A field test of behavioural flexibility in Zenaida doves (Zenaida aurita)

Animals’ ability to adjust their behaviour when environmental conditions change can increase their likelihood of survival. Although such behavioural flexibility is regularly observed in the field, it has proven difficult to systematically quantify and predict inter-individual differences in free-living animals. We presented 24 Zenaida doves (Zenaida aurita) on 12 territories with two learning tests in their natural habitat in Barbados. The dove pairs showed high site fidelity and territoriality, allowing us to test individuals repeatedly while accounting for the effects of territorial chases and pair bonds on our learning measures. We used a foraging apparatus that enabled Zenaida doves to access seed, yet excluded other species, and measured doves’ performance on colour discrimination and reversal learning tests. We found that (1) doves on all 12 territories passed the two tests; (2) mates within a pair were consistently solvers or scroungers; (3) sex, body condition and territorial chases did not consistently affect learning rates; (4) tameness was a significant negative predictor of learning to feed from the foraging apparatus and (5) scrounging within pairs seemed to facilitate learning. Our study presents a method to quantify intraspecific differences in behavioural flexibility in the field and relate these to individuals’ physical and social traits.     

Learning Differences between Feral Pigeons and Zenaida Doves: The Role of Neophobia and Human Proximity

Learning differences predicted from ecological variables can be confounded with differences in wariness of novel stimuli (neophobia). Previous work on feral pigeons ( Columba livia ), as well as on group-feeding and territorial zenaida doves ( Zenaida aurita ), reported individual and social learning differences predicted from social foraging mode. In the present study, we show that speed of learning a foraging task covaries with neophobia and latency to feed from a familiar dish in the three types of columbids. Pigeons were much faster than either territorial or group-feeding zenaida doves on all tests conducted in captivity, but showed unexpectedly strong neophobia in some urban flocks during field tests. Human proximity strongly affected performance in group-feeding doves both in the field and in captivity. They were slightly faster at learning than their territorial conspecifics in cage tests. In multiple regressions, species identity, but not social foraging mode, significantly predicted individual variation in learning, as did individual variation in neophobia. Wariness of novel stimuli and species differences associated with artificial selection appear to be more important than foraging mode and wariness of humans in accounting for learning differences between these columbids.     

Behavioural and morphological characteristics of white doves in Osmaniye,Turkey identify the population as Laughing Doves (Streptopelia senegalensis)

Observation of an unusual population of white-plumaged doves in Osmaniye suggests that these birds are conspecific with the Laughing Dove (Streptopelia senegalensis, Linnaeus, 1766) population in the town. The white-morph is not found outside the urban area. Aside from colouration, the white doves shared identical morphological characteristics with wild-type brown Laughing Doves. Additionally, the white doves and wild-type Laughing Doves formed mixed flocks and readily paired. Based on the observations of four inter-morph pairings, the white morph appears to be a recessive, single autosomal locus mutation. It appears that the white colouration may have originated from one or more hybridization events between Laughing Doves and feral white Barbary Doves (Streptopelia risoria). This study not only identifies an anomalous population of birds in an urban setting, but highlights the importance of traditional knowledge in understanding biodiversity.     

The Role of Song Phonology and Syntax in Vocal Learning Preferences in the Song Sparrow,Melospiza melodia

Are young songbirds ready to learn virtually any song, or are they predisposed to learn songs of their own species? To explore this question tests were conducted on the equipotentiality of auditory song learning stimuli in the song sparrow. 23 males reared as nestlings were exposed to tape recordings of their own and other species songs in early life and subsequent song production was analyzed for imitations. Birds exposed to natural song sparrow songs, including their fathers', and equal numbers of swamp sparrow songs, strongly preferred conspecific songs. They neither favored nor eschewed paternal songs despite having had access to them for 6–10 days as nestlings. In three other experiments synthetic songs were used in which some properties were held constant and others were systematically varied. Birds were exposed to 1–4 segmented songs varying in phrase order, tempo and syllable number, each synthesized in two versions, one from conspecific and the other from heterospecific (swamp sparrow) song syllables. With one-segmented songs (alien syntax) subjects favored conspecific over heterospecific syllable songs. Heterospecific syllables were rendered more acceptable by incorporation into two-segmented trilled songs (more song sparrow-like syntax). Heterogeneous summation of phonological and syntactical cues appeared to occur. There was also evidence of interaction between phonology and syntax. When another phrase type, the note complex, was added, in three- and four-segmented songs, a preference for conspecific syllables reappeared. Heterospecific syllables may be more readily accepted as a trilled sequence than without repetition, as in a note-complex. When phrase structure within four-segmented songs was varied, birds favored patterns most like normal conspecific song. We conclude that there are innate learning preferences in the song sparrow, based on note and syllabic structure (phonology and syllabic syntax), and temporal organization of phrases (segmental syntax), differing from those of the closely related swamp sparrow, Melospiza georgiana, in which song syntax plays no role in learning preferences.     

Conspecific and heterospecific song discrimination in male zebra finches with lesions in the anterior forebrain pathway

Adult zebra finches can produce normal song in the absence of Area X, lMAN, or DLM, nuclei that constitute the anterior forebrain pathway of songbirds. Here, we address whether lesions involving Area X and lMAN affect adult male zebra finches' ability to discriminate between conspecific or heterospecific songs. Intact birds and lesioned birds were trained on an operant GO/NOGO conditioning paradigm to discriminate between hetero- or conspecific songs. Both lesioned and intact birds were able to learn all discriminations. Lesioned and intact birds performed equivalently on canary song discriminations. In contrast, discriminations involving bird's own song took significantly more trials to learn for lesioned birds than for intact birds. Discrimination between conspecific songs in general also took longer in the lesioned birds, but missed significance level. Birds with control lesions medial to Area X did not show any differences from intact animals. Our results suggest that an intact anterior forebrain pathway is not required to discriminate between heterospecific songs. In contrast, Area X and lMAN contribute to a male zebra finch's ability to discriminate between its own song and that of other zebra finches. © 1998 John Wiley & Sons, Inc. J Neurobiol 36: 81–90, 1998     

Song learning and mate choice in estrildid finches raised by two species

Male zebra finches, Taeniopygia guttata, and Bengalese finches, Lonchura striata, were raised normally or cross-fostered to the other species until 35 days of age and then housed until 70 days old with two song tutors, one from each species. Males raised normally based their song on that of the conspecific tutor whereas cross-fostered males also learned from the other tutor, reflecting both own-species bias and a tendency to learn from the tutor whose song was similar to the father's. Males raised by one bird from each species learned from the father as well as the tutor(s) but were more likely to learn from the tutor whose song was similar to the father's if the father was a conspecific. Comparing these song learning results with those from male choice tests suggests there is no direct link between song learning and sexual imprinting.     

Vocal imitation in blindfolded zebra finches (<Emphasis Type="Italic">Taeniopygia guttata</Emphasis>) is facilitated in the presence of a non-singing conspecific female

Song acquisition in young male zebra finches, Taeniopygia guttata, is viewed as a learning process by imitation from a visible conspecific male acting as a song tutor. The role played by non-singing conspecific females in this process has been poorly documented. The influence of social contact on the song learning of blindfolded young males was investigated in both female-raised and pair-raised birds. Pupils with both eyes occluded from about 35 to 65 days post-hatch, the sensitive phase for song learning, copied significantly more from an adult male sharing their cage when tutored in the presence of a female sibling than in her absence. Interestingly, the effect was more pronounced in female-raised birds compared to pair-raised birds. I conclude that physical contact in the absence of visual cues is sufficient for song imitation to occur. The results demonstrate an instance of social stimulation by non-singing females in the song acquisition of male songbirds.     

Territoriality and testosterone in an equatorial population of rufous-collared sparrows, Zonotrichia capensis

Territorial aggression, displayed by male vertebrates in a reproductive context, is generally thought to be mediated by testosterone. The challenge hypothesis predicts that in socially monogamous species, territorial challenges should induce an increase in plasma testosterone concentrations, which will enhance aggressive behaviour and territory defence. This hypothesis is based on northern latitude birds and needs to be tested in tropical birds before it can be universally accepted. We tested the challenge hypothesis in an equatorial population of rufous-collared sparrows in Papallacta, Ecuador. This population shows an extended breeding period during which males aggressively guard territories. During the early breeding season, males were challenged with conspecific or heterospecific simulated territorial intrusions (STIs) lasting 10 min. Conspecific-challenged males responded more aggressively than heterospecific-challenged males. However, there was no increase in plasma testosterone in response to the conspecific STI. During the breeding season, males were challenged with conspecific STIs lasting 0, 10 or 30 min. Males behaved aggressively regardless of STI duration, and did not differ in plasma testosterone or luteinizing hormone concentrations. During the breeding season, males were implanted with testosterone-filled or empty silastic tubes and subsequently challenged with a conspecific STI. Testosterone implants significantly raised plasma testosterone concentrations, but testosterone-implanted males were not more aggressive than blank-implanted controls. Combined, these findings suggest that testosterone concentrations above breeding baseline are not related to territorial aggression in this population and therefore do not support the challenge hypothesis.     

Former Experience Can Modify Social Selectivity during Song Learning in the Nightingale (Luscinia megarhynchos)

Changes in preference for a specific song-learning context, characterized by close proximity of a tutor, were investigated in the nightingale, Luscinia megarhynchos. Two groups of males were tutored with conspecific song for two periods, days 42 to 56, and days 57 to 71. Song types were either presented from tape alone (group A) or were played in the presence of a familiar tutor, i.e. the person who hand-raised the birds (group B). Acquisition success did not differ between the groups for period 2. However, while males of group B acquired songs during both tutoring periods, males of group A learned only during period 2. This indicates that in nightingales the preference for a specific song-learning context decreases during development. A comparison with an earlier study suggests that this shift is not age dependent but primarily due to auditory experience with the song patterns to be learned. Such a mechanism has also been described for the termination of sensitive phases for song learning. Because song acquisition in adult nightingales does not depend any more on close spatial proximity of a familiar tutor, a male in his first spring and later on can learn from a number of singing territorial neighbours, and by this means acquire the large song-type repertoire typical for the species.     

Quantitative genetics of the use of conspecific and heterospecific social cues for breeding site choice

Social information use for decision-making is common and affects ecological and evolutionary processes, including social aggregation, species coexistence, and cultural evolution. Despite increasing ecological knowledge on social information use, very little is known about its genetic basis and therefore its evolutionary potential. Genetic variation in a trait affecting an individual's social and nonsocial environment may have important implications for population dynamics, interspecific interactions, and, for expression of other, environmentally plastic traits. We estimated repeatability, additive genetic variance, and heritability of the use of conspecific and heterospecific social cues (abundance and breeding success) for breeding site choice in a population of wild collared flycatchers Ficedula albicollis. Repeatability was found for two social cues: previous year conspecific breeding success and previous year heterospecific abundance. Yet, additive genetic variances for these two social cues, and thus heritabilities, were low. This suggests that most of the phenotypic variation in the use of social cues and resulting conspecific and heterospecific social environment experienced by individuals in this population stems from phenotypic plasticity. Given the important role of social information use on ecological and evolutionary processes, more studies on genetic versus environmental determinism of social information use are needed.     

Song development in the white-crowned sparrow: modification of learned song

Previous research has shown that laboratory-tutored white-crowned sparrows, Zonotrichia leucophrys nuttalli, can learn tape-recorded song only until they are about 50 days of age. However, they can learn either conspecific or allospecific song after they are 50 days of age when a live tutor is used. Because the live-tutored birds had not been exposed to song during the first 50 days of life, a question regarding the reasonableness of applying these results to the natural, field situation can be raised. In the experiments reported here, hand-raised nestling white-crowned sparrows between 10 and 50 days of age were tutored in the laboratory with one song, and were then placed with a live tutor singing a different dialect when they were over 50 days of age. Eight of 13 males, and none of 10 females, adopted the song of the second tutor. Birds were also captured in the field as fledglings, and were placed with a live tutor singing a song different from that of the natal area: three of seven males, and one of five females, adopted the song of the live tutor. Four birds that had been group-isolated (two males and two females) were exposed to a live tutor when they were 100 days old, and none acquired normal song; all sang isolate song. The results of these studies indicate that there is considerable plasticity in the song learning of whitecrowned sparrows, and that, for many individuals, song can be modified quite readily. The implications of these findings for the nature of the sensitive phase and for mechanisms of song learning are discussed.     

Conspecific and heterospecific information use in bumblebees

Heterospecific social learning has been understudied in comparison to interactions between members of the same species. However, the learning mechanisms behind such information use can allow animals to be flexible in the cues that are used. This raises the question of whether conspecific cues are inherently more influential than cues provided by heterospecifics, or whether animals can simply use any cue that predicts fitness enhancing conditions, including those provided by heterospecifics. To determine how freely social information travels across species boundaries, we trained bumblebees (Bombus terrestris) to learn to use cues provided by conspecifics and heterospecific honey bees (Apis mellifera) to locate valuable floral resources. We found that heterospecific demonstrators did not differ from conspecifics in the extent to which they guided observers'' choices, whereas various types of inorganic visual cues were consistently less effective than conspecifics. This was also true in a transfer test where bees were confronted with a novel flower type. However, in the transfer test, conspecifics were slightly more effective than heterospecific demonstrators. We then repeated the experiment with entirely naïve bees that had never foraged alongside conspecifics before. In this case, heterospecific demonstrators were equally efficient as conspecifics both in the initial learning task and the transfer test. Our findings demonstrate that social learning is not a unique process limited to conspecifics and that through associative learning, interspecifically sourced information can be just as valuable as that provided by conspecific individuals. Furthermore the results of this study highlight potential implications for understanding competition within natural pollinator communities.     

Experimental transfer of Trichomonas gallinae (Rivolta, 1878) from white-winged doves to mourning doves

Isolates of Trichomonas gallinae (Rivolta, 1878) from white-winged doves, Zenaida asiatica (L.), were transferred experimentally to young mourning doves, Zenaida macroura (L.). Twenty-three of 25 mourning doves developed infections with isolates of T. gallinae from 25 white-winged doves. In addition, eight of eight rock doves (Columba livia Gmelin) were infected with duplicate isolates. All infected recipient birds harbored avirulent isolates except for one mourning dove which died from extensive oral lesions. However, repeated attempts using this isolate of T. gallinae to produce lesions in additional recipients were unsuccessful. Despite the findings of this study, it was suggested that future dove management strategies consider the possibility of disease outbreaks involving white-winged doves and susceptible populations of mourning doves.     

Song Tutor Choice in Polyandrous Dunnocks

The songs of a population of wild dunnocks, Prunella modularis , were recorded over 3 yrs to investigate song tutor choice by first year males. Young males often settled on occupied territories as subordinates and most of their earliest territorial interactions were with the male on whose territory they settled (the co-male). Yearlings learned their song repertoire from their comales and territorial neighbours. This supports results of laboratory studies which suggest that social interactions influence song tutor choice and that yearlings are most likely to learn from the males that are most aggressive towards them. Repertoire overlap between neighbouring males was high (76%), so learning the repertoire of the comale may provide yearling males with a 'short cut' route to learning a few of the songs of every neighbour.     

Repertoire size,auditory templates,and selective vocal learning in songbirds

When vocal variability, here measured by song repertoire size, increases in songbirds, it may become increasingly difficult to encode genetically all the information which is required to ensure the learning of only conspecific songs. Marsh wrens (Cistothorus palustris) have sizeable song repertoires, and while no vocal mimicry is evident in the field, males will readily learn heterospecific songs in the laboratory. These data, together with data from the literature, support the proposed relationship between increased repertoire sizes and reduced specificity of the innate auditory template which guides vocal learning.     

Interspecific interactions and learning variability jointly drive geographic differences in mate preferences

Co‐occurrence of closely related species can cause behavioral interference in mating and increase hybridization risk. Theoretically, this could lead to the evolution of more species‐specific mate preferences and sexual signaling traits. Alternatively, females can learn to reject heterospecific males, to avoid male sexual interference from closely related species. Such learned mate discrimination could also affect conspecific mate preferences if females generalize from between species differences to prefer more species‐specific mating signals. Female damselflies of the banded demoiselle (Calopteryx splendens) learn to reject heterospecific males of the beautiful demoiselle (C. virgo) through direct premating interactions. These two species co‐occur in a geographic mosaic of sympatric and microallopatric populations. Whereas C. virgo males have fully melanized wings, male C. splendens wings are partly melanized. We show that C. splendens females in sympatry with C. virgo prefer smaller male wing patches in conspecific males after learning to reject heterospecific males. In contrast, allopatric C. splendens females with experimentally induced experience with C. virgo males did not discriminate against larger male wing patches. Wing patch size might indicate conspecific male quality in allopatry. Co‐occurrence with C. virgo therefore causes females to prefer conspecific male traits that are more species specific, contributing to population divergence and geographic variation in female mate preferences.     

Wild fledgling tits do not mob in response to conspecific or heterospecific mobbing calls

Mobbing, where birds harass a predator through a combination of vocalizations and stereotyped behaviours, is an effective anti-predator behaviour for many species. Mobbing may be particularly important for juveniles, as these individuals are often more vulnerable than adults. Although the component behaviours of mobbing are often considered to be un-learned, there are few confirmatory data, and the developmental trajectory of mobbing is unknown. In this study, we tested whether conspecific or heterospecific mobbing calls initiated mobbing behaviour in juvenile Blue Tits Cyanistes caeruleus. We located wild adult and recently fledged juvenile Blue Tits and presented them with playback recordings of adult conspecific (Blue Tit) and heterospecific (Great Tit Parus major) mobbing alarm calls. Although adult birds readily mob in response to these types of playbacks, juveniles did not exhibit characteristic mobbing behaviour. Some juveniles did, however, exhibit individual components of mobbing behaviour found in mobbing, despite not producing adult-like mobbing behaviour in response to either conspecific or heterospecific playback. These results suggest that, although birds might be capable of mobbing as juveniles, the associations between the non-vocal stereotyped mobbing behaviours and mobbing calls may be learned.     

Survival,fidelity, and recovery rates of white-winged doves in Texas

Management of migratory birds at the national level has historically relied on regulatory boundaries for definition of harvest restrictions and estimation of demographic parameters. Most species of migratory game birds are not expanding their ranges, so migratory corridors are approximately fixed. White-winged doves (Zenaida asiatica), however, have undergone significant variation in population structure with marked range expansion occurring in Texas, and range contraction in Arizona, during the last 30 years. Because >85% of white-winged dove harvest in the United States (approx. 1.3 million annually) now occurs in Texas, information on vital rates of expanding white-winged dove populations is necessary for informed management. We used band recovery and mark–recapture data to investigate variation in survival and harvest across 3 geographic strata for white-winged doves banded in the pre-hunting season in Texas during 2007–2010. We banded 60,742 white-winged doves, recovered 2,458 bands via harvest reporting, and recaptured 455 known-age birds between 2007 and 2010. The best supporting model found some evidence for geographic differences in survival rates among strata (A–C) in both hatch-year (juvenile; A = 0.205 [SE = 0.0476], B = 0.213 [SE = 0.0278], C = 0.364 [SE = 0.0254]) and after-hatch year (adult; A = 0.483 [SE = 0.0775], B = 0.465 [SE = 0.0366], C = 0.538 [SE = 0.251]) birds. White-winged doves had a low probability of moving among strata (0.009) or being recaptured (0.002) across all strata. Harvest recovery rates were concordant with estimates for other dove species, but were variable across geographic strata. Based on our results, harvest management strategies for white-winged doves in Texas and elsewhere should consider differences in population vital rates among geographic strata. © 2012 The Wildlife Society.     

A community context for aggression? Multi‐species audience effects on territorial aggression in two species of Paridae

1. Territorial aggression in birds is widely observed and is commonly linked to sex, age, body size, physiology, seasonal cues, food resource, urbanization, and a variety of social contexts including conspecific audience effects. However, little is known about the heterospecific audience effects on territorial aggression.
2. Here, we address an emerging idea that heterospecific audience effects may be pervasive influences in the social lives of free‐living birds. We tested the hypothesis that the composition, number, and relative body size of heterospecific audiences observing an aggressive contest will influence the response probability and intensity of aggression displayed.
3. We subjected two Paridae species, tufted titmouse (TUTI, Baeolophus bicolor) and Carolina chickadee (CACH, Poecile carolinensis), to playbacks of aggressive calls during a breeding season in north‐central Florida. At widely spaced playback sites (N = 134) in woodland habitats, we characterized the makeup of heterospecific audiences, aggression type (intra vs. interspecific territoriality), local population density, and various environmental factors (tree density, wind speed, and noise level) that are likely to influence territorial aggression.
4. We found that the presence of heterospecific audiences increased TUTI aggression levels and that both parids were more likely to respond to playback stimuli when their audiences had higher heterospecific diversity (more heterospecific individuals and species). We also found TUTI were more likely to respond when CACH were present but not vice versa.
5. In conclusion, we found evidence that heterospecific audiences significantly influenced the metrics of territorial aggression of free‐living animals and we suggest that the definition of audience effects on the behavior of free‐living animals be expanded to incorporate heterospecific audiences.