Salt marsh harvest mouse demography and habitat use in the Suisun Marsh, California

Abstract

We undertook a 2-year (2002)(2003)(2004) mark-recapture study to investigate demographic performance and habitat use of salt marsh harvest mice (Reithrodontomys raviventris halicoetes) in the Suisun Marsh. We examined the effects of different wetland types and microhabitats on 3 demographic variables: density, reproductive potential, and persistence. Our results indicate that microhabitats dominated by mixed vegetation or pickleweed (Salicornia spp.) supported similar salt marsh harvest mouse densities, reproductive potential, and persistence throughout much of the year, whereas few salt marsh harvest mice inhabited upland grass-dominated microhabitats. We found that densities were higher in diked wetlands, whereas post-winter persistence was higher in tidal wetlands, and reproductive potential did not differ statistically between wetland types. Our results emphasize the importance of mixed vegetation for providing adequate salt marsh harvest mouse habitat and suggest that, despite their physiognomic and hydrological differences, both diked and tidal wetlands support salt marsh harvest mouse populations by promoting different demographic attributes. We recommend that habitat management, restoration, and enhancement efforts include areas containing mixed vegetation in addition to pickleweed in both diked and tidal wetlands.

Potential effects of sea-level rise on plant productivity: species-specific responses in northeast Pacific tidal marshes

“…With long residence times in anoxic wetland sediments, non-labile organic matter constitutes a coastal carbon storage pool (Ouyang & Lee 2014), while wetland loss can release large quantities of sequestered carbon into the atmosphere (Pendleton et al 2012). The aboveground physical structure of salt marsh plants also provides other important coastal ecosystem services such as attenuating wave energy (Shepard et al 2011), facil-itating sediment accretion (Gleason et al 1979, Mudd et al 2010, and providing habitat for wetlanddependent vertebrates (Sustaita et al 2011).…”

Habitat of the endangered salt marsh harvest mouse (Reithrodontomys raviventris) in San Francisco Bay

“…RERA individuals are thought to disperse randomly during prebreeding, but are associated with pickleweed sites with midrange salinity levels during breeding and postbreeding (Padgett‐Flohr & Isakson, ). In Suisun Bay, RERA were associated with sites dominated with mixed vegetation or pickleweed (Sustaita, Quickert, Patterson, Barthman‐Thompson, & Estrella, ).…”

Distinguishing between northern salt marsh and western harvest mice

“…We obtained the samples used in this study (Table S1, available online in Supporting Information; see also Sustaita et al ) during long‐term salt marsh harvest mouse population surveys, and targeted western harvest mouse trapping throughout the Suisun Marsh, Solano County, California (122° 0’ W, 38° 10’ N), from 1999–2004 (California Department of Water Resources , ; Sustaita et al ). The Suisun Marsh consisted of diked marshes managed for waterfowl and other wildlife, relatively unaltered tidal marsh, uplands, bays, sloughs, and other waterways (California Department of Water Resources [CDWR] , Sustaita et al ). The annual precipitation was 38–50 cm, with temperatures averaging 8° C in January and 22° C in July.…”

“…The congeneric western harvest mouse ( R. megalotis ) is geographically widespread and inhabits most of California and contiguous states. The western harvest mouse occurs in a diversity of vegetation types and in San Francisco and associated bays, it overlaps the range of, and coexists with, both salt marsh harvest mouse subspecies (Fisler , Shellhammer , Webster and Jones , Bias and Morrison , Sustaita et al ). This presents a problem for identifying and monitoring salt marsh harvest mouse populations in the field because of difficulties distinguishing between some ambiguous individuals with intermediate morphology (Hooper , Fisler , Bias and Morrison , Statham et al ).…”

“…In a more general sense, because these keys (and the analyses upon which they were based) are operationally univariate, they do not account for potential differences between sex and age classes, allometry, or interactions among them when considering differences along key discriminatory metrics. Therefore, more probabilistic, statistical approaches based on morphological characteristics (Rich et al , Maldonado et al ) are necessary, given that ambiguous or intermediate individuals occur in the field (Hooper , Fisler , Sustaita et al ).…”