Steller's Jays Research Articles

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Deep ecomorphological and genetic divergence in Steller's Jays (Cyanocitta stelleri, Aves: Corvidae).

The relationship between ecology and morphology is a cornerstone of evolutionary biology, and quantifying variation across environments can shed light on processes that give rise to biodiversity. Three morphotypes of the Steller's Jay (Cyanocitta stelleri) occupy different ecoregions in western North America, which vary in climate and landcover. These morphotypes (Coastal, Interior, Rocky Mountain) differ in size, plumage coloration, and head pattern. We sampled 1080 Steller's Jays from 68 populations (plus 11 outgroups) to address three main questions using data on morphology, plumage, genetics (mtDNA, microsatellites), and ecological niches: (1) How do phenotypic and genetic traits vary within and among populations, morphotypes, and ecoregions? (2) How do population-level differences in Steller's Jays compare with other sister species pairs of North American birds? (3) What can we infer about the population history of Steller's Jays in relation to past climates, paleoecology, and niche evolution? We found substantial morphological, genetic, and ecological differentiation among morphotypes. The greatest genetic divergence separated Coastal and Interior morphotypes from the Rocky Mountain morphotype, which was associated with warmer, drier, and more open habitats. Microsatellites revealed additional structure between Coastal and Interior groups. The deep mtDNA split between Coastal/Interior and Rocky Mountain lineages of Steller's Jay (ND2 ~ 7.8%) is older than most North American avian sister species and dates to approximately 4.3mya. Interior and Rocky Mountain morphotypes contact across a narrow zone with steep clines in traits and reduced gene flow. The distribution of the three morphotypes coincides with divergent varieties of ponderosa pine and Douglas fir. Species distribution models support multiple glacial refugia for Steller's Jays. Our integrative dataset combined with extensive geographic sampling provides compelling evidence for recognizing at least two species of Steller's Jay.

KNEMIDOKOPTES MITES AND THEIR EFFECTS ON THE GRIPPING POSITION OF THE FEET OF STELLER'S JAYS (CYANOCITTA STELLERI).

Steller's Jays (Cyanocitta stelleri) with swollen legs and feet resembling the signs of scaly leg have been commonly seen around Arcata, California, US. The clinical signs are thought to be caused by knemidokoptic mites, a group of parasites specialized on avian hosts. Between February 2019 and March 2020, we analyzed the long-term database of Steller's Jays collected by Humboldt State University for trends in the prevalence of signs of scaly leg, compared the gripping position in the feet of Steller's Jays with variable signs of this condition as an index of their ability to perch, identified the mites using a partial sequence of the cytochrome oxidase subunit I gene, and examined genetic distances between mites collected from different host species both sequenced in this study and from GenBank. Overall, 27% of jays recorded in the long-term database had shown signs of scaly leg. Jays with signs captured in this study had greater variability in and a reduced degree of contraction in the gripping position of their feet compared to jays without signs, suggesting that infestation may have an impact on the host's ability to perch. The cytochrome oxidase subunit I sequence (578 base pairs) from mites collected from Steller's Jays was compared to sequences from Knemidokoptes jamaicensis, Knemidokoptes derooi, and to unidentified Knemidokoptes spp. collected from different hosts. The mites from Steller's Jays were most closely related to Knemidokoptes jamaicensis but had a relatively high sequence divergence, 7.8%, supporting the possibility that the form infesting these jays may be an undescribed species.

Human food subsidies drive individual specialization and intrapopulation dietary differences in a generalist predator

AbstractGeneralist species can exhibit individual specialization (IS), where individuals adopt specialized foraging behaviors not attributable to age, sex, or social dominance. While IS increases with the diversity of available foraging resources (ecological opportunity), the potential impact of human food subsidies on ecological opportunity is unknown. We quantified the isotopic niche width of Steller's Jays (Cyanocitta stelleri), a synanthropic predator and dietary generalist, across a gradient of human land‐use categories ranging from subsidized (park campgrounds) to unsubsidized (forest interior) habitats in a protected area in California. We asked (1) if isotopic niche width was better predicted by individual foraging behavior than sex, social dominance, or habitat category (indicating IS) and (2) if degree of IS exhibited by jays increased with the availability of human food subsidies. We characterized the isotopic niche space occupied by individual jays relative to the population using carbon (δ13C) and nitrogen (δ15N) isotope values. Using linear models, we found that jay diet variation was best explained by individual behavior and habitat use rather than by sex or social dominance. While the degree of IS increased with the availability of human foods, individual jays exhibited a variety of foraging behaviors in all habitats that were segregated by foraging stratum and use of human foods. Individual diet also determined the degree of specialization, as jays that specialized on human foods had the narrowest niche width regardless of habitat. Management efforts targeted at generalist wildlife exhibiting large degrees of IS should therefore account for the impact of food subsidies on foraging behavior. Approaches that involve aversive conditioning may fail where highly specialized individuals are unlikely to encounter treatments; therefore, we recommend simultaneous efforts to limit human food subsidies (e.g., information campaigns and improved containment of human food and food waste), and deployment across the largest possible extent of foraging microhabitats and substrates in order to ensure exposure of whole populations to emetic eggs.

Predator-prey interactions in the canopy.

Small mammal abundances are frequently limited by resource availability, but predators can exert strong lethal (mortality) and nonlethal (e.g., nest abandonment) limitations. Artificially increasing resource availability for uncommon small mammals provides a unique opportunity to examine predator–prey interactions. We used remote cameras to monitor 168 nest platforms placed in the live tree canopy (n = 23 young forest stands), primarily for arboreal red tree voles (tree voles; Arborimus longicaudus), over 3 years (n = 15,510 monitoring‐weeks). Tree voles frequently built nests and were detected 37% of monitoring‐weeks, whereas flying squirrels (Glaucomys oregonensis) built nests infrequently but were detected 45% of monitoring‐weeks. Most nest predators were detected infrequently (<1% of monitoring‐weeks) and were positively correlated with tree vole presence. Weasels (Mustela spp.) were highly effective predators of tree voles (n = 8 mortalities; 10% of detections) compared to owls (n = 1), flying squirrels (n = 2), and Steller's jays (n = 1). Tree vole activity decreased from 84.1 (95% confidence interval [CI]: 56.2, 111.9) detections/week 1‐week prior to a weasel detection to 4.7 detections/week (95% CI: 1.7, 7.8) 1‐week postdetection and remained low for at least 12 weeks. Interpretations of predator–prey interactions were highly sensitive to how we binned continuously collected data and model results from our finest bin width were biologically counter‐intuitive. Average annual survival of female tree voles was consistent with a previous study (0.14; 95% CI: −0.04 [0.01], 0.32) and high compared to many terrestrial voles. The relative infrequency of weasel detections and inefficiency of other predators did not provide strong support for the hypothesis that predation per se limited populations. Rather, predation pressure, by reducing occupancy of already scarce nest sites through mortality and nest abandonment, may contribute to long‐term local instability of tree vole populations in young forests. Additional monitoring would be needed to assess this hypothesis.

When protected areas produce source populations of overabundant species

While protected areas are a cornerstone of biodiversity conservation, human activities in these areas can negatively affect native species in direct and indirect ways. However, the potential effects of food subsidies provided by visitors on the local- and landscape-scale population dynamics of overabundant species, and how these effects may be augmented by human development outside of parks, are largely unexplored. Here, we investigated how human foods at heavily-visited sites within California parks benefited populations of Steller's jays (Cyanocitta stelleri), an overabundant predator of a threatened seabird that nests in remnant old-growth forests. Our study population was heavily subsidized with both juveniles and adults consuming substantial amounts of human foods by biomass (46% and 57%, respectively), as indicated by stable isotope analyses. Juvenile survival, adult survival, and fecundity—estimated from radio-telemetry data—were high and the population was projected to grow rapidly (25% annually). Most juveniles dispersed from parks following seasonal declines in human visitation to areas with high housing densities and more stable resources—with almost half of dispersers returning to old-growth forests the following breeding season. Thus, we found that local food subsidies at heavily-visited sites promoted source populations of jays that may bolster populations in old-growth forests at broader spatial scales, and that this effect was likely augmented by more temporally stable resources in developed areas outside of parks during the nonbreeding season. These novel results indicate that curbing populations of overabundant predators may require reductions in food subsidies both within protected areas and surrounding landscapes.

Ravine

Ravine Arthur Sze (bio) Keywords Arthur Sze, poetry Stopping to catch my breath on a switchback,I run my fingers along the leaves of a yucca: each blade curved, sharp, radiating from a core—in this warmest of Novembers, the dead push out of thawing permafrost: in a hugeblotch of black ink that now hangs, framed, on a wall, Gu Cheng wrote the characterfate, and a woman shrugs, "When you look at me, you're far away." Last night, gazingat Orion's belt and sword sparkling in the sky, I saw how we yearn for connection whereno connection exists: what belt, what sword? Glancing at boulders in the ravine, I spota flock of Steller's jays scavenging along the ground; I scavenge among pine needlesto breathe into flame, gaze at yuccas whose blades collect dew at dawnand at dust floating in sunlight above the trail. [End Page 643] Arthur Sze arthur sze's tenth book of poetry, Sight Lines, will be published in 2019 by Copper Canyon Press. He is a recipient of the Jackson Poet Prize from Poets & Writers and was elected to the American Academy of Arts & Sciences. He was a chancellor of the Academy of American Poets from 2012 to 2017. Copyright © 2018 The Massachusetts Review, Inc.

Behavioral mechanisms leading to improved fitness in a subsidized predator.

General mechanisms underlying the distribution and fitness of synanthropic predators in human-influenced landscapes remain unclear. Under the consumer resource-matching hypothesis, synanthropes are expected to distribute themselves among habitats according to resource availability, such that densities are greater in human-subsidized habitats, but mean individual fitness is equal among habitats because of negative density dependence. However, "under-matching" to human food resources can occur, because dominant individuals exclude subordinates from subsidized habitats and realize relatively high fitness. We integrated physiological, behavioral, and demographic information to test resource-matching hypotheses in Steller's jays (Cyanocitta stelleri), a synanthropic nest predator, to understand how behavior and social systems can influence how synanthropes respond to food subsidies. Jays consumed more human foods at subsidized (park campground) sites than jays at unsubsidized (interior forest) sites based on stable isotope analyses. Jays that occurred at higher densities were in better body condition (based on feather growth bars and lipid analyses), and had greater reproductive output at subsidized than unsubsidized sites. Jays with breeding territories in subsidized sites maintained relatively small home ranges that overlapped with multiple conspecifics, and exhibited a social system where dominant individuals typically won contests over food. Thus, jays appeared to be under-matched to prevalent resource subsidies despite high densities and behaviors expected to lead to resource matching. Our results also indicate that local resource subsidies within protected areas can result in source habitats for synanthropes, potentially impacting sensitive species over broader spatial scales.

Serosurvey for West Nile Virus Antibodies in Steller's Jays ( Cyanocitta stelleri ) Captured in Coastal California, USA.

West Nile virus (WNV) was first detected in New York in 1999 and, during its expansion across the continental US, southern Canada, and Mexico, members of the Corvidae (ravens, crows, magpies, and jays) were frequently infected and highly susceptible to the virus. As part of a behavioral study of Steller's Jays ( Cyanocitta stelleri ) conducted from 2011-14 in the coastal California counties of San Mateo and Santa Cruz, 380 Steller's Jays were captured and tested for antibodies to WNV. Using the wild bird immunoglobulin G enzyme linked immunoassay, we failed to detect antibodies to WNV, indicating either that there was no previous exposure to the virus or that exposed birds had died.

Influence of food subsidies on the foraging ecology of a synanthropic species in protected areas

AbstractThe expansion of many synanthropic species is linked to changes in the abundance and distribution of human‐derived foods, and understanding how food subsidies influence the foraging ecology of synanthropes can facilitate reducing impacts to rare species. We combined stable isotope analyses and radiotelemetry information to characterize space‐use and dietary patterns in Steller's jays (Cyanocitta stelleri), a known nest predator of marbled murrelets, sampled at both campground and forest sites in California state parks. We classified jays into four groups based on patterns of space use: (1) campground (jays captured in campgrounds that predominantly used these areas), (2) periphery (jays captured in campgrounds that commonly used adjacent forests), (3) intermediate (jays captured at forest sites that made long‐distance movements between forests and campgrounds), and (4) forest (jays captured and only detected in forests). In the most heavily visited park, human foods comprised more than half of the diet of campground jays based on stable isotopes; moreover, campground jays consumed a greater proportion of human foods than periphery or intermediate jays, which both consumed more human foods than forest jays. Campground jays exhibited a functional response to human foods as park visitation increased, and breeding individuals preferentially provisioned their young with human‐derived foods. Based on space‐use patterns of intermediate jays, we estimated that the “ecological footprint” of campgrounds extended 2 km beyond their spatial footprint. Thus, the impacts of seemingly spatially constrained human recreational activities can have spillover effects on animal communities at relatively broad spatial scales within protected areas.

Steller's Jay (Cyanocitta stelleri) space use and behavior in campground and non-campground sites in coastal redwood forests

ABSTRACT Small-scale disturbance and trash associated with campgrounds may provide opportunities for generalist species in areas important for conservation. We examined the influence of campgrounds on the space use and behavior of Steller's Jays (Cyanocitta stelleri) in Redwood National and State Parks, California, USA. In 2010 and 2011, we used radiotelemetry to monitor the movements of adult male Steller's Jays. We found that home range size of campground jays (16.4 ± 2.6 ha, n = 20) did not differ from non-campground jays (15.0 ± 2.0 ha, n = 10). However, we observed extensive home range overlap among campground jays, possibly contributing to the high density of Steller's Jays previously observed at these sites. Jays roosted alone, primarily in old-growth forest stands away from campgrounds and other human recreation areas. Campground jays regularly commuted between campgrounds and nocturnal roosts. Commuting distance was positively associated with home range size. Campground jays were more frequently ...

Genetic sequence data reveals widespread sharing of Leucocytozoon lineages in corvids.

Leucocytozoon, a widespread hemosporidian blood parasite that infects a broad group of avian families, has been studied in corvids (family: Corvidae) for over a century. Current taxonomic classification indicates that Leucocytozoon sakharoffi infects crows and related Corvus spp., while Leucocytozoon berestneffi infects magpies (Pica spp.) and blue jays (Cyanocitta sp.). This intrafamily host specificity was based on the experimental transmissibility of the parasites, as well as slight differences in their morphology and life cycle development. Genetic sequence data from Leucocytozoon spp. infecting corvids is scarce, and until the present study, sequence data has not been analyzed to confirm the current taxonomic distinctions. Here, we predict the phylogenetic relationships of Leucocytozoon cytochrome b lineages recovered from infected American Crows (Corvus brachyrhynchos), yellow-billed magpies (Pica nuttalli), and Steller's jays (Cyanocitta stelleri) to explore the host specificity pattern of L. sakharoffi and L. berestneffi. Phylogenetic reconstruction revealed a single large clade containing nearly every lineage recovered from the three host species, while showing no evidence of the expected distinction between L. sakharoffi and L. berestneffi. In addition, five of the detected lineages were recovered from both crows and magpies. This absence of the previously described host specificity in corvid Leucocytozoon spp. suggests that L. sakharoffi and L. berestneffi be reexamined from a taxonomic perspective.

Steller sex: infidelity and sexual selection in a social Corvid (Cyanocitta stelleri).

Genetic analysis of avian mating systems has revealed that more than 70% of monogamous species show incidence of offspring parentage that does not match the social partner. Extra-pair parentage (EPP) has been linked to a variety of factors, including size and symmetry of ornamental traits, coloration, resource availability, and local conspecific density. We examined how ornamental plumage traits of individual Steller's jays (Cyanocitta stelleri) and territory characteristics influence genetic fidelity of socially monogamous pairs. We used seven highly polymorphic microsatellite markers to assign paternity to 79 offspring, and identified 12 (15.2%) as extra-pair young (EPY). Steller's jays with extra-pair young had significantly lower values of feather brightness and hue, indicating more ultraviolet-blue shifted coloration, and nested in closer proximity to the forest edge than Steller's jays with no detected EPY. Body size, crest height, asymmetry of ornamental crest stripes, as well as vegetative composition of territories and their proximity to supplemental feeders appeared to have little relationship to EPP. These results indicate that extra-pair parentage plays a role in the evolution of secondary sexual characteristics in both sexes, and suggest local density and availability of resources may influence Steller's jay mating dynamics.

Who's watching influences caching effort in wild Steller's jays (Cyanocitta stelleri).

Steller's jays (Cyanocitta stelleri) often store food and return to retrieve the stored items at a later time. Between caching and consumption, stored food has the potential to be pilfered by conspecific observers. We investigated whether individually marked Steller's jays in suburban neighborhoods of Arcata, California, USA, adjusted cache concealment effort when in the presence of conspecifics. Both male and female jays traveled the shortest distances to cache when alone, traveled further when a mate was present, and traveled furthest when neighbors from adjacent territories were present. These results suggest that Steller's jays recognize and respond to social contexts when concealing food items.

Aversive conditioning of Steller's Jays to improve marbled murrelet nest survival

ABSTRACTPredation 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.

Foraging dynamics in Steller's jays: size and viability of cacheable food items

Several species of birds and mammals cache food items, which in harsh conditions may translate into improved survival or reproductive success. Animals may benefit from evaluating the quality of cache items in terms of size, nutrition and storage viability. Steller’s jays, Cyanocitta stelleri, which cache seeds for later consumption, may handle multiple food items with their beak prior to making a selection. By picking items up, individuals may use visual and tactile cues to evaluate size and shell condition. The number of items an individual jay handles is repeatable, reflecting consistent individual-specific foraging behaviours that may differentiate success at selecting high-quality cache items. In this study we quantified population-level preferences for food items based on size and shell integrity, and individual Steller’s jay sampling behaviour when presented with these choices. Using field trials with free-ranging subjects, we quantified sampling frequency in a variety of choice tests and measured individuals’ success at choosing higher-quality items. We found that Steller’s jays selected items of greater weight and items with intact shells, and preferences for these properties were of comparable magnitude. Jays sampled more nuts during choice sets involving cracked and intact shells, resulting in individuals selecting more profitable nuts for caching. These results may suggest that Steller’s jays evaluate cache items based on both current and future expected energetic values, and that sampling behaviour may enable them to choose more valuable forage items.

Parasites and plumage in Steller's jays: an experimental field test of the parasite-mediated handicap hypothesis

The handicap hypothesis broadly argues that ornamental traits and displays are costly to produce and are a function of individual quality and condition. Consequently, the extent of ornament expression can act as an honest indicator of quality, condition or susceptibility to parasites, and influence the behavior of mates or competitors. We used reflectance spectrometry to quantify non-iridescent, ultraviolet (UV) and blue structurally-based plumage color and character size in relation to individual condition (feather growth rate) and occurrence of disease caused by a parasite infestation (knemidokoptic mange) in wild male Steller's jays (Cyanocitta stelleri). We then attempted to experimentally reduce parasite load prior to molt and quantified the relative change in plumage and condition. Those birds with faster feather growth rates (i.e., in better condition) had lower hues (i.e., reflected shorter wavelengths, displaying a more intense, brilliant UV-blue color), suggesting the possibility of condition or feather growth rate-dependent production of color. We found that UV reflectance (UV chroma) was positively related to the occurrence of disease. We detected no effect of experimental treatment on plumage or condition. In conclusion, our results are suggestive of possible condition-dependent development of structurally-based plumage, and the positive relationship between macro-parasite-caused disease intensity and UV blue plumage color, demonstrated for the first time in this study, did not support the parasite-mediated handicap hypothesis.

Correlates and Consequences of the Pair Bond in Steller's Jays

AbstractIndividuals that maintain pair bonds over multiple breeding attempts are often able to improve reproductive success compared to conspecifics that switch partners. However, the behavioral mechanisms driving this ‘mate familiarity effect’ are still largely unknown. We investigated whether long‐standing pairs in the long‐lived, socially monogamous Steller's jay improved their coordination of movements and behaviors, invested more time in pair bond maintenance, or became more compatible in their tendency to take risks over time compared to newly established pairs. We then compared these pair bond characteristics for successful and unsuccessful partnerships in terms of producing offspring. Jay partners regularly perched together, gave soft contact calls and travelled as a pair even in the non‐breeding season. However, the proportion of observations jay partners spent in each other's company (pair tenacity) was unrelated to risk‐taking behavior of pair members, pair bond duration, or the performance of subtle pair bond maintenance behaviors (i.e., a principle component of behaviors, including soft contact calls, proximity to mates, and frequency of arrival and departure flights with mate). However, evidence suggests that reproductive performance still improved in continuing compared to new pair bonds in Steller's jays. Variation in pair tenacity and frequency of pair bond behaviors may be inconsequential because of jays’ overall high level of contact with partners. Additionally, if jays are able to maximize familiarity early in the pair bond through high overall pair tenacity, the additional benefit of increasing coordination and familiarity with increasing pair bond age may be limited.

Reproduction in Steller's Jays (Cyanocitta stelleri): individual characteristics and behavioral strategies

ABSTRACT. We explored the consequences of male and female explorative and risk-taking behaviors that are components of a behavioral syndrome, as well as basic demographic and physical characteristics of three measures of reproductive performance in Steller's Jays (Cyanocitta stelleri). Older individuals of both sexes performed slightly better in measures of annual reproductive performance. Age was also positively correlated within pairs. In some years, males in better winter body condition performed better, whereas higher-performing females were in worse condition. Because winter body condition was negatively correlated within pairs, males in better condition possibly enabled their mates to invest more in reproduction in a given year, losing more body mass than low-performing females. Overall, variation in individual male and female traits, especially behavioral traits, explained little of the variation in annual reproductive performance. That age was identified as the single most consistent factor, which...

Marbled Murrelet nest predation risk in managed forest landscapes: dynamic fragmentation effects at multiple scales

The effects of forest fragmentation on bird populations have been studied primarily as static phenomena. Yet when forests are allowed to regenerate, local edge contrast and landscape matrix composition change with time, and we would expect fragmentation effects to change accordingly. Describing this process is critical for the conservation of avian species sensitive to forest fragmentation, including the Marbled Murrelet (Brachyramphus marmoratus), a seabird threatened by ongoing harvest of old-growth forest nesting habitat. We experimentally assessed potential murrelet nest predation probability in four regions of southwestern British Columbia, Canada. We compared the fates of 448 simulated murrelet nests at paired edge and interior treatments, at sites with "hard" edges (recent clearcuts), "soft" edges (regenerating forest), and natural edges (i.e., riparian areas). Motion-sensitive digital nest cameras enabled us to focus on known predators of real nests, and patterns of nest fates did not differ between real and simulated nests. Using information-theoretic model selection (AIC) with the combined data set (116 sites), we assessed effects at patch (approximately 13 ha), landscape (approximately 1700 ha), and regional (approximately 96000 ha) scales. Nest disturbance probability at hard edges was 2.5 times that of interior sites, but soft edges had less than half the disturbance probability of interiors. There was no edge effect at natural edges. At the landscape scale, overall avian disturbance risk declined by as much as 50% with increasing amounts of regenerating forest in the surrounding matrix. These results indicate that initially negative fragmentation effects decrease as forests regenerate, at both patch and landscape scales. There was no evidence that these patterns differed between regions. Predator surveys suggested that Steller's Jays drive patterns of nest predation risk at the regional scale. Assuming that corvids are the most important predators, larger reserves of habitat will lessen negative hard-edge effects. Smaller reserves should be embedded in a protective matrix of regenerating forest to reduce predation risk at both patch and landscape scales. Our results suggest that dynamic fragmentation effects are generalizable across widespread regions and can be broadly applied to both murrelet management and the conservation of old-growth forest-breeding birds in general.