Explore the vast range of titles available.

Non-native fish and bullfrogs (Lithobates catesbeianus) are frequently cited as contributing to the decline of ranid frogs in the western United States, so we hypothesized that non-native species, habitat, or a combination of these relate to the probability of local extinction for northern red-legged frogs (Rana aurora) in Oregon, USA. We also hypothesized that the probability of colonization relates to land use, wetland size, or riparian forest. In a 5-yr study, we found no support for an effect of non-native species on northern red-legged frogs. Instead, probability of local extinction decreased with the extent of emergent vegetation and riparian forest. This finding suggests that managers consider the role of habitat when confronting non-native species problems.

A case of predation by a Belted Kingfisher (Megaceryle alcyon) on adult Long-toed Salamanders (Ambystoma macrodactylum) and a Northern Red-legged Frog (Rana aurora) is reported. This general note provides a description of the predation events with photographs of the amphibians being devoured. Additional photographs showing scars in long-toed salamanders are presented and considered in review of types of predatory attacks and defensive strategies. A literature review was completed to identify reported cases of predation on these two amphibian species. We discuss what is known about their anti-predator defensive strategies and what species are involved in the ecological and evolutionary dynamics at play. Traits exhibited by these amphibians are discussed as anti-predator adaptations that include warning colorations, defensive postures, tail dropping, crypsis, and glandular skin secretions that can be adhesive, unpalatable, or toxic. A potentially significant role of avian predators is considered in light of the evidence presented.

Introduction In the Pacific Northwest of North America, research addressing lentic-breeding amphibian population vulnerability has emphasized aquatic habitats, frequently neglecting terrestrial habitats. Consequently, wetland protection and restoration often fails to preserve or restore adjacent uplands required by lentic-breeding amphibians. Inattention to the juxtaposition and connectivity of uplands to wetlands could locally extirpate lentic-breeding amphibians. The objective of this research is to identify the relative importance of juxtaposed terrestrial and aquatic habitats in a lentic-breeding amphibian, the northern red-legged frog ( Rana aurora ), by evaluating the relationship between its occurrence and abundance with its aquatic and terrestrial habitats. To accomplish this, egg mass counts were used to quantify R. aurora populations in 30 stillwater habitats across an urbanization gradient. Using a Geographic Information System, seven descriptors of aquatic and surrounding terrestrial habitats were measured to evaluate their relationships to R. aurora occurrence and abundance. Results Rana aurora occurrence and breeding abundance both reflect the forested area around wetland breeding sites and forest connectivity to those sites. Rana aurora breeding abundance also strongly reflects the percent of forested perimeter around wetland breeding sites. The forest habitat most important for R. aurora breeding abundance seems to be > 200 m from the breeding wetlands. The American bullfrog presence and the two aquatic parameters measured, wetland area and vegetated area, were unrelated to R. aurora occurrence and breeding abundance. Conclusions Area and connectivity of juxtaposed forested terrestrial habitat may represent a basic control on R. aurora presence and population size. Urban development policies should consider preservation and restoration of upland forest habitats beyond current fixed-width buffers and wetland habitat area at landscape scales.

This study tested whether amphipods (Crangonyx spp.), traditionally thought to be detritivores, prey on Northern Red-legged Frog (Rana aurora) embryos at the Humboldt Bay National Wildlife Refuge in California (HBNWR). Following observations that amphipods were associated with the disappearance of frog embryos, we performed experiments in which embryos were placed in 1 of 4 treatments: chambers open to all predators; screened chambers allowing access by small predators <1.5 mm in diameter (including amphipods); enclosed chambers with all visible predators excluded; and enclosed chambers with amphipods added and all other visible predators excluded. Trials with the first 2 treatments were repeated at a nearby site with no amphipods (BL). We found that average predation rates on viable embryos were similar among open/screened chambers at HBNWR and open chambers at BL (21–32%), whereas the average predation rate in amphipod-addition chambers was 15%. Egg-loss rates were ≤1% for amphipod-exclusion chambers at HBNWR and screened chambers at BL. We conclude that embryo predation by amphipods does occur and has the potential to be as important a mortality factor as predation by other larger predators. However, the significance of this interaction is likely to be highly context-dependent and affected by factors such as amphipod density and food availability, and the size and cohesiveness of egg masses.