Publications

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salmonellosis in songbirds in the canadian atlantic provinces during winter-summer 1997-98.from winter 1997 to summer 1998, an epizootic of salmonellosis affected several species of songbirds over a large area of the eastern north american continent. this article describes the details of this epizootic in the canadian atlantic provinces, based on laboratory examination of dead affected birds and on suspected but unconfirmed cases of salmonellosis reported by members of the public. the common redpoll (carduelis flammea) was the species most often affected, followed by pine siskins (c. ...200010642873
interspecific variation in photo-induced gnrh plasticity among nomadic cardueline finches.changes in response to photoperiod are of fundamental importance to seasonal cycles in avian reproductive development. in this study we present data on photo-induced changes in gonadotropin-releasing hormone (gnrh) immunoreactivity associated with the development of photorefractoriness in males of 3 closely related species of cardueline finch: common redpoll (carduelis flammea), pine siskin (c. pinus) and white-winged crossbill (loxia leucoptera). all are nomadic, mid- to high-latitude breeders ...200515821347
use of spatial and colour cues by foraging pine siskins (carduelis pinus): a field study.pine siskins (carduelis pinus) frequently forage at known high quality food supplies such as backyard feeders. in this field study, pine siskins visited backyard feeders of differing colour and spatial position. the three feeders contained varying amounts of food in a ratio of 3:2:1. the birds quickly distributed their visits in this ratio to the three feeders. during unbaited tests, two feeders on a given day had their positions swapped. the siskins appeared to primarily use both large-scale sp ...200920522314
epidemiology of a salmonella enterica subsp. enterica serovar typhimurium strain associated with a songbird outbreak.salmonella enterica subsp. enterica serovar typhimurium is responsible for the majority of salmonellosis cases worldwide. this salmonella serovar is also responsible for die-offs in songbird populations. in 2009, there was an s. typhimurium epizootic reported in pine siskins in the eastern united states. at the time, there was also a human outbreak with this serovar that was associated with contaminated peanuts. as peanuts are also used in wild-bird food, it was hypothesized that the pine siskin ...201222885752
foraging pattern of pine siskins and its influence on winter moth survival in an apple orchard.foraging by migratory pine siskins in an apple orchard infested with varying densities of winter moth was observed, and winter moth mortality in the presence and absence of birds was recorded. time spent foraging in a tree and number of birds foraging per tree was positively related to larval density but number of larvae removed per leaf cluster or per unit time was not. level of defoliation was a better predictor of the number of clusters searched per tree than was prey density. despite poor pr ...198628311683
tests of absolute photorefractoriness in four species of cardueline finch that differ in reproductive schedule.species with different reproductive schedules may differ in how they respond to the annual change in photoperiod (the adaptive specialization hypothesis). seasonally breeding species are predicted to use photorefractoriness to terminate reproduction prior to inclement conditions in autumn and winter, whereas opportunistically breeding species may not exhibit photorefractoriness. we tested for absolute photorefractoriness in four species of cardueline finch that differ in their reproductive sched ...200616985195
non-photoperiodic regulation of reproductive physiology in the flexibly breeding pine siskin (spinus pinus).in order to time reproduction to coincide with favorable conditions, animals use environmental cues to up- and down-regulate the reproductive axis appropriately. although photoperiodic cues are one of the best studied of such environmental cues, animals also attend to others such as temperature, food availability, rainfall and social cues. such non-photic cues are expected to be particularly important for tropical species and temperate-zone species that exhibit flexible or opportunistic breeding ...201222569115
climatic dipoles drive two principal modes of north american boreal bird irruption.pine siskins exemplify normally boreal seed-eating birds that can be sparse or absent across entire regions of north america in one year and then appear in large numbers the next. these dramatic avian "irruptions" are thought to stem from intermittent but broadly synchronous seed production (masting) in one year and meager seed crops in the next. a prevalent hypothesis is that widespread masting in the boreal forest at high latitudes is driven primarily by favorable climate during the two to thr ...201525964328
a potential mate influences reproductive development in female, but not male, pine siskins.the role of photoperiod in avian reproductive timing has been well studied, and we are increasingly recognizing the roles of other environmental cues such as social cues. however, few studies have evaluated the extent to which males and females of the same species respond similarly to the same type of cue. moreover, previous studies have rarely examined how variation in the quality or nature of a given social cue might modulate its effect. here, we examine the sensitivity of male and female pine ...201626836771
estrogen levels influence medullary bone quantity and density in female house finches and pine siskins.medullary bone, a non-structural osseous tissue, serves as a temporary storage site for calcium that is needed for eggshell production in a number of avian species. previous research focusing primarily on domesticated species belonging to the anseriformes, galliformes, and columbiformes has indicated that rising estrogen levels are a key signal stimulating medullary bone formation; passeriformes (which constitute over half of extant bird species and are generally small) have received little atte ...201728039066
structure and variation of the fringillidae (aves: passeriformes) mitochondrial dna control region and their phylogenetic relationship.the control region is the major noncoding segment of animal mitochondrial dna. to infer the structure and variation of fringillidae mitochondrial dna control region, the entire control region sequences of 25 species were analyzed. the length of the control region sequences was very conserved (1230 ± 18) and can be separated into three domains. the frequency of both substitutions and gaps was highest in the third domain and lowest in the central region. the control region has the same flanking ge ...201627549748
physiological responses to photoperiod in three cardueline finch species.cardueline finches (canaries, goldfinches, and rosefinches, etc.) vary widely in the degree to which their natural reproductive schedules track seasonal changes in photoperiod. in this study, we tested for photo-induction of reproductive development and photorefractoriness in males of three cardueline finch species: pine siskins (carduelis pinus), common redpolls (carduelis flammea), and white-winged crossbills (loxia leucoptera). exposure to long days (20l:4d) in winter induced gonadal growth a ...200415094340
modeling the effects of environmental disturbance on wildlife communities: avian responses to prescribed fire.prescribed fire is a management tool used to reduce fuel loads on public lands in forested areas in the western united states. identifying the impacts of prescribed fire on bird communities in ponderosa pine (pinus ponderosa) forests is necessary for providing land management agencies with information regarding the effects of fuel reduction on sensitive, threatened, and migratory bird species. recent developments in occupancy modeling have established a framework for quantifying the impacts of m ...200919688932
the effect of corticosterone on standard metabolic rates of small passerine birds.resting metabolic rates of gambel's white-crowned sparrows (zonotrichia leucophrys gambelii) and pine siskins (carduelis pinus) were evaluated at thermoneutral temperatures before and after administration of corticosterone (b) at physiological doses. there was no effect of b on basal metabolic rate of either species, but nocturnal metabolic rate varied significantly less over the 3-h period of measurement in b-treated sparrows and siskins than in control birds. these results, coupled with observ ...19911939747
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