Chickadee Flocks Research Articles

Complexity in Chick‐a‐Dee Calls of Mountain Chickadees (Poecile gambeli): Call Variation Associated With Flock Size and Flight

ABSTRACTThe chick‐a‐dee call of chickadees, tits, and titmice is a vocal system used in a wide range of social contexts by both sexes throughout the year and is one of the more structurally complicated vocal systems outside of human language. Relatively little is known about the chick‐a‐dee calls of mountain chickadees, Poecile gambeli, however. This is an important species for increasing our comparative understanding of variation in chick‐a‐dee calls as they are one of the chickadee species with the largest naturally occurring flock sizes. Flock size relates to the social complexity of flocks, and the social complexity hypothesis for communication predicts that individuals in more complex social groups should communicate with greater complexity than individuals in simpler social groups. Correlational and experimental evidence in support of the hypothesis has been found in the calls of a wide range of species, including Carolina chickadees, P. carolinensis. Here, we provide the first description of the variation in note composition and note‐ordering rules in calls from mountain chickadee flocks in California and Colorado. California flocks were found to be significantly larger than Colorado flocks. Analysis of note‐type usage and transition probabilities between note types found that calls of California birds were more complex than calls of Colorado birds, supporting a key prediction of the social complexity hypothesis for communication. We also found relatively high rates of reversals of note‐ordering rules in mountain chickadee calls, which might help explain the complexity of the chick‐a‐dee calls of this species. Additionally, birds in flight produced calls with different note compositions when compared to perched birds. Generally, the note‐type ordering and transition probabilities of calls of mountain chickadees seem comparable to other better‐studied chickadee species, although their frequent note‐type order rule reversals suggest potential syntax‐like properties in this call system.

Single‐species and multi‐species playbacks elicit asymmetrical responses within mixed‐species chickadee, titmouse, and nuthatch flocks

AbstractIndividuals join mixed‐species groups to gain benefits such as improved foraging and predator detection. Birds in the family Paridae often drive mixed‐species flocking in North America, and these species can act as community informants for forest‐wide eavesdropping networks. Although we know a great deal about how this communication functions in anti‐predator contexts, less is known about how the vocalizations of members of these flocks may affect the foraging behavior of potential flockmates. In this study, we presented naturally occurring mixed‐species flocks of chickadees, titmice, and nuthatches with one of four playback conditions: chickadee‐only calls, nuthatch‐only calls, calls of both species, and a silent control. We hypothesized that the flocks would be most responsive to playbacks that contained calls from more than one species. We also tested an alternative hypothesis that predicted that birds would be most responsive to the nuclear species within the flock (chickadees). We found that birds were more likely to arrive, and arrived more quickly, for the playbacks with calls from both species compared to playbacks of nuthatches alone or the silent control. Playbacks of chickadee calls alone attracted an intermediate number of birds, which did not differ significantly from the mixed‐species flock condition, or the nuthatch call alone condition. Our hypotheses were not supported due to the lack of significant difference between the mixed‐species playbacks and the chickadee playbacks. However, our findings do indicate that different species in these flocks can react differently to the calls of members of these flocks and that future studies may continue to find asymmetries in attraction to these different social signals.

Mixed-species flock composition matters: interspecific influences on finding novel food in North American parids.

Individuals of a wide range of species are sensitive to the presence of other species, and can often benefit from associations with other species in mixed-species groups (MSGs) through food-finding or avoiding predation. In an earlier field study, we found that both Carolina chickadees, Poecile carolinensis, and tufted titmice, Baeolphus bicolor, were better able to solve a novel feeder task when their MSGs were more diverse in terms of species composition. Like most studies of MSGs, however, that earlier study did not experimentally manipulate MSG size and composition. We did that manipulation here, providing experimental flocks of chickadees and titmice with three novel feeder tasks in semi-natural aviary environments. We found that successful titmouse flocks generally had a higher proportion of titmice in them, going against the findings of our earlier field study. Conversely, successful chickadee flocks solved one of the novel feeder tasks more quickly with a higher proportion of titmice in them, corroborating the findings of our earlier field study. We now need to assess socio-ecological influences on MSG size and composition, and how those relate to individual behaviour. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Do Carolina chickadees (Poecile carolinensis) and tufted titmice (Baeolophus bicolor) use predator eyes in risk assessment?

Previous studies have found that Carolina chickadees and tufted titmice use a predator's head orientation to determine risk, taking fewer seeds from a feeder if an avian predator model's head is facing the feeder while ignoring the head orientation. In addition to head orientation, eyes are a cue of predator risk. In the current study, I examined whether or not chickadees and titmice used the presence of eyes of a predator model to determine when to forage for food. Plastic owl models, with their eyes covered or uncovered, were presented to wild flocks of chickadees and titmice. To test whether or not chickadees and titmice would respond to the presence of eyes, the number of seeds taken and the calling behavior of birds were compared between the two types of predator presentations (eyes covered or uncovered). Chickadees and titmice took fewer seeds when the eyes were uncovered than when they were covered. Chickadees also gave significantly more introductory notes, often used in association with the presence of predators or risk, in their calls when the eyes were visible than when the eyes of the predator model were covered. The results indicate that chickadees and titmice can use the presence of eyes on predators to determine predation risk and possibly use eye gaze to determine where a predator is looking.

Traffic noise and responses to a simulated approaching avian predator in mixed‐species flocks of chickadees, titmice, and nuthatches

AbstractTraffic noise likely reaches a wide range of species and populations throughout the world, but we still know relatively little about how it affects anti‐predator behavior of populations. We tested for possible effects of traffic noise on responses to predator acoustic cues in Carolina chickadees (Poecile carolinensis), tufted titmice (Baeolophus bicolor), and white‐breasted nuthatches (Sitta carolinensis) near 14 independent feeding stations in eastern Tennessee. We compared anti‐predator calling and seed‐taking behavior in response to playbacks of predator stimuli (screech owl calls) at sites naturally exposed to traffic noise and at sites that faced relatively little traffic noise. The screech owl call playback was designed to simulate the approach of this dangerous predator to a feeder being used by these small songbirds. We found that chickadees responded consistently to the owl stimuli across different levels of traffic noise. However, titmice, and nuthatches exhibited different behavioral responses to the predator stimulus, suggesting that traffic noise masked these low‐frequency predator calls. Overall, chickadees and nuthatches showed the broadest anti‐predator behavioral responses in comparison to titmice, corroborating earlier published work with an Indiana population. Finally, populations exposed to traffic noise overall seemed less able to detect predator cues potentially masked by that noise, and future work will need to assess likely seasonal variation in these responses as well as species‐level variation in anti‐predator responses in mixed‐species groups.

Diversity in mixed species groups improves success in a novel feeder test in a wild songbird community

Mixed-species groups are common and are thought to provide benefits to group members via enhanced food finding and antipredator abilities. These benefits could accrue due to larger group sizes in general but also to the diverse species composition in the groups. We tested these possibilities using a novel feeder test in a wild songbird community containing three species that varied in their dominant-subordinate status and in their nuclear-satellite roles: Carolina chickadees (Poecile carolinensis), tufted titmice (Baeolophus bicolor), and white-breasted nuthatches (Sitta carolinensis). We found that chickadees and titmice were more likely to obtain seed from the novel feeder with greater diversity of species composition in their mixed-species flocks. For successful chickadee flocks, furthermore, the latency to obtain seed from the novel feeder was shorter the more diverse their flocks were. These results in a natural setting indicate that diversity, per se, can benefit individuals in mixed-species groups in biologically meaningful contexts such as finding food in novel places.

Asymmetries in Mobbing Behavior Among Nuclear Flockmates

Abstract Tufted Titmice (Baeolophus bicolor) and Carolina Chickadees (Poecile carolinensis) often occur together in mixed species flocks during the non-breeding 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 closes...

Winter Habitat Use by Boreal Chickadee Flocks in a Managed Forest

There are increasing conservation concerns associated with boreal regions, but little is known about winter habitat requirements of bird species inhabiting them. We examined flock size, winter habitat preference, and home range size of Boreal Chickadees (Poecile hudsonica) in a boreal forest harvested for timber near Quebec City, Quebec, Canada. We investigated whether and to what extent home range size was affected by clearcuts and regeneration forest stands. Flocks included an average of four individuals and occupied a mean winter home range of 14.7 ha. Flock membership and size were stable during the winter. Boreal Chickadees strongly preferred mature stands of commercial value (>7 m in height) and used regenerating stands (4–7 m in height) to a lesser extent. Younger stands (<4 m in height) and open areas were avoided. Home range size was not associated with landscape composition, but flocks with larger home ranges used them less evenly than those with smaller home ranges. This resident species prefers stands of commercial value and logging may contribute to apparent population declines of Boreal Chickadees.

RESPONSE OF WINTERING BOREAL CHICKADEES (POECILE HUDSONICA) TO FOREST EDGES: DOES WEATHER MATTER?

Abstract Avian responses to forest edges have received much attention in recent years, particularly because of the potential effects of deforestation on the quality of remaining forest patches. However, individual birds' responses to forest edges are more often inferred than observed, and most studies of space use emphasize territory placement, with little or no detail on within-territory movements. Thus, our understanding of the effects of edges on movements of forest birds remains limited. We recorded movements of 85 winter flocks of the little-known Boreal Chickadee (Poecile hudsonica), in a 66-km2 boreal forest harvested for timber near Quebec City, Quebec. From January to March 2004 and 2005, we followed flocks on snowshoes and recorded their trajectory in real time using a handheld global positioning system (GPS) receiver. Boreal Chickadee flocks showed no response to forest edges when using mature forest stands. However, flocks mostly used edges of regenerating forest habitat (4–7 m high). Inside r...

Understanding avian responses to forest boundaries: a case study with chickadee winter flocks

Avian species diversity and territory location are often associated with sharp forest edges, or boundaries. However, our understanding of behaviours underlying avian distribution near forest boundaries, especially species with large home ranges, remains poor. In a two‐year study, we measured chickadee flock movements in forests at 0–300 m from boundaries in an agricultural landscape near Edmonton, Alberta, Canada. Even though flocks foraged in all forested parts of the study area, only six of the 53 flocks studied foraged further from forest boundaries than expected if they had used their home range irrespectively of the distance to boundaries. We found no evidence that the association of chickadee flocks to forest boundaries resulted from vegetation changes near boundaries, or to changes in their foraging sites and foraging success near boundaries. However, chickadee flocks moved parallel to boundaries (&lt;75 m away) twice as frequently as expected from random movement, thus suggesting that forest boundaries act as movement conduits. Even when birds do not apparently seek special features near forest boundaries, they may be closely associated with them, simply because their passive movements are constrained by habitat barriers defined by boundaries.

Social rank influences conspicuous behaviour of black-capped chickadees, Parus atricapillus

Abstract. This study on black-capped chickadees, Parus atricapillus, assesses whether social rank influences the behaviour of chickadees in predator situations. Chickadee flocks were restricted to an area of an outdoor aviary containing no vegetative cover to ensure that all flock members were equally exposed to potential danger. Each flock was presented with two different predator stimuli and one control stimulus. All flocks formed stable, linear hierarchies and there appeared to be dominance-related risk-taking. After hearing hawk vocalizations, the chickadees uttered 'seeet' alarm calls and all birds became immobile (froze), but subordinate and middle-ranked birds (subdominants) typically were the first to break the freeze. No differences were found for the 'seeet' alarm call. When exposed to a hawk mount, all birds gave repeated 'chick-a-dee' calls but subdominants consistently gave the call sooner than their dominant flockmate. These results could not be attributed to a bird's sex. It is suggested that greater risk-taking by subdominants could be one mechanism causing higher rates of winter mortality among low-ranking birds in free-ranging chickadee flocks.

Vocalizations in Aptenodytes Penguins: Application of the Two-Voice Theory

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Female demands: some fitness implications in chickadee flocks

Female black-capped chickadees (Parus atricapillus), besides searching for their own food, "demand" food from their mates in the spring for extra energy needed to produce and incubate eggs. This behaviour signals their readiness to copulate and it is followed by increased levels of male – male aggression, probably to prevent cuckoldry. Increased aggression owing to limited nest site availability may also be locally important. Subordinate pairs disperse and many presumably die. The extra food allows females with nest sites to breed earlier than if they fed themselves exclusively, and producing early broods appears to be a better fitness strategy than having larger clutches or additional broods. Juveniles from early broods survive better and attain higher social ranks in flock hierarchies, and dominant pairs have the highest overwinter survival rates as well as a better chance than subordinate pairs of obtaining a territory in the spring.

Flock Switching in Chickadees: Why Be a Winter Floater?

Winter chickadee flocks contain two sorts of birds: those that always stay in a single flock (flock regulars), and those that do not. Most of the birds that move from flock to flock are young low-ranked birds that lack pair bonds. These flock switchers are the true winter floaters in the population. When a high-ranked regular disappears during the winter, it is rapidly replaced not by the flock's next highest regular, but by the dominant local switcher of the appropriate sex. A young bird entering the flock system as it forms in early fall must choose between two strategies: to be a regular in one flock, or to be a flock switcher. When flocks form, high-ranked regular slots will probably be filled first, followed by top-ranked switcher positions; only later will the lowest regular slots be filled. Calculations suggest that the present mixed strategy of the study population, with about 20% switchers and 80% regulars, is evolutionarily stable. The many similarities between chickadee flock switchers and underworld rufous-collared sparrows suggest that complex organization among floaters may be widespread.

Individual differences and within-flock convergence in chickadee calls

A detailed sound analysis of the Chick-adee call of the black-capped chickadee (Parus atricapillus) was performed in order to determine a basis for individual recognition and for imitation within winter flocks. During the winter of 1978–1979 members of five free-living black-capped chickadee flocks were uniquely marked for individual identification, and their calls were recorded in the field. Nested analysis of variance of temporal call parameters measured from sonagrams and spectral parameters from frequency spectra showed that there were significant differences between individuals within flocks for every parameter measured. There were significant differences between flocks in the frequency ranges 800–2,200 Hz and 4,000–5,300 Hz, in the spectral parameters bandwidth and maximum frequency, and in the duration of the Dee syllable and total call duration.

Social learning and the significance of mixed-species flocks of chickadees (Parus spp.)

The experiments described in this paper show that two species of chickadees learn from one another about the location and nature of potential feeding places when they are foraging together in mixed flocks in large aviaries. In the first experiment, I show that when an individual of one species finds a single food item, members of the other species modify their foraging behavior over the next few seconds so that they put more effort into searching near the site of the find. This applies to both species. Further, members of both species modify their foraging behavior when a bird of the other species searches in a place unsuccessfully. This response to an unsuccessful search is similar to, but weaker than, the response to a food find. The second experiment shows that when the two species are trained to forage in different positions in the experimental trees, they converge in their foraging behavior when they are put in mixed flocks, This is a result of copying. The third experiment shows that individuals of both species are more likely to discover a completely new foraging place if they are in the presence of an experienced bird of the other species.I discuss these results in relation to theories on the adaptive significance of flocking, and conclude that learning about potential feeding places from other species is an important function of mixed flocks, at least for some species. This does not exclude the possibility of other functions of mixed flocks.