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Electrocution of raptors is an ongoing conservation concern in western North America. Mitigating electrocution risk focuses primarily on insulating energized equipment or increasing the separation between electrical components, but these approaches are not effective on some electric power pole configurations. In some cases, providing a supplemental perch to encourage raptors to perch away from the energized components on a pole may offer a cost-effective alternative. Though numerous supplemental perch designs exist, to our knowledge, raptor responses to them have not been objectively evaluated. To offer an initial quantification of the use of a supplemental perch, we installed a supplemental perch in a flight enclosure at a raptor rehabilitation facility. We then used compositional analysis to evaluate whether and how much rehabilitated raptors used the supplemental perch in a captive setting. The 17 raptors we tested used the supplemental perch 63.3% of the time, used the crossarm below the supplemental perch 3.4% of the time, and used a control crossarm without a supplemental perch 33.3% of the time. These data demonstrate that at least in a captive setting, raptors can be shifted from high-risk perching in the energized zone of a power pole where wires occur, to lower risk perching elsewhere, potentially reducing electrocution risk on some configurations.
Single specimens of Finescale Triggerfish (Balistes polylepis) and Louvar (Luvarus imperialis) were found in British Columbia’s coastal waters in 2014. Both B. polylepis and L. imperialis normally are found off southern-most California and Baja California. Although a stray B. polylepis was caught as far north as Metlakatla, Alaska, during the 1982–1983 El Niño event, and L. imperialis is known to stray north along the Washington coastline, these 2 new specimens represent 1st records for British Columbia. Both probably moved north during the warm-water anomaly that has persisted along the North American coast since 2013.
Species that overlap in their morphologies are sometimes difficult to distinguish from one another, which can complicate species’ conservation and management. The Little Brown Bat (Myotis lucifugus) and Yuma Myotis (Myotis yumanensis) are sympatric in parts of their range in western North America, and they overlap in morphology, making them difficult to tell apart in the hand in some areas, such as the Pacific Northwest. We compared various methods of distinguishing between M. lucifugus and M. yumanensis to genetic results, using a blind test approach to remove observer bias. Using multiple independent observers, we used external morphology and echolocation-call structure to classify bats from a maternity colony consisting of both species. Genetic analysis confirmed 13 M. lucifugus and 40 M. yumanensis. Minimum echolocation-call frequency separated 100% of M. lucifugus from M. yumanensis using a cut-off of 43 kHz. All M. lucifugus had a minimum echolocation-call frequency ≤42.8 kHz, whereas M. yumanensis had a minimum frequency ≥44.55 kHz. There was some overlap in forearm length; a cut-off of 36 mm would have correctly identified 77% of M. lucifugus and 100% of M. yumanensis to species. Criteria based on subjective assessment of fur sheen and length as well as ear color were moderately successful (90.5 and 77% success by 2 separate observers) in distinguishing between the 2 species. The use of Munsell soil color charts and multivariate statistics to classify fur and membrane color and confirm species identification was not successful. Our results suggest that mean minimum call frequency alone is sufficient for distinguishing between M. lucifugus and M. yumanensis. Use of quantitative rather than qualitative criteria eliminates observer bias and appears to be better for identifying these 2 species.
In July 2014, we conducted nest counts at 7 of 8 known breeding colonies of Pelagic Cormorants (Phalacrocorax pelagicus) in western Queen Charlotte Strait, British Columbia, to assess the current status of this population. Four nests were found on Dugout Rocks, the only known colony still used; 1 nest was found at Pine Island, a 9th (newly recorded) breeding location in the region. Total numbers of nests in this region declined 97% from 197 to 231 nests in 1975–1976, to 60 nests in 1982–1988, to 5 nests in 2014. Limited evidence suggests that Bald Eagle (Haliaeetus leucocephalus) disturbance and predation may be the main reason for this major decline in the cormorant breeding population. Historical population size of Pelagic Cormorants prior to the 1960s also may have been quite low, with breeding 1st recorded in this region in 1968, although little prior survey effort occurred. Population growth probably occurred in the 1960s and early 1970s to reach the population size noted during the 1st complete survey in 1975–1976, during a period of reduced impacts from eagles.
North American River Otter (Lontra canadensis) predation on salmon is of concern in the Lake Ozette watershed due to potential impacts on ESA listed Lake Ozette Sockeye Salmon (Oncorhynchus nerka). To better understand the impact of River Otters on Lake Ozette Sockeye Salmon, we examined prey remains recovered from 291 scat samples collected around Lake Ozette and near a fish counting weir in the Ozette River between 1998 and 2003. We found evidence that prey taxon differs by habitat type with significantly greater occurrence of fish and amphibians recovered from scat collected in the lake habitat, while a significantly higher occurrence of invertebrates was identified in scat from the river habitat. We also found a significantly greater frequency of adult salmon prey remains in scat collected in the river habitat than in the lake habitat. It is likely the fish counting weir increased adult salmon vulnerability to River Otter predation in Ozette River. Genetic analysis revealed that 79.4% of the adult salmon consumed by River Otters were Lake Ozette Sockeye Salmon. The frequency of occurrence of adult Sockeye Salmon in scat samples peaked in July with 25% of scat collected having adult Sockeye Salmon remains, well after the late May to the middle of June peak in upriver migration. Predation of Sockeye Salmon at all life stages has been listed as a key factor in limiting the ability of Sockeye Salmon to recover in the Lake Ozette watershed. Efforts are currently underway to address many of the factors limiting recovery of Lake Ozette Sockeye Salmon. The high occurrence of adult salmon remains near the fish counting weir, and results of past studies, suggests that predator mitigation at the weir through acoustic harassment devices or other methods could benefit the recovery of Lake Ozette Sockeye Salmon.
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