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The Marbled Murrelet (Brachyramphus marmoratus) is a small seabird that is currently listed as threatened in Canada. Understanding this species' marine habitat preferences plays a vital role in our ability to focus conservation planning. We used the longest-running at-sea survey dataset available in British Columbia to examine hotspot persistence and habitat use at Laskeek Bay, Haida Gwaii, BC. The Laskeek Bay Conservation Society has been conducting spring and summer surveys along fixed transect routes in open and shoreline waters from 1997 to 2018. Along with analyzing this long-term dataset, we conducted surveys to measure oceanographic variables (2018–2019) and tested whether Marbled Murrelets in the same area used prey and oceanographic information to select marine habitat in conjunction with physical habitat features. Our hotspot persistence map, defined as areas that repeatedly had counts above a 75% threshold relative to other areas during a given survey, showed that murrelets consistently preferred shoreline transects. Murrelets also preferred shallow marine areas closer to streams, above higher proportions of sandy substrate and closer proximity to abundant nesting habitat. Modeling weather and time variables contributed little additional predictive power. Nonetheless, models that included physical environmental, oceanographic, and prey variables outperformed those with only physical environmental variables. Stratified water was the oceanographic variable most strongly related to higher counts. Our study suggests that stratified waters could work with stream systems to create productive zones for foraging murrelets, and highlights the importance of murrelets having access to marine areas with the preferred physical features. LAY SUMMARY Marine habitat preference studies for the threatened Marbled Murrelet are critical in management and conservation decisions. We used at-sea surveys conducted in Haida Gwaii, BC, by the Laskeek Bay Conservation Society (1997–2018) and performed additional oceanographic variables surveys (2018–2019). Persistence hotspot mapping showed that murrelet distributions were substantially consistent across 22 years of surveys. Murrelet usage was strongly associated with being closer to streams, shallower waters, higher proportions of sandy sediment, proximity to abundant potential nesting habitat, and stratified water conditions.

Habitat Conservation Plans (HCPs) commonly facilitate habitat conservation on private land in the United States, yet the effectiveness of individual HCPs is rarely evaluated. Here, we assess the effectiveness of a high-profile HCP created by a lumber company to protect old-growth forests used for breeding by Marbled Murrelets (Brachyramphus marmoratus) on private land. We used 17 years of HCP-monitoring data to compare trends in murrelet occupancy and inland counts between private HCP areas and public reference areas over time. Based on occupancy models applied to audio-visual survey data, average occupancy was higher in public reference areas (0.85; 85% confidence intervals [CI]: 0.79–0.90) than in private HCP areas (0.46; 85% CI: 0.38–0.54). Numerically, trends in occupancy were slightly positive in public areas (= 1.01; 85% CI: 0.94–1.08) and slightly negative in private areas (= 0.97; 85% CI: 0.87–1.06), but CI did not preclude stable occupancy on both ownerships. Based on generalized linear mixed models applied to inland radar survey data, murrelet counts in private HCP areas (least-squares [LS] mean = 8.7; 85% CI: 6.2–12.2) were lower than those in public reference areas (LS mean = 14.8; 85% CI: 10.1–21.7), but CI overlapped. Murrelet counts declined by 12–17% annually on both ownerships over the study period based on the top model, but a closely competing interactive model suggested more rapid declines in public reference (14–20%) than in private HCP (10–15%) areas. Both models indicated that murrelet counts were negatively related to sea surface temperature, suggesting that warm ocean conditions negatively affect murrelet breeding effort. Collectively, these results suggest that while HCP habitat may be lower quality than public reference areas, the HCP has likely not exacerbated ongoing declines of murrelets in the region. This work highlights the importance of including reference areas when evaluating conservation policies. LAY SUMMARY Habitat Conservation Plans (HCPs) are a common conservation tool used to protect habitat on private land in the United States, but the effectiveness of individual HCPs is rarely evaluated. We assessed the ability of 1 high-profile HCP to protect breeding habitat for a threatened seabird, the Marbled Murrelet (Brachyramphus marmoratus), on land owned by a lumber company. To do this, we compared trends in murrelet occupancy and abundance between private HCP conservation areas and public reference areas. We found that habitat protected within public reference areas was higher quality, but lack of differences in trends between ownerships indicated that the HCP did not exacerbate ongoing declines of murrelet populations in our study area. Additionally, habitat in private HCP areas is likely to improve as forests continue to mature. We also found that the abundance of murrelets on both landownerships was declining rapidly over time, likely due to reduced breeding effort because of broad-scale environmental factors. Rigorous assessments of conservation policies are imperative for guiding future conservation initiatives and investments, especially on private land where species are most vulnerable to habitat loss.

Incidental mortality of marine birds in fisheries is an international conservation concern, including in Canada where globally significant populations of vulnerable diving species overlap with coastal gillnet fisheries. In British Columbia (BC), commercial salmon gillnet fishing effort was historically very high (>200,000 days fished annually in the early 1950's), and although this fishery has declined, over 6,400 days were fished annually in the 2006-2016 decade. Observations of seabird bycatch within the commercial fishery, however, are limited in both scope (comprising

Mercury (Hg) is a non-essential, toxic metal that is distributed worldwide. Mercury biomagnifies in food webs and can threaten the health of top predators such as seabirds. The Kittlitz's murrelet (Brachyramphus brevirostris) is a seabird endemic to Alaska and the Russian Far East and is a species of conservation concern in the region. We determined Hg concentrations in eggshells, guano, blood, and feathers of Kittlitz's murrelets sampled from four locations in Alaska. Mercury concentrations in eggshells, guano, and blood were low compared to other seabird species. Mean Hg concentrations of breast feathers from Adak Island and Glacier Bay were significantly greater than those from Agattu Island or Icy Bay. Two Kittlitz's murrelets at Glacier Bay and one Kittlitz's murrelet at Adak Island had Hg concentrations above those associated with impaired reproduction in other bird species, and may merit further investigation as a potential threat to individuals and populations.

The Marbled Murrelet (Brachyramphus marmoratus) is federally threatened in part of its range in western North America. Information on density and productivity is important for managing populations. Over an 18-yr period, we monitored murrelet density and productivity ratios during the breeding season along 170 km of shoreline of the San Juan Islands, Washington, USA. While murrelets occur throughout the coastal marine waters of Washington, the San Juan Islands support higher densities of murrelets during the breeding season than most other areas. From 1995 to 2012, the average density of adult murrelets declined significantly from 11.16 to 5.76 murrelets km−2, a decline that mirrored large-scale at-sea surveys in Washington. Despite this consistent and ominous decline in overall murrelet density, the density of juvenile murrelets and murrelet productivity ratio (juveniles:adults) did not decline over this time period. Thus, the declining density of murrelets in the San Juan Islands was due to decl...

Understanding bird distributions outside of the breeding season may help to identify important criteria for winter refuge. We surveyed marine birds in Prince William Sound, Alaska, USA over nine winters from 2007 to 2016. Our objectives were twofold: to examine the seasonal patterns of piscivorous species overwintering in Prince William Sound, and to explore the relationships between spatial covariates and bird distributions, accounting for inherent spatial structure. We used hurdle models to examine nine species groups of piscivorous seabirds: loons, grebes, cormorants, mergansers, large gulls, small gulls, kittiwakes, Brachyramphus murrelets, and murres. Seven groups showed pronounced seasonal patterns. The models with the most support identified water depth and distance to shore as key environmental covariates, while habitat type, wave exposure, sea surface temperature and seafloor slope had less support. Environmental associations are consistent with the available knowledge of forage fish distribution during this time, but studies that address habitat associations of prey fish in winter could strengthen our understanding of processes in Prince William Sound.

The marbled murrelet (Brachyramphus marmoratus) is a threatened seabird that forages in nearshore marine waters but nests inland, commonly in older coniferous forests. Information on ranging behavior and breeding propensity can be useful for informing management, especially when comparisons can be made between declining or threatened populations and more stable, unthreatened populations. Over 5 years, we measured ranging behavior and breeding propensity of marbled murrelets in Washington, USA where murrelets are considered threatened. Our primary objective was to compare space use and breeding by murrelets in Washington with those from other regions and where the species is not considered threatened. We radio tracked 157 murrelets from 2004 to 2008. Median marine 95% kernel ranges were 487 km2 (x¯=938±1,348 [SD]) and larger than those reported for non-threatened populations in Alaska, USA in other studies. Ranges computed from minimum convex polygons (MCPs; median = 404 km2; x¯=708±847) were on average similar to those reported for threatened populations in California, USA, although larger than those reported for Alaska. Distances traveled between consecutive marine telemetry locations were greater than reported previously in Alaska. Variation in movements in our study were not associated with oceanographic conditions although appeared greater for murrelets captured along the Pacific Coast compared to those occupying interior marine waters in the Salish Sea. Twenty individuals (12.7%) attempted to breed in our study, and we estimated breeding propensity was 13.1–20.0%. This is the lowest breeding propensity reported for a population of murrelets to date. For breeders, nest-sea commuting distances were greater than reported previously, with 4 breeders traveling farther than the previously reported maximum of 125 km. The low breeding propensity, large marine ranges, and long nest-sea commutes in this study may point to poor-quality marine habitat in Washington compared to other parts of the murrelet's range. In combination with reported declines in terrestrial nesting habitat from other studies, this indicates that additional management is needed to improve murrelet breeding habitat in Washington. Future management actions should focus on improving both terrestrial and marine habitat. © 2016 The Wildlife Society.

Most abundance estimation methods assume that all sampled individuals are identified correctly. In practice, this assumption may be difficult to meet and can bias abundance estimates, especially when morphologically similar species overlap in range. Over the past 2 decades, Kittlitz's Murrelet (Brachyramphus brevirostris) populations appear to have declined across parts of their Alaskan range, where they co-occur with the Marbled Murrelet (B. marmoratus). Recently, the reliability of Kittlitz's Murrelet declines has been questioned due to variability and uncertainty in species identification between the 2 species. We conducted a field experiment to quantify misidentification and partial identification (identification to genus [Brachyramphus] level only) of Kittlitz's and Marbled murrelets during abundance surveys, and to evaluate the relative impacts of environmental and observational factors on misidentification and partial identification. We applied these results to previously collected survey ...

article The marbled murrelet (Brachyramphus marmoratus) is a seabird in the family Alcidae that forages in nearshore waters of the Pacific Northwest, and nests in adjacent older-forest conifers within 80 km offshore. The species is of conservation concern due to habitat loss and declining numbers, and is listed as Threatened in British Columbia, Canada and in the United States portion of its range south of Canada. Recent monitoring in the UnitedStatesindicatedthatmurreletnumberscontinuedtodeclinethere,especiallyinthewatersofWashington State. To better understand this decline, and to inform conservation planning for the species, we evaluated how terrestrial and marine factors influence the distribution and abundance of the murrelet in coastal waters, includ- ing whether at-sea hotspots of murrelet abundance exist. Murrelet at-sea abundance and distribution were de- termined by surveys conducted annually from 2000 to 2012 in coastal waters from the United States-Canada border south to San Francisco Bay. We summarized mean and variance of murrelet density at the scale of 5-km segments of coastal waters throughout this area. We used a boosted regression tree analysis to investigate

Kittlitz's Murrelet (Brachyramphus brevirostris) is a dispersed-nesting seabird endemic to Alaska and eastern Russia that may have experienced considerable population declines in some parts of its range in the past few decades. Poor reproduction has been suggested as the demographic bottleneck, yet there are no direct estimates of reproduction in a glaciated area where this species reaches its highest densities at sea during the breeding season. The lack of demographic information in glacial habitats has limited our ability to interpret population trends and to clarify whether the presence of glaciers affects reproductive performance. Between 2007 and 2012, we radio-tagged Kittlitz's Murrelets to measure breeding propensity, nesting success, and fecundity in the heavily glaciated landscape of Icy Bay, Alaska, USA. Of 156 radio-tagged birds, 20% were breeders, 68% were potential breeders, and 12% were nonbreeders. Radio-tagged males (29%) were more likely to be breeders compared to females (11%). ...

In subarctic waters winter may be the period during which seabirds face the greatest environmental and physiological pressures, yet seabird distribution during this time is poorly understood. Using at-sea surveys conducted in Prince William Sound, Alaska on research ‘ships of opportunity’ from November 2007 to March 2009, we investigated how seabird abundance and distribution vary within and between winters for three common seabird species with extensive ranges: common murre (Uria aalge), marbled murrelet (Brachyramphus marmoratus), and black-legged kittiwake (Rissa tridactyla). Due to a large proportion of zeros in the survey data, hurdle models were performed using generalized additive mixed models. Across the two winters, consistent temporal patterns in density and distribution were observed for all species. Common murre and marbled murrelet both increased in number in midwinter, while black-legged kittiwake decreased to very low numbers. Habitat association models revealed that common murre f...

Predation on eggs of marbled murrelets (Brachyramphus marmoratus) has been linked to poor recruitment of young, especially in California, Oregon, and Washington. Corvids have been implicated as the most influential egg predators on murrelets. Remnant murrelet nesting habitats in California and elsewhere support a high population density of opportunistic corvids like the Steller's jay (Cyanocitta stelleri). We exposed Steller's jays to eggs mimicking murrelet eggs in color and size that contained the emetic carbachol. In laboratory tests, we effectively induced aversive conditioning subsequent to exposure to the murrelet-mimic eggs. Attack latencies on murrelet-mimic eggs increased following exposure to carbachol eggs and the strength of aversion was consistent over the range of retention periods tested (8 weeks). We conducted field trials on murrelet-mimic eggs and control eggs deployed across a systematic 428-ha grid in murrelet breeding habitat. After a period of aversive conditioning, the percentage of murrelet-mimic eggs that were attacked by corvids in the field experiment was reduced by at least 37% in comparison to control eggs. We concluded that corvid predation can be reduced significantly using aversive training in the field, and could be practically applied to jay territories within murrelet breeding habitat. We suggest that aversive conditioning treatment may be a cost-effective emergency tool to improve reproductive success of murrelets in the Pacific Northwest. © 2014 The Wildlife Society.

Studying the ecology of endangered species in portions of their range where the population remains abundant can provide fundamental information for conservation planners. We studied nesting by radio-tagged Marbled Murrelets (Brachyramphus marmoratus) during 2007 and 2008 in Port Snettisham, a relatively pristine, remote mainland fjord in southeast Alaska with high at-sea densities of Marbled Murrelets during the breeding season. Of 33 active Marbled Murrelet nest sites located during the study, we found 15 within forested habitat (tree nest sites), 16 in nonforested habitat (ground nest sites), and 2 that could not be determined. Some nests were located farther inland from the coast (range: 1–52 km) and at higher elevations (range: 42–1,100 m) than previously documented in Alaska. Nesting success to ≥20 days posthatch (0.20 ± 0.07 [SE]) was less than half of similar estimates in British Columbia and more comparable to estimates from California and Washington. A logistic regression found that nest...

LiDAR (Light Detection And Ranging) is an emerging remote-sensing tool that can provide fine-scale data describing vertical complexity of vegetation relevant to species that are responsive to forest structure. We used LiDAR data to estimate occupancy probability for the federally threatened marbled murrelet (Brachyramphus marmoratus) in the Oregon Coast Range of the United States. Our goal was to address the need identified in the Recovery Plan for a more accurate estimate of the availability of nesting habitat by developing occupancy maps based on refined measures of nest-strand structure. We used murrelet occupancy data collected by the Bureau of Land Management Coos Bay District, and canopy metrics calculated from discrete return airborne LiDAR data, to fit a logistic regression model predicting the probability of occupancy. Our final model for stand-level occupancy included distance to coast, and 5 LiDAR-derived variables describing canopy structure. With an area under the curve value (AUC) of 0.74, this model had acceptable discrimination and fair agreement (Cohen's k ¼0.24), especially considering that all sites in our sample were regarded by managers as potential habitat. The LiDAR model provided better discrimination between occupied and unoccupied sites than did a model using variables derived from Gradient Nearest Neighbor maps that were previously reported as important predictors of murrelet occupancy (AUC ¼0.64, k ¼0.12). We also evaluated LiDAR metrics at 11 known murrelet nest sites. Two LiDAR-derived variables accurately discriminated nest sites from random sites (average AUC ¼0.91). LiDAR provided a means of quantifying 3-dimensional canopy structure with variables that are ecologically relevant to murrelet nesting habitat, and have not been as accurately quantified by other mensuration methods. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

The Kittlitz's Murrelet (Brachyramphus brevirostris) has been proposed for listing under the U.S. Endangered Species Act, and is classified as critically endangered by the International Union for the Conservation of Nature (IUCN). A significant portion of the global population occurs in Glacier Bay, Alaska, where steep population declines have been previously reported. To further examine Kittlitz's Murrelet population trends we replicated a 1993 survey in 2009 and 2010 using the same lead observer, the same transect lines, and similar methods. We found the number of Kittlitz's Murrelets unchanged since 1993. Other seabird surveys were conducted in Glacier Bay between 1991 and 2008 by federal agencies, using a variety of sampling designs. We added our surveys to previously published surveys, correcting for percentage of murrelets identified to species to enable comparison. When all surveys were analyzed collectively, the Kittlitz's Murrelet population showed no significant trend between 1991 and 2...

Seabirds are known to associate with marine mammals to facilitate prey capture. These occur when mammals either force prey near the surface or provide small scraps of larger prey victims. Gray whales (Eschrichtius robustus (Lilljeborg, 1861)) have been observed to provide invertebrate prey to a variety of seabird species; however, there are no published reports of Marbled Murrelets (Brachyramphus marmoratus (Gmelin, 1789)) feeding in association with gray whales. We observed Marbled Murrelets foraging within several metres of gray whales off Vancouver Island, British Columbia, feeding on epibenthic zooplankton in 2006 and 2008. Join-count statistics identified significant clustering (p = 0.1) of 258 Marbled Murrelets within 300 m of 39 feeding gray whales in June of 2006, and no association between 3 gray whales and 34 Marbled Murrelets in June and July of 2008, marking a foraging association conditional on the abundance of both gray whales and their prey, but potentially significant to Marbled Murrelet survival and fecundity.

Conserving genetic variation is critical for maintaining the evolutionary potential and viability of a species. Genetic studies seeking to delineate conservation units, however, typically focus on characterizing neutral genetic variation and may not identify populations harboring local adaptations. Here, variation at two major histocompatibility complex (MHC) class II B genes was characterized in four populations of marbled murrelets Brachyramphus marmoratus, a threatened species in which little neutral genetic population structure has been detected. High diversity, as well as evidence of balancing selection, was detected in exon 2 of these genes. Genetic population structure based on MHC markers was uncorrelated to genetic structure estimated with neutral markers, suggesting that selection played a more important role in shaping population structure at these markers than genetic drift. A high proportion of alleles and inferred peptides were unique to a single population, with the Aleutian Islands and southeast Alaska having the highest richness of both. Murrelets sampled in Oregon had low MHC exon 2 allele and inferred peptide richness, and were significantly differentiated from individuals sampled in the Aleutian Islands based on the frequency of exon 2 alleles. In addition, murrelets sampled in Oregon were differentiated from murrelets in both the Aleutian Islands and southeast Alaska based on inferred peptide frequencies, suggesting that the Oregon population could be prioritized for conservation measures. More broadly, combining information from neutral and adaptive genetic markers can improve the delineation of conservation units in threatened species.

Little is known about space use by Common Ravens (Corvus corax) in coastal old-growth redwood (Sequoia sempervirens) forests in northern California despite their identification as nest predators of federally threatened Marbled Murrelets (Brachyramphus marmoratus). We used radio-telemetry to examine home range sizes and space use of breeding Common Ravens in Redwood National and State Parks (RNSP), California, in 2009 (N = 3) and 2010 (N = 8). Mean home range size was 182.5 ha and no home ranges were >2 km from roads or human-use areas. Ravens exhibited high site fidelity between years, and we found little overlap in the home ranges of adjacent ravens. Areas where ranges did overlap were centered on anthropogenic food sources near territory boundaries. Areas most frequently used by ravens were near roads, old-growth edge, bare ground, and in mixed hardwood and prairie habitats; areas near human-use areas and in old-growth habitat were used less by ravens. Mean perch height of ravens (52 m, N = 38) in redwood trees was similar to the mean height of Marbled Murrelet nests in RNSP (48 m). In RNSP, Marbled Murrelet nests that have been located were in old-growth forest within 2 km of roads. The attraction to anthropogenic resources with frequent use of roads and old-growth edges and their tendency to perch high in the canopy may increase the likelihood of ravens locating and predating nests of murrelets in RNSP. RESUMEN Uso del espacio por Corvus corax en habitat de anidacion de Brachyramphus marmoratus en el norte de California Poco se conoce sobre el uso del espacio por Corvus corax en los bosques maduros costeros de Sequoia sempervirens en el norte de California a pesar de que han sido identificados como depredadores de nidos del federalmente amenazado Brachyramphus marmoratus. Usamos radio telemetria para examinar el tamano de los rangos de hogar y el uso del espacio de C. corax en reproduccion en Redwood Parque Nacional y Estatal (RPNS), California, en el 2009 (N = 3) y 2010 (N = 8). El promedio del tamano del rango de hogar fue de 182.5 ha y ningun rango de hogar fue >2 km desde las carreteras o areas usadas por humanos. C. corax mostro una alta fidelidad a lugares entre anos y encontramos poca superposicion en los rangos de hogar de C. corax adyacentes. Areas en donde los rangos se traslaparon se concentraron en fuentes de alimento antropogenico cercanas a los limites del territorio. Las areas usadas con mayor frecuencia por C. corax estuvieron cerca de las carreteras, bordes de los bosques maduros, suelo expuesto y en la mezcla de habitat de pradera y bosque; areas cerca de areas usadas por humanos y habitat de bosque maduro fueron usadas poco por C. corax. La altura promedio de las perchas de C. corax (52 m, N = 38) en arboles de S. sempervirens fueron similares a la altura promedio de los nidos de B. marmoratus en RPNS (48 m). En RPNS, los nidos de B. marmoratus que se han localizado en bosque maduro dentro de un rango de 2 km desde la carretera. La atraccion a recursos antropogenicos con frecuentes usos de carreteras y bordes de bosques maduros, y la tendencia a percharse alto en le dosel puede incrementar la probabilidad de que C. corax localice y deprede nidos de B. marmoratus en RPNS.

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the “zone of disturbance” for Kittlitz’s and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz’s murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship’s larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship’s typical route, we estimated that a minimum of 9.8–19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.

Spatial patterns of marine predator communities are influenced to varying degrees by prey distribution and environmental gradients. We examined physical and biological attributes of an estuarine fjord with strong glacier influence to determine the factors that most influence the structure of predator and prey communities. Our results suggest that some species, such as walleye pollock (Theragra chalcogramma), black-legged kittiwake (Rissa tridactyla), and glaucous-winged gull (Larus glaucescens), were widely distributed across environmental gradients, indicating less specialization, whereas species such as capelin (Mallotus villosus), harbor seal (Phoca vitulina), and Kittlitz's murrelet (Brachyramphus brevirostris) appeared to have more specialized habitat requirements related to glacial influence. We found that upper trophic level communities were well correlated with their mid trophic level prey community, but strong physical gradients in photic depth, temperature, and nutrients played an important role in community structure as well. Mid-trophic level forage fish communities were correlated with the physical gradients more closely than upper trophic levels were, and they showed strong affinity to tidewater glaciers. Silica was closely correlated with the distribution of fish communities, the mechanisms of which deserve further study.

We document here a decline of nearly 30% in the Marbled Murrelet (Brachyramphus marmoratus) population of Washington, Oregon, and northern California between 2000 and 2010. The Northwest Forest Plan is an ecosystem-management plan for federal forest lands in the Pacific Northwest of the United States that incorporates monitoring to determine if species' conservation objectives are met. To evaluate the plan's effectiveness in conserving populations of the murrelet, a species associated with older, late-successional forests, we estimated the murrelet's density in near-shore marine waters of Washington, Oregon, and northern California south to San Francisco Bay. We sampled annually, using line transects and distance estimation. We divided the study area of about 8800 km2 into five geographic subareas corresponding to existing murrelet-conservation zones. Annual population estimates for the plan ranged from an estimated 23 700 (95% CI: 18 300 to 29 000) birds in 2002 to a low of 16 700 (95% CI: 13 1...

Although seabirds search large areas for food, their distributions often correlate with physical characteristics of the marine environment that can serve to aggregate prey. Kittlitz's murrelets Brachyramphus brevirostris are found almost exclusively in Alaskan waters, where they are closely associated with glacial fjords, suggesting that the distribution of this bird might be tightly linked to specific physical habitat characteristics of the fjords. We investigated relation- ships among locations used by Kittlitz's murrelets, water column characteristics, and landscape features in Harriman Fjord and Heather Bay, Prince William Sound, Alaska, USA. In Harriman Fjord, Kittlitz's murrelets were observed in shallow water near upwelling areas, indicated by a cold-water wedge near the surface (~10 m depth) in temperature-depth profiles. In Heather Bay, Kittlitz's murrelets used locations closer to the glacial moraine than the average available habitat. The temperature-depth profiles at these locations showed a cold, fresh surface layer (near surface to 5 m depth); however, the temperature-depth profile variable was statistically insignificant, likely because of small sample size. Although the best temperature-depth profile variables were dramatically different between the 2 fjords, both of these glacially influenced water column char- acteristics may serve to concentrate prey at an optimal depth, allowing Kittlitz's murrelets to focus their effort at predictable foraging locations. Given the widespread wasting of glaciers throughout their range, Kittlitz's murrelets may face increased pressure as changes in water column dynamics within glacial fjords affect the distribution and concentration of preferred prey.

Although nest prospecting, natal philopatry, and nest-site fidelity have been observed in many alcids, few data demonstrate these behaviors in Marbled Murrelets (Brachyramphus marmoratus). Prior to the 2003 breeding season, we installed a permanent video camera adjacent to a Marbled Murrelet nest site that had been used in 2001 and 2002. Video recordings in 2003 detected the simultaneous presence of 3 murrelets in alternate plumage on the nest branch, once during the incubation period, and once during the chick period. We did not observe aggression, suggesting familiarity between the extra-pair birds and site holders, and possibly avoidance of detection by predators. Without banded individuals we hypothesize extra-pair visitations at an active nest reflect nest-site prospecting, natal philopatry, or nest-site fidelity.