Brachyramphus Marmoratus Research Articles

Predicting regional cumulative effects of future development on coastal ecosystems to support Indigenous governance

Abstract To achieve better biodiversity outcomes and match local governance capacity, cumulative effects assessment frameworks that combine Indigenous and western knowledge to predict future development impacts on biodiversity are needed. We developed a spatial future‐focused model informed by inclusive elicitation and strategic foresight to assess the regional cumulative effects of development on ecosystem health across the land and sea. We collaborated with three First Nations on the Central Coast of British Columbia, Canada, enabling Indigenous priorities, knowledge and values to drive the process, from the choice of priority ecosystem components (including salmon, herring, seabirds and bears), to identifying future development scenarios (based on forestry, energy/mining, tourism and salmon aquaculture sectors). Bayesian networks were populated with empirical data and expert judgement elicited from knowledge holders to predict the cumulative effects of current and future pressures on species and ecosystems. Under current conditions, the lowest probability of persistence was predicted for Pacific salmon (37%), followed by Pacific herring (43%). Under future conditions, the greatest declines in species health were associated with the intense development of mining, tourism and forestry, with up to a 54% decline from the current baseline health estimates predicted for Marbled Murrelets and old‐growth forest. Future outcomes for overall ecosystem health were predicted to be worst in scenarios with high future forestry activities (>60% decline in some areas). The continuation or development of all four industries resulted in an 8% decline overall in ecosystem health across the Central Coast. In contrast, predicted ecosystem health in the tourism economy scenario increased up to 15% in some marine areas, primarily driven by the removal of salmon aquaculture and forestry activities. Synthesis and applications. Our study demonstrates an inclusive, regional approach to assessing the cumulative effects of future development on coastal species. The novel participatory tools and predictive framework draw upon and interweave multiple forms of knowledge, enabling Indigenous values to drive the process, and appropriately integrate Indigenous knowledge into regional cumulative effects assessment. Our interactive web application provides First Nations partners access to all outputs, supporting Indigenous‐led governance and in situ ecosystem‐based management of their lands and water.

Passive acoustic monitoring and convolutional neural networks facilitate high-resolution and broadscale monitoring of a threatened species

Population monitoring is an essential component of biodiversity conservation and management, but low detection probabilities for rare and/or cryptic species makes estimating abundance and occupancy challenging. Passive acoustic monitoring combined with machine learning algorithms represents a potential path forward to effectively and efficiently monitor the occurrence of rare vocalizing species across entire forest landscapes. Our objectives were to develop and implement a convolutional neural network (PNW-Cnet) to identify vocalizations of a rare and threatened forest nesting bird species – the marbled murrelet (Brachyramphus marmoratus) – in the Pacific Northwest, U.S.A., 2018–2021. We used PNW-Cnet predictions from broadscale passive acoustic monitoring data to examine spatiotemporal patterns in the distribution of murrelets. PNW-Cnet showed sufficiently high prediction accuracy (overall precision > 0.9) to enable broadscale population monitoring. Spatiotemporal analysis showed that annual peak murrelet call abundance occurs in ordinal weeks 28–32 (late July–Mid August) but this varied by study area. The greatest number of detections typically occurred in the Olympic Peninsula and Oregon Coast Range where late-successional forest dominates and nearer to ocean habitats. We demonstrate that passive acoustic monitoring can be used to understand intensity of use across broad scales for a rare and cryptic species in addition to the typical detection/non-detection data that are often collected. Passive acoustic monitoring combined with PNW-Cnet offers considerable promise for species distribution modeling and long-term population monitoring for rare species.

Potential Nutritional Effects of Missed Feedings to Marbled Murrelet (Brachyramphus marmoratus) Chicks Due to Disturbance

Potential Nutritional Effects of Missed Feedings to Marbled Murrelet (Brachyramphus marmoratus) Chicks Due to Disturbance

Considerations for a threatened seabird: The impact of shoreline avian predators on at‐sea marbled murrelets

AbstractWe tested the influence of on‐shore avian predators on the at‐sea distribution and abundance of marbled murrelets (Brachyramphus marmoratus) during their breeding season in Haida Gwaii, British Columbia, Canada. We conducted a field experiment using deterrent predator decoy kites that mimicked flying bald eagles (Haliaeetus leucocephalus). In the summers of 2018 and 2019, we conducted at‐sea surveys of murrelet distributions along inshore and offshore transects with and without kites flying, and tallied real eagles along the shoreline and fish schools encountered. Kites negatively influenced overall murrelet counts (estimate = −1.19, 95% CI = −1.88 to −0.51), but we did not detect inshore to offshore movements within the study site. Our results indicate murrelet movement out of the study area in response to the kites. Overall murrelet counts were also lower when real eagle counts were higher (estimate = −0.22, 95% CI = −0.35 to −0.09). When kites were flying, a higher proportion of the murrelets remaining along inshore transects were found between rather than adjacent to kite locations (estimate = −1.61, 95% CI = −2.67 to −0.54), indicating avoidance of kites. Since avian predator populations have steadily increased in the past 30 years throughout the murrelet's breeding range, these avoidance effects could create a negative bias in long‐term shoreline count trends. Our findings highlight the importance of considering non‐lethal predator effects on murrelets when conducting at‐sea censuses and constructing conservation plans.

Marine habitat use and movement in response to ocean warming by a threatened forest-nesting seabird

Although anthropogenic climate change has resulted in significant alterations of ocean environments, the degree to which marine organisms can respond behaviorally to climate effects remains poorly understood, especially for species with increased extinction risk. We monitored marine space use and movement of the threatened marbled murrelet (Brachyramphus marmoratus) along the central coast of Oregon, USA during the 2017–2019 breeding seasons to quantify marine habitat selection patterns across a range of ocean conditions. We hypothesized that marine locations characterized by upwelling, nearshore areas adjacent to old-growth forest nesting habitat, and protected marine areas would be preferentially selected by tagged birds. Using >4800 locations collected from >180 individuals, we found that murrelets selected areas near small estuaries and with localized upwelling (as characterized by decreased sea-surface temperatures and high salinity), both of which are expected to lead to greater food availability during periods when sea-surface temperatures are elevated and coastal upwelling is reduced (i.e., poor ocean conditions). In addition, we found that individuals did not preferentially select marine areas adjacent to potential old-growth nesting habitat, and that murrelets exhibited limited overlap with protected marine areas regardless of ocean conditions. Unexpectedly, the majority (62%) of tagged individuals moved beyond the boundaries of our 135-km long study area in the year with the poorest ocean conditions (2017), with 15% of birds moving >500 km from their capture location. Our results confirm that marine habitat selection in murrelets becomes decoupled from terrestrial nesting habitat during periods of poor ocean conditions, and that such conditions are associated with low breeding propensity and long-distance movements during the breeding season. In addition to demonstrating murrelets undertake fine- and coarse-scale movements to buffer against poor ocean conditions, our study also emphasizes the importance of considering broad spatial scales in the marine environment when undertaking measures to conserve murrelet populations.

Fragmentation effects on an endangered species across a gradient from the interior to edge of its range.

Understanding how habitat fragmentation affects individual species is complicated by challenges associated with quantifying species-specific habitat and spatial variability in fragmentation effects within a species' range. We aggregated a 29-year breeding survey data set for the endangered marbled murrelet (Brachyramphus marmoratus) from >42,000 forest sites throughout the Pacific Northwest (Oregon, Washington, and northern California) of the United States. We built a species distribution model (SDM) in which occupied sites were linked with Landsat imagery to quantify murrelet-specific habitat and then used occupancy models to test the hypotheses that fragmentation negatively affects murrelet breeding distribution and that these effects are amplified with distance from the marine foraging habitat toward the edge of the species' nesting range. Murrelet habitat declined in the Pacific Northwest by 20% since 1988, whereas the proportion of habitat comprising edges increased by 17%, indicating increased fragmentation. Furthermore, fragmentation of murrelet habitat at landscape scales (within 2km of survey stations) negatively affected occupancy of potential breeding sites, and these effects were amplified near the range edge. On the coast, the odds of occupancy decreased by 37% (95% confidence interval [CI] -54 to 12) for each 10% increase in edge habitat (i.e., fragmentation), but at the range edge (88km inland) these odds decreased by 99% (95% CI 98 to 99). Conversely, odds of murrelet occupancy increased by 31% (95% CI 14 to 52) for each 10% increase in local edge habitat (within 100m of survey stations). Avoidance of fragmentation at broad scales but use of locally fragmented habitat with reduced quality may help explain the lack of murrelet population recovery. Further, our results emphasize that fragmentation effects can be nuanced, scale dependent, and geographically variable. Awareness of these nuances is critical for developing landscape-level conservation strategies for species experiencing broad-scale habitat loss and fragmentation.

Cover Picture and Issue Information

Journal of Applied EcologyVolume 60, Issue 4 p. 565-567 COVER PICTURE AND ISSUE INFORMATIONFree Access Cover Picture and Issue Information First published: 04 April 2023 https://doi.org/10.1111/1365-2664.14209AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Cover image: Marbled murrelets (Brachyramphus marmoratus), listed as threatened under the U.S. Endangered Species Act, nest on large moss-covered tree branches in old-growth temperate rainforests. In this issue, Harris and Betts model landscape-scale forest management strategies to assess the tradeoffs between conservation, timber production, and other forest values. (pp. 737–750). Photo: © Brett Lovelace/Oregon State University. Volume60, Issue4April 2023Pages 565-567 RelatedInformation

Aerial hearing thresholds and ecoacoustics of a threatened pursuit-diving seabird, the marbled murrelet Brachyramphus marmoratus

As humans increasingly utilize sensitive coastal areas, diving seabirds like the marbled murrelet Brachyramphus marmoratus face a unique combination of exposure to pervasive anthropogenic sound and acoustically mediated disturbances in terrestrial and marine environments. Despite its threatened status, the sound sensitivities and sensory ecology of this species are unknown, limiting any predictions of the frequencies or sound levels that may induce acoustic impacts. In this study, we measured electrophysiological aerial hearing thresholds for 10 wild individuals captured, sedated, examined inside a field-deployed anechoic chamber and subsequently released. Auditory responses were detected across a 0.5 to 6 kHz frequency range. The median auditory threshold was lowest at 2 kHz (33 dB), while hearing was generally sensitive between 0.75 and 3.8 kHz. B. marmoratus thresholds were elevated compared to other studied alcid species. In-air sensitivities were used to provide an initial prediction of underwater hearing thresholds. To further explore the auditory sensory ecology of this solitary-nesting species, hearing data were also compared to short-term recordings (5 d) of the aerial soundscape of a marbled murrelet nesting habitat. The soundscape contained both abiotic and biotic sounds that contributed to broadband sound levels of 46-55 dB re: 20 µPa rms (0.2-10 kHz). This comparatively quiet habitat enabled relatively frequent detection of anthropogenic sounds within the soundscape. Energy from this acoustic pollution consistently overlapped marbled murrelet sound sensitivities, indicating that the species is susceptible to disturbance from a range of noise types.

Summer movements of marbled murrelets from Canada to Alaska

Knowledge of seasonal marine bird migration patterns is required to inform marine bird conservation and management efforts. We deployed solar-powered satellite transmitters to track the movements of threatened marbled murrelet Brachyramphus marmoratus during the breeding and post breeding periods. We tagged birds (n = 27) in British Columbia (BC), Canada, over 3 years (2014-2016) from 3 different marbled murrelet conservation regions as defined by the species’ recovery strategy. Of 4 tagged birds which provided movement data for more than 57 d, 3 (1 in each year) revealed long-distance movements from BC to Alaska, USA, during breeding or post-breeding periods. The 3 birds which moved northward originated from the 3 different conservation regions. We found limited support for the concept that birds tracked cooler waters as they headed northward. One bird remained in unusually warm waters near the capture sight in Desolation Sound in 2016. Importantly, the arrival of BC birds in Alaska during summer could contribute to at-sea survey estimates of marbled murrelet abundance during the Alaska breeding season, and their occcurence in Alaska has implications for BC populations with respect to anthropogenic threats in the marine habitat, including the potential for incidental take in gillnet fisheries and risks from oiling. Our results demonstrate connectivity between BC and Alaska marbled murrelet populations. Overall, tracking duration was relatively short, and locations were confined to the deployment areas in BC. Our results indicate capture and tagging impacted study individuals and may have contributed to increased mortality. Our research, coupled with that of others, suggests that long-distance northerly migrations patterns may not be unusual in Brachyramphus murrelets.

Impacts of lost fishing nets in the U.S. portion of the Salish Sea

The negative impact of lost (or derelict) gillnets on marine species and habitats has been reported for decades in the U.S. portion of the Salish Sea. Impacts of derelict nets are recognized as stressors to taxa listed under the U.S. Endangered Species Act (ESA), including rockfish and marbled murrelet. This study reports results from a concerted effort to remove derelict nets from the marine environment conducted using diver retrieval methods from 2002 through 2021. Also reported are results from a Reporting, Response, and Retrieval (RRR) Program designed to retrieve newly lost nets that was implemented in 2012. A total of 5638 unique derelict nets or portions of nets was removed. Nets measured a total of 11.6 km2. The majority of nets were recovered from habitats of boulders on sand/mud/gravel, followed by low-relief rocky substrate, and high-relief rocky substrate. Age, water depth, and suspension in the water column are reported for all nets removed. A total of 126,308 individual species impacts representing 119 unique species were documented including commercially and recreationally harvested species. The RRR Program has received 124 reports since 2012 and has proved effective at reducing re-accumulation and long-term species and habitat impacts from lost fishing nets. Recommendations to increase its effectiveness include continued outreach to fishers to encourage compliance with the mandated reporting coupled with increased penalties for not reporting. Systematic retrieval of derelict nets coupled with a program to rapidly retrieve newly lost nets could serve as a model for other coastal net fisheries.

Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines.

The marbled murrelet (Brachyramphus marmoratus) is classified as a threatened species under the US Endangered Species Act in Washington, Oregon, and California USA due to population declines, loss of breeding habitat, and other factors. To date, population assessments have focused on breeding season at-sea surveys. Consequently, there is little information on this species’ distribution, abundance, and population trends during the non-breeding season, when murrelets are found exclusively in the marine environment. To address this information need, we assessed non-breeding (Sep—Mar) at-sea murrelet abundance patterns and population trends over 8 years, in a portion of its range where breeding season surveys indicate a 20-year population decline, Puget Sound, Washington, USA. This allowed us to assess whether non-breeding population trends mirrored those observed during the breeding season suggesting regional year-round conservation concerns and to also identify important over-wintering areas (areas of high abundance). We integrated our non-breeding abundance information with breeding season information to assess year-round patterns of abundance. This allowed us to test the prediction that murrelets move into the relatively protected inner marine waters of Puget Sound from harsher outer coastal habitats during the non-breeding season to molt and over-winter. Similar to trends from the breeding season, we observed strong murrelet density declines across the entire non-breeding period (Sep and Apr) with declines most pronounced in the fall and early winter (lateSep–Dec) survey windows when birds molt and in the spring just prior to breeding (Mar-Apr). Despite these declines, there was essentially no change in murrelet density in mid-winter (January—February) when overall density was lower. Puget Sound murrelet density exhibited a strong north-south gradient with relatively high densities to the north and low densities to the south; murrelets were largely absent from Central Puget Sound. For strata other than Central Puget Sound, density varied seasonally with birds more evenly distributed among strata between September and December but in the late winter/early spring period (Jan–Apr), murrelets were largely absent from all strata except the most northerly Admiralty Inlet Stratum, which appears to be important to murrelets year-round. Depending on the year, non-breeding season densities were nearly the same or higher than breeding season densities indicate that murrelets were not moving into the relatively protected inner marine waters of Puget Sound from more outer coastal environments during the non-breeding season as predicted.

POPULATION TRENDS AND VITAL RATES FOR MARBLED MURRELET (BRACHYRAMPHUS MARMORATUS) IN THE PACIFIC NORTHWEST, USA

The Marbled Murrelet (Brachyramphus marmoratus) is a small seabird found on the western coast of North America, listed as federally threatened in the US. It has been in decline for a prolonged period over most of its range. To better understand this population trend, we analyzed relative abundance from at-sea survey transects of Marbled Murrelets throughout the California, Oregon, and Washington region, 2001–2017. We assessed the consistency of trends at different spatial extents, evidence of among-region movements, and consistency between long-term trends and published estimates of demographic parameters. Yearly changes in population survey estimates in Oregon and northern California versus Washington were negatively correlated, suggesting significant bird movement between the 2 regions. Observed declines in the north and gains in the south may be due to Marbled Murrelet movements rather than differing regional demographics. Annual fluctuations were, in some cases, greater than what observed at-sea recruitment rates would allow for the species, especially at the state and zone scales, and were more variable by year in smaller regions. Trends for smaller spatial extents did not align with the 3-state stable trend estimate, suggesting that larger survey regions may be more reliable. The lifespan/recruitment rate scenarios that would allow persistence (λ=1) were also evaluated. Recruitment levels of 0.06/y require a longevity of 16.7 y for population stability, whereas a 0.1/y recruitment only requires a 10-y lifespan. Better resolution of Marbled Murrelet movement and vital rates is needed to resolve the contradiction between demographic analyses that project population declines and the observed stability of Marbled Murrelets quantified through the 3-state at-sea survey transects.

Marbled Murrelets prefer stratified waters close to freshwater inputs in Haida Gwaii, British Columbia, Canada

Abstract 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.

Assessing the effectiveness of a forest Habitat Conservation Plan for a threatened seabird, the Marbled Murrelet

Abstract 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.

Experimental evidence that social information affects habitat selection in Marbled Murrelets

Abstract Habitat selection decisions can impact individual fitness and ultimately scale up to mediate population dynamics. Understanding how birds select habitat is thus critical for discerning the biological processes structuring populations and for developing conservation strategies, particularly for species in decline. Marbled Murrelet (Brachyramphus marmoratus; hereafter murrelet) populations have declined in recent decades due to loss of late-successional forest nesting habitat and changing ocean conditions that impact foraging success. Most other seabirds in the family Alcidae nest colonially and evidence suggests nesting murrelets may aggregate in stands, yet no studies have examined murrelet use of social information in nest-site selection. In 2016, we experimentally simulated the presence of murrelets at 14 randomly chosen potential breeding sites by broadcasting murrelet calls throughout the breeding period. Between broadcasting bouts, we recorded calls of wild murrelets and compared call rates with those recorded at 14 control sites (no broadcast). One year after playbacks ceased (2017) we conducted breeding season surveys to document behaviors indicative of murrelet breeding activity. Broadcasting murrelet calls in 2016 increased daily odds of wild murrelets vocalizing during the treatment period by up to 15.4× (95% CI: 2.3, 125.4) relative to control sites. During the 2017 breeding season, the odds of occupancy were 10.0× (CI: 1.2, 81.4) greater at treatment sites than control sites. These results indicate that social information influences murrelet breeding site selection because the simulated conspecific presence in potential nesting habitat appeared to attract prospectors in 2016 that continued occupying treatment sites the following year. This conspecific attraction implies murrelet nesting sites are likely to remain occupied over time and that large tracts of nesting habitat may be important for supporting murrelet populations. Murrelets may also be susceptible to information-mediated Allee effects whereby a lack of conspecific information about nesting habitat could exacerbate long-term population declines.

Modelling entanglement rates to estimate mortality of marine birds in British Columbia commercial salmon gillnet fisheries

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 <2% of cumulative effort 2001–2016) and in time (being available only from 1995 onwards and only for a small number of areas). Using onboard fishery observer data from commercial, test and experimental fisheries (1995–2016), we developed two models to estimate the number of marine birds captured per set in sockeye (Oncorhynchus nerka) and chum (O. keta) salmon gillnet fisheries employing a Generalized Linear Mixed Modeling (GLMM) approach in a hierarchical Bayesian framework, with observer data post-stratified by fisheries management area and year. Using estimates of total commercial fishing effort (estimated number of sets, 2001–2016) we applied the models to extrapolate annual take for the main bird species (or groups) of interest. Multinomial probability estimates of species composition were calculated based upon a sample of 852 birds identified to species that were associated with sockeye or chum fisheries, enabling estimates (with CIs) of potential numbers of the mostly commonly observed species (common murres (Uria aalge), rhinoceros auklets (Cerorhinca monocerata), and marbled murrelets (Brachyramphus marmoratus)) entangled annually in commercial sockeye and chum salmon gillnet fisheries throughout BC. Conservative estimates of annual losses to entanglement were greatest for common murres (2,846, 95% CI: 2,628–3,047), followed by rhinoceros auklets (641, CI: 549–770) and marbled murrelets (228 CI: 156–346). Populations of all three of these alcids species are currently in decline in BC and entanglement mortality is a conservation concern. Gillnet mortality has been identified as a longstanding threat to marbled murrelet populations, which are recognized as Threatened in the Canada and the United States of America (USA). In addition, 622 (CI: 458–827) birds from 12 other species were estimated to be entangled annually. We conclude that cumulative mortality from incidental take in salmon gillnet fisheries is one of the largest sources of human-induced mortality for marine birds in BC waters, a conservation concern impacting both breeders and visiting migrants.

Squeezed by a habitat split: Warm ocean conditions and old‐forest loss interact to reduce long‐term occupancy of a threatened seabird

AbstractTheory predicts that species requiring multiple habitat types simultaneously should have heightened sensitivity to anthropogenic pressures, yet tests of this prediction are especially rare. We tested whether breeding site occupancy of the threatened marbled murrelet (Brachyramphus marmoratus) was driven by the synergistic effects of nesting habitat loss in forests, and changing ocean conditions. We paired 70,700 murrelet surveys at 19,837 sites across 20 years from the Oregon Coast Range with annual data on the extent of old forest and biophysical ocean conditions. Dynamic occupancy models indicated that local murrelet colonization rates were strongly reduced during warm ocean conditions with low prey availability. Landscapes that contained more old forest and were closer to the ocean showed reduced rates of local extinction. Given predictions of accelerated ocean warming and increased global timber demand, our results suggest murrelets may continue to be imperiled by deterioration of the two habitats upon which they depend.

Marine bird response to forage fish during winter in subarctic bays

AbstractDespite the importance of understanding marine bird response to prey fish, few studies have examined this relationship during winter. Over a 5‐year period, we conducted synoptic marine bird and hydroacoustic forage fish surveys during early (November) and late (March) winter to characterize the factors influencing marine bird and forage fish dynamics at two spatial scales (fish school and bay) within subarctic bays of coastal Alaska, USA. Over 40% of observed marine birds were associated with a fish school (within 150 m of a fish school), although only 20% of fish schools were associated with birds. Seasonally, we recorded significantly more schools during early winter. The marine bird community also shifted from being comprised primarily of marbled murrelets (Brachyramphus marmoratus) and large gulls (Larus spp.) in early winter to common murres (Uria aalge) in late winter. At the school level, marine birds were more likely to be associated with shallow fish schools within 500 m of shore and in smaller prey patches. At the bay level, gull abundance was positively associated with the total number of fish schools recorded, while diving birds were more abundant when fish schools were higher in the water column, in shallower bottom depths, and in areas with more eel grass habitat. Our results indicate the importance of temporal, habitat, and fish school variables as drivers of marine bird presence and abundance, underscoring the complexity of predator–prey dynamics in the marine environment during winter.

Collision and displacement vulnerability to offshore wind energy infrastructure among marine birds of the Pacific Outer Continental Shelf

Marine birds are vulnerable to collision with and displacement by offshore wind energy infrastructure (OWEI). Here we present the first assessment of marine bird vulnerability to potential OWEI in the California Current System portion of the U.S. Pacific Outer Continental Shelf (POCS). Using population size, demography, life history, flight heights, and avoidance behavior for 62 seabird and 19 marine water bird species that occur in the POCS, we present and apply equations to calculate Population Vulnerability, Collision Vulnerability, and Displacement Vulnerability to OWEI for each species. Species with greatest Population vulnerability included those listed as species of concern (e.g., Least Tern [Sternula antillarum], Marbled Murrelet [Brachyramphus marmoratus], Pink-footed Shearwater [Puffinus creatopus]) and resident year-round species with small population sizes (e.g., Ashy Storm-Petrel [Oceanodroma homochroa], Brandt's Cormorant [Phalacrocorax penicillatus], and Brown Pelican [Pelecanus occidentalis]). Species groups with the greatest Collision Vulnerability included jaegers/skuas, pelicans, terns and gulls that spend significant amounts of time flying at rotor sweep zone height and don't show macro-avoidance behavior (avoidance of entire OWEI area). Species groups with the greatest Displacement Vulnerability show high macro-avoidance behavior and low habitat flexibility and included loons, grebes, sea ducks, and alcids. Using at-sea survey data from the southern POCS, we combined species-specific vulnerabilities described above with at-sea species densities to assess vulnerabilities spatially. Spatial vulnerability densities were greatest in areas with high species densities (e.g., near-shore areas) and locations where species with high vulnerability were found in abundance. Our vulnerability assessment helps understand and minimize potential impacts of OWEI infrastructure on marine birds in the POCS and could inform management decisions.

The Reliability and Application of Methods Used to Predict Suitable Nesting Habitat for Marbled Murrelets

Identifying and mapping suitable nesting habitat within coastal forests is a key element in the recovery and management of the Marbled Murrelet (Brachyramphus marmoratus), which is listed as Threatened in Canada. This article reviews the reliability and application of three primary methods used to assess habitat suitability: the BC Model, a GIS-based algorithm using Vegetation Resources Inventory (VRI); air photo interpretation (API), direct assessments from air photos based on forest structure; and low-level aerial surveys (LLAS), helicopter surveys assessing forest canopy structure and the presence of potential nest platforms. In general, LLAS provides the most reliable identification and is the only method of the three that estimates the occurrence of potential nest platforms in the forest canopy. The other two methods, API and the BC Model, are substantially less reliable in identifying habitat actually used by nesting murrelets. Spatial scale and survey intensity affect habitat classification using all three methods. Generally, fine-scale (~3 ha), high-intensity classifications with LLAS and API are more likely to detect suitable habitat at known nest sites than those using medium-scale (10s or 100s ha) and/or low-intensity classifications. Even with fine-scale high-intensity application, 15% and 25% of known nest sites were still classified as “unsuitable” habitat with LLAS and API, respectively. All three methods applied at the medium scale for mapping appeared to miss fine-scale nesting habitat (i.e., small numbers of suitable trees occurring in otherwise unsuitable habitat). Areas of mapped suitable habitat can therefore be adjusted to take this discrepancy into account, and methods to do this are discussed.