally designated as the park) have been monitored through the I&M program. San Miguel Island is the only location where both deer mice and island foxes are monitored. Park: CHIS Protocol Objectives: The objectives of the legacy deer mouse monitoring program were to: (1) determine population status and trend for deer mice on Santa Barbara, Anacapa and San Miguel Islands, and (2) document mouse population cycles and their potential causes (Fellers et al. 1988, Davis et al. 1994). Schwemm et al. (in prep) suggested new, island-specific objectives in the draft 2015 protocol.

MEDN Deer Mouse Monitoring

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