| duration of alphavirus neutralizing antibody in naturally infected birds. | native birds, mostly passerine species, ecologically associated with culiseta melanura, the enzootic vector of eastern equine encephalomyelitis and highlands j viruses in the eastern united states, were examined over a 12-year period in southeastern massachusetts. these studies concentrated on those individual birds known, by banding returns, to be residents of large wooded swamps where both eastern equine encephalomyelitis and highlands j viruses were known to be enzootic. of 8,417 birds sample ... | 1988 | 2829638 |
| no sex difference occurs in hippocampus, food-storing, or memory for food caches in black-capped chickadees. | a number of recent studies have described sex differences in the relative size of the hippocampus that are associated with sex differences in the use of space. voles, kangaroo rats, and cowbirds all exhibit a sex difference in relative size of the hippocampal formation that is correlated with a sex difference in spatial behaviour. we wished to determine whether sex differences in the size of the hippocampus occur in the absence of a difference in the use of space, and whether the previously desc ... | 1996 | 8883812 |
| the seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels. | the dentate gyrus is one of two areas in the mammalian brain that produces neurons in adulthood. neurogenesis (proliferation, survival, and differentiation of new neurons) is regulated by experience, and increased neurogenesis appears to be correlated with improved spatial learning in mammals and birds. we tested the hypothesis that in long-lived mammals that scatter-hoard food, seasonal variations in spatial memory processing (i.e. increased processing during caching season in the autumn) might ... | 2000 | 10712644 |
| allometry of alarm calls: black-capped chickadees encode information about predator size. | many animals produce alarm signals when they detect a potential predator, but we still know little about the information contained in these signals. using presentations of 15 species of live predators, we show that acoustic features of the mobbing calls of black-capped chickadees (poecile atricapilla) vary with the size of the predator. companion playback experiments revealed that chickadees detect this information and that the intensity of mobbing behavior is related to the size and threat of t ... | 2005 | 15976305 |
| comparing black-capped (poecile atricapillus) and mountain chickadees (poecile gambeli): use of geometric and featural information in a spatial orientation task. | since cheng (cognition 23:149-178, 1986) first proposed the "geometric module" in rats, a great deal of research has focused on how other species use geometric information and how geometric encoding may differ across species. here, hand-reared and wild-caught black-capped chickadees and wild-caught mountain chickadees searched for food hidden in one corner in a rectangular environment. previous research has shown that mountain chickadees do not spontaneously encode geometric information when a s ... | 2009 | 19381699 |
| memory for what, where, and when in the black-capped chickadee (poecile atricapillus). | episodic memory is the ability to remember personally experienced past events (tulving in organization of memory. academic press, san diego, pp. 381-403, 1972). in non-human animals, the behavioural criterion for episodic-like memory is remembering "what" occurred in conjunction with "when" and "where" (clayton and dickinson in nature 395:272-274, 1998). we conducted tests for "what, where, and when" memory in a food-storing bird, the black-capped chickadee (poecile atricapillus). in experiment ... | 2009 | 19466468 |
| black-capped chickadee (poecile atricapillus) and human (homo sapiens) chord discrimination. | human music perception is related both to musical experience and the physical properties of sound. examining the processing of music by nonhuman animals has been generally neglected. we tested both black-capped chickadees and humans in a chord discrimination task that replicates and extends prior research with pigeons. we found that chickadees and humans, in common with pigeons, showed similar patterns of discrimination across manipulations of the 3rd and 5th notes of the triadic chords. for all ... | 2011 | 21942569 |
| flexibility in animal signals facilitates adaptation to rapidly changing environments. | charles darwin posited that secondary sexual characteristics result from competition to attract mates. in male songbirds, specialized vocalizations represent secondary sexual characteristics of particular importance because females prefer songs at specific frequencies, amplitudes, and duration. for birds living in human-dominated landscapes, historic selection for song characteristics that convey fitness may compete with novel selective pressures from anthropogenic noise. here we show that black ... | 2011 | 21980449 |
| bilateral syringeal coupling during phonation of a songbird. | the syrinx of oscine birds ("true songbirds") is a double vocal organ, and each side has generally been presumed to function independently under separate neural control during phonation. a significant counterexample is demonstrated here in the production of a common vocalization by the black-capped chickadee (parus atricapillus), in which the 2 acoustic sources of the syrinx interact in a nonlinear fashion. the chickadee produces a sound with multiple frequency components that superficially rese ... | 2013 | 3794791 |
| dynamics of vector-host interactions in avian communities in four eastern equine encephalitis virus foci in the northeastern u.s. | eastern equine encephalitis (eee) virus (togaviridae, alphavirus) is a highly pathogenic mosquito-borne zoonosis that is responsible for occasional outbreaks of severe disease in humans and equines, resulting in high mortality and neurological impairment in most survivors. in the past, human disease outbreaks in the northeastern u.s. have occurred intermittently with no apparent pattern; however, during the last decade we have witnessed recurring annual emergence where eee virus activity had bee ... | 2016 | 26751704 |
| vector-host interactions and epizootiology of eastern equine encephalitis virus in massachusetts. | eastern equine encephalitis (eee) virus is a highly pathogenic mosquito-borne zoonosis that is responsible for outbreaks of severe disease in humans and equines, resulting in high mortality or severe neurological impairment in most survivors. in the northeastern united states, eee virus is maintained in an enzootic cycle involving the ornithophilic mosquito, culiseta melanura (coquillett) and passerine birds in freshwater swamp habitats. to evaluate the role of cs. melanura and culiseta morsitan ... | 2013 | 23473221 |
| ten years of research into avian models of episodic-like memory and its implications for developmental and comparative cognition. | episodic memory refers to the ability to remember specific personal events from the past. ever since tulving first made the distinction between episodic memory and other forms of declarative memory in 1972, most cognitive psychologists and neuroscientists have assumed that episodic recall is unique to humans. the seminal paper on episodic-like memory in western scrub-jays (aphelocoma californica) by clayton and dickinson [4] has inspired a number of studies and in a wide range of species over th ... | 2010 | 20600352 |
| response of black-capped chickadees to house finch mycoplasma gallisepticum. | tests for the presence of pathogen dna or antibodies are routinely used to survey for current or past infections. in diseases that emerge following a host jump estimates of infection rate might be under- or overestimated. we here examine whether observed rates of infection are biased for a non-focal host species in a model system. the bacterium mycoplasma gallisepticum is a widespread pathogen in house finches (haemorhous mexicanus), a fringillid finch, but an unknown proportion of individuals o ... | 2015 | 25880849 |
| a survey of the prevalence of selected bacteria in wild birds. | we determined the prevalence of six genera of bacteria from a sample of 387 cloacal swabs from 364 passerines and woodpeckers. the prevalence of bacteria were as follows: escherichia coli (1%), pseudomonas spp. (22%), salmonella spp. (0%), staphylococcus spp. (15%), streptococcus spp. (18%), and yersinia spp. (1%). the prevalence of streptococcus spp. was higher in omnivorous species than in granivorous species (20% versus 8%). individuals captured at feeders had a lower prevalence of both strep ... | 1988 | 3286907 |
| vocal production and playback of altered song do not affect zenk expression in black-capped chickadees (poecile atricapillus). | the two-note fee bee song of the black-capped chickadee (poecile atricapillus) is sung at many different absolute frequencies, but the relative frequencies between the start and end of the fee note (the glissando) and between the fee and the bee notes (the inter-note ratio) are preserved regardless of absolute frequency. if these relative frequencies are experimentally manipulated, birds exhibit reduced behavioural responses to playback of altered songs both in field studies and laboratory studi ... | 2016 | 26523856 |
| female song in black-capped chickadees (poecile atricapillus): acoustic song features that contain individual identity information and sex differences. | in temperate songbirds, song has traditionally been considered a vocalization mainly produced by males. however, in many temperate species, it is now recognized that both males and females produce song. the function and structure of male black-capped chickadee (poecile atricapillus) fee-bee song have been well-studied, but female song, although briefly described in some field reports, has not often been quantitatively examined. we recorded spontaneous fee-bee songs produced by wild-caught male a ... | 2013 | 23694740 |
| zenk expression in auditory regions changes with breeding condition in male black-capped chickadees (poecile atricapillus). | black-capped chickadees (poecile atricapillus) produce different vocalizations at different times of year: the fee-bee song is produced by males primarily in spring, whereas the chick-a-dee call is produced year-round but most frequently in the fall and winter. we wanted to determine if neural response to playback in auditory regions of the songbird brain varied with season in parallel to production. we captured adult male black-capped chickadees from the wild in either breeding condition or non ... | 2011 | 21854811 |
| biological relevance of acoustic signal affects discrimination performance in a songbird. | the fee-bee song of the black-capped chickadee (poecile atricapillus) is a two-note, tonal song that can be sung at different absolute pitches within an individual. however, these two notes are produced at a consistent relative pitch. moreover, dominant birds more reliably produce songs with this species-typical interval, compared to subordinate birds. therefore, we asked whether presenting the species-typical relative pitch interval would aid chickadees in solving pitch interval discriminations ... | 2012 | 22526691 |
| seasonal variation of vocal behaviour in a temperate songbird: assessing the effects of laboratory housing on wild-caught, seasonally breeding birds. | many laboratories are conducting research using songbirds as their animal model. in particular, songbirds are widely used for studying the behavioural and neural mechanisms underlying vocal learning. many researchers use wild-caught birds to conduct this research, although few studies of behaviour have been conducted to determine the effects of captive housing on these species. we investigated the vocal production pattern of wild-caught black-capped chickadees (poecile atricapillus) over an enti ... | 2011 | 21946095 |
| annual cycle of the black-capped chickadee: seasonality of singing rates and vocal-control brain regions. | black-capped chickadees have a rich vocal repertoire including learned calls and the learned fee-bee song. however, the neural regions underlying these vocalizations, such as hvc, area x, and ra (robust nucleus of arcopallium), remain understudied. here, we document seasonal changes in fee-bee song production and show a marked peak in singing rate during march through may. despite this, we found only minimal seasonal plasticity in vocal control regions of the brain in males. there was no signifi ... | 2006 | 16779824 |
| seasonal and diurnal patterns of black-capped chickadee (poecile atricapillus) vocal production. | changes in vocal behaviour observed in temperate songbirds have been linked to changes in photoperiod. research has focused on the fluctuation of hormones that lead to photosensitivity, photostimulation and photorefractoriness, as well as the 'dawn chorus' observed in numerous species. however, photoperiod in the natural environment is a complex event that occurs as seasons change. to determine the natural relationships between photoperiod and vocal behaviour we sampled vocal production of black ... | 2008 | 18243575 |
| failure to detect seasonal changes in the song system nuclei of the black-capped chickadee (poecile atricapillus). | most temperate songbird species sing seasonally, and the brain areas involved in producing song (the song system) vary in size alongside the changes in behavior. black-capped chickadees (poecile atricapillus) also sing seasonally, and we find that there are changes in the stereotypy and the length of the fee-bee song from the nonbreeding to the breeding season. yet despite these changes, we fail to find any evidence of seasonal changes in the song system. the song system of males is larger than ... | 2006 | 16779823 |
| discrimination of individual vocalizations by black-capped chickadees (poecile atricapilla). | the auditory perceptual abilities of male black-capped chickadees (poecile atricapilla) were examined using an operant go/no-go discrimination among 16 individual vocalizations recorded at 5 m. the birds learned to discriminate about equally well among eight male chickadee fee-bee songs and eight female zebra finch (taeniopygia guttata) distance calls. these results do not indicate that chickadees have a species-specific advantage in individual recognition for conspecific over heterospecific voc ... | 2002 | 12017967 |
| effects of songs and calls on zenk expression in the auditory telencephalon of field- and isolate-reared black capped chickadees. | we examined the effects of hearing two different conspecific vocalizations on expression of the immediate-early gene zenk in the caudomedial neostriatum (ncm) and the caudomedial portion of the ventral hyperstriatum (cmhv) in male and female black-capped chickadees (poecile atricapilla). both the fee-bee song and the chick-a-dee call induced zenk protein expression in ncm and in cmhv, however, patterns of expression to songs and calls varied across brain region. in the dorsal region of ncm, fee- ... | 2003 | 14659578 |
| representation of conspecific song by chickadees: comparisons among embedded 'fee bees'. | captive black-capped chickadees (parus atricapillus) were presented with normal (2-note) and lengthened (3-note) songs to investigate how note number and order are represented. normal fee bee (fb) song was embedded in four different 3-note sequences containing an additional fee (f) or bee (b). latency to vocalize after playback varied with the position, but not the type of added note, (i.e. slower responses to bfb and ffb than to fbf and fbb). latency did not differ appreciably between normal (2 ... | 1988 | 24897546 |
| song sequence discrimination in the black-capped chickadee (parus atricapillus). | captive black-capped chickadees (parus atricapillus) were presented with normal and altered versions of their species-specific "fee bee" song, to determine how note type, number, and sequence affect recognition. the number of perch changes and vocalizations (analyzed separately) given in response to playback did not differ reliably as a function of song type, whereas latency to first vocalization after playback did. in an initial experiment using two-note songs, birds vocalized sooner to songs b ... | 1986 | 3802781 |
| benefits to satellite members in mixed-species foraging groups: an experimental analysis. | hypotheses proposed to explain the formation of mixed-species foraging groups have focused on both foraging and antipredation benefits. mixed-species flocks of bark-foraging birds form during the winter in the eastern deciduous forests of north america. these flocks are composed of two parid nuclear species, tufted titmice, baeolophus bicolor, and either carolina or black-capped chickadees, poecile carolinensis or p. atricapillus, and several satellite species including downy woodpeckers, picoid ... | 1998 | 9787042 |
| novel picornavirus associated with avian keratin disorder in alaskan birds. | avian keratin disorder (akd), characterized by debilitating overgrowth of the avian beak, was first documented in black-capped chickadees (poecile atricapillus) in alaska. subsequently, similar deformities have appeared in numerous species across continents. despite the widespread distribution of this emerging pathology, the cause of akd remains elusive. as a result, it is unknown whether suspected cases of akd in the afflicted species are causally linked, and the impacts of this pathology at th ... | 2016 | 27460795 |
| food storing and the hippocampus in paridae. | food storing passerines have a larger hippocampus, relative to the rest of the telencephalon and/or body mass, than do non-storing species. this study looked at the relationship between relative size of the hippocampus and degree of food storing in six species of paridae (blue tit, parus caeruleus, great tit, p major, marsh tit, p palustris, coal tit, p ater, black-capped chickadee, p. atricapillus, and willow tit, p montanus). the degree of storing by these species varies from little or none to ... | 1996 | 9156782 |
| different seasonal patterns in song system volume in willow tits and great tits. | in most species of seasonally breeding songbirds studied to date, the brain areas that control singing (i.e. the song control system, scs) are larger during the breeding season than at other times of the year. in the family of titmice and chickadees (paridae), one species, the blue tit (cyanistes caeruleus), shows the typical pattern of seasonal changes, while another species, the black-capped chickadee (poecile atricapillus), shows, at best, very reduced seasonal changes in the scs. to test whe ... | 2016 | 27442125 |
| the distribution of substance p and neuropeptide y in four songbird species: a comparison of food-storing and non-storing birds. | the distributions of the neuropeptides substance p (sp) and neuropeptide y (npy) were investigated in four songbird species that differ in their food-storing behavior. the food-storing black-capped chickadee (parus atricapillus) was compared to the non-storing blue tit (parus caeruleus) and great tit (parus major) within the avian family paridae, as well as to the non-storing dark-eyed junco (junco hyemalis). all four species showed a similar distribution of sp throughout the brain with the exce ... | 2001 | 11684045 |
| intraspecific correlations of basal and maximal metabolic rates in birds and the aerobic capacity model for the evolution of endothermy. | the underlying assumption of the aerobic capacity model for the evolution of endothermy is that basal (bmr) and maximal aerobic metabolic rates are phenotypically linked. however, because bmr is largely a function of central organs whereas maximal metabolic output is largely a function of skeletal muscles, the mechanistic underpinnings for their linkage are not obvious. interspecific studies in birds generally support a phenotypic correlation between bmr and maximal metabolic output. if the aero ... | 2012 | 22479584 |
| are summit metabolism and thermogenic endurance correlated in winter-acclimatized passerine birds? | small birds exhibiting marked winter improvement of cold tolerance also show elevated summit metabolic rates (maximum cold-induced metabolic rate) in winter relative to summer. however, relatively large increases in cold tolerance can occur with only minor increments of maximum cold-induced metabolic rate and geographic variation in cold tolerance is not always positively correlated with variation in maximum cold-induced metabolic rate. thus, it is uncertain whether maximum cold-induced metaboli ... | 2001 | 11585259 |
| evidence for a proximate influence of winter temperature on metabolism in passerine birds. | the roles of ultimate and proximate factors in regulating basal and summit metabolic rates of passerine birds during winter have received little study, and the extent to which winter temperatures affect these variables is unknown. to address this question, we measured basal and summit (maximum cold-induced) metabolic rates in black-capped chickadees (poecile atricapillus), dark-eyed juncos (junco hyemalis), and american tree sparrows (spizella arborea) during winters from 1991/1992 to 1997 in so ... | 2008 | 10521324 |
| hippocampus and memory in a food-storing and in a nonstoring bird species. | food-storing birds maintain in memory a large and constantly changing catalog of the locations of stored food. the hippocampus of food-storing black-capped chickadees (parus atricapillus) is proportionally larger than that of nonstoring dark-eyed juncos (junco hyemalis). chickadees perform better than do juncos in an operant test of spatial non-matching-to-sample (snmts), and chickadees are more resistant to interference in this paradigm. hippocampal lesions attenuate performance in snmts and in ... | 1996 | 8918998 |
| hippocampal lesions impair memory for location but not color in passerine birds. | the effects of hippocampal complex lesions on memory for location and color were assessed in black-capped chickadees (parus atricapillus) and dark-eyed juncos (junco hyemalis) in operant tests of matching to sample. before surgery, most birds were more accurate on tests of memory for location than on tests of memory for color. damage to the hippocampal complex caused a decline in memory for location, whereas memory for color was not affected in the same birds. this dissociation indicates that th ... | 1996 | 8864273 |
| septum volume and food-storing behavior are related in parids. | the hippocampal formation (hf) of food-storing birds is larger than non-storing species, and the size of the hf in food-storing black-capped chickadees (poecile atricapillus) varies seasonally. we examined whether the volume of the septum, a medial forebrain structure that shares reciprocal connections with the hf, demonstrates the same species and seasonal variation as has been shown in the hf. we compared septum volume in three parid species; non-storing blue tits (parus caeruleus) and great t ... | 2002 | 11984843 |
| species-specific injury-induced cell proliferation in the hippocampus and subventricular zone of food-storing and nonstoring wild birds. | cells are continuously born and incorporated into the adult hippocampus (hp). adult neurogenesis might act to increase the total number of cells or replace dead cells. thus, neurogenesis might be a primary factor in augmenting, maintaining, or even recovering functions. in zebra finches, hp injury increases cell proliferation in the hp and stem cell rich subventricular zone (svz). it is unknown what effect injury has on a species dependent upon the hp for survival in the wild. in food-storing bi ... | 2010 | 19885828 |
| divided attention, memory, and spatial discrimination in food-storing and nonstoring birds, black-capped chickadees (poecile atricapilla) and dark-eyed juncos (junco hyemalis). | food-storing birds, black-capped chickadees (poecile atricapilla), and nonstoring birds, dark-eyed juncos (junco hyemalis), matched color or location on a touch screen. both species showed a divided attention effect for color but not for location (experiment 1). chickadees performed better on location than on color with retention intervals up to 40 s, but juncos did not (experiment 2). increasing sample-distractor distance improved performance similarly in both species. multidimensional scaling ... | 2002 | 12136700 |
| the effect of polychlorinated biphenyls on the song of two passerine species. | polychlorinated biphenyls (pcbs) are synthetic chemical pollutants with demonstrated detrimental toxic and developmental effects on humans and wildlife. laboratory studies suggest that pcbs influence behavior due to their effects on endocrine and neurological systems, yet little is known about the behavioral consequences of sublethal pcb exposure in the field. additionally, specific pcb congener data (in contrast to total pcb load) is necessary to understand the possible effects of pcbs in livin ... | 2013 | 24058475 |
| exploration of a novel space is associated with individual differences in learning speed in black-capped chickadees, poecile atricapillus. | individual variation in exploratory behaviour has been demonstrated in a diverse array of animal species. understanding the evolutionary antecedents and ecological consequences of this variation is an active research area within animal behaviour. here we investigate whether different exploration styles exhibited by black-capped chickadees (poecile atricapillus) in a novel environment are related to how quickly these birds learn an acoustic discrimination task. we found that birds that readily en ... | 2009 | 19635531 |
| sometimes slower is better: slow-exploring birds are more sensitive to changes in a vocal discrimination task. | animal personality, defined as consistent individual differences across context and time, has attracted much recent research interest in the study of animal behaviour. more recently, this field has begun to examine how such variation arose and is maintained within populations. the habitat-dependent selection hypothesis, which posits that animals with differing personality types may fare better (i.e. have a fitness advantage) in different habitats, suggests one possible mechanism. in the current ... | 2011 | 20843853 |
| phenotypic flexibility in passerine birds: seasonal variation in fuel storage, mobilization and transport. | winter acclimatization in small birds living in cold climates produces a winter phenotype characterized by upregulation of metabolic rates to meet enhanced thermoregulatory demands. we measured several key aspects of fuel storage, mobilization and transport in summer and winter to determine whether black-capped chickadees (poecile atricapillus), white-breasted nuthatches (sitta carolinensis), and house sparrows (passer domesticus) seasonally modulate these attributes to meet enhanced winter ther ... | 2014 | 24704472 |
| effects of photoperiod on food-storing and the hippocampus in birds. | birds that store food have a relatively large hippocampus compared to non-storing species. the hippocampus shows seasonal differences in neurogenesis and volume in black-capped chikadees (parus atricapillus) taken from the wild at different times of year. we compared hippocampal volumes in black-capped chickadees captured at the same time but differing in food-storing behaviour because of manipulations of photoperiod in the laboratory. differences in food-storing behaviour were not accompanied b ... | 1995 | 8527745 |
| zenk expression following conspecific and heterospecific playback in the zebra finch auditory forebrain. | zebra finches (taeniopygia guttata) are sexually dimorphic songbirds, not only in appearance but also in vocal production: while males produce both calls and songs, females only produce calls. this dimorphism provides a means to contrast the auditory perception of vocalizations produced by songbird species of varying degrees of relatedness in a dimorphic species to that of a monomorphic species, species in which both males and females produce calls and songs (e.g., black-capped chickadees, poeci ... | 2017 | 28506621 |
| territorial black-capped chickadee males respond faster to high- than to low-frequency songs in experimentally elevated noise conditions. | low-frequency urban noise can interfere with avian communication through masking. some species are able to shift the frequency of their vocalizations upwards in noisy conditions, which may reduce the effects of masking. however, results from playback studies investigating whether or not such vocal changes improve audibility in noisy conditions are not clear; the responses of free-ranging individuals to shifted signals are potentially confounded by functional trade-offs between masking-related au ... | 2017 | 28462051 |
| basal and maximal metabolic rates differ in their response to rapid temperature change among avian species. | in birds, acclimation and acclimatization to temperature are associated with changes in basal (bmr), summit (msum) and maximal (mmr) metabolic rates but little is known about the rate at which species adjust their phenotype to short-term temperature variations. our aims were (1) to determine the pattern of metabolic adjustments following a rapid temperature change, (2) to determine whether performance varies at similar rates during exposure to warm or cold environments, and (3) to determine if b ... | 2016 | 27233918 |
| body temperature responses to handling stress in wintering black-capped chickadees (poecile atricapillus l.). | body temperature variation in response to acute stress is typically characterized by peripheral vasoconstriction and a concomitant increase in core body temperature (stress-induced hyperthermia). it is poorly understood how this response differs between species and within individuals of the same species, and how it is affected by the environment. we therefore investigated stress-induced body temperature changes in a non-model species, the black-capped chickadee, in two environmental conditions: ... | 2017 | 28528893 |
| operant discrimination of relative frequency ratios in black-capped chickadee song. | the two-note fee bee song of the black-capped chickadee (poecile atricapillus) is sung at many different absolute frequencies, but the relative frequencies, or "pitch ratios", between the start and end of the fee note (glissando) and the fee and the bee notes (inter-note interval) are preserved with each pitch-shift. ability to perceive these ratios and their relative salience varies with sex of the bird and setting: while both sexes appear to perceive changes in the inter-note interval, males a ... | 2017 | 28721574 |
| chickadees faced with unpredictable food increase fat reserves but certain components of their immune function decline. | in winter, temperate resident birds are often faced with periodic low natural food availability. this reduction or unpredictability in resource availability might then have a negative impact on immune function, given that immune system support is highly resource dependent. we investigated the balance between energetic and immune management in captive black-capped chickadees (poecile atricapilus) by manipulating the predictability of resources. the control group received food ad lib. every day, w ... | 2017 | 28277950 |
| an investigation of sex differences in acoustic features in black-capped chickadee (poecile atricapillus) chick-a-dee calls. | sex differences have been identified in a number of black-capped chickadee vocalizations and in the chick-a-dee calls of other chickadee species [i.e., carolina chickadees (poecile carolinensis)]. in the current study, 12 acoustic features in black-capped chickadee chick-a-dee calls were investigated, including both frequency and duration measurements. using permuted discriminant function analyses, these features were examined to determine if any features could be used to identify the sex of the ... | 2016 | 27914410 |
| blood serum chemistry of wild alaskan black-capped chickadees ( poecile atricapillus ) with avian keratin disorder. | we measured serum chemistries in wild black-capped chickadees ( poecile atricapillus ) from alaska to test for potential differences associated with beak deformities characteristic of avian keratin disorder. lower uric acid in affected birds was the only difference detected between groups, although sample sizes were small. this difference could be associated with fasting or malnutrition in birds with beak deformities, but it is challenging to interpret its biologic significance without reference ... | 2016 | 27434412 |
| learning to cope: vocal adjustment to urban noise is correlated with prior experience in black-capped chickadees. | urban noise can interfere with avian communication through masking, but birds can reduce this interference by altering their vocalizations. although several experimental studies indicate that birds can rapidly change their vocalizations in response to sudden increases in ambient noise, none have investigated whether this is a learned response that depends on previous exposure. black-capped chickadees (poecile atricapillus) change the frequency of their songs in response to both fluctuating traff ... | 2016 | 27358372 |
| influence of landscape features on the microgeographic genetic structure of a resident songbird. | landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. the landscape of british columbia, canada, is already highly heterogeneous because of natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. in this study, we evaluated the effects of landscape heterogeneity on the genetic struct ... | 2016 | 26905462 |
| avian malaria in a boreal resident species: long-term temporal variability, and increased prevalence in birds with avian keratin disorder. | the prevalence of vector-borne parasitic diseases is widely influenced by biological and ecological factors. environmental conditions such as temperature and precipitation can have a marked effect on haemosporidian parasites (plasmodium spp.) that cause malaria and those that cause other malaria-like diseases in birds. however, there have been few long-term studies monitoring haemosporidian infections in birds in northern latitudes, where weather conditions can be highly variable and the effects ... | 2016 | 26828894 |
| summer-to-winter phenotypic flexibility of fatty acid transport and catabolism in skeletal muscle and heart of small birds. | prolonged shivering in birds is mainly fueled by lipids. consequently, lipid transport and catabolism are vital for thermogenic performance and could be upregulated along with thermogenic capacity as part of the winter phenotype. we investigated summer-to-winter variation in lipid transport and catabolism by measuring mrna expression, protein levels, and enzyme activities for several key steps of lipid transport and catabolic pathways in pectoralis muscle and heart in two small temperate-zone re ... | 2015 | 26658250 |
| differential effects of climate and species interactions on range limits at a hybrid zone: potential direct and indirect impacts of climate change. | the relative contributions of climate versus interspecific interactions in shaping species distributions have important implications for closely related species at contact zones. when hybridization occurs within a contact zone, these factors regulate hybrid zone location and movement. while a hybrid zone's position may depend on both climate and interactions between the hybridizing species, little is known about how these factors interact to affect hybrid zone dynamics. here, we utilize sdm (spe ... | 2015 | 26640687 |
| gene flow of a forest-dependent bird across a fragmented landscape. | habitat loss and fragmentation can affect the persistence of populations by reducing connectivity and restricting the ability of individuals to disperse across landscapes. dispersal corridors promote population connectivity and therefore play important roles in maintaining gene flow in natural populations inhabiting fragmented landscapes. in the prairies, forests are restricted to riparian areas along river systems which act as important dispersal corridors for forest dependent species across la ... | 2015 | 26580222 |
| rapid area change in pitch-up manoeuvres of small perching birds. | rapid pitch-up has been highlighted as a mechanism to generate large lift and drag during landing manoeuvres. however, pitching rates had not been measured previously in perching birds, and so the direct applicability of computations and experiments to observed behaviour was not known. we measure pitch rates in a small, wild bird (the black-capped chickadee; poecile atricapillus), and show that these rates are within the parameter range used in experiments. pitching rates were characterized by t ... | 2015 | 26502303 |
| isolation of a complete circular virus genome sequence from an alaskan black-capped chickadee (poecile atricapillus) gastrointestinal tract sample. | we report here the genome sequence of a circular virus isolated from samples of an alaskan black-capped chickadee (poecile atricapillus) gastrointestinal tract. the genome is 2,152 bp in length and is most similar (30 to 44.5% amino acid identity) to the genome sequences of other single-stranded dna (ssdna) circular viruses belonging to the gemycircularvirus group. | 2015 | 26404604 |
| frequency sensitivity in the auditory periphery of male and female black-capped chickadees (poecile atricapillus). | the black-capped chickadee is a songbird that has been used extensively as a model of animal communication in field and laboratory settings. although many studies have focused on the complex call and song systems of the black-capped chickadee, relatively fewer studies have focused on chickadee audition. however, we do know from behavioral and molecular work that chickadees (and auditory processing areas in their brains) discriminate between artificially generated tones, between conspecific and h ... | 2015 | 26163861 |
| estimation of muscle mass by ultrasonography differs between observers and life states of models in small birds. | ultrasonography has proven to be a valuable noninvasive method of measure of muscle size in birds, but validation of its use in birds as small as black-capped chickadees (poecile atricapillus; 11 g) is scarce. the effect of observers and life state (dead or alive) of models used for calibration on measurement quality is also poorly documented. using 31 dead and 22 live chickadees, linear regressions between ultrasound and dissection measurements of pectoral and thigh muscles were fitted and comp ... | 2016 | 25860831 |
| sequence and organization of the complete mitochondrial genome of the marsh tit poecile palustris (aves: paridae). | the complete mitochondrial genome of the marsh tit poecile palustris (linnaeus, 1758) was sequenced using a combined illumina and sanger sequencing approach. using the known sequence of poecile atricapillus linnaeus, 1766 (paridae) homologous ngs reads were identified and assembled. the genome is 16,824 bp in length and includes 13 protein-coding genes, 2 ribosomal rna genes, 22 transfer rna genes and a control region. gene order resembles that of the standard avian gene order. the base composit ... | 2016 | 25845385 |
| experience affects immediate early gene expression in response to conspecific call notes in black-capped chickadees (poecile atricapillus). | black-capped chickadees (poecile atricapillus) produce numerous vocalizations, including the acoustically complex chick-a-dee call that is composed of a, b, c, and d notes. d notes are longer in duration and lower in frequency than the other note types and contain information regarding flock and species identification. adult wild-caught black-capped chickadees have been shown to have similar amounts of immediate early gene (ieg) expression following playback of vocalizations with harmonic-like a ... | 2015 | 25813748 |
| individual inconsistencies in basal and summit metabolic rate highlight flexibility of metabolic performance in a wintering passerine. | resident passerines inhabiting high latitude environments are faced with strong seasonal changes in thermal conditions and energy availability. summit metabolic rate (maximal metabolic rate elicited by shivering during cold exposure: m(sum)) and basal metabolic rate (bmr) vary in parallel among seasons and increase in winter due to cold acclimatization, and these adjustments are thought to be critical for survival. wintering individuals expressing consistently higher m(sum) and bmr could therefo ... | 2015 | 25690265 |
| reaction norms in natural conditions: how does metabolic performance respond to weather variations in a small endotherm facing cold environments? | reaction norms reflect an organisms' capacity to adjust its phenotype to the environment and allows for identifying trait values associated with physiological limits. however, reaction norms of physiological parameters are mostly unknown for endotherms living in natural conditions. black-capped chickadees (poecile atricapillus) increase their metabolic performance during winter acclimatization and are thus good model to measure reaction norms in the wild. we repeatedly measured basal (bmr) and s ... | 2014 | 25426860 |
| environmental contaminants and chromosomal damage associated with beak deformities in a resident north american passerine. | a large cluster of beak abnormalities among black-capped chickadees (poecile atricapillus) in alaska raised concern about underlying environmental factors in this region. metals and trace elements, organochlorine pesticides, polychlorinated biphenyls (pcbs), and polychlorinated dibenzo-dioxins and polychlorinated dibenzofurans (pcdd-fs) were analyzed in adults, nestlings, and eggs of the affected population; local bird seed was also tested for organochlorine pesticides. the results offered no su ... | 2015 | 25376148 |
| timbre influences chord discrimination in black-capped chickadees (poecile atricapillus) but not humans (homo sapiens). | timbre is an important attribute of sound both in music and nature. previously, using an operant conditioning paradigm, we found that black-capped chickadees and humans show similar response patterns in discriminating triadic chords of the same timbre and transferred this discrimination to a novel key center (novel absolute pitch). the current study examined how varying the timbre of the chords influenced discrimination. using a similar operant conditioning procedure, we trained humans (experime ... | 2014 | 25150964 |
| spatiotemporally consistent genomic signatures of reproductive isolation in a moving hybrid zone. | studies of hybrid zone dynamics often investigate a single sampling period and draw conclusions from that temporal snapshot. stochasticity can, however, result in loci with spurious outlier patterns, which is exacerbated by limited temporal or geographic sampling. comparing admixed populations from different geographic regions is one way to detect repeatedly divergent genomic regions potentially involved in reproductive isolation. temporal comparisons also allow us to control partially for the r ... | 2014 | 25138643 |
| detection and molecular characterization of a reovirus in black-capped chickadees (poecile atricapillus) from minnesota, usa. | in 2011, the minnesota rehabilitation center submitted four dead black-capped chickadees (poecile atricapillus) for necropsy to the minnesota veterinary diagnostic laboratory. all four chickadees were underweight and dehydrated and their intestinal contents were watery and yellowish. no significant lesions were observed upon histopathologic examination. viral particles of the family reoviridae were detected after negative-contrast electron microscopic examination of intestinal contents. analysis ... | 2014 | 25121410 |
| effects of sex and seasonality on the song control system and foxp2 protein expression in black-capped chickadees (poecile atricapillus). | plasticity in behavior is mirrored by corresponding plasticity in the brain in many songbird species. in some species, song system nuclei (phillmore et al. [2006]: j neurobiol 66:1002-1010) are larger in birds in breeding condition than birds in nonbreeding condition, possibly due to increased vocal output in spring. foxp2, a transcription factor associated with language expression and comprehension in humans and song learning in songbirds, also shows plasticity. foxp2 expression in songbird are ... | 2015 | 25081094 |
| influence of ecological and geological features on rangewide patterns of genetic structure in a widespread passerine. | geological and ecological features restrict dispersal and gene flow, leading to isolated populations. dispersal barriers can be obvious physical structures in the landscape; however microgeographic differences can also lead to genetic isolation. our study examined dispersal barriers at both macro- and micro-geographical scales in the black-capped chickadee, a resident north american songbird. although birds have high dispersal potential, evidence suggests dispersal is restricted by barriers. the ... | 2015 | 25074576 |
| lipid metabolites as markers of fattening rate in a non-migratory passerine: effects of ambient temperature and individual variation. | plasma lipid metabolites triglycerides (trig) and glycerol (gly) are used as indicators of fattening rate and nutritional condition in migratory birds. requiring only one blood sample, they could also be used for studying daily and seasonal fattening rates in relation with habitat quality or weather variations in species wintering in cold climates. using black-capped chickadees exposed to three experimental temperatures (0 °c, 15 °c, and 30 °c), the goal of this experiment was to determine the r ... | 2014 | 25064332 |
| individual differences in learning speed, performance accuracy and exploratory behaviour in black-capped chickadees. | cognitive processes are important to animals because they not only influence how animals acquire, store and recall information, but also may underpin behaviours such as deciding where to look for food, build a nest, or with whom to mate. several recent studies have begun to examine the potential interaction between variation in cognition and variation in personality traits. one hypothesis proposed that there is a speed-accuracy trade-off in cognition ability that aligns with a fast-slow behaviou ... | 2015 | 25060576 |
| chickadees with bigger brains have smaller digestive tracts: a multipopulation comparison. | the factors leading to the evolution of large brain size remain controversial. brains are metabolically expensive and larger brains demand higher maintenance costs. the expensive-tissue hypothesis suggests that when selection favors larger brains, evolutionary changes in brain size can occur without an overall increase in energetic costs when brain size represents a trade-off with the size of other expensive tissues, such as the digestive tract. still, support for this hypothesis is equivocal. w ... | 2014 | 25059294 |
| melanin-based color of plumage: role of condition and of feathers' microstructure. | whether melanin-based colors honestly signal a bird's condition during the growth of feathers is controversial, and it is unclear if, or how, the physiological processes underlying melanogenesis or the role of the microstructure of feathers in imparting structural color to feathers may be adversely affected by condition. here, we report results from two experiments designed to measure the effect of condition on expression of eumelanic and pheomelanic coloration in black-capped chickadees (poecil ... | 2014 | 24987010 |
| zenk activation in the nidopallium of black-capped chickadees in response to both conspecific and heterospecific calls. | neuronal populations in the songbird nidopallium increase in activity the most to conspecific vocalizations relative to heterospecific songbird vocalizations or artificial stimuli such as tones. here, we tested whether the difference in neural activity between conspecific and heterospecific vocalizations is due to acoustic differences or to the degree of phylogenetic relatedness of the species producing the vocalizations. to compare differences in neural responses of black-capped chickadees, poe ... | 2014 | 24963707 |
| how does flexibility in body composition relate to seasonal changes in metabolic performance in a small passerine wintering at northern latitude? | abstract small avian species wintering at northern latitudes typically show increases in basal metabolic rate (bmr) and maximal thermogenic capacity (msum). those are widely assumed to reflect changes in body composition, with enlargement of digestive and excretory organs resulting in elevated winter bmr and larger body muscles driving the increase in msum. using free-living black-capped chickadees (poecile atricapillus) as our model species, we investigated seasonal changes in body composition ... | 2014 | 24940918 |
| inhibition of cell proliferation in black-capped chickadees suggests a role for neurogenesis in spatial learning. | following development, the avian brain continues to produce neurons throughout adulthood, which functionally integrate throughout the telencephalon, including the hippocampus. in food-storing birds like the black-capped chickadee (poecile atricapillus), new neurons incorporated into the hippocampus are hypothesized to play a role in spatial learning. previous results on the relation between hippocampal neurogenesis and spatial learning, however, are correlational. in this study, we experimentall ... | 2014 | 24723376 |
| climate-mediated movement of an avian hybrid zone. | the interaction between sibling species that share a zone of contact is a multifaceted relationship affected by climate change [1, 2]. between sibling species, interactions may occur at whole-organism (direct or indirect competition) or genomic (hybridization and introgression) levels [3-5]. tracking hybrid zone movements can provide insights about influences of environmental change on species interactions [1]. here, we explore the extent and mechanism of movement of the contact zone between bla ... | 2014 | 24613306 |
| seasonal variation in pectoralis muscle and heart myostatin and tolloid-like proteinases in small birds: a regulatory role for seasonal phenotypic flexibility? | seasonally variable environments produce seasonal phenotypes in small birds such that winter birds have higher thermogenic capacities and pectoralis and heart masses. one potential regulator of these seasonal phenotypes is myostatin, a muscle growth inhibitor, which may be downregulated under conditions promoting increased energy demand. we examined summer-to-winter variation in skeletal muscle and heart masses and used qpcr and western blots to measure levels of myostatin and its metalloprotein ... | 2014 | 24395519 |
| discrimination of acoustically similar conspecific and heterospecific vocalizations by black-capped chickadees (poecile atricapillus). | chickadees produce a multi-note chick-a-dee call in multiple socially relevant contexts. one component of this call is the d note, which is a low-frequency and acoustically complex note with a harmonic-like structure. in the current study, we tested black-capped chickadees on a between-category operant discrimination task using vocalizations with acoustic structures similar to black-capped chickadee d notes, but produced by various songbird species, in order to examine the role that phylogenetic ... | 2017 | 28393311 |
| chickadees discriminate contingency reversals presented consistently, but not frequently. | chickadees are high-metabolism, non-migratory birds, and thus an especially interesting model for studying how animals follow patterns of food availability over time. here, we studied whether black-capped chickadees (poecile atricapillus) could learn to reverse their behavior and/or to anticipate changes in reinforcement when the reinforcer contingencies for each stimulus were not stably fixed in time. in experiment 1, we examined the responses of chickadees on an auditory go/no-go task, with co ... | 2017 | 28382429 |
| increasing winter maximal metabolic rate improves intrawinter survival in small birds. | small resident bird species living at northern latitudes increase their metabolism in winter, and this is widely assumed to improve their chances of survival. however, the relationship between winter metabolic performance and survival has yet to be demonstrated. using capture-mark-recapture, we followed a population of free-living black-capped chickadees (poecile atricapillus) over 3 yr and evaluated their survival probability within and among winters. we also measured the size-independent body ... | 2017 | 28277959 |
| phenotype manipulations confirm the role of pectoral muscles and haematocrit in avian maximal thermogenic capacity. | in small resident bird species living at northern latitudes, winter cold acclimatization is associated with an increase in pectoral muscle size and haematocrit level, and this is thought to drive the seasonal increase in summit metabolic rate (msum, a measure of maximal shivering thermogenic capacity). however, evidence suggesting that pectoral muscle size influences msum is correlational and the link between haematrocrit level and msum remains to be demonstrated. we experimentally tested the re ... | 2014 | 24198261 |
| habitat quality affects early physiology and subsequent neuromotor development of juvenile black-capped chickadees. | in songbirds, the ability to learn and render the species-specific song is influenced by the development of both the song nuclei in the brain and the syrinx (bird's vocal apparatus) early in the bird's life. in black-capped chickadees (poecille atricapillus), habitat quality is known to affect song structure, with birds in high-quality habitat (mature forest) having a higher song consistency than birds in low-quality habitat (young forest). although this difference is suspected to stem from diff ... | 2013 | 23951257 |
| if a bird flies in the forest, does an insect hear it? | birds are major predators of many eared insects including moths, butterflies, crickets and cicadas. we provide evidence supporting the hypothesis that insect ears can function as 'bird detectors'. first, we show that birds produce flight sounds while foraging. eastern phoebes (sayornis phoebe) and chickadees (poecile atricapillus) generate broadband sounds composed of distinct repetitive elements (approx. 18 and 20 hz, respectively) that correspond to cyclic wing beating. we estimate that insect ... | 2013 | 23945205 |
| intra-seasonal flexibility in avian metabolic performance highlights the uncoupling of basal metabolic rate and thermogenic capacity. | stochastic winter weather events are predicted to increase in occurrence and amplitude at northern latitudes and organisms are expected to cope through phenotypic flexibility. small avian species wintering in these environments show acclimatization where basal metabolic rate (bmr) and maximal thermogenic capacity (msum) are typically elevated. however, little is known on intra-seasonal variation in metabolic performance and on how population trends truly reflect individual flexibility. here we r ... | 2013 | 23840843 |
| avian incubation patterns reflect temporal changes in developing clutches. | incubation conditions for eggs influence offspring quality and reproductive success. one way in which parents regulate brooding conditions is by balancing the thermal requirements of embryos with time spent away from the nest for self-maintenance. age related changes in embryo thermal tolerance would thus be expected to shape parental incubation behavior. we use data from unmanipulated black-capped chickadee (poecile atricapillus) nests to examine the temporal dynamics of incubation, testing the ... | 2013 | 23840339 |
| macroscopic, histologic, and ultrastructural lesions associated with avian keratin disorder in black-capped chickadees (poecile atricapillus). | an epizootic of beak abnormalities (avian keratin disorder) was recently detected among wild birds in alaska. here we describe the gross, histologic, and ultrastructural features of the disease in 30 affected adult black-capped chickadees (poecile atricapillus). grossly, there was elongation of the rhamphotheca, with varying degrees of lateral deviation, crossing, and gapping between the upper and lower beak. not uncommonly, the claws were overgrown, and there was alopecia, scaling, and crusting ... | 2013 | 23399850 |
| variation in hippocampal glial cell numbers in food-caching birds from different climates. | enhancements to memory are associated with enhanced neural structures that support those capabilities. a great deal of work has examined this relationship in the context of natural variation in spatial memory capability and hippocampal (hp) structure. most studies have focused on volumetric and neuron measures, but have seldom examined the role of glial cells. once considered involved only in supportive functions associated with neurons, the importance of glial cells in cognitive processes, incl ... | 2013 | 23382130 |
| chickadees fail standardized operant tests for octave equivalence. | octave equivalence occurs when an observer judges notes separated by a doubling in frequency perceptually similar. the octave appears to form the basis of pitch change in all human cultures and thus may be of biological origin. previously, we developed a nonverbal operant conditioning test of octave generalization and transfer in humans. the results of this testing showed that humans with and without musical training perceive the octave relationship between pitches. our goal in the current study ... | 2013 | 23354548 |
| differential hippocampal gene expression is associated with climate-related natural variation in memory and the hippocampus in food-caching chickadees. | there is significant and often heritable variation in cognition and its underlying neural mechanisms, yet specific genetic contributions to such variation are not well characterized. black-capped chickadees present a good model to investigate the genetic basis of cognition because they exhibit tremendous climate-related variation in memory, hippocampal morphology and neurogenesis rates throughout the north american continent, and these cognitive traits appear to have a heritable basis. we examin ... | 2013 | 23205699 |
| heterospecific discrimination of poecile vocalizations by zebra finches (taeniopygia guttata). | previous perceptual research with black-capped and mountain chickadees has demonstrated that the d note of the namesake chick-a-dee call controlled species-based discrimination compared to other note types in this call. in the current experiment, we sought to determine whether discrimination performance of the chickadees was controlled by stimulus-specific properties or due to learning through experience. to accomplish this, we tested zebra finches, a songbird species that is distantly related t ... | 2013 | 23106805 |
| auditory same/different concept learning and generalization in black-capped chickadees (poecile atricapillus). | abstract concept learning was thought to be uniquely human, but has since been observed in many other species. discriminating same from different is one abstract relation that has been studied frequently. in the current experiment, using operant conditioning, we tested whether black-capped chickadees (poecile atricapillus) could discriminate sets of auditory stimuli based on whether all the sounds within a sequence were the same or different from one another. the chickadees were successful at so ... | 2012 | 23077660 |
| consolidation and reconsolidation of memory in black-capped chickadees (poecile atricapillus). | multiple phases of protein synthesis are necessary for the synaptic modifications that consolidate long-term memory. the reconsolidation hypothesis supposes that information in long-term memory becomes labile and subject to change when retrieved and must be reconsolidated into long-term memory. the current study used the protein synthesis inhibitor anisomycin to examine memory consolidation in birds and to test the reconsolidation hypothesis. black-capped chickadees store food and usually rememb ... | 2012 | 23067383 |
| population genetic structure and its implications for adaptive variation in memory and the hippocampus on a continental scale in food-caching black-capped chickadees. | food-caching birds rely on stored food to survive the winter, and spatial memory has been shown to be critical in successful cache recovery. both spatial memory and the hippocampus, an area of the brain involved in spatial memory, exhibit significant geographic variation linked to climate-based environmental harshness and the potential reliance on food caches for survival. such geographic variation has been suggested to have a heritable basis associated with differential selection. here, we ask ... | 2012 | 22882305 |
| evidence of accelerated beak growth associated with avian keratin disorder in black-capped chickadees (poecile atricapillus). | we recently documented an epizootic of beak deformities in more than 2,000 blackcapped chickadees (poecile atricapillus) and other wild bird species in north america. this emerging avian disease, which has been termed avian keratin disorder, results in gross overgrowth of the rhamphotheca, the outer, keratinized layer of the beak. to test the hypothesis that the beak deformities characteristic of this disorder are associated with accelerated keratin production, we measured rates of beak growth a ... | 2012 | 22740534 |
| variation in brain regions associated with fear and learning in contrasting climates. | in environments where resources are difficult to obtain and enhanced cognitive capabilities might be adaptive, brain structures associated with cognitive traits may also be enhanced. in our previous studies, we documented a clear and significant relationship among environmental conditions, memory and hippocampal structure using ten populations of black-capped chickadees (poecile atricapillus) over a large geographic range. in addition, focusing on just the two populations from the geographical e ... | 2012 | 22286546 |
| vocal parameters that indicate threat level correlate with fos immunolabeling in social and vocal control brain regions. | transmitting information via communicative signals is integral to interacting with conspecifics, and some species achieve this task by varying vocalizations to reflect context. although signal variation is critical to social interactions, the underlying neural control has not been studied. in response to a predator, black-capped chickadees (poecile atricapilla) produce mobbing calls (chick-a-dee calls) with various parameters, some of which convey information about the threat stimulus. we predic ... | 2012 | 22179056 |