Model-Based Predictions of the Effects of Harvest Mortality on Population Size and Trend of Yellow-Billed Loons

Schmutz, Joel A.

doi:10.3133/ofr20091040

Cited by 2 publications

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“…Fish and Wildlife Service [USFWS], Migratory Bird Management, unpublished data). Few reliable data are available from Canada and Russia, the primary breeding areas outside Alaska; yellow‐billed loons may number 16,000–32,000 on breeding grounds worldwide (Fair , Schmutz ).…”

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Territory occupancy by breeding yellow‐billed loons near oil development

et al. 2018

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Less than 4,000 yellow-billed loons (Gavia adamsii) breed in remote and disjunct locations in northern Alaska, USA. Over 75% of the United States population of yellow-billed loons nests in the National Petroleum Reserve-Alaska (NPRA), where impending oil and gas development will intersect their breeding range. We investigated the relationship of recent oilfield development to occupancy of yellow-billed loon territories by breeding pairs (indicated by active nests) and broods using 14 years of aerial surveys on the Colville River delta. We also evaluated the survey requirements prescribed by the Bureau of Land Management (BLM) for NPRA. We began aerial surveys for yellow-billed loons in 1993, prior to construction of the Alpine oilfield in 1998, and followed territories through 2008, after construction of 2 additional satellite drill sites. We used records from 37 breeding territories on 36 lakes in model selection analyses to examine how habitat and disturbance factors (proximity to facilities and construction time period) influenced occupancy by breeding pairs and broods. Annually, 13 AE 2.5 (SE)% (n ¼ 14 yr) of broods (n ¼ 19) moved from nesting lakes to adjacent brood-rearing lakes, and the remainder stayed in nesting lakes (n ¼ 128). Lakes used for nesting and brood-rearing were almost 25 times larger ( x ¼ 95.9 AE 25 ha, n ¼ 23 lakes) than nesting lakes from which broods left ( x ¼ 4.0 AE 1.1 ha, n ¼ 7 lakes, P < 0.001). Thirty-eight percent of territories (n ¼ 14 territories) were on lakes shared by >1 breeding pair. Lake type (deep open lakes with islands or polygonized margins, deep open lakes without islands or polygonized margins, and tapped lakes with high-water connections) was the most influential covariate on occupancy by breeding pairs, and lake area was most influential on occupancy by broods. Time period and distance to facilities (as discrete zones at 1.6 km and 3.2 km and as linear distance) were factors in the highest-ranked models for 5 of the 6 model sets that included disturbance parameters. Interaction terms for time period and distance to oilfield facilities were factors in 3 of 6 model sets. The pattern of occupancy of breeding territories, however, was not consistent with disturbance-related effects. Occupancy of territories by breeding pairs was lower in the predevelopment period (lowest human activity) than in the latest development period (highest human activity) and higher in the zones near oilfield facilities than far from facilities. Occupancy of territories by broods was highest in the latest development period and similarly high in zones near and far from facilities. Application of BLM minimum survey requirements (3 yr with 2 surveys/yr) to the initial 3 years of surveys in this study resulted in detecting 81% of the known territories on the Colville River delta. The BLM restrictions on development were judged conservative in maintaining breeding territories around oilfield developments. Our results did not demonstrate displacement of nests or broods from long-standing territori...

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Territory occupancy by breeding yellow‐billed loons near oil development

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“…Yellow-billed loon migration routes and timing are poorly known (North 1994;Schmutz 2009;USFWS 2014). However, bird counts and local and traditional knowledge supported that, on St. Lawrence Island, loons typically occur as single birds or pairs and sporadically as groups of dozens of birds (Day et al 2003;Lehman 2016; this study).…”

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“…Data on loon ecology, distribution, and harvest on the mainland area indicated relatively low loon numbers potentially available for harvest as well as low harvest levels (North 1994;CSIS 2017). Yellow-billed loons breeding in Alaska and Canada migrate westward over the Beaufort Sea and southward across the Bering Sea, nearing St. Lawrence Island, to winter in Asia (Schmutz 2009;Schmutz and Rizzolo 2012;USFWS 2014). Unknown migratory concentrations near St. Lawrence Island could make large loon numbers accessible for harvest.…”

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“…Because most loon harvest occurred in fall, counts were conducted from mid-September to midOctober (Naves 2014). This period covers most of the postbreeding migration of all loon species (North 1994;Schmutz 2009;Zeller et al 2011;Lehman 2016). Count stations were located on the seashore close to Gambell (n ¼ 4) and Savoonga (n ¼ 7).…”

Section: Shore-based Bird Point Countsmentioning

confidence: 99%

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Yellow-Billed Loon Subsistence Harvest in Alaska: Challenges in Harvest Assessment of a Conservation Concern Species

Naves

Zeller

2017

Journal of Fish and Wildlife Management

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The yellow-billed loon Gavia adamsii was designated as a candidate species for listing as threatened or endangered under the U.S. Endangered Species Act in 2009. Subsistence harvest was identified as a threat based on the 2007 harvest estimate for the Bering Strait region of Alaska. This estimate was unusually high and inconsistent with data on the species' abundance and distribution. We conducted this study in 2011-2012 on St. Lawrence Island, in the Bering Sea, to fulfill data needs related to this Endangered Species Act listing process. Our objectives were to clarify 1) loon species harvested, 2) numbers of loons harvested, and 3) loon harvest methods and uses by local subsistence communities. We conducted harvest surveys, ethnographic research, and shore-based bird counts. Loons were ,1% of all bird harvest. Pacific loons Gavia pacifica were 96% of observed loons and likely comprised the majority of loons harvested. Local ethnotaxonomy grouped loons by size (large or small) and overall plumage (breeding or nonbreeding), differing from scientific taxonomy. We found no evidence that loon migratory aggregations occurred near St. Lawrence Island or that intense harvest effort targeted loons. We estimated that five yellow-billed loons were harvested annually in 2011 and 2012. Hatch-year loons were likely at least half of the loon harvest, lessening effects of harvest on loon populations. Our study exemplifies the importance of using multidisciplinary approaches and engaging subsistence users to improve harvest assessment and inform wildlife conservation policy.

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Model-Based Predictions of the Effects of Harvest Mortality on Population Size and Trend of Yellow-Billed Loons

Cited by 2 publications

References 2 publications

Territory occupancy by breeding yellow‐billed loons near oil development

Territory occupancy by breeding yellow‐billed loons near oil development

Yellow-Billed Loon Subsistence Harvest in Alaska: Challenges in Harvest Assessment of a Conservation Concern Species

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