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The biotic and abiotic factors responsible for determining ranges of most species are poorly understood. The Canada Jay (Perisoreus canadensis (Linnaeus, 1766)) relies on perishable cached food for over-winter survival and late-winter breeding and the persistence of cached food could be a driver of range limits. We confirmed that the Canada Jay’s lower elevational limit on Vancouver Island, British Columbia, Canada, matches that of the subalpine zone (900 m) and then conducted simulated caching experiments to examine the influence of antimicrobial properties of subalpine tree species (biotic) and of temperature (abiotic) on the preservation of cached food. We found that two high-elevation species, yellow cedar (Callitropsis nootkatensis (D. Don) D.P. Little) and Amabilis fir (Abies amabilis Douglas ex J. Forbes), preserved cached blueberries and chicken flesh better than other trees, but they also occurred well below the lower limit of Canada Jays. The effect of temperature was similarly unclear; while food cached at 1150 m retained 17% more mass than food cached at 550 m, there was no difference in percent mass remaining of food placed 70 m above versus 120 m below the Canada Jay’s lower elevational limit. Thus, we were unable to provide definitive evidence that either of the proposed abiotic or biotic factors was responsible for setting thelower elevational limit of resident Canada Jays.

Breeding dispersal can influence fitness as well as the dynamics and genetic architecture of populations, but the patterns and causes of dispersal in most species are still poorly understood. Here, we used 55 years of re-sighting and breeding data from 530 individually marked adult Canada jays at the southern edge of their range in Algonquin Provincial Park, Ontario, Canada to evaluate factors that influence the probability of breeding dispersal occurrences and distances. Breeding dispersal within the study area was rare, occurring in 3% (N = 81) of the 2477 cases in which individuals were observed defending a territory in consecutive years, and only 13% (N = 68) of individuals dispersed at least once in their lifetime (mean age of dispersers = 4.75 ± 2.8). Of the 81 breeding dispersal cases, 68% (N = 55) involved a single bird, while the remaining 32% (N = 26) involved 13 cases of a mated pair dispersing together. The probability of breeding dispersal was similar between sexes, but females tended to disperse farther. Surprisingly, almost half of breeding dispersal events occurred during the autumn and winter when all or most food had already been cached. However, 70% (N = 57) of breeding dispersal events involved settlement on a neighbouring territory, which may have allowed adults to retrieve previously cached food on their original territory. Overall, adults were most likely to disperse locally when they lost a mate, had originally occupied a lower-quality territory, and a vacant position was available nearby. While the distance and rates of breeding dispersal did not change over time (N = 55), breeding dispersal events caused by mate loss, were highest in years with the steepest population decline, suggesting that a diminishing pool of mate replacements influenced breeding dispersal decisions.

Food caching is a behaviour used by a variety of birds and mammals and can be an essential strategy for surviving food-scarce periods. Ensuring that cached food remains available for later recovery is critical to the fitness of caching individuals. Cache robbers, conspecific or heterospecific individuals that remove and consume food stored by the original cacher, present a unique threat to food-caching individuals. Accordingly, caching species have evolved a variety of cache protection strategies to limit the potential risk of cache robbery. We assessed these cache protection strategies in Canada jays, year-round residents of Canada and the western United States that rely on cached food to survive food-scarce winters. We evaluated caching behaviour and movement patterns of captive Canada jays in caching contexts that varied in potential risk of cache robbing: presence versus absence of a model cache robber and visual cover from the cache robber. We found that depending on perceived risk, Canada jays flexibly used a variety of nonmutually exclusive cache protection strategies including cache depression, out-of-sight caching and spacing. These cache protection strategies likely reduce the risk of cache robbing and increase the probability of caches remaining available for recovery and consumption.

Avian and mammalian colours are thought to be constant in life and in museum specimens, but several early 20th-century taxonomists singled out the Canada Jay (Perisoreus canadensis (Linnaeus, 1766)) as having unstable feather pigments and warned against using old museum specimens for taxonomic purposes. One such error was Brisson’s (1760) original naming of the species as “the Brown Jay of Canada”. Another was Ridgway’s (1899) naming of the “Gray Jay” as a new subspecies, Perisoreus (canadensis) griseus, through inappropriate comparison of fresh grey specimens with old brown ones. We discovered that browning of initially grey plumage also occurs between annual moults in living individuals of the Canada Jay’s Pacific morphotype. We documented this change using photographs and re-sightings of colour-banded individuals and through spectral analysis of year-old (brown) and incoming (grey) rectrices collected from the same moulting individuals. To assess the distribution of this colour change, we compared September vs. May eBird photographs from across North America. We showed that seasonal colour change is normal in the Pacific morphotype but rare in the two other morphotypes. Collectively, these data have important implications for the taxonomy of the Canada Jay and are a cautionary tale for taxonomists studying animal colouration.

Three distinct Canada jay (Perisoreus canadensis) morphotypes with easily recognizable plumage traits come into contact in western North America. Recent work demonstrated high genetic structure across the species’ range; however, patterns of genetic variation in these contact zones remain unknown. We categorized 605 individuals into one of three morphotypes (Pacific, Rocky Mountain, and Boreal) based on plumage, and genotyped individuals at the mtDNA control region and 12 microsatellite loci to assess the extent of hybridization between morphotypes. Our data showed cryptic genetic diversity and high cytonuclear discordance among morphotypes within contact zones, which is likely the result of recent and historical admixture. The distributions of the Boreal and Pacific morphotypes each showed a strong association with a single, distinct genetic group, whereas the Rocky Mountain morphotype exhibited higher genetic diversity and was associated with multiple genotypes. Our analyses show the importance of considering both plumage and genetic traits when examining contact zones between closely related taxa. Finally the data presented in this study reaffirm that the Pacific morphotype is distinct from the Boreal and Rocky Mountain morphotypes based on genetic, phenotypic and ecological data, indicating that the Pacific morphotype should be re-elevated to a full species.

Understanding how events throughout the annual cycle are linked is important for predicting variation in individual fitness, but whether and how carry-over effects scale up to influence population dynamics is poorly understood. Using 38 years of demographic data from Algonquin Provincial Park, Ontario, and a full annual cycle integrated population model, we examined the influence of environmental conditions and density on the population growth rate of Canada jays (Perisoreus canadensis), a resident boreal passerine that relies on perishable cached food for over-winter survival and late-winter breeding. Our results demonstrate that fall environmental variables, most notably the number of freeze-thaw events, carried over to influence late-winter fecundity, which, in turn, was the main vital rate driving population growth. These results are consistent with the hypothesis that warmer and more variable fall conditions accelerate the degradation of perishable stored food that is relied upon for successful reproduction. Future warming during the fall and winter may compromise the viability of cached food that requires consistent subzero temperatures for effective preservation, potentially exacerbating climate-driven carry-over effects that impact long-term population dynamics.

New breeding records for 10 species of tundra and boreal nesting birds were documented near the community of Kugluktuk (Nunavut, Canada) over the course of the 2015 and 2016 breeding seasons and incidentally in 2017 and 2018. These species include American Wigeon (Mareca americana), Mallard (Anas platyrhynchos), Northern Shoveler (Anas clypeata), Green-winged Teal (Anas carolinensis), Greater Scaup (Aythya marila), Say’s Phoebe (Sayornis saya), Canada Jay (Perisoreus canadensis), Greycheeked Thrush (Catharus minimus), Yellow-rumped Warbler (Setophaga coronata), and Dark-eyed Junco (Junco hyemalis). Previously unpublished breeding evidence for Bald Eagle (Haliaeetus leucocephalus) is also discussed along with suspected breeding of Barn Swallow (Hirundo rustica), Bohemian Waxwing (Bombycilla garrulus), White-throated Sparrow (Zonotrichia albicollis), and Pine Grosbeak (Pinicola enucleator). These records represent the first described breeding occurrences for these species in the Kitikmeot region, or new records for the mainland of Nunavut. A lack of historical ornithological survey effort in this area has likely led to the diversity of these previously unrecorded breeding observations. These results highlight the need to increase geographic coverage of bird surveys in northern Canada to more accurately delineate the northern limit of breeding ranges and suggest that further formal survey effort will undoubtedly lead to additional new breeding records.

While many animals rely on stored food to survive periods of no or few resources, some of these species may also use cached food to feed young. The Canada Jay (Perisoreus canadensis (Linnaeus, 1766)) is a territorial, food-caching resident of North American boreal forests. Canada Jays have high winter survival when fresh food is rarely available and achieve high fledging rates before the return and breeding of most sympatric migratory passerines. Stored food must account for the Canada Jay’s winter survival, but it is less certain that stores are also used to feed nestlings. We conducted two experiments seeking evidence of such use, one using food marked with dye and a second using 15N-enriched glycine. Breeding pairs were supplemented with marked food in the pre-incubation period, followed by our attempts to find the marker in nestling feces (dye experiment) or feathers (15N-enrichment experiment). Both experiments provided evidence that at least some nestlings had ingested the marker, although the importance of this behaviour within the population remains unknown. Our study demonstrates how food markers can be used to infer feeding behaviour that has not been directly recorded in the wild, even after over 50 years of close observation.

Despite the interest of birds in reconstructing ancient environments, there are but few works concerning Quaternary avian remains. We have the opportunity to show in the present paper, the fossil avian remains of one of the more interesting natural, high-mountanous regions in southern Europe: the Spanish Pyrenees. In the central part of the Pyrenees, in the province of Huesca, Spain, five new paleontological sites with bird remains have been described: La Brecha del Rincon B-9 cave, the B-8 cave (Secus Range), Los Batanes C-4 (Tendenera Range), and C-15 and D-2 (Lecherines System). Their ages range from the Upper Pleistocene up to the Holocene. At least twenty three taxa are recorded: Galliformes indet., Lagopus muta , Coturnix coturnix , Bonasa bonasia , Rallus aquaticus , Columba oenas , Columba palumbus , Columba sp., Passeriformes indet., Ficedula hypoleuca , Ficedula sp., Lanius sp., Coccothraustes coccothraustes , Phoenicurus ochruros, Oenanthe oenanthe , Corvidae indet., cf. Perisoreus infaustus , Corvus frugilegus , Corvus monedula , Pyrrhocorax sp., Pyrrhocorax pyrrhocorax , Pyrrhocorax graculus , and Aves indet. In this work we present the highest-altitude paleontological record for Coturnix coturnix, Bonasa bonasia, Columba palumbus, and Corvus frugilegus, and the southernmost record of cf. Perisoreus infaustus . The new data go some way towards filling the gap in our information on avian assemblages in the Aragonese Pyrenees (especially by comparison with the vast knowledge that exist on the avian assemblages of the French Pyrenees sites) as well as the gap in what is known about avian assemblages in high-mountain systems, for La Brecha del Rincon B-9 and B-8 are the highest-altitude avian paleontological assemblages described in the Pyrenees Range.

An increasing body of studies of widely distributed, high latitude species shows a variety of refugial locations and population genetic patterns. We examined the effects of glaciations and dispersal barriers on the population genetic patterns of a widely distributed, high latitude, resident corvid, the gray jay (Perisoreus canadensis), using the highly variable mitochondrial DNA (mtDNA) control region and microsatellite markers combined with species distribution modeling. We sequenced 914 bp of mtDNA control region for 375 individuals from 37 populations and screened seven loci for 402 individuals from 27 populations across the gray jay range. We used species distribution modeling and a range of phylogeographic analyses (haplotype diversity, ΦST, SAMOVA, FST, Bayesian clustering analyses) to examine evolutionary history and population genetic structure. MtDNA and microsatellite markers revealed significant genetic differentiation among populations with high concordance between markers. Paleodistribution models supported at least five potential areas of suitable gray jay habitat during the last glacial maximum and revealed distributions similar to the gray jay's contemporary during the last interglacial. Colonization from and prolonged isolation in multiple refugia is evident. Historical climatic fluctuations, the presence of multiple dispersal barriers, and highly restricted gene flow appear to be responsible for strong genetic diversification and differentiation in gray jays.

Timing of reproduction can influence individual fitness whereby early breeders tend to have higher reproductive success than late breeders. However, the fitness consequences of timing of breeding may also be influenced by environmental conditions after the commencement of breeding. We tested whether ambient temperatures during the incubation and early nestling periods modulated the effect of laying date on brood size and dominant juvenile survival in gray jays (Perisoreus canadensis), a sedentary boreal species whose late winter nesting depends, in part, on caches of perishable food. Previous evidence has suggested that warmer temperatures degrade the quality of these food hoards, and we asked whether warmer ambient temperatures during the incubation and early nestling periods would be associated with smaller brood sizes and lower summer survival of dominant juveniles. We used 38 years of data from a range‐edge population of gray jays in Algonquin Provincial Park, Ontario, where the population has declined over 50% since the study began. Consistent with the “hoard‐rot” hypothesis, we found that cold temperatures during incubation were associated with larger brood sizes in later breeding attempts, but temperatures had little effect on brood size for females breeding early in the season. This is the first evidence that laying date and temperature during incubation interactively influence brood size in any bird species. We did not find evidence that ambient temperatures during the incubation period or early part of the nestling period influenced summer survival of dominant juveniles. Our findings provide evidence that warming temperatures are associated with some aspects of reduced reproductive performance in a species that is reliant on cold temperatures to store perishable food caches, some of which are later consumed during the reproductive period.

Food availability early in life can play a vital role in an individual's development and success, but experimental evidence for the direct effects of food on body condition, physiology, and survival of young animals in the wild is still relatively scarce. Food-caching Canada Jays (Perisoreus canadensis) begin breeding in the late winter and, therefore, rely on either cached food or seemingly limited quantities of fresh food to feed nestlings in the early spring. Using a 2-yr food supplementation experiment conducted during the nestling period and 40 yr of observational data on food supplemented by the public, we examined whether food quantity during early life influenced the physiology, body condition, timing of fledging, and survival of young Canada Jays in Algonquin Provincial Park, Ontario, Canada. Experimental food supplementation of breeding pairs advanced the fledging date of young by 24% (5.5 d) compared to controls. In 1 yr of the experiment, nestlings raised on experimentally supplemented territories had lower feather corticosterone concentrations and were in higher body condition than controls. Across treatment and control nests, young that successfully fledged had lower concentrations of feather corticosterone and were in higher body condition than those that did not fledge. Based on 40 yr of observational data, nestling body condition was positively related to the degree of food supplementation by park visitors and nestlings in higher body condition were more likely to be observed in the population in the following fall. Our results demonstrate how food availability early in life can have important downstream consequences on metrics related to individual fitness, including first year survival.

Several species of birds and mammals overcome periods of scarcity by caching food, but for the vast majority of species, it is virtually unknown whether they are food limited during these periods. The Gray Jay (Perisoreus canadensis) is a boreal-resident, food-caching passerine that breeds in late winter when fresh food is scarce. Using a two-year experiment and 43 years of monitoring data, we examined the food limitation hypothesis in a population of Gray Jays in Algonquin Park, Ontario, Canada, that has declined by over 50% in the last three decades. Breeding pairs that were experimentally food supplemented during the pre-breeding period laid eggs earlier in the season and had larger brood sizes than non-supplemented controls. From the long-term data, we found strong evidence that pairs that were regularly supplemented by the public (park visitors) tended to lay eggs earlier and have larger clutches and brood sizes compared to pairs that were not supplemented. Nestling body condition (mass controlled for body size) was not influenced by either experimental or public food supplementation. Our results support the hypothesis that Gray Jays are food limited during their late-winter breeding period and suggest that warmer fall temperatures, which have been hypothesized to lead to cache spoilage, may have a significant impact on reproductive success in this declining population. Moreover, our results contribute to understanding how public feeding can influence the fitness of wild animals.

The island rule refers to the tendency of small vertebrates to become larger when isolated on islands and the frequent dwarfing of large forms. It implies genetic control, and a necessary linkage, of size and body-mass differences between insular and mainland populations. To examine the island rule, we compared body size and mass of gray jays (Perisoreus canadensis) on Anticosti Island, Québec, located in the Gulf of St. Lawrence, with three mainland populations (2 in Québec and 1 in Ontario). Although gray jays on Anticosti Island were ca 10% heavier, they were not structurally larger, than the three mainland populations. This suggests that Anticosti jays are not necessarily genetically distinct from mainland gray jays and that they may have achieved their greater body masses solely through packing more mass onto mainland-sized body frames. As such, they may be the first-known example of a proposed, purely phenotypic initial step in the adherence to the island rule by an insular population. Greater jay body mass is probably advantageous in Anticosti's high-density, intensely competitive social environment that may have resulted from the island's lack of mammalian nest predators.

Continental-scale monitoring programs with standardized survey protocols play an important role in conservation science by identifying species in decline and prioritizing conservation action. However, rare, inaccessible, or spatially fragmented communities may be underrepresented in continental-scale surveys. Data on these communities often come from decentralized, local monitoring efforts that differ in their goals and survey protocols. We combine 16 point count datasets, controlling for differences in protocol and detection probabilities to estimate regional trends for 14 spruce-fir forest bird species across Northeastern and Midwestern United States, a vulnerable community threatened by numerous anthropogenic stressors and widely considered a priority for conservation. Our analyses indicated that four species considered as ecological indicators for this community, Bicknell’s Thrush (Catharus bicknelli), Magnolia Warbler (Setophaga magnolia), Blackpoll Warbler (Setophaga striata) and Yellow-bellied Flycatcher (Empidonax flaviventris), each exhibited significant declines. Olive-sided Flycatcher (Contopus cooperi), a species of concern in parts of its range, and two additional species for which no previous concern existed, the Evening Grosbeak (Coccothruastes vespertinus) and the Gray Jay (Perisoreus canadensis), each also showed significant overall declines. Five out of nine species with sufficient data for analyses from Northeastern and Midwestern surveys showed significant differences in trends between these regions. Spruce-fir obligate species were more likely to decline significantly than species that use spruce-fir in addition to other habitat types. These results demonstrate the value of combining disparate data sources for analyzing regional patterns of population trends to confirm and extend conservation concern for some species and identify others for which additional attention may be needed.

Understanding how long-term changes in climate influence populations requires knowledge of the mechanisms by which climate influences individual success and population abundance. We explored the implications of warmer falls and winters on a nonmigratory, food-caching bird, the Gray Jay (Perisoreus canadensis (L., 1766)), in Algonquin Park, Ontario, by experimentally examining the influence of temperature on the caloric content and mass of simulated cached food. Using three sites in, north of, and south of Algonquin, we examined the hypothesis that warmer temperatures would negatively influence the preservation of cached food by accelerating decay. Food cached at the highest latitude site retained the greatest mass and caloric content over 180 days of exposure, but there was no difference between the intermediate and the low latitude sites. We also show that Algonquin experienced a winter climate similar to our northernmost site as recently as 1990, and our results suggest that food availability in Algonquin has likely decreased since then, due to a warming climate. Interestingly, this coincides with a decline in territory occupancy by Gray Jays in Algonquin. Our results point to a unique mechanism by which climate warming may influence the persistence of a boreal species through its influence on winter food availability.

As urban areas have grown in population, use of nearby natural areas for outdoor recreation has also increased, potentially influencing bird distribution in landscapes managed for conservation. Members of the family Corvidae (crows, ravens, jays, and magpies) have strong interactions with humans and may be directly affected by recreation in wild landscapes. In Mount Rainier National Park, we evaluated the effects of vegetation, visitor use, and the availability of human-subsidized food on the use of landscape features by 4 corvid species: Steller's Jay (Cyanocitta stelleri), Gray Jay (Perisoreus canadensis), Common Raven (Corvus corax), and Clark's Nutcracker (Nucifraga columbiana). We conducted >1,400 point counts across areas that varied in habitat and in the degree of human recreational impact. We calculated predicted occupancy values while allowing for variation in detection probability. In addition to species-specific suites of vegetation and landscape variables, we found that patterns of hu...

Spatial and temporal phenotypic differentiation in mean body size is of commonplace occurrence, but the underlying causes remain often unclear: both genetic differentiation in response to selection (or drift) and environmentally induced plasticity can create similar phenotypic patterns. Studying changes in body mass in Siberian jays (Perisoreus infaustus) over three decades, we discovered that mean body mass declined drastically (ca. 10%) over the first two decades, but increased markedly thereafter back to almost the initial level. Quantitative genetic analyses revealed that although body mass was heritable (h(2) = 0.46), the pronounced temporal decrease in body mass was mainly a product of phenotypic plasticity. However, a concomitant and statistically significant decrease in predicted breeding values suggests a genetic component to this change. The subsequent increase in mean body mass was indicated to be entirely due to plasticity. Selection on body mass was estimated to be too weak to fully account for the observed genetic decline in body mass, but bias in selection differential estimates due to environmental covariance between body mass and fitness is possible. Hence, the observed body mass changes appear to be driven mainly by phenotypic plasticity. Although we were not able to identify the ecological driver of the observed plastic changes, the results highlight the utility of quantitative genetic approaches in disentangling genetic and phenotypic changes in natural populations.

Animals that reside at high latitudes and altitudes year-round often use cached food to survive over the winter months, but a few species also rely on stored food to sustain them during the breeding season when the nutritional requirements of females are higher than normal. Gray jays Perisoreus canadensis rely on perishable cached food during the winter and females begin breeding in late winter when fresh food is rarely available. To examine pre-laying patterns of weight gain, as well as the causes and consequences of weight gain among individuals, we weighed females regularly throughout the pre-laying period. Females began increasing their weight approximately nine days prior to their fi rst egg date, and on average increased their body weight by 25%, which is on par with other bird species that rely on non-cached food. Final pre-laying weight was positively infl uenced by the percent of conifers on territories, providing some support for previous results showing that coniferous trees are better able to preserve cached food. We also found that both fi nal pre-laying weight and the rate of weight gain were positively related to female age, supporting the hypothesis that female caching ability improves with age. With increasing fi nal weight, females tended to lay larger clutches and hatched more nestlings, despite the fact that fi nal weight was not infl uenced by weight at the beginning of the weighing period. Our results confi rm that gray jays are able to reach breeding condition while relying primarily on food stored before winter, and suggest a novel mechanism by which habitat-mediated carry-over eff ects and female age may infl uence reproductive performance in a food-caching animal.

A profusion of theoretical and empirical studies has successfully explored the issue of adaptive management of body mass by small birds threatened with both starvation and predation. In addition to diurnal body mass cycles, body mass tends to increase with either poorer mean conditions or more variable conditions, such as those often experienced during winter. In many species, individual dominance status will affect access to food and predation risk, and is therefore predicted to influence patterns of optimal body mass further. We investigated body mass regulation via repeated measurements without capture in groups of Siberian jays, Perisoreus infaustus , during autumn. As predicted, body mass of individuals increased throughout the day and towards the winter and was higher during colder periods. Jay body mass was also correlated with wind chill conditions 23 h before. This makes sense since conditions 24 h earlier were a better predictor of current conditions than conditions either 12 or 48 h earlier. Dominant birds (i.e. breeders) that were large carried relatively lower fat reserves than large subordinate individuals. The opposite was true for morphologically small birds. Together this suggests tighter requirements for individual variation in mass for dominant breeders in these groups. Our findings in this food-hoarding corvid are in general agreement with models and results concerning much smaller birds.

Responding appropriately during the first predatory attack in life is often critical for survival. In many social species, naive juveniles acquire this skill from conspecifics, but its fitness consequences remain virtually unknown. Here we experimentally demonstrate how naive juvenile Siberian jays (Perisoreus infaustus) derive a long-term fitness benefit from witnessing knowledgeable adults mobbing their principal predator, the goshawk (Accipiter gentilis). Siberian jays live in family groups of two to six individuals that also can include unrelated nonbreeders. Field observations showed that Siberian jays encounter predators only rarely, and, indeed, naive juveniles do not respond to predator models when on their own but do when observing other individuals mobbing them. Predator exposure experiments demonstrated that naive juveniles had a substantially higher first-winter survival after observing knowledgeable group members mobbing a goshawk model, increasing their likelihood of acquiring a breeding position later in life. Previous research showed that naive individuals may learn from others how to respond to predators, care for offspring, or choose mates, generally assuming that social learning has long-term fitness consequences without empirical evidence. Our results demonstrate a long-term fitness benefit of vertical social learning for naive individuals in the wild, emphasizing its evolutionary importance in animals, including humans.

In the southern and central parts of Finland, Siberian jay (Perisoreus infaustus) lives in large non-fragmented spruce-dominated forests. Due to the reduction of such forests, Siberian jay has disappeared from the southern parts of Finland. This study analyzed continuous-cover uneven-aged forest management as a way to maintain Siberian jay habitats simultaneously with timber production. Continuous cover management is able to provide the necessary spatial and temporal continuity of forest features important to the viability of Siberian jay populations. The study analyzed the relationship between habitat quality of Siberian jay and profitability of uneven-aged management of Norway spruce (Picea abies) stands. Profitability was evaluated by the net present value of timber sales, calculated with 2% discount rate. The results showed that uneven-aged management that maximizes economic profitability is not seriously in conflict with the maintenance of feeding habitats; there was a temporary decline in habitat quality after the cutting treatment but the decline was not drastic and the habitat recovered during the 15-year cutting cycle. Maintenance of nesting habitat reduced the profitability of timber production by 50–60% and wood production was decreased by 23%. Since nesting habitats cover only some tens of hectares within a home range of 200–500 ha, the impact of habitat maintenance on timber production would be rather small in continuous cover forest management.

In variable environments variance-sensitive foraging should be replaced by more profitable sampling behaviour whenever the variation in foraging rewards becomes predictable enough to track. We tested this suggestion in groups of wild Siberian jays, Perisoreus infaustus, during prewinter food-hoarding visits to experimental feeders. As predicted, all groups of jays switched to sampling once food items were clumped into ‘patches’ to create reliable patch-based information concerning prey sizes. However, increases in individual foraging success above chance were not achieved according to a simple ‘win-stay lose-shift’ rule of thumb. Instead jays employed a win-and-return-later strategy, returning more often over the experimental session to privately sampled patches containing the four largest of five prey sizes. In contrast, public information that was gained by observing patch sampling by other group members involved a more gradual increase in the probability of patch use with the prey size involved. Use of public versus private information did not differ according to sex or social status. Even though the jays did not achieve the individually optimal strategy in this specific experimental set-up, their sampling behaviour using both public and private information are suggested to maximize both individual and group-wide foraging efficiencies when exploiting the ephemeral food sources typical of boreal taiga forests.

We describe range-wide phylogeographic variation in gray jays (Perisoreus canadensis), a boreal Nearctic corvid that occurs today primarily in recently glaciated regions. Phylogenetic analysis of mitochondrial DNA (1041 base pairs ND2 gene; N = 205, 50 localities) revealed four reciprocally monophyletic groups. One widespread clade occurs across the North American boreal zone, from Newfoundland to Alaska and southwest into Utah. Three other clades occur at lower latitudes in the montane West in Colorado, the northern Rocky Mountains, and the Pacific Northwest respectively. The geographic distribution of clades in gray jays corresponds with a general pattern that is emerging for boreal taxa, having one widespread northern clade and one or more geographically restricted southwestern clades. Population genetic analyses indicate that the larger boreal clade is genetically structured and harbors significantly more genetic diversity than those clades occurring at lower latitudes. Species distribution modeling (SDM) revealed multiple putative Pleistocene refugia including several occurring at higher latitudes. We suggest that multiple post-glacial colonization routes, some of which originate from these northern refugia, are responsible for the relatively high genetic diversity at high latitudes. Conversely, lower latitude clades show little variation, probably as a result of historical restriction to smaller geographical areas with smaller long-term population sizes. This ‘upside-down’ pattern of genetic diversity contrasts with the conventional view that populations of north-temperate species occupying previously glaciated habitats should possess lower levels of diversity than their southern counterparts.

The results of comparative electron microscope study of the fine structure of the definitive contour feathers of ten Crows species (Perisoreus infaustus, Garrulus glandarius, Cyanopica cyanus, Pica Pica, Podoceus panderi, Nucifraga caryocatactes, Corvus monedula, C.frugilegus, C. cornix, C. corax) are presented. The results of the research allowed us to conclude that crows, along with the traditional elements of feather architectonics, have a number of species-specific microstructure characteristics that are taxonomically important.

Sex-bias in natal dispersal patterns can have important genetic and evolutionary consequences; however, reliable information about sex-biased dispersal can be difficult to obtain with observational methods. We analysed the sex-specific patterns of genetic differentiation among three Siberian jay (Perisoreus infaustus) populations, using 11 autosomal and six Z-chromosomal microsatellite markers. Irrespective of marker-type and indices used (viz. F(ST), average pairwise relatedness and effective number of immigrants), all analyses provided strong evidence for male-biased dispersal. Population structuring at autosomal loci (F(ST) =0.046, P

In most birds, natal dispersal is female-biased, but the selective pressures leading to this pattern have rarely been explored with comprehensive data on lifetime reproductive success. In territorial birds, the benefit of philopatry should be higher for males than for females when males establish territories for which knowledge about the local environment is important. As females may use male characteristics for mate choice, and hence indirectly for territory choice, the benefit from the direct knowledge of the local environment may be lower for females than males. We tested this hypothesis using data from a long-term study of group living corvids, the Siberian jays (Perisoreus infaustus). In this species, the socially dominant offspring delay dispersal while the sub-dominant offspring leave the family group directly after reaching independence. Our results show that natal dispersal distance (a proxy for local knowledge) was related to sex and dispersal timing (a proxy for “quality”): Females and early dispersers traveled further on average than males and delayed dispersers. Furthermore, dispersal distance and timing were negatively related to the number of recruits produced over an individual’s lifetime in males, but not in females. Hence, the results support the hypothesis that the female-biased natal dispersal found in this and other bird species may come about through higher lifetime reproductive success of philopatric males than females.

Animals that store food items in scattered sites must decide how to distribute their caches in space. Our theoretical approach is based on the assumption that such animals disperse their caches in a manner that maximizes the long-term rate of storage of recoverable (surviving) food items in the habitat. We investigate the cache-spacing behavior of theoretical scatter hoarders that encounter food sources differing in the energetic content of the items they contain. We then describe a field experiment in which gray jays (Perisoreus canadensis) were presented with both small- and large-item food sources. The jays compensated for source type by spacing larger-item caches more widely, a compensation that would tend to yield a high rate of storage of recoverable food energy over the long term and throughout the territory. Previous models do not adequately account for the observed patterns of cache dispersion.

Condition, defined as the amount of 'internal resources' an individual can freely allocate, is often assumed to be environmentally determined and to reflect an individual's health and nutritional status. However, an additive genetic component of condition is possible if it 'captures' the genetic variance of many underlying traits as many fitness-related traits appear to do. Yet, the heritability of condition can be low if selection has eroded much of its additive genetic variance, or if the environmental influences are strong. Here, we tested whether feather growth rate - presumably a condition-dependent trait - has a heritable component, and whether variation in feather growth rate is related to variation in fitness. To this end, we utilized data from a long-term population study of Siberian jays (Perisoreus infaustus), and found that feather growth rate, measured as the width of feather growth bars (GB), differed between age-classes and sexes, but was only weakly related to variation in fitness as measured by annual and life-time reproductive success. As revealed by animal model analyses, GB width was significantly heritable (h(2) = 0.10 +/- 0.05), showing that this measure of condition is not solely environmentally determined, but reflects at least partly inherited genetic differences among individuals. Consequently, variation in feather growth rates as assessed with ptilochronological methods can provide information about heritable genetic differences in condition.

Over 3 years we observed the breeding behavior of four groups of the Sichuan Jay (Perisoreus internigrans), a poorly known Chinese endemic restricted to fragments of high-altitude spruce—fir forest on the east side of the Qinghai—Tibetan Plateau. The first seven known nests of this species were well hidden in tall conifers at 3350–3700 m above sea level, and clutches were initiated in cold, snowy conditions in late March and early April. Only the presumed breeding males fed incubating females, but all members of a group (mean size 3.8) regularly fed nestlings and fledglings. We contrast this pattern of alloparenting with that seen in the two other species of Perisoreus: alloparenting is restricted to the fledgling period in the Gray Jay (P. canadensis) and entirely absent in the Siberian Jay (P. infaustus). The differences may be explained by differences in the defensive capabilities of the three species and/ or by differences in the abundance and capabilities of their potential nest predators.

We studied the distribution of birds breeding within five ecological landforms in Yukon-Charley Rivers National Preserve, a 10,194-km2 roadless conservation unit on the Alaska-Canada border in the boreal forest zone. Passerines dominated the avifauna numerically, comprising 97% of individuals surveyed but less than half of the 115 species recorded in the Preserve. We used distance-sampling and discrete-removal models to estimate detection probabilities, densities, and population sizes across the Preserve for 23 species of migrant passerines and five species of resident passerines. Yellow-rumped Warblers (Dendroica coronata) and Dark-eyed Juncos (Junco hyemalis) were the most abundant species, together accounting for 41% of the migrant passerine populations estimated. White-winged Crossbills (Loxia leucoptera), Boreal Chickadees (Poecile hudsonica), and Gray Jays (Perisoreus canadensis) were the most abundant residents. Species richness was greatest in the Floodplain/Terrace landform flanking the ...

Many prey species gather together to approach and harass their predators despite the associated risks. While mobbing, prey usually utter calls and previous experiments have demonstrated that mobbing calls can convey information about risk to conspecifics. However, the risk posed by predators also differs between predator categories. The ability to communicate predator category would be adaptive because it would allow other mobbers to adjust their risk taking. I tested this idea in Siberian jays Perisoreus infaustus , a group-living bird species, by exposing jay groups to mounts of three hawk and three owl species of varying risks. Groups immediately approached to mob the mount and uttered up to 14 different call types. Jays gave more calls when mobbing a more dangerous predator and when in the presence of kin. Five call types were predator-category-specific and jays uttered two hawk-specific and three owl-specific call types. Thus, this is one of the first studies to demonstrate that mobbing calls can simultaneously encode information about both predator category and the risk posed by a predator. Since antipredator calls of Siberian jays are known to specifically aim at reducing the risk to relatives, kin-based sociality could be an important factor in facilitating the evolution of predator-category-specific mobbing calls.