Larissa Bailey (Colorado State), USGS, FWS, and SCC volunteers building vernal pools at Patuxent NWR, to adaptively manage for climate change. Photo by: A. Green.
Only a few years ago, amphibians were rarely considered in the development and implementation of management plans. But now, itís not uncommon to see amphibian populations as the primary targets of management activities.
ARMI scientists conduct research on the impacts of various traditional management actions on amphibians, and have worked with partners to develop and test novel management options specifically to benefit amphibians.
Important decisions are made every day on management and policy that affect multiple wildlife species. ARMI works with its partners in Federal and State agencies to develop processes for structuring their natural resource decisions to achieve their conservation objectives related to amphibians.
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Notes on the Distribution of Tiger Salamanders (presumed <i>Ambystoma mavortium stebbinsi</i>) in Sonora, Mexico
Authors: Hossack, BR, Muths, E, Rorabaugh, JC, Lemos Espinal, JA, Sigafus, BH, Chambert, T, Carreon Arroyo, G, Hurtado Felix, D, Toyos Martinez, D, Jones, TR | Date: 2016-06 | Outlet: Herpetological Review
Movement and True Survival of a Stream Amphibian in Relation to Sediment and Culvert Design
Authors: Honeycutt, RK, Lowe WH, Hossack BR | Date: 2016 | Outlet: Journal of Wildlife Management
Habitat disturbance from stream culverts can affect aquatic organisms by increasing sedimentation or forming barriers to movement. Land managers are replacing many culverts to reduce these negative effects, primarily for stream fishes. However, these management actions are likely to have broad implications for many organisms, including amphibians in small streams. To assess the effects of culverts on movement and survival of Dicamptodon aterrimus, the Idaho giant salamander, we used capture-mark-recapture surveys and measured sediment in 9 streams with 3 culvert types: unimproved culverts, improved culverts, and no culverts. We predicted culverts would increase stream sediment levels, limit movement, and reduce survival of D. aterrimus. We also determined the effect of sediment levels on survival of salamanders, because although sediment is often associated with distribution and abundance of stream amphibians, links with vital rates remain unclear. To estimate survival, we used a spatial Cormack-Jolly-Seber (CJS) model that explicitly incorporated information on movement, eliminating bias in apparent survival estimated from traditional (i.e., non-spatial) CJS models caused by permanent emigration beyond the study area. To demonstrate the importance of using spatial data in studies of wildlife populations, we compared estimates from the spatial CJS to estimates of apparent survival from a traditional CJS model. Although high levels of sediment reduced survival of salamanders, culvert type was unrelated to sediment levels or true survival of salamanders. Across all streams, we documented only 15 movement events between study reaches. All movement events were downstream, and they occurred disproportionately in 1 stream, which precluded measuring the effect of culvert design on movement. Interestingly, although movement was low overall, the variance among streams was high enough to bias estimates of apparent survival compared to true survival. Our results suggest that where sedimentation occurs from roads and culverts, survival of D. aterrimus could be reduced. Though culverts clearly do not completely block downstream movements of D. aterrimus, the degree to which culvert improvements affect movements under roads in comparison to unimproved culverts remains unclear, especially for rare, but potentially important, upstream movements.
Integrating biology, field logistics, and simulations to optimize parameter estimation for imperiled species
Authors: Lanier WE, Bailey LL, Muths E | Date: 2016 | Outlet: Ecological Modeling | Format: .PDF
Conservation of imperiled species often requires knowledge of vital rates and population dynamics. However, these can be difficult to estimate for rare species and small populations. This problem is further exacerbated when individuals are not available for detection during some surveys due to limited access, delaying surveys and creating mismatches between the breeding behavior and survey timing. Here we use simulations to explore the impacts of this issue using four separate boreal toad (Anaxyrus boreas boreas) populations, representing combinations of logistical access (accessible, inaccessible) and breeding behavior (synchronous, asynchronous). We examine the bias and precision of survival and breeding probability estimates generated by survey designs that differ in effort and timing for these populations.