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For longer-lived species, individuals hedge their bets by skipping breeding when conditions are poor to preserve the opportunity for future breeding attempts. Thus, understanding the ecological drivers behind the 'choice' to reproduce or not is a key step in identifying and diagnosing causes of population change. We investigated both marine and terrestrial factors that might influence whether Kittlitz's Murrelets Brachyramphus brevirostris--a long-lived seabird of conservation concern that is often associated with glacially-influenced habitats--choose to breed in a given year. We used a suite of proxies to explain variation in reproductive metrics of radio-tagged Kittlitz's Murrelets, exploring three hypotheses related to prey availability, nest depredation risk, and energetic costs of nesting in Icy Bay, Alaska, 2007-2012. In two of the years, we compared results with the locally co-occurring, closely-related Marbled Murrelet B. marmoraus. Across the six-year period of our study, the posterior mean breeding propensity of Kittlitz's Murrelets was 0.21 (95% credible interval [CrI] = 0.15-0.27), nesting success was 0.41 (CrI = 0.25-0.57), and fecundity was 0.04 (CrI = 0.02-0.06). Although none of our three hypotheses were strongly supported by the data, our results collectively suggest that successful nesters expended greater effort than failed nesters and non-nesters to acquire sufficient prey--they stayed longer in the study area, had larger marine core use areas, spent slightly less time diving, and had shorter commuting distances and longer incubation shifts. Also, in years when fecundity was highest, overlap of individual marine core use areas was greatest, suggesting predictable foraging hotspots for murrelets in those years. Importantly, when comparing Brachyramphus species, we found that Marbled Murrelets outperformed Kittlitz's Murrelets reproductively by three to four times in overlapping years, suggesting different drivers of reproduction. From our collective results, we posit that the limitation to reproduction of Kittlitz's Murrelets may not be prey abundance or quality, but instead efficient access to prey. While our associations with indices of prey availability, depredation risk, and energetic costs to nesting did not explain much of the variation in fitness metrics, our study demonstrates the value of using a comparative approach and multiple metrics to diagnose factors limiting a population, especially when data are sparse. For bet-hedging species with complex life histories, we recommend using a combination of integrated modeling and a monitoring framework designed to accumulate evidence across studies to estimate population dynamics and improve inferences about ecological drivers. [ABSTRACT FROM AUTHOR]

The Kittlitz's Murrelet Brachyramphus brevirostris is an uncommon, dispersed-nesting seabird endemic to coastal waters of Alaska and eastern Russia. While the range-wide status of this species is unclear, proximate concerns regarding its viability are driven by low breeding propensity and nesting success. We studied individual and environmental factors associated with the decision to breed and timing of nest initiation of Kittlitz's Murrelets in Icy Bay, Alaska, over a 6-year period between 2007 and 2012. We radio-tagged 191 of 569 individuals captured during the spring pre-breeding period. At the time of capture, nearly all murrelets were exhibiting signs of breeding; most were in alternate plumage, paired, in apparently good body condition, and developing a brood patch. Yet an average of only 20% (range 5%-45%) of the radio-tagged murrelets nested annually. More individuals chose to breed during years with an intense Aleutian low-pressure system (i.e. low North Pacific Index) and low average wind speeds in the spring, with such conditions apparently leading to an earlier and stronger phytoplankton bloom. Our results also indicated a weak, positive association between the peak magnitude of chlorophyll-a and delayed nest initiation. While we infer that the decision to breed and timing of nest initiation are related in part to factors that reflect spring bloom dynamics, we encourage more directed studies on the relationship between environmental conditions during the spring pre-breeding period and the chronically low reproductive output exhibited by this species. [ABSTRACT FROM AUTHOR]

ABSTRACT Conditions in Alaska, USA, pose a challenge for monitoring populations of Brachyramphus murrelets using standard survey methods, because of strong winds, 2 sympatric species, short nights, and variable nesting habitat. We tested 3 methods for monitoring Brachyramphus murrelets breeding in the Kodiak Archipelago, Alaska, in 2010-2012. In addition to standard audio-visual and radar methods, we tested-for the first time with murrelets in Alaska-the application of autonomous acoustic recorders for monitoring vocal activity. We completed 74 radar, 124 audio-visual, and 134 autonomous acoustic surveys, focused on presunrise activity peaks; this yielded 26,375 murrelet detections. Marbled ( B. marmoratus) and Kittlitz's murrelets ( B. brevirostris) could not be distinguished using combinations of radar and acoustic recordings; therefore, at-sea surveys will be required to determine localized species proportions. Of the 3 methods, radar sampled the largest area and detected silently flying murrelets, providing the most reliable data on local populations; however, radar identification of murrelets was unreliable in winds exceeding 18 km/hr. Audio-visual surveys were useful for species identification and to document behaviors associated with local nesting, whereas autonomous acoustic recorders allowed season-long monitoring of murrelet vocal activity. Within potential forest-nesting habitat of marbled murrelets, all 3 methods gave similar measures of presunrise murrelet activity, but only radar reliably sampled murrelets commuting between nest and ocean. Because of their low cost and flexible programming, automated sound recorders offer an affordable way to sample vocal activity prior to more intensive or expensive radar and audio-visual surveys. We recommend that population monitoring and habitat studies of Brachyramphus murrelets in Alaska include combinations of all 3 methods. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT Autonomous sensors and automated analysis have great potential to reduce cost and increase efficacy of wildlife monitoring. By increasing sampling effort, autonomous sensors are powerful at detecting rare and elusive species such as the marbled murrelet ( Brachyramphus marmoratus). New approaches must be tested for comparability to existing methodologies, so we compared the results of inland audio-visual and of automated acoustic monitoring for marbled murrelets, conducted during the 2010 breeding season, at 7 sites in the Santa Cruz Mountains, California, USA. We found automated acoustic surveys and analysis had fewer detections per morning compared with audio-visual surveyors, but the rate of automated acoustic detections per morning was positively and strongly correlated with the rate of audio-visual detections per mornings ( r = 0.96, P < 0.01). Furthermore, acoustic monitoring sampled 10 times more mornings per site ( [ABSTRACT FROM AUTHOR]

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 data to measure the potential bias of abundance estimates resulting from varying identification rates. Overall, the misidentification rate during our field experiment was 0.036 ± 0.004 (SE), with observer experience best explaining the variation. Abundance estimates adjusted for misidentification reflected little bias. The overall partial identification rate was much higher than the misidentification rate (0.211 ± 0.007 SE). Partial identification rates increased in choppy sea states, with greater observation distances, and when murrelets exhibited diving behavior; rates decreased with increased observer experience and when murrelets exhibited flushing behavior. Because observer experience was an important driver of both misidentification and partial identification, we stress the importance of conducting rigorous observer training before and during surveys to increase confidence in species identification and precision in abundance estimates. The methods developed in this study could be modified for any at-sea survey scenario to measure identification rates and the factors influencing these rates. Results may reveal important relationships for adjusting survey protocols to increase confidence in species identification and thereby to increase the precision of abundance estimates. [ABSTRACT FROM AUTHOR]

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%). Across all years, we located 34 Kittlitz's Murrelet nests, 38% of which were successful. Daily nest survival probability (± SE) was 0.979 ± 0.005, with most nests failing during incubation; if extrapolated to a 55-day period from nest initiation to fledging, the nest survival rate was 0.307 ± 0.083. Low fecundity was due largely to low breeding propensity, not low nesting success. For context, we also determined the breeding status of 14 radio-tagged Marbled Murrelets ( B. marmoratus), most of which were breeders (79%) and successfully fledged young (69%). Our data demonstrated that Kittlitz's Murrelets were outperformed in all facets of reproduction compared to Marbled Murrelets. Low fecundity estimates for Kittlitz's Murrelet were consistent with a 10% per annum decline in Icy Bay between 2002 and 2012, suggesting that poor reproductive performance contributed to the local population decline of this species. [ABSTRACT FROM AUTHOR]

ABSTRACT The Kittlitz's murrelet ( Brachyramphus brevirostris) is a small, dispersed-nesting seabird that often occurs in glacially influenced marine waters of Alaska and eastern Russia during the breeding season. Owing to its association with glacial habitats and apparent population declines in some parts of its range, the Kittlitz's murrelet has been the subject of considerable conservation concern in recent years. We present the first-ever estimates of breeding season and annual survival of the Kittlitz's murrelet. We estimated survival by capturing 914 murrelets and radiotagging 191 of them in Icy Bay, Alaska, 2007-2012. We used a multi-state mark-recapture framework to estimate breeding season survival. Daily survival probabilities were similar in the 3 spatial states (Icy Bay, Gulf of Alaska, nest; range = 0.996-0.999), resulting in an overall 60-day breeding season survival probability of 0.89 (SE = 0.04). The only apparent source of fatality of Kittlitz's murrelets during the breeding season was avian predators, specifically bald eagle ( Haliaeetus leucocephalus) and peregrine falcon ( Falco peregrinus). We estimated mean apparent annual survival across all years as 0.80 (SE = 0.33) with a recapture probability of 0.079 (SE = 0.032), resulting in a 305-day non-breeding season survival probability of 0.90 (SE = 0.37). We found that survival was lower than expected based on life-history theory and allometry, and that fatality risk was greater in the breeding season compared to other parts of the year. Our results indicating low survival rates of Kittlitz's murrelets are consistent with the observed decline of 10% per annum in the local population of this species in Icy Bay. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

The article discusses findings of a study to quantify inland activity patterns and flight altitudes of Marbled Murrelets or Brachyramphus marmoratus in Northern California. It notes the threatened species status of the Marbled Murrelet and the effectiveness of using marine radar to measure passage rates and altitudes of murrelets. The research shows that 2,780 murrelets were detected flying towards land during 78 dawn surveys conducted in February to December 2012.

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 hábitat (tree nest sites), 16 in nonforested hábitat (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 ≥2O 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 nesting success did not differ between years, but nesting success was higher for tree nests than for ground nests. Conservation planners should consider that Marbled Murrelets will use certain nonforest hábitat types for nesting in mainland southeast Alaska. Our reported nesting success was likely a maximum, and our results indicate that nesting success can be low even when nesting hábitat is seemingly abundant and marine hábitat appears excellent. [ABSTRACT FROM AUTHOR]

The article focuses on a study which described the historical breeding and at-sea occurrence of Long-billed Murrelets (Brachyramphus perdix) off the coast of the Iburi Region, located in southern Hokkaido, Japan between 2010 and 2011. Information is given on the distribution of the shore bird species on the northern coast of Asia. It also describes the specimens of Long-billed Murrelet at the Natural History Museum of Hokkaido University Botanical Garden.

Highlights: [•] We monitored the abundance and genetic structure of Marbled Murrelets over time. [•] A large apparent decline in abundance was followed by a rapid recovery. [•] Apparent changes in abundance were due local shifts distribution not demographic recovery or immigration. [Copyright &y& Elsevier]

The article evaluates Kittlitz's Murrelet Brachyramphus brevirostris population trend for the initial time frame, from 1986 to 2012, for Prince William Sound, Alaska. It reveals that Prince William Sound had factors that would make the population estimates to be sensitive to misidentification of species. It offers evidence that misidentification took place, and re-analyzes the population trend censoring two years with suspected misidentification. It also explains that analyses made suggest no significant drop of Kittlitz's Murrelets in Prince William Sound.

The article presents a study on whether at-sea distributions of Marbled Murrelets BRachyramphus marmoratus on the southwest coast of Vancouver Island in British Columbia are spatially associated with Gray Whales Eschrichtius robustus. The researchers performed surveys of Marbled Murrelets and whales from a 10.6 meter passenger vessel along a 105 kilometer transect from Bamfield to Port Renfrew. They used the Pythagorean theorem to measure the distance to the nearest whale for every transect segment. They found that varying oceanic conditions may cause changes in the abundance and distribution of Marbled Murrelets.

The article presents a study on the habitat use and spatial distribution of Marbled Murrelets Brachyramphus marmoratus at Port Snettisham in Juneau, Alaska. The researchers used voice recorders to note the numbers of birds sitting on the water within 50 meters on either side of the boat as well as the observation times. They used the Classification and Regression Tree (CART) methods to analyze murrelet distribution with respect to habitat features. They found that Port Snettisham is important for murrelets because they occurred at higher densities than studies of other areas have found.

The article discusses a study of the distribution, abundance and trend estimates of the Kittlitz's Murrelet Brachyramphus brevirostris in Prince William Sound (PWS), Alaska from 1972 and 2007. A population model was developed for the study using the field estimates and variances for Marbled, Kittlitz's and unidentified murrelets. The populations of Brachyramphus murrelets were found to be declining based on field and model estimates. The possible role of a regional, contemporaneous alteration in the environment in the long-term decline of the two species is mentioned. Also emphasized is the need to include the Brachyramphus species in a list of conservation priorities.

The article presents study on the performative molt of Marbled Murrelet (Brachyramphus marmoratus). Study shows that juvenile murrelets may serve as a replacement of the juvenal contour feathers at sea following fledging. It notes that the plumage transition covers the uniform dark brown to black feathers on the upper part of the juveniles' body. This is attributed to the performative molt of at least the feathers of the neck, upper abdomen, chin, and breast. It points out that juveniles need to invest energy in their transition from camouflaged terrestrial juvenal plumage to counter-shaded formative plumage.

The article presents a study which examines the potential of Marbled Murrelet, a seabird, nest predation probability in the regions of southwestern British Columbia. It compares 488 simulated murrelet nests covering the sites with hard edges or recent clearcuts, soft edges or regenerating forests, and natural edges such riparian areas. The study reveals that managed forest landscapes provide risk to Marbles Murrelet nest predation. The results also indicates that dynamic fragmentation decreases as forests regenerate.

Abstract: The molecular phylogenetics of decapod crustaceans has been based on sequence data from a limited number of genes. These have included rapidly evolving mitochondrial genes, which are most appropriate for studies of closely related species, and slowly evolving nuclear ribosomal RNA genes, which have been most useful for resolution of deep branches within the Decapoda. Here we examine the utility of the nuclear gene that encodes arginine kinase for phylogenetic reconstruction at intermediate levels (relationships among genera and families) within the decapod infraorder Brachyura (the true crabs). Analyses based on arginine kinase sequences were compared and combined with those for the mitochondrial cytochrome oxidase I gene. All of the genera in our taxon sample were resolved with high support with arginine kinase data alone. However, some of these genera were grouped into clades that are in conflict with recognized brachyuran families. A phylogeny based on cytochrome oxidase I was consistent with the arginine kinase phylogeny, but with weaker support. A recently proposed measure of phylogenetic informativeness indicated that arginine kinase was generally more informative than cytochrome oxidase I for relationships above the level of genus. Combined analysis of data from both genes provided strong support for clades that are in conflict with current assignments of genera to the families Epialtidae, Mithracidae, Pisidae, and Portunidae. [Copyright &y& Elsevier]

The article examines the abundance patterns of Kittlitz's Murrelet (KM), a rare, non-colonial seabird often associated with tidewater glaciers and a recent candidate for listing under the Endangered Species Act. The authors estimate the abundance of KMs across space and time from at-sea surveys along Alaska coast, and the use these data to develop spatial models to describe abundance patterns and identify environmental factors affecting abundance. Results of the study are discussed, and recommendations for monitoring KMs and other marine species are provided.

1. For the overwhelming majority of species, we lack long-term information on the dynamics of populations. As a consequence, we face considerable uncertainty about how to discriminate among competing hypotheses of population decline and design conservation plans. 2. The marbled murrelet Brachyramphus marmoratus is a small seabird that nests in coastal old-growth forest but feeds year-round in near-shore waters of the north-eastern Pacific. Although a decline in nesting habitat is the primary reason why marbled murrelets are listed as threatened in Canada, nest predation and food availability may also influence population abundance. To examine the hypothesis that murrelet populations are influenced by variation in diet quality, we analysed stable-carbon and -nitrogen isotopes in feathers of museum specimens collected in the Georgia Basin, British Columbia. 3. Between 1889 and 1996, we found a decline in stable isotopic signatures that was approximately equal to a 62% drop in trophic feeding level. We also found that the estimated proportion of fish in murrelet diet was related closely to murrelet abundance over the past 40 years, as estimated from volunteer surveys. Using these isotopic data, we modelled population size as a function of variation in reproductive rate due to changes in diet quality and found that our model matched closely the 40-year field estimates. We then applied our 107-year isotopic record to the model to back-cast estimates of population growth rate to 1889. 4. Our results suggest that, up to the 1950s, murrelet populations in the Georgia Basin were capable of growing and were probably limited by factors other than diet quality. After this period, however, our results imply that murrelets were often, but not solely, limited by diet quality. 5. Synthesis and applications. Protecting nesting habitat may not be sufficient to rebuild populations of this highly secretive and threatened seabird and recovery might also require the restoration of marine habitat quality, as well as a better understanding of how ocean climate affects prey abundance and reproductive rate. Combined with contemporary demographic data, stable isotope analysis of historic samples provides a unique opportunity to reconstruct population histories for species where we lack long-term information. [ABSTRACT FROM AUTHOR]

We estimated annual local survival rates for after-hatch-year (≥1-yr old) marbled murrelets (Brachyramphus marmoratus) in central California using Cormack­Jolly­Seber mark-recapture models and radiotelemetry, and we modeled the effect of oceanographic conditions, sex, and radiotagging. We captured 331 after-hatch-year murrelets from 1997 to 2003, of which 117 were radiotagged. Recapture rates were best modeled using a term that reflected differences in capture effort among sampling occasions (ρeffort) and ranged from 0.068 to 0.166. The most highly ranked model (ΦPDO+radio, ρeffort) indicated that survival rates were positively related to the strength of the Pacific Decadal Oscillation (PDO) and were negatively affected by radiotransmitters in the year following tagging. Mortality was relatively low in warm-water years, perhaps because murrelets flew inland to breed less frequently and were less exposed to avian predators. Two competing models indicated that survival in the year following tagging was affected by (1) only radiotagging (model Φradio, ρeffort), and (2) radiotagging and sex (model Φsex+radio, ρeffort). Model-averaged survival estimates were 0.868 (SE = 0.074) and 0.896 (SE = 0.067) for males and females, respectively, that were not radiotagged and 0.53 1 (SE = 0.175) and 0.572 (SE = 0.181) for males and females, respectively, that were radiotagged. Mortality of radiomarked individuals was greatest during a domoic acid (a neurotoxin in the marine environment) bloom in 1998 (Φ = 0.160–0.400) and radiomarking impacts were much less pronounced during typical years (Φ = 0.724–0.810). Additional causes of mortality included predation by peregrine falcons (Falco peregrinus) and oil spills. Survival for nonmarked individuals was similar or higher than what was estimated for murrelets in British Columbia and what was predicted for murrelets based on comparative analyses of other Alcid species, suggesting that mortality of after-hatch-year murrelets is not an immediate threat to population viability in the region. [ABSTRACT FROM AUTHOR]

We used two metrics, occupancy and relative abundance, to study forest stand characteristics believed to be important to a threatened seabird that nests in old-growth forests, the Marbled Murrelet (Brachyramphus marmoratus). Occupancy refers to murrelet presence or absence based on observed bird behaviors, while relative abundance refers to categories of low, medium, and high numbers of bird observations per survey in a forest stand. Within the murrelet's nesting range in California and southern Oregon, we measured habitat and climatic variables in all old-growth stands surveyed for murrelets between 1991 and 1997. The two bird metrics produced similar results. In California, murrelets most often occupied, or were abundant in, redwood (Sequoia sempervirens) stands with large trees (>100 cm diameter at breast height) located on gentle, low-elevation slopes or on alluvial flats close to streams. In stands of the less flood-tolerant Douglas-fir (Pseudotsuga menziesii) in southern Oregon, murrelets most often occupied, or were abundant on, gentle, low-elevation, west-facing slopes that were not close to streams. Murrelets tended to use areas farther from roads. The important climatic requirements for murrelet stands in both states were cool temperatures and high amounts of rainfall. [ABSTRACT FROM AUTHOR]

We measured flight speeds (n = 3000) of Marbled Murrelet, Brachyramphus marmoratus (J.F. Gmelin, 1789), to determine whether flight speeds of an exceptionably fast bird coincide with the maximum-range speeds (Vmr) predicted by aerodynamic theory. The mean (±SE) speed of 22.6 ± 0.21 m·s–1 was significantly higher than the Vmr predicted by four models, using conventional values for the parasite drag coefficient (CDpar). In order for the Penny cuick model to predict a Vmr of 22 m·s–1, a CDpar of 0.05, which is lower than any previously reported, is necessary; the other models would need to assume even lower values for CDpar. We concluded that the cruising speed of Marbled Murrelets exceeds Vmr. Marbled Murrelets may exceed Vmr as a result of behavioural decisions, and we examined two behavioural hypotheses: that flight speeds exceed Vmr to (1) minimize predation rate and (2) maximize chick growth rate. However, there was no significant difference between flight speeds during high (daylight) and low (darkness) predation periods or between chick-rearing and non-breeding periods. Marbled Murrelets may also appear to fly at a speed that exceeds Vmr because the underlying aerodynamic theory is inaccurate for this species. To examine the reliability of aerodynamic theory for Marble Murrelets, we compared measured wingbeat frequencies (f) to those predicted by Pennycuick's model. The mean f was significantly lower than the fref predicted by Pennycuick's model, and generally, f = 7.9m–0.22 is a better model for auks than Pennycuick's model. In addition, the Strouhal number was particularly low (0.12 ± 0.02). We conclude that the current aerodynamic models are insufficient for an exceptionally fast-flying bird. [ABSTRACT FROM AUTHOR]

Marbled Murrelets (Brachyramphus marmoratus) observed at sea usually are in pairs throughout the year. Although it has been assumed that these pairs are mates, this assumption has not been formally examined. Using data from three study sites during the breeding seasons of 1997-2001, we found that 92% of the birds that were paired at capture were of male-female pairs, and that paired females were more likely (73%) to be producing eggs than were single females (8%). Fourteen of fifteen pairs were tracked to a single nest location per pair. No pair members caught at sea were found breeding at separate nest sites. One pair was caught in two successive seasons, suggesting that at least some pairs are long lasting. Notably, pair members breeding together and radio tracked throughout the summer were detected without their breeding partners for 77% of the time. Thus, while pairs of Marbled Murrelets observed at sea most likely are members of a breeding pair, single murrelets observed at sea should not be assumed to be unpaired or nonbreeders. [ABSTRACT FROM AUTHOR]

Interspecific hybridization can have importantconsequences for conservation, but can bedifficult to detect using morphologicalmarkers. To test the utility of nuclear intronsfor investigating hybridization and geneticintrogression, we analyzed variation in fivenuclear introns and the mitochondrialcytochrome b gene in two species ofseabirds that are declining and may behybridizing: marbled murrelets( Brachyramphus marmoratus) and Kittlitz'smurrelets ( B. brevirostris). No alleleswere shared between samples of the two species,and intron alleles formed reciprocallymonophyletic groups in gene trees. Our resultssuggest that few murrelets in Alaska are F1, F2or back-cross hybrids,and that gene pools of these species have beenindependent for 1.8 to 5.7 million years. Weconclude that introns are a potentially richsource of markers for analyzing hybridizationand introgression in endangered or decliningspecies. [ABSTRACT FROM AUTHOR]

Presents a documentation of Kittlitz's Murrelet (Brachyramphus brevirostris) vocalizations based on recordings made in Glacier Bay, Alaska in 1994. Study area; Comparison with Marbled Murrelet; Results.

The article focuses on a study that analyzed survey data as a part of the Symposium on Population Status and Trends of Kittlitz's Murrelet in Prince William Sound (PWS), Alaska, between 1989 and 2007. The study showed that Brachyramphus murrelets in PWS declined by about 68 percent between 1989 and 2007.