| arsenic speciation in terrestrial birds from yellowknife, northwest territories, canada: the unexpected finding of arsenobetaine. | the surrounding area of yellowknife, northwest territories, canada, is known for naturally and anthropogenically elevated concentrations of arsenic. five bird species (gray jay [perisoreus canadensis], american tree sparrow [spizella arborea], dark-eyed junco [junco hyemalis], yellow-rumped warbler [dendroica coronata], and spruce grouse [dendragapus canadensis]) were collected from this area. their tissues were analyzed for total arsenic and for arsenic species, allowing us to report, to our kn ... | 2005 | 16117124 |
| reduced reproductive performance associated with warmer ambient temperatures during incubation in a winter-breeding, food-storing passerine. | 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 sedentar ... | 2017 | 28480002 |
| experimental evidence and 43 years of monitoring data show that food limits reproduction in a food-caching passerine. | 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 ... | 2015 | 27070019 |
| an example of phenotypic adherence to the island rule? - anticosti gray jays are heavier but not structurally larger than mainland conspecifics. | 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). a ... | 2015 | 26380697 |
| contrasting patterns of survival and dispersal in multiple habitats reveal an ecological trap in a food-caching bird. | a comprehensive understanding of how natural and anthropogenic variation in habitat influences populations requires long-term information on how such variation affects survival and dispersal throughout the annual cycle. gray jays perisoreus canadensis are widespread boreal resident passerines that use cached food to survive over the winter and to begin breeding during the late winter. using multistate capture-recapture analysis, we examined apparent survival and dispersal in relation to habitat ... | 2013 | 23681287 |
| high latitudes and high genetic diversity: phylogeography of a widespread boreal bird, the gray jay (perisoreus canadensis). | 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 co ... | 2012 | 22321688 |
| experimental evidence for a novel mechanism driving variation in habitat quality in a food-caching bird. | variation in habitat quality can have important consequences for fitness and population dynamics. for food-caching species, a critical determinant of habitat quality is normally the density of storable food, but it is also possible that quality is driven by the ability of habitats to preserve food items. the food-caching gray jay (perisoreus canadensis) occupies year-round territories in the coniferous boreal and subalpine forests of north america, but does not use conifer seed crops as a source ... | 2011 | 21681486 |
| preference for oddity: uniqueness heuristic or hierarchical choice process? | traditional economic theories assume decision makers in multialternative choice tasks "assign" a value to each option and then express rational preferences. here, i report an apparent violation of such rationality in gray jays (perisoreus canadensis). i tested the jays' preference in a quaternary choice task where three options were the same color and the fourth option was a different color. all options offered an identical food reward and so the strictly rational expectation was that subjects w ... | 2008 | 18528719 |
| state-dependent choice and ecological rationality. | decision makers who minimize costly errors should flexibly adjust the way they trade off competing demands, depending on their current state. we explore how state (amount of hoarded food) affects willingness to take extra predation risk to obtain larger food rewards, particularly in animals that may overemphasize safety. assuming a sigmoid fitness function, we explore how a supplement in state influences this willingness trade danger for food energy. above a threshold, the model predicts the sup ... | 2007 | 17467743 |
| climate change and the demographic demise of a hoarding bird living on the edge. | population declines along the lower-latitude edge of a species' range may be diagnostic of climate change. we report evidence that climate change has contributed to deteriorating reproductive success in a rapidly declining population of the grey jay (perisoreus canadensis) at the southern edge of its range. this non-migratory bird of boreal and subalpine forest lives on permanent territories, where it hoards enormous amounts of food for winter and then breeds very early, under still-wintry condi ... | 2006 | 17015367 |
| interruptions improve choice performance in gray jays: prolonged information processing versus minimization of costly errors. | under the assumption that selection favors minimization of costly errors, erroneous choice may be common when its fitness cost is low. according to an adaptive-choice model, this cost depends on the rate at which an animal encounters the choice: the higher this rate, the smaller the cost of choosing a less valuable option. errors should thus be more common when interruptions to foraging are shorter. a previous experiment supported this prediction: gray jays, perisoreus canadensis, were more erro ... | 2002 | 12461598 |
| selective predation of gray jays, perisoreus canadensis, upon boreal chorus frogs, pseudacris triseriata. | | 1980 | 28581143 |
| [pterylography of the gray jay perisoreus canadensis (linnaeus), (aves: corvidae)]. | | 1971 | 5101967 |
| environmental conditions modulate compensatory effects of site dependence in a food-caching passerine. | although density regulates the abundance of most wild animal populations by influencing vital rates, such as fecundity and survival, the mechanisms responsible for generating negative density dependence are unclear for many species. site dependence occurs when there is preferential filling of high-quality territories, which results in higher per capita vital rates at low densities because a larger proportion of occupied territories are of high quality. using 41 yr of territory occupancy and demo ... | 2020 | 32970843 |
| raising young with limited resources: supplementation improves body condition and advances fledging of canada jays. | 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 ... | 2020 | 31605623 |
| autumn freeze-thaw events carry over to depress late-winter reproductive performance in canada jays. | evidence suggests that range-edge populations are highly vulnerable to the impacts of climate change, but few studies have examined the specific mechanisms that are driving observed declines. species that store perishable food for extended periods of time may be particularly susceptible to environmental change because shifts in climatic conditions could accelerate the natural degradation of their cached food. here, we use 40 years of breeding data from a marked population of canada jays (perisor ... | 2019 | 31183119 |
| multilocus genetic analyses and spatial modeling reveal complex population structure and history in a widespread resident north american passerine (perisoreus canadensis). | 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 ... | 2017 | 29238522 |