Predator avoidance behavior minimizes predation risk because the prey never enters the perceptual field of the predator. For toxic species, avoiding potential predators indiscriminately is unlikely to be the best predator avoidance strategy because many predators will be incapable of consuming the toxin. We investigated the role of chemical-based avoidance behavior in predator-prey interactions between a toxic prey species, the Rough-skinned Newt (Taricha granulosa), and its major predator, the Common Garter Snake (Thamnophis sirtalis). Terrestrial newts avoided predator kairomones only when the predator had recently consumed a conspecific, but did not avoid damage-released alarm cues. These results indicate newts may be able to chemically differentiate between toxin-resistant and toxin-sensitive snakes in the same population and avoid only those snakes actively preying upon their cohort.

Bald Eagle (Haliaeetus leucocephalus) populations along the north Pacific coast from southern British Columbia to the Alaska Peninsula have been monitored since 1967 with aerial surveys using a universal random plot design. This survey consisted of 233 plots, each 168.3 km². The expanded population estimate for adults totaled 58,000 after applying a visibility correction factor of 2.0. This accounted for roughly half of the world's population. With multiple surveys, I determined that populations in southeast Alaska, Prince William Sound, and the Alaska Peninsula increased until the late 1980s and remained stable thereafter. All possible plots, under this survey design, can be delineated for future replication or modification using 2 simple equations.

Great Gray Owls (Strix nebulosa) in the Sierra Nevada Mountains feed primarily on rodents, especially voles and pocket gophers. Voles have been shown to be negatively affected by cattle grazing, but effects of grazing on gophers in the Sierra Nevada Mountains are unknown. We investigated the effects of grazing on pocket gophers (Thomomys monticola and T. bottae) in 21 grazed and 21 ungrazed montane meadow sites in the central Sierra Nevada Mountains of California. Pocket gopher densities were significantly higher in grazed meadows than ungrazed meadows. Vegetation cover and height, thatch depth, and the frequency of sedge occurrence were higher in ungrazed meadows and there were negative correlations between pocket gopher densities and these vegetation variables. We suggest that potential negative effects of grazing on Great Gray Owls could be minimized by managing meadow vegetation commensurate with the habitat needs of their prey.

The Northern Spotted Owl (Strix occidentalis caurina) population is declining throughout its range in the United States and adjacent Canada and is facing increasing pressure from the invading Barred Owl (Strix varia). In this study, we characterize Spotted Owl habitat associations and develop 2 new habitat selection models for the eastern Washington Cascade Range. Topographic and habitat data were compiled at 2 scales (0.25 and 1.0 mi) around 224 Spotted Owl activity centers, or sites, and at 160 random locations in the same geographic region, and used to develop models for predicting owl distributions. Univariate analysis found that owl sites occurred below 5000-ft elevation and were more likely to occur as area in the >71% crown-cover class increased. Owl sites were found to be more likely to occur closer to streams and to be rare in the Subalpine Fir (Abies lasiocarpa) vegetation type. The 9–25″ tree size-class was a significant predictor of the distribution of owl sites. Habitat models were constructed that were moderately successful at predicting owl-site distribution. Models from the largest scale tested (1.0-mi radius) were the most predictive, at 80% accuracy. Top-ranked models included overstory canopy cover, tree size, elevation, precipitation, distance to stream, and tree species as predictors. The resulting models can be used to help identify likely sites for surveys and to inform conservation and landscape management activities associated with forest-health restoration.

To better understand historical breeding distribution and population changes, breeding records from the period 1858–1910 (most pre-dating previous summaries) were assembled for 4 species of alcid in British Columbia (BC) and southeastern Alaska (SEAK), based on re-evaluation of museum specimens, literature, and unpublished sources. Earliest records for each species were: Ancient Murrelet (Synthliboramphus antiquus) at St Lazaria Island, SEAK, in 1866; Cassin's Auklet (Ptychoramphus aleuticus) at Forrester Island, SEAK, in 1897; Rhinoceros Auklet (Cerorhinca monocerata) at Pine Island, BC, in 1860; and Tufted Puffin (Fratercula cirrhata) at Mandarte Island, BC, in 1858. Other breeding records for these species in BC and SEAK prior to 1911 were reviewed, historical literature was clarified, and certain historical population changes of Rhinoceros Auklets and Tufted Puffins were examined.

High nest predation rates are one of the main sources of nesting failure in passerines. Mountain meadows in the Sierra Nevada have been intensively modified, reducing meadow wetness and potentially favoring easy access for mammalian predators to reach nesting areas in the meadow interior. We conducted mammal trapping in wet and dry areas of montane meadows during May through August of 2007 and 2008 to identify the assemblage of potential mammalian nest predators and determine the relationship between activity and meadow wetness. Chipmunk (Tamias spp.) activity was primarily restricted to dry areas. Activity of Yellow-pine Chipmunks (Tamias amoenus) was >90% higher in dry versus wet areas. Deer Mice (Peromyscus maniculatus) were equally active in both site types in 2007, but declined and were only captured in wet areas in 2008. Overall activity was higher in 2007 and 2008 for both wet and dry areas (68% and 52%, respectively). Our results suggest that increasing the proportion of inundated areas in meadows may reduce small mammal activity (for instance Yellow-pine Chipmunks) and potentially reduce nest predation.

Fisher (Martes pennanti) occur broadly across northcentral North America, and are a species of conservation concern in most of western North America. Fisher reach the northwestern edge of their distributional range in the Yukon, Canada; however, their abundance and distribution has been poorly documented there. We used museum collections, trapping records, and sightings to update the relative abundance and distribution of Fisher in the Yukon between 1956 and 2009, with a particular emphasis on the last 3 decades. We compiled 100 records of Fisher that were trapped, observed, or whose tracks were noted in the Yukon. Harvest data suggested that Fisher may be increasing in relative abundance in the Yukon, but densities likely are very low. Anecdotal observations and harvest of Fisher in southwestern Yukon have increased in the last 10 to 20 y and suggest that they may be expanding their range westward. Trapping records and museum collections in adjacent Alaska and northwestern British Columbia corroborate records from the Yukon. Monitoring Fisher will be necessary to confirm changes in the abundance and distribution of Fisher in the Yukon and neighboring jurisdictions.