Search

Vocal mimicry can develop either through imitation of heterospecific models (primary mimicry) or through imitation of conspecifics already producing mimetic song (secondary mimicry). Distinguishing primary versus secondary mimicry is important from ecological, evolutionary, and neurobiological perspectives. We outline four empirical strategies for researchers to detect the usage of secondary mimicry: (1) model selection strategy (heterospecific model commonly mimicked but rare or absent locally), (2) usage frequency strategy (syllable types commonly mimicked but rarely used by the model), (3) acoustic structure strategy (acoustic divergence in how a syllable type gets produced by mimics versus models), and (4) syntax strategy (consistent variation between mimic and model in the ordering of syllable types). We then use these strategies to produce evidence for secondary mimicry in northern mockingbirds (Mimus polyglottos), focusing mostly on the mimicked songs of northern cardinals (Cardinalis cardinalis) and tufted titmice (Baeolophus bicolor). As further evidence of the mechanisms by which secondary mimicry might occur, we also demonstrate that mockingbirds match countersing much more frequently in response to conspecifics versus heterospecifics. Deeper questions about the precise extent of primary versus secondary mimicry in mockingbirds and other mimicking species still need answers. [ABSTRACT FROM AUTHOR]

We studied hybridization between the Black-crested and Tufted titmouse across two geographically distinct transects that differ in the timing of secondary contact by hundreds to thousands of years. We found that hybridization patterns correspond to localized hybrid swarms and that the titmouse hybrid zone is likely slowly expanding over time, a product of short post-natal dispersal distances coupled with weak or absent selection against admixture. We show the southern part of the hybrid zone located in Texas is four times wider than the northern region of hybridization in Oklahoma, which is likely due to geographic differences in hybrid zone age. Despite differences in width, most individuals in both transects are advanced-generation hybrids and backcrosses, suggesting geographically consistent hybridization dynamics. We documented a strong correlation between genotypes and plumage index, suggesting that hybridization has not yet resulted in the decoupling of plumage and genome-wide ancestry as observed in some other avian hybrid zones. Although our results suggest the ongoing expansion of the hybrid zone, the rate of expansion appears to be slow, on the scale of tens of meters a year, and it will likely take hundreds of thousands to millions of years before homogenization of the parental populations. While we did not find support for partial reproductive isolation in the hybrid zone itself, there is the possibility that ecological or sexual selection limits introgression into allopatric regions. Broadly, the results of our study highlight the value of multiple, geographically distant, transects across a hybrid zone for assessing the evolutionary dynamics of hybridizing lineages. [ABSTRACT FROM AUTHOR]

The predictive nature of the hippocampus is thought to be useful for memory-guided cognitive behaviors. Inspired by the reinforcement learning literature, this notion has been formalized as a predictive map called the successor representation (SR). The SR captures a number of observations about hippocampal activity. However, the algorithm does not provide a neural mechanism for how such representations arise. Here, we show the dynamics of a recurrent neural network naturally calculate the SR when the synaptic weights match the transition probability matrix. Interestingly, the predictive horizon can be flexibly modulated simply by changing the network gain. We derive simple, biologically plausible learning rules to learn the SR in a recurrent network. We test our model with realistic inputs and match hippocampal data recorded during random foraging. Taken together, our results suggest that the SR is more accessible in neural circuits than previously thought and can support a broad range of cognitive functions.

The meninges and associated vasculature (MAV) play a crucial role in maintaining cerebral integrity and homeostasis. Recent advances in transcriptomic analysis have illuminated the significance of the MAV in understanding the complex physiological interactions at the interface between the skull and the brain after exposure to mechanical stress. To investigate how physiological responses may confer resilience against repetitive mechanical stress, we performed the first transcriptomic analysis of avian MAV tissues using the Downy Woodpecker (Dryobates pubescens) and Tufted Titmouse (Baeolophus bicolor) as the comparison species. Our findings reveal divergences in gene expression profiles related to immune response, cellular stress management, and protein translation machinery. The male woodpeckers exhibit a tailored immune modulation strategy that potentially dampens neuroinflammation while preserving protective immunity. Overrepresented genes involved in cellular stress responses suggest enhanced mechanisms for mitigating damage and promoting repair. Additionally, the enrichment of translation-associated pathways hints at increased capacity for protein turnover and cellular remodeling vital for recovery. Our study not only fills a critical gap in avian neurobiology but also lays the groundwork for research in comparative neuroprotection., (© 2024 American Association for Anatomy.)

The northward range expansion of Tufted Titmice (Baeolophus bicolor) has increased their contact with Black-capped Chickadees (Poecile atricapillus). Tufted Titmice and Black-capped Chickadees were observed foraging naturally in 3 Connecticut forests and at a residential bird feeder to assess the degree of foraging niche overlap and competition between the 2 species during winter 2015–2016. Chickadees spent significantly more time in the outer portion of the upper canopy than did titmice, which used different subsections of the canopy fairly evenly. Chickadees also foraged in shrubs significantly more than did titmice. Titmice spent much of their time foraging on the ground, which chickadees largely avoided. These differences may be explained by the ability of larger titmice to better forage on larger branches and to flip leaves to forage on the ground. The larger size of titmice may also explain their dominance to chickadees at the bird feeder. Given a choice between safflower seeds, black oil sunflower seeds with shells, and black oil sunflower seeds without shells, both species took some of each, but titmice most often chose safflower seeds while chickadees most often chose black oil sunflower seeds without shells. Although chickadees and titmice showed some overlap in their food choices and foraging locations, the significant differences we found may mitigate competition between these species, at least under the environmental conditions of this study. As titmice continue to expand their range northward, competition may be greater in areas with harsher winter conditions and less human-supplied bird seed. [ABSTRACT FROM AUTHOR]

In this study I examined heterospecific eavesdropping in passerines by investigating how information broadcast by the Tufted Titmouse ( Baeolophus bicolor) at dusk modifies singing and calling vocalizations of a common avian dusk chorus species, the Veery ( Catharus fuscescens). The Veery nests on or near the ground and is a highly vocal participant of the avian dusk chorus, which also renders it vulnerable to a wide array of diurnal and crepuscular predators. Thus, the Veery is expected to be sensitive to signals of predation risk. Here, I report findings of simulated exposure to indirect predation risk (recorded playbacks of Tufted Titmouse alarm calls) that alter acoustic output by the Veery. From 19 May to 6 July 2013, 14 plots in Veery territories were selected and exposed to playback calls of the gray tree frog ( Hyla versicolor; control treatment) and playbacks of the Tufted Titmouse high seet call (experimental treatment). Each plot was subjected to two 65 min playback-recording trials (one experimental and one control); Veery song and call output were quantified via spectrograms to compare Veery acoustic response between treatments. The Veery produced a greater call output while song output remained unchanged between control and experimental treatments. These results reveal that the Veery indeed detected and responded to heterospecific alarm calls. Moreover, the Veery acted as a secondary community informant, further transmitting information regarding predation risk to conspecifics and the dusk chorus community at large. [ABSTRACT FROM AUTHOR]

Hemosporidians are a diverse group of blood parasites that infect terrestrial vertebrates worldwide, but there is variability in parasite prevalence and parasitemia with infections ranging from virtually inconsequential to lethal. In this study, we determined prevalence and parasitemia of avian hemosporidians in the Tufted Titmouse ( Baeolophus bicolor; n = 81). Plasmodium and Parahaemoproteus were detected and quantified from blood samples using microscopy, polymerase chain reaction (PCR), and quantitative PCR. Thirteen mitochondrial cytochrome b lineages of hemosporidian parasites were found, including generalist and specialist lineages, and the data indicate that prevalence is 69.1% ( Plasmodium 89.3%; Parahaemoproteus 7.1%; double infection 3.6%). However, parasitemia was low in all infected birds. Seasonally, parasite prevalence varied significantly, although prevalence and parasitemia were not associated with host sex, age, or health. Observations of infection in this naturally infected bird provide details on host susceptibility that are applicable to the understanding of hemosporidian parasites in other avian hosts. [ABSTRACT FROM AUTHOR]

The risk of predation varies with behavioral cues and body characteristics of potential predators. One such body characteristic is the head/face orientation of the predator. However, a prey individual's ability to detect the head may be more difficult when the predator's body is serpentine, with little distinguishing the head from the tail. Here, we tested whether individuals in mixed-species flocks of Carolina chickadees ( Poecile carolinensis) and tufted titmice ( Baeolophus bicolor) distinguish the head orientation of predator snake models. We conducted behavioral observations at multiple sites each having a bird feeder stocked with seed. Each chickadee and titmouse flock was exposed to two counterbalanced trials: a snake model with head closest to the seed area of the feeder and with tail closest to the seed area of the feeder. Observers recorded the number of seeds taken by each species and also the number of unsuccessful feeder visits. Chickadees and, to a lesser extent, titmice took fewer seeds and had more unsuccessful feeder visits when the head of the snake model was closest to the seed, compared to when the tail was closest to the seed. Titmice, furthermore, had more unsuccessful feeder visits to the black snake model type representing a real snake nest predator for these small songbirds. Therefore, head orientation seems an important factor that some species use to assess predation risk, even for predatory species where head orientation may be a subtle cue. [ABSTRACT FROM AUTHOR]

The predictive nature of the hippocampus is thought to be useful for memory-guided cognitive behaviors. Inspired by the reinforcement learning literature, this notion has been formalized as a predictive map called the successor representation (SR). The SR captures a number of observations about hippocampal activity. However, the algorithm does not provide a neural mechanism for how such representations arise. Here, we show the dynamics of a recurrent neural network naturally calculate the SR when the synaptic weights match the transition probability matrix. Interestingly, the predictive horizon can be flexibly modulated simply by changing the network gain. We derive simple, biologically plausible learning rules to learn the SR in a recurrent network. We test our model with realistic inputs and match hippocampal data recorded during random foraging. Taken together, our results suggest that the SR is more accessible in neural circuits than previously thought and can support a broad range of cognitive functions., Competing Interests: CF, DA, LA, EM No competing interests declared, (© 2023, Fang et al.)

Although anti-predator behavior systems have been studied in diverse taxa, less is known about how prey species detect and assess the immediate threat posed by a predator based on its behavior. In this study, we evaluated a potential cue that some species may utilize when assessing predation threat-the predator's body and head orientation. We tested the effect of this orientation cue on signaling and predation-risk-sensitive foraging of a prey species, tufted titmice ( Baeolophus bicolor). Earlier work revealed sensitivity of titmice and related species to the presence of predator stimuli. Here, we manipulated cat models to face either toward or away from a food source preferred by titmice and then measured titmouse calling and seed-taking behavior. Titmice showed greater feeder avoidance when the cat predator models faced the feeder, compared to when the models faced away from the feeder or when titmice were exposed to control stimuli. Titmouse calling was also sensitive to predator head/body orientation, depending upon whether titmice were from sites where real cats had been observed or not. This study experimentally demonstrated that both calling and foraging of prey species can be affected by the head and body orientation of an important terrestrial predator. Prey species may therefore signal in strategic ways to conspecifics not just about predator presence, but also urgency of threat related to the more subtle cue of the head and body orientation of the predator. These findings hold potential implications for understanding animal cognition and learning processes. [ABSTRACT FROM AUTHOR]

Individuals often produce alarm or mobbing calls when they detect a threat such as a predator. Little is known about whether such calling is affected by the facial orientation of a potential threat, however. We tested for an effect of facial orientation of a potential threat on tufted titmice, Baeolophus bicolor, a songbird that uses chick- a- dee calls in a variety of social contexts. In two studies, a human observer wore an animal mask that either faced or faced away from the focal bird(s). In Study 1, focal birds were individual titmice captured in a walk-in trap, and the observer stood near the trapped bird. In Study 2, focal birds were titmouse flocks utilizing a feeding station and the observer stood near the station. In both studies, calling behavior was affected by mask orientation. In Study 2, foraging and agonistic behavior were also affected. Titmice can therefore perceive the facial orientation of a potential threat, and this perception affects different behavioral systems, including calling. Our results indicate sensitivity of titmice to the facial orientation of a potential predator in two quite different motivational contexts. This work suggests the possibility of strategic signaling by prey species depending upon the perceptual space of a detected predator. [ABSTRACT FROM AUTHOR]

An interview with biologist Nick Komar of the Centers for Disease Control and Prevention in Colorado is presented. Topics discussed include Komar's favorite hotspot for bird watching in Colorado, his approach to appreciate and identify birds, and the five species of birds that will be added to the list of Colorado including White-tailed Kite, Black-tailed Gull, and Tufted Titmouse.

Hybrid zones, where phenotypically distinct populations interbreed, should expand or contract until reaching a balance between selection and dispersal. Few studies examine multiple contacts within one species complex to compare how their extent changes over time. Black-crested and Tufted Titmice (Baeolophus atriaistatus and B. bicolor) hybridize extensively within a narrow zone in Texas and southwestern Oklahoma. In Texas, hybridization has been occurring for several thousands of years, while evidence suggests the southwestern Oklahoma contact is more recent, beginning within the past century. We quantify plumage and morphology of the two species across both the younger and older hybrid zones and compare the current and historical extent of phenotypic variation in the older Texas contact with that in the younger Oklahoma contact. Variation in plumage between species is similar in the younger and older contacts, while overlap in morphological characters is broader in the older contact. Recently and historically surveyed transects in the older zone have similar cline widths, indicating selection, at least on crest and forehead plumage, has reached equilibrium with dispersal over the time periods involved (comparing both the historically surveyed data from 1955 vs. the recently surveyed data from the 2000s in Texas). In the recently surveyed younger Oklahoma contact, cline width is narrower, indicating potential for expansion if it follows the course of the older contact. This temporal complexity should make this species complex a productive system for future work, using plumage and additional traits such as song and genetics, on the relative influences of both natural and sexual selection on the evolution of reproductive isolation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Emerging vector-borne infectious diseases, including West Nile virus (WNV) threaten many wildlife species. [•] We develop a mathematical framework for conservation planning to predict impacts of vector-borne diseases on multiple species. [•] Models using mosquito feeding and WNV seroprevalence data predict substantial mortality in tufted titmouse and Carolina wren. [•] Infection studies support these predictions with 100% mortality in titmice and 27% in wrens and high infectiousness in both. [•] This mathematical framework is general and can be used for most vector-borne diseases and host taxa. [ABSTRACT FROM AUTHOR]

Tufted titmice, Baeolophus bicolor, produce calls in the contexts related to threat and approach of, and capture by, a predator. In titmice, these calls transition from the chick-a-dee call, used in a wide range of social contexts, to 'distress' calls that are produced by birds when captured and held by a predator or human observer. A recent study indicated that titmice modify the note composition of their calls in the presence of such threatening stimuli. Here, we tested whether female and male titmice differed in their calling behavior, as relatively few sex differences have been documented in calls shared by female and male songbirds. Individual titmice were captured in walk-in treadle traps, and we gradually increased the level of fear or arousal by approaching and finally capturing the bird in the hand. Male titmice produced more chick-a-dee calls than females as the level of threat increased, up to the point of capturing the bird in the hand. Furthermore, the note composition of calls produced by males differed from that of calls produced by females. A limitation to our study is that our method did not allow us to rule out the possibility that size or dominance differences, rather than sex, were the main reason for the differences in calling we detected. However, increased size generally was not associated with increased calling. We discuss some possible explanations for variation in distress calling behavior in titmice. [ABSTRACT FROM AUTHOR]

Tufted Titmice (Baeolophus bicolor) and Carolina Chickadees (Poecile carolinensis) often occur together in mixed species flocks during the nonbreeding season and, as nuclear species, often initiate mobbing bouts. We compared the mobbing behavior of Tufted Titmice and Carolina Chickadees and, specifically, their tendency to approach five potential predators. We exposed flocks of chickadees and titmice to study skins of five species of raptors in 2008; raptors were categorized as either low-threat (rarely preying on chickadees or titmice) or high-threat (more likely to prey on chickadees or titmice). We noted the distance of closest approach by titmice and chickadees during trials, and whether a chickadee or titmouse spent more time within 5 m of the raptor. Titmice were more likely to remain within 5 m of both low (P = 0.0008) and high-threat (P = 0.0015) raptors. Titmice approached low-threat raptors closer than chickadees (P = 0.014). There was no difference in the mean distance of closest approach by chickadees and titmice during high-threat trials (P = 0.34). Titmice generally approached and remained closer to raptors during mobbing bouts than chickadees, possibly because larger titmice (∼ 21 g) are more likely targets of aerial predators than smaller chickadees (∼ 11 g). Titmice may be willing to take greater risks because the potential benefits (reduced risk of predation) are greater if mobbing causes potential predators to leave an area. [ABSTRACT FROM AUTHOR]

Distress calls are produced by a wide variety of small prey species when they are captured by a predator and may serve as signals to warn group members of danger, to attract others that might aid the captured individual, and to confuse the predator. Tufted titmice (Baeolophus bicolor) produce distress calls when captured by a predator or a human. Here, we tested several hypotheses to explain the distress calling in this species. Individual titmice were captured in walk-in treadle traps. We recorded captured individuals in an ordered sequence that modeled approaching threat, capture, and finally escape. Titmice produced more total notes as the level of threat increased (as the observer moved closer to the trap restraining them) and as they were captured and held. Captured titmice produced distress calls comprising many high-frequency components but also many low-frequency broadband components and did so whether other titmice were present or absent. Playbacks of distress calls indicate that the notes of these calls transmit over long distances (>60 m) and do not readily attract larger avian predators to the area. Variation in production of lower frequency and broadband notes by captured titmice was not associated with variation in aggressive behavior. Taken together, our results lend support both to the “protean defense” hypothesis and to a dual “mobbing/alarm” hypothesis. Distress calls in titmice may therefore function either to confuse the predator or to warn conspecifics and facilitate their mobbing behavior. [ABSTRACT FROM PUBLISHER]

Use of socially derived information from other species is common in many types of decision making, but particularly in predation avoidance. In communities with diverse prey that share generalist predators, public information concerning predator location, type, or activity is often used by heterospecifics. Given that exploration and exploitation of the environment is constrained by predator avoidance, exactly how information about predators affects subsequent prey behavior is of increasing interest. In this study, we tested how social information (predation threat encoded in antipredator vocalizations of the tufted titmouse, Baeolophus bicolor) influences the exploratory behavior (movement, vigilance, and space use) of Northern cardinals (Cardinalis cardinalis). Cardinals, placed inside a small flight cage equipped with an array of perches, experienced randomly assigned playback treatments of titmouse antipredator vocalizations that varied in threat level. Exploratory behavior was videotaped during 3 periods—Before (B), During (D), and After (A) playbacks of titmouse calls. When titmouse vocalizations encoding more dangerous and immediate predation threats were played, cardinals significantly reduced active movements but increased visual scanning relative to subjects hearing calls that encoded low threat levels. Furthermore, they were also slower to return to prethreat behavior. Thus, we conclude that cardinals interpreted the antipredator signals correctly and responded accordingly, adjusting their activities to potentially reduce risk (decreasing movement and increasing vigilance). Our work demonstrates specifically how the trade-off between exploration (comprised of both movement and sensory scanning) and predator avoidance is actuated via spatial decision making in the cardinal. [ABSTRACT FROM PUBLISHER]

Abstract: Fire is frequently applied as a management tool on both public and private lands. However, in some ecosystems there is little information about bird species’ responses to these fire programs. In 2004 we measured habitat characteristics and conducted point counts in 12 burned sites and four unburned sites in the Chattahoochee National Forest of northern Georgia. Burns were categorized by severity (low, medium, or high) and time since fire (1–2 or 3–6years). The basal area of snags, shrub stem density and percent canopy cover were similar among all treatments except high severity. Otherwise, fire severity had limited impacts on measured habitat characteristics. Following fires the densities of early-succession species such as eastern towhee (Pipilo erythropthalmus) and indigo bunting (Passerina cyanea) were greatest in areas of higher fire severity. A ground-nesting species (ovenbird [Seiurus aurocapilla]) was less abundant in burned sites and the density of a shrub nesting species, the hooded warbler (Setophaga citrine) was greatest in areas that received low severity fires. Scarlet tanager (Piranga olivacea), tufted titmouse (Baeolophus bicolor), red-eyed vireo (Vireo olivaceus), black-throated green warbler (Setophaga virens), and black-and-white warbler (Mniotilta varia) had similar densities among all burn severities and showed no relationships with time since fire. Low and medium severity fires provided few benefits for most bird species. When conditions allow for their application, severe fires may be considered as a useful and historically appropriate management tool for some high-priority bird species in the southern Appalachian Mountains. [Copyright &y& Elsevier]

The tufted titmouse (Baeolophus bicolor, TUTI) is a nuclear species in winter foraging flocks whose antipredator calls are used to manage predation risk by diverse heterospecifics. We hypothesized that satellite species in mixed flocks follow TUTI (not vice versa), thereby defining the role of TUTI as a"passive" nuclear species. We followed 20 winter mixed-species flocks in North-Central Florida and assessed angular-angular correlations between overall flock, TUTI, and satellite species movement directions. We observed significant correlations between overall flock movement directions and those of TUTI, confirming our central prediction. Within flocks, however, fine-scale movement directions of satellite species were often more highly correlated with those of other satellites than with TUTI movements. We conclude that TUTI are passive nuclear species whose movements define flock paths, but within flocks, TUTI movements may have less influence on satellite movements than do other factors. [ABSTRACT FROM AUTHOR]

1. Environmental constraints in woodland habitats favour long-range communication signals with slow modulations of frequency and amplitude, while constraints in open habitats favour faster modulations. 2. Spectral filtering by the peripheral auditory system results in a trade-off between frequency resolution and temporal resolution of modulations. Greater frequency resolution requires integration of acoustic signals over a longer period of time, which in turn decreases responsiveness to temporal modulations. 3. Here, we test the hypothesis in songbirds that woodland habitats have selected for narrowly tuned auditory filters with high frequency resolution of tonal elements, while open habitats have selected for broader auditory filters with greater temporal resolution of rapid modulation. 4. Auditory filter shapes were measured at 2, 3 and 4 kHz in three woodland species, the dark-eyed junco ( Junco hyemalis), tufted titmouse ( Baeolophus bicolor) and white-breasted nuthatch ( Sitta carolinensis), and two open-habitat species, the house sparrow ( Passer domesticus) and white-crowned sparrow ( Zonotrichia leucophrys). Auditory filter shapes were derived from auditory brainstem response thresholds in notched noise using Patterson’s rounded exponential (roex) auditory filter model. 5. Auditory filters increased in bandwidth with increasing frequency in all species except the dark-eyed junco . Auditory filters were generally narrower in woodland species than open-habitat species as predicted, although auditory filters of the junco were relatively narrow only at 4 kHz, and the difference between white-crowned sparrows and tufted titmice was not significant. Finally, at 4 kHz, open-habitat species had auditory filters with lower signal-to-noise response thresholds than woodland species (i.e. greater response efficiency). 6. The results suggest that environmental constraints on song structure have influenced the evolution of peripheral auditory filters in songbirds, although species using signals not optimized for long-range transmission should be less affected. Differences in filter bandwidth between dark-eyed juncos and white-crowned sparrows are noteworthy because Junco and Zonotrichia share a recent common ancestor as sister genera within the Emberizidae. Finally, open-habitat species may compensate for inherently lower sensitivity in noise of broad auditory filters with greater response efficiency. [ABSTRACT FROM AUTHOR]

Evidence from different chickadee species ( Poecile genus) indicates that birds can modify the note composition of their “chick-a-dee” calls in the presence of predator stimuli. Here, we tested the effects of predator models and the distance of those models on calls of three species foraging together at feeding stations: Carolina chickadees ( Poecile carolinensis) and tufted titmice ( Baeolophus bicolor), both members of the Paridae family, and white-breasted nuthatches ( Sitta carolinensis), a member of the Sittidae family. Model and distance affected seed-taking rates in all three species. “Chick-a-dee” calling rates were higher in the predator context for both chickadees and titmice, but we detected no predator context effects on “quank” call rates for nuthatches. Predator and distance contexts affected acoustic parameters of notes of the “chick-a-dee” calls of chickadees and titmice; no such effects were detected for nuthatch “quank” calls. These results suggest species differences in encoding of information in the primary social calls of these three species that commonly occur in multi-species flocks. Chickadees and titmice are “nuclear” species and nuthatches are “satellite” species, and these different roles might be related to the differences in vocal signaling that we detected. [ABSTRACT FROM AUTHOR]

Many mammal and bird species respond to predator encounters with alarm vocalizations that generate risk-appropriate responses in listeners. Two conceptual frameworks are typically applied to the information encoded in alarm calls and to associated anti-predator behaviors. 'Functionally referential' alarm systems encode nominal classes or categories of risk in distinct call types that refer to distinct predation-risk situations. 'Risk-based' alarms encode graded or ranked threat-levels by varying the production patterns of the same call types as the urgency of predation threat changes. Recent work suggests that viewing alarm-response interactions as either referential or risk-based may oversimplify how animals use information in decision-making. Specifically, we explore whether graded alarm cues may be useful in classifying risks, supporting a referential decision-making framework. We presented predator (hawk, owl, cat, snake) and control treatments to captive adult tufted titmice Baeolophus bicolor and recorded their vocalizations, which included 'chick-a-dee' mobbing calls (composed of chick and D notes), 'seet' notes, two types of contact notes ('chip', 'chink'), and song. No single call type was uniquely associated with any treatment and the majority of acoustic measures varied significantly among treatments (46 of 60). The strongest models (ANOVA and classification tree analysis) grouped hawk with cat and owl, and control with snake, and were based on the number or proportion of a) chick and D notes per chick-a-dee call, b) chip versus chink notes produced following treatment exposure, and c) the frequency metrics of other note types. We conclude that (1) the predation-threat information available in complex titmouse alarm calls was largely encoded in graded acoustic measures that were (2) numerous and variable across treatments and (3) could be used singly or in combinations for either ranking or classification of threats. We call attention to the potential use of mixed threat identification strategies, where risk-based signal information may be used in referential decision-making contexts. [ABSTRACT FROM AUTHOR]

In mixed-species foraging flocks of forest birds, one or a few nuclear species frequently produce alarm calls and are followed by other species in the flock. We tested the hypothesis that similar asymmetries may exist in a second interspecific social context, multispecies mobbing behaviour. We examined mobbing behaviour evoked by an eastern screech-owl, Megascops asio, model and playback in two nuclear species, Carolina chickadees, Poecile carolinensis, and tufted titmice, Baeolophus bicolor, and in a species that follows them, the white-breasted nuthatch, Sitta carolinensis. Asymmetries in mobbing were not the same as those in mixed-species flocks. Nuthatches and chickadees mobbed with greater frequency and intensity compared to titmice, which remained at greater distances from the owl model and vocalized less frequently. We also tested for the existence and nature of potential interspecific vocal information flow during mobbing. Chickadee and nuthatch calling rates were positively correlated, as were chickadee and titmouse calling rates. Nuthatches and titmice rarely mobbed simultaneously. These results suggest the existence of positive feedback among species'' mobbing intensity during a multispecies mobbing association as opposed to heterospecific vocal interference or a lack of heterospecific influence. However, randomization simulations showed that this positive feedback was not driven by a particular ‘nuclear’ species during mobbing, suggesting that the correlations may result from a mutually interdependent escalation of mobbing intensity. [Copyright &y& Elsevier]

The article presents the 2008 reports of bird banding stations in the U.S. St. Andrews Bird Banding Station in New Brunswick, New Jersey banded new species including Hooded Warbler, Tufted Titmouse, and White-winged Crossbill. Wing Island Banding Station in Brewster, Massachusetts banded Broad-billed Hummingbird along with a Hooded Warbler and Red-bellied Woodpecker. Island Beach State Park in Seaside Park, New Jersey noted birds such as Ruby-throated Hummingbird and Hairy Woodpecker.

Coevolution between senders and receivers is expected to produce a close match between signal design and sensory biology. We evaluated this hypothesis in songbirds by comparing aspects of acoustic signal space with the frequency range of auditory sensitivity and temporal resolution in tufted titmice, Baeolophus bicolor; house sparrows, Passer domesticus; and white-breasted nuthatches, Sitta carolinensis. Auditory measurements were made electrophysiologically from the scalp using two classes of auditory-evoked potentials: the auditory brain-stem response (ABR) and the envelope-following response (EFR). ABRs to tone-burst stimuli indicated maximum sensitivity from 2.2 to 3.2kHz in all species, but 12–14dB greater sensitivity in titmice than in sparrows and nuthatches at 6.4kHz (the highest frequency tested). Modulation rate transfer functions based on EFRs to amplitude-modulated tones suggested greater temporal resolution in titmice and sparrows than in nuthatches. Conservation of the frequency range of maximum sensitivity across species resulted in a mismatch with the dominant frequency of song in sparrows. The mismatch may reflect auditory constraints coupled with selection for high-frequency song and relaxed selection for a close match between sender and receiver due to small territory size. Consistent with coevolution between senders and receivers, high-frequency sensitivity varied with the maximum frequency of species-specific vocalizations, whereas temporal resolution varied with the maximum rate of envelope periodicity. Enhanced high-frequency sensitivity of the titmouse may reflect a specialization for processing high-frequency communication signals such as alarm calls. [Copyright &y& Elsevier]

The chick-a-dee call of chickadee species (genus Poecile) has been the focus of much research. A great deal is known about the structural complexity and the meaning of variation in notes making up calls in these species. However, little is known about the likely homologous “chick-a-dee” call of the closely related tufted titmouse, Baeolophus bicolor. Tufted titmice are a prime candidate for comparative analyses of the call, because their vocal and social systems share many characteristics with those of chickadees. To address the paucity of data on the structure of chick-a-dee calls of tufted titmice, we recorded birds in field and aviary settings. Four main note types were identified in the call: Z, A, Dh, and D notes. Several acoustic parameters of each note type were measured, and statistical analyses revealed that the note types are acoustically distinct from one another. Furthermore, note types vary in the extent of individual distinctiveness reflected in their acoustic parameters. This first step towards understanding the chick-a-dee call of tufted titmice indicates that the call is comparable in structure and complexity to the calls of chickadees. [ABSTRACT FROM AUTHOR]

Using standardized mist-net captures collected over a 32-year period (1970-2001), we examined changes in the capture rates of passerines recorded in coastal Massachusetts during fall (78 species) and spring (72 species) migration. Capture rates of 45 species of fall migrants (58%) declined significantly between early (1970-1985) and late (1986-2001) years of the study; 36 species of spring migrants (50%) showed significant declines. Only Carolina Wren (Thryothorus ludovicianus), Tufted Titmouse (Baeolophus bicolor), Northern Cardinal (Cardinalis cardinalis), and Orchard Oriole (Icterus spurius) showed significant increases during spring migration; fall sampling indicated that Carolina Wren, Tufted Titmouse, Black-throated Blue Warbler (Dendroica caerulescens), and Northern Cardinal had significantly higher capture rates. Of 37 species included in the migration monitoring data but not reliably represented by Breeding Bird Survey (BBS) data in any of the northeastern physiographic strata, 23 (62%) showed significant declines at Manomet during at least one of the two migration periods. There were significant correlations in percent changes in migrant capture rates between fall and spring. BBS trends reported from the southern New England and northern New England physiographic strata were correlated with changes in migrant capture rates. However, there were also inconsistencies between results obtained by the two monitoring approaches, suggesting that factors in addition to actual changes in breeding populations may be reflected in the migration capture data. [ABSTRACT FROM AUTHOR]

In a previous study we found that survivorship of several species of permanent-resident, temperate-zone birds was positively related to forest fragment size and presence of supplemental food, and negatively related to extent of snow cover (Doherty and Grubb 2002). Here, we test the hypothesis that such trends are related to differential nutritional condition during winter. Employing rate of growth of induced feathers, we found that woodlot size and presence of supplemental food interacted to increase the nutritional condition of Carolina Chickadees (Poecile carolinensis) and that Tufted Titmouse (Baeolophus bicolor) nutritional condition was reduced in years with high snow cover. Assuming that nutritional condition is positively related to survivorship, these results have possible implications for the viability of permanent-resident birds in small woodlots, with the effects on subordinate species in foraging flocks in very small woodlots possibly being the most severe. Received 8 April 2002, accepted 25 November 2002. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the influence of kinship on nutritional condition in winter social groups of Tufted Titmice, Baeolophus bicolor. Methodology; Results and discussion.

The prolonged brood care model rests on the assumption that retaining an offspring through the winter months in the face of a limited food supply should have a cost for parents. We tested this idea with a New World permanent-resident bird, the tufted titmouse (Baeolophus bicolor). Using DNA fingerprinting, we assessed the degree of relatedness between adult and juvenile birds in 17 winter groups, finding that in 8 of the groups no young bird was the offspring of the territorial pair. We compared the nutritional condition of territorial adult birds in small forest fragments from which their own offspring and other young had been removed with the nutritional condition of control birds from unmanipulated fragments. Contrary to the model's assumption, the nutritional condition of adults in treatment groups (young removed) appeared to be worse, not better, than in groups where a related juvenile was present. These results suggest that the prolonged brood care model may not be universal in its application and that under some ecological conditions, retaining offspring through the winter can result in a net benefit for territorial adults despite the necessity of sharing resources. [ABSTRACT FROM AUTHOR]

Focuses on the social groupings of Tufted Titmouse (Baeolophus bicolor) in central Ohio. How often offspring are retained by the bird specie; Factors which determine the size and composition of winter groups; Multilocus minisatellite DNA fingerprinting.

Looks at a study which investigated the prediction that birds should decrease their mass in relation to the increased risk of predation, in the Baelophus bicolar, tufted titmouse. Importance of fat reserves for animals in the winter; Details on risk-dependent foraging; Methodology used to conduct the study; Results of the study.

We discovered a live Baeolophus bicolor (Tufted Titmouse) entangled in the burrs of Hoc/celia virginiana (Beggar's Lice) on 28 September 2012 in Kutztown, PA. We extracted and released the titmouse because it appeared to be unable to free itself from the plant. To our knowledge, this is the second published report of a bird becoming entangled in Beggar's Lice and the first documentation of a Tufted Titmouse becoming entangled in any plant. Entanglement in Beggar's Lice is unusual because of the small size (3-4 mm) of its burrs. [ABSTRACT FROM AUTHOR]

Presents information on a study which estimated paternity and degree of relatedness in central Ohio broods of the Tufted Titmouse socially monogamous species. Location of the natural cavities used by titmice as nesting sites; Use of multilocus minisatellite DNA fingerprinting; Level of band-sharing values between attending male and the nestlings.

An introduction is presented in which the authors discuss various reports within the issue on topics related to the use of biological information in the ecological context including signalling in blue jays, anti-predator signals in tufted titmice, and coexistence of species.

In the temperate zone, permanent-resident birds and mammals that do not hibernate must survive harsh winter conditions of low ambient temperature, long nights, and reduced food levels. To understand the energy management strategy of food-hoarding birds, it has been hypothesized that such birds respond to increased starvation risk by increasing the number of their hoards rather than by increasing their fat reserves and that they cache early in the day and retrieve their caches later to achieve fat reserves necessary to survive the night. We tested these hypotheses by observing the responses in captivity of a caching bird, the tufted titmouse (Parris bicolor), to the combined influences of reduced predictability of food and naturally occurring ambient temperature and photoperiod. When the food supply was unpredictable, birds significantly increased both internal fat reserves at dusk and external food caches. Initially leaner birds tended to increase their fat reserves to a greater extent and initially fatter birds tendedto cache more food and to fly significantly less. Half the birds also increased their dawn and mean daily body mass. All birds tended to forage, gain body mass, and cache food at significantly lower rates in the morning and at significantly higher rates in the evening. Cacheretrieval showed the opposite trend, with birds retrieving most of their caches in the morning. Our results do not support the hypothesisthat caching birds increase caching rate but not body mass under an unpredictable food regime. Instead fat reserves and food caches are both important complementary sources of energy in food-hoarding birds.Energy management by wintering birds occurs in response to a number of biotic and abiotic factors acting simultaneously; thus future models must incorporate independent variables in addition to the state ofthe food supply and time of day. [ABSTRACT FROM AUTHOR]