Nonnative species have been widely introduced, and once established, often exhibit secondary spread to new areas. For instance, after its initial introduction in the John Day River, Oregon, smallmouth bass (Micropterus dolomieu) has expanded upstream into headwater habitats. Recruitment is a key component of successful range expansion and has been highlighted as a potential bottleneck to continued expansion by smallmouth bass. We explored growth, body lengths, and survival of young-of-the-year (YOY) smallmouth bass in the North Fork John Day River to better understand the recruitment dynamics near its invasion boundary. In 2014–2015, we collected YOY across the upstream 63 km of smallmouth bass distribution at the end of the first growth season and after a winter starvation period. We found that growth, body length, and survival showed varied correspondence with patterns in water temperature. Specifically, body lengths matched temperature predictions in upstream sites (after accounting for spawning delays) where smallmouth bass density is low. By contrast, individuals achieved smaller than predicted body lengths in downstream sites where density is relatively high. Model selection revealed that temperature and age ≥ 1 density were the most important predictors of body length. Additionally, individuals predicted to be too small to survive a winter starvation period were present. Our findings reveal nuanced recruitment dynamics at the invasion boundary, where departures from temperature-based predictions point to multiple mechanisms affecting growth and survival. Understanding mechanisms operating at invasion boundaries may help develop management strategies to prevent future spread of smallmouth bass into headwater salmon habitat.

Chickaloon Flats, Kenai National Wildlife Refuge, is a 10,000 ha tidal mudflat complex on the Kenai Peninsula in southcentral Alaska. It is a protected coastal estuary stopover area along the Pacific Flyway, covering 7% of the total estuarine intertidal area from Cook Inlet to Prince William Sound. Because Chickaloon Flats is historically an important avian migratory stopover and has relative regional importance in terms of estuarine intertidal area, there was a need to evaluate the current vegetation and determine any changes since the last ground study in 1972. We collected land cover data at a sample of ground-truthed points on Chickaloon Flats during 2009–2010 to evaluate existing vegetation communities as compared to historic 1970–71 values. A maximum likelihood supervised classification was performed on 2005 Landsat TM imagery to create an updated land cover classification of Chickaloon Flats. We used two different analytical approaches to show that the most notable changes in land cover types from 1975–2005 were the increase in early successional communities and a decline in unvegetated mud. Additionally, inland land cover types, which represent the more stable marsh-like communities, decreased in area as a whole. The documented changes in vegetation composition and structure over the four decade study period are attributable to elevation changes from sediment accretion and post-1964 Earthquake subsidence. As a result, evidence points to reduced shorebird use of the Flats.

Models that predict the distributions and habitat suitability for species of conservation concern can be useful for guiding survey, monitoring, and conservation planning efforts. The Humboldt marten (Martes caurina humboldtensis) has significantly declined throughout its historical range in coastal California and Oregon and this taxon is known from a few remnant populations. We developed a landscape habitat suitability model to identify areas of suitable habitat not yet surveyed, to provide a template for designing monitoring programs and research studies, and to inform the development of a conservation strategy. We used the results of 1,159 occupancy surveys to develop a predictive habitat model using Generalized Additive Modeling to relate Humboldt marten detections to combinations of environmental and habitat attributes hypothesized to influence marten distribution. We measured 30 candidate variables at three spatial scales, using 0.5, 1.0, and 3.0 km, and although several models were competitive, each contained the same three core variables: old growth structural index measured at the 1-km scale, serpentine habitat measured at the 3-km scale, and annual precipitation measured at the 3-km scale. The final model had an overall correct classification rate of 91% for marten detections, 82% for non-detections and a true skill statistic of 0.73. Model predictions were stable when cross-validated, with the correct classification of marten detections (89%) varying little. The largest complexes of predicted suitable habitat occurred in the areas with the three extant marten populations (north coastal California, south coastal Oregon, and central coastal Oregon), however connectivity of suitable habitat to areas outside these three areas appears limited.

The decline of the northern red-legged frog, Rana aurora, in the Pacific Northwest has been attributed to invasive species, habitat loss, and climate change. Rana aurora lay eggs on emergent vegetation, and larval development occurs in shallow, often ephemeral wetlands. In 2015 and 2016 we investigated how habitat and water quality parameters influence breeding productivity and development of R. aurora. Early season temperatures in southwestern British Columbia during both years were warmer than in the previous two decades and egg-laying occurred much earlier than any previous records, allowing us to follow the development of R. aurora under unusual climatic conditions. We monitored 43 wetlands in the Little Campbell River Watershed and nearby areas in 2015 and selected six sites to monitor tadpole metamorphosis. Peak egg mass abundance was inversely proportional to concentrations of nitrates and orthophosphates, and colder water appeared to support greater egg mass abundance. Although warmer ambient temperatures facilitated earlier onset of R. aurora breeding, we observed some egg mortality due to subsequent frost. Sites with earlier peak egg mass abundance dates did not exhibit earlier peak metamorph dates, nor did warmer water appear to facilitate quicker larval development. In 2015, one wetland dried up before tadpoles completed metamorphosis. The frog's reproductive cycle may adapt to warmer temperatures to some degree, but erratic precipitation or frost events could reduce R. aurora survivorship beyond recovery. The disruption of larval development we observed under unusually warm spring conditions provides a useful vantage point for predicting future impacts of climate change.

Passive acoustic recordings can identify whale species presence and behaviour in an area over time. Here a combination of moored and mobile receivers were used for acoustic surveillance of the deep-coastal and offshore waters of Clayoquot Sound, off the west coast of Vancouver Island. This study adds to the acoustic record of fin whale (Balaenoptera physalus) presence in the Canadian Pacific. Whale calls are a proxy for presence, and call type is an indicator of behaviour and habitat use. The recordings suggest a change in behaviour and social context of whales in this area as winter progresses to spring. There is a distinct temporal separation in call type used by fin whales, whereby recordings taken between December and late February are dominated by the 20-Hz pulse, while the 40-Hz call is prevalent in early spring (March–April). The presence of doublet song sequences is also noted for the winter recordings. The use of 20-Hz song sequences and 40-Hz calls suggest this area is used for both breeding and feeding behaviours. For 40-Hz especially, the calls are most frequently recorded along the continental shelf break, and areas of topographical complexity that may entrain prey. This study adds to the little that is known of fin whale presence and use of this area. Further works will continue to add to our knowledge of distribution and habitat use of fin whales in the northeastern Pacific as populations recover from whaling.

The fisher is a mammalian carnivore that chooses resting locations each day. Refugia are essential, thus most of the fisher's resting locations are cavities in large live or dead trees. Tree growth and decomposition influence the creation of cavity-bearing structures, which may take centuries, but they can be lost to fire or harvest in an instant. Thus, the conservation of the fisher relies on an equilibrium between the loss of structures via disturbance and their creation. In the mid-1990s we studied fisher resting habitat by following radio-marked individuals to their resting locations. In 2016, roughly 20 years later, we assessed the risks that the resting structures were exposed to by overlaying the perimeters of fires and tree harvest units on the location of 192 resting structures. We also assess the effect of disturbance by examining 36 of them in the field. The mean distance from a resting structure to the nearest harvest unit was 651 m, with 16.8% estimated to be within a harvest unit. The mean distance of the resting structures to the nearest fire was 635 m with 51.0% estimated to be within a fire. Of 36 resting structures that were reevaluated or relocated in the field, 16 (44.4%) were of questionable use in 2016. Based on GIS analyses of disturbance coupled with field data on relocated structures, approximately 15–25% were potentially usable after 20 years. Managers planning actions should consider this a background level of loss of resting structures over 20 years—a background against which additional vegetation management can be considered.

Rocky Mountain tailed frogs (Ascaphus montanus) were thought to exist exclusively in two tributaries of Warm Springs Creek watershed—Storm Lake Creek and Twin Lakes Creek, based on opportunistic observations of tailed frogs during fish sampling rather than formal basin-wide sampling for frogs. We used extant environmental DNA (eDNA) samples originally collected to delineate bull trout (Savelinus confluentus) occupancy to determine whether tailed frogs reside outside of their current known distribution in the Warm Springs Creek watershed. We were able to rapidly confirm tailed frog occupancy in these two tributaries of Warm Springs Creek watershed, and located tailed frogs throughout the mainstem of Warm Springs Creek where their presence was previously unknown. Repurposing eDNA samples provides a sensitive and extremely cost effective way to determine species distributions, because existing samples can continue to be retested for unrelated taxa without repeating field collections.