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We used track plates to monitor American Marten (Martes americana) over 2 field seasons in 2003 and 2004 to test the efficacy of applying this technique to Late-Successional Reserves on the east side of the North Cascades. We stratified our sample area into wet and dry late-successional forest habitats in order to account for differences in habitat structure, disturbance regimes, and forest management strategies. We detected no Marten during either year in the dry-forest habitats. In the wet-forest habitats, detection rates were 0.29 in 2003 and 0.73 in 2004. The latency to detection in the wet-forest habitats was 5.5 d (s = 3.1) in 2003 and 5.6 d (s = 3.8) in 2004. The corrected probability of detection at a survey unit in the wet-forest habitat was 0.26 in 2003 and 0.42 in 2004. We then used the variability from our 2 sample years to estimate sample size requirements for different levels of power to detect changes in our abundance indices. Our study indicates that conservation efforts for the American Marten should be focused on the wet-forest habitats. This information should be useful to managers in designing a long-term monitoring program for American Marten.
Triangle Island, the most westerly of the Scott Islands, supports the larger of 2 active Common Murre (Uria aalge) breeding colonies (about 3000 pairs) in British Columbia, Canada. However, little is known about the species' breeding ecology at this site. Here, we report on investigations of murre biology at Triangle Island between 2002 and 2007. Possibly indicative of their zoogeographic affinities, Triangle Island Common Murres are more similar in size to those that breed at colonies to the north than to the south. Murres were first seen on the colony between late March and early April. The 1st eggs were laid in mid- to late May, and latest eggs (1st or replacement) in mid-July. Median laying dates varied by about 25 d across 5 y (2003 to 2007). Despite differences in adult size, eggs laid at Triangle Island were similar in size to those at murre colonies across western North America. Breeding success for murres at Triangle Island ranged from 54% (2007) to 82% (2004) over 5 y, which is on the high end of the range for Pacific colonies. Adult Pacific Sand Lance (Ammodytes hexapterus) and juvenile rockfish (Sebastes spp.) combined formed the bulk (71 to 80%) of prey items delivered to nestling murres. Chick mass measured just prior to the start of fledging was notably reduced in 2005 compared to the other 5 y of the study, an obvious manifestation of the extreme oceanic conditions in the California Current system in that year. This report forms the most comprehensive account of the breeding biology of Common Murres in British Columbia, and should provide a benchmark against which future changes in this colony can be measured.
The 25,000 km of shoreline in southeast Alaska was surveyed for waterbirds by fixed-wing aircraft in summer and winter during the period 1997 to 2002. A ground/boat survey double sampled 20% of the summer habitat and 5% of the winter habitat to adjust and enhance the air survey. The most abundant species during the summer surveys, with visibility correction factors applied, were gulls (Larus spp.; 306,200, CV = 0.004), scoters (Melanitta spp.; 185,700, CV = 0.004), and Harlequin Duck (Histrionicus histrionicus; 34,640, CV = 0.03). The most abundant species observed during the winter surveys were goldeneyes (Bucephala islandica and B. clangula; 121,920, CV = 0.01), gulls (105,000, CV = 0.01), Mallard (Anas platyrhynchos; 98,090, CV = 0.01), scoters (77,300, CV = 0.01), Harlequin Duck (54,540, CV = 0.02), Bufflehead (Bucephala albeola; 46,840, CV = 0.03), and mergansers (Mergus spp.; 39,940, CV = 0.02). The variance estimates did not include uncertainty about the visibility correction factors. We observed 2.4 times as many scoters in summer as in winter and surmise they were sub-adults, failed breeders, and adult males which had deserted females on the breeding grounds. Complete shoreline coverage provided precise estimates for the abundant species. Meaningful population values could be generated for very specific subunits selected after completion of the survey because all shoreline was covered and all observations were tied to a geographic location.
We studied American Dippers nesting near Juneau, AK, for 4 years. Few dippers in our area live long enough to breed in 3 or more seasons. The nest exterior is composed of a variety of moss species. Nest success ranged from 62 to 87% of first nesting attempts and was lowest in a cool, wet spring. Nesting phenology was delayed in years with cool, wet springs, at higher elevations, and on lowland stream reaches that supported few fish. Second broods were uncommon but were most often reared when 1st broods were early and on stream reaches with ready access to small fish. Hourly chick-feeding rates varied widely, from 0 to 35 trips/h. Fish were delivered to some nests, up to 17 fish/h per nest, especially by female parents. In a few cases a female nested successfully with the same male in 3 successive years. Most changes of mate and territory were associated with the disappearance of 1 member of a pair, and all changes of territory occurred within the same watershed. Females that lost their mates after egg-laying were capable of rearing a brood alone. Some nests were infested with bird-blowflies (Protocalliphoridae). Dippers commonly removed nest lining after fledging of the 1st brood. This behavior can be a good predictor of nest success in the absence of direct observation.
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