Progress 09/01/99 to 09/30/12
Outputs
OUTPUTS: This project focused on vocal communication of birds with particular attention to the functions of vocal variability in parrots and songbirds. The methods involved field recordings of a variety of species in the field, development and application of quantitative analytical methods for species with noisy vocal repertoires, use of multiple microphone arrays to characterize sound fields and assign specific calls to specific individuals, short-term capture of wild birds for intensive recording and playback experiments, playbacks of natural and manipulated calls to wild individuals, laboratory experiments to characterize parrot hearing, and geographical surveys of wild and feral parrot populations to characterize spatial patterns of variation. Five wild species of parrots were studied in Costa Rica, Venezuela, Bonaire, and Australia, and one feral species in the United States. In all of the studies out of the United States, field data collected as part of these studies were shared with local wildlife management programs to aid in conservation and breeding of wild populations. Results were presented at a variety of international and national scientific meetings, in informal outreach contexts, and in both peer-reviewed scientific journals and lay publications. A large number of undergraduate students were recruited to work on the projects, both in our laboratory at Cornell University, and in the field in other countries. PARTICIPANTS: The PI on this project was Dr. Jack W. Bradbury, currently Professor Emeritus at Cornell University. Doctoral dissertation students who undertook their thesis research on this project were Dr. Susannah Buhrman-Deever, Dr. Judith Scarl, and Karl Berg (still working to complete thesis). Post-doctoral fellows on the project included Dr. Kathryn Cortopassi, Dr. Jessica Eberhard, Dr. Gail Patricelli, and Dr. Thorsten Balsby. A total of 34 different undergraduate students from Cornell University participated on this project either in the field, in the laboratory, or in both. This study was undertaken with support from the National Science Foundation. Efforts in the field were coordinated with staff of the Area Conservacion de Guanacaste (Costa Rica), wildlife conservation officials in Australia and Bonaire, and the Instituto Venezolano de Investigaciones Cientificas in Venezuela. TARGET AUDIENCES: One lay article in the popular parrot journal Psittascene was designed to provide results and perspectives from our study the many parrot fanciers around the world. The PI, graduate students, and postdocs have all given talks on the study to lay audiences including high school classes, birders at the Cornell Lab of Ornithology, and local radio programs. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
A major change in knowledge was our discovery that wild parrots modify their own signature calls to match those of other birds during inter-flock interactions that might or might not lead to flock fusions. This was totally unexpected and discovered during playbacks of calls to a focal group of calls recorded at varying distances from the focal unit. It resulted in a major shift in focus of playbacks and recordings of wild and captive individuals. A major technique change was the development of spectrographic cross correlation followed by principal coordinate analysis. This allows all data in spectrograms to be compared simultaneously without making prior subjective judgments about which measures might be important to the birds. The principal coordinates step extracts major latent factors from calls and eliminates random noise effects during call comparisons. This method is now being used by a variety of other researchers studying noisy vocal signals.
Publications
- Balsby, T.J.S. and J.W. Bradbury. 2009. Vocal matching by orange-fronted conures (Aratinga canicularis). Behavioral Processes 82:133-139.
- Bradbury, J.W. and Vehrencamp, S.L. 2000. Economic models of animal communication. Anim. Behav. 59:259-268.
- Cortopassi, K.A. and J.W. Bradbury. 2000. The comparison of harmonically rich sounds using spectrographic cross-correlation and principal coordinates analysis. Bioacoustics 11:89-127.
- Bradbury, J. W., K. A. Cortopassi, and J. R. Clemmons. 2001. Geographical variation in the contact calls of Orange-fronted Conures. The Auk 118:958-972.
- Bradbury, J.W. 2003. Vocal communication in wild parrots. In: Animal Social Complexity: Intelligence, Culture and Individualized Societies. F.B.M. DeWaal and P. L. Tyack, eds. Harvard University Press, Cambridge MA,, pp. 293-316.
- Wright, T.F., K.A. Cortopassi, J.W. Bradbury, and R.J. Dooling. 2003. Hearing and vocalizations in the conure Aratinga canicularis. J. Comp. Psychol. 117:87-95.
- Vehrencamp, S.L., A. Ritter, M. Keever, and J. W. Bradbury. 2003. Responses to playback of local versus distant contact calls in the Orange-Fronted Conure (Aratinga canicularis). Ethology 109:37-54.
- Cortopassi, K.A. and J.W. Bradbury. 2006. Contact call diversity in wild orange-fronted parakeet pairs, Aratinga canicularis. Anim. Behav. 71: 1141-1154.
- Patricelli, G.L., M.S. Dantzker, and J.W. Bradbury. 2006. Differences in acoustic directionality in male red-winged blackbird vocalizations are related to function in communication. J. Ornith. 147:225-226.
- Buhrman-Deever, S.C., A.R. Rappaport, and J.W. Bradbury. 2007. Geographic variation in contact calls of feral US populations of the monk parakeet. The Condor 109:389-398.
- Adams, D.M., Balsby, T.J.S. and Bradbury, J.W. 2009. The function of double contact calls in Orange-Fronted Conures (Aratinga canicularis) as revealed by interactive playback. Behaviour 146:171-188.
- Scarl, J.C. and J.W. Bradbury. 2009. Rapid vocal convergence in an Australian cockatoo, the galah (Eolophus rosei capillus). Animal Behaviour 77:1019-1026.
- Scarl, J.C. 2009. Heightened responsiveness to female-initiated aggressive interactions in an Australian cockatoo, the Galah (Eolophus roseicapillus). Behaviour 146:1313-1330.
- Scarl, J.C. 2009. Male and female contact calls differentially influence behaviour in a cockatoo, the Galah (Eolophus roseicapillus). Emu, in press.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: This year's efforts focused on two species of wild parrots. The results of four field seasons by graduate student Judith Scarl studying the vocal communication systems of the Australian galah cockatoo and the Orange-fronted Conure in Costa Rica were written up, submitted to major journals for publication, and successfully submitted as Ms (now Dr.) Scarl's PhD dissertation. Graduate student Karl Berg returned to Venezuela to continue collecting vocal ontogeny data on wild Green-rumped Parrotlets. Concurrent video and audio recordings were made inside and outside another 20 nests using new higher resolution video equipment. The resulting footage is extremely clear allowing better assignment of recorded calls to marked chicks in each nest. We continued to swap eggs between a subset of nests to permit subsequent discrimination between genetic and learned influences on fledgling contact calls. Several offspring studied in prior years returned this year as adults allowing us to record their final adult contact calls and monitor contact calls of their chicks (third generation). We also initiated collaborations with Dr. Virginia Sanz at the Instituto Venezolano de Investigacion Cientifica) to radio-track identified chicks as they disperse after fledging. Initial results look very promising. Mr. Berg also collected the first recordings of counter-warbling in wild parrotlet pairs in which the independent contributions of each pair could be separated. Undergraduate Christina Masco worked with Mr. Berg and the PI both spring and fall semesters of 2008 on analyzing recordings made in the prior season in Venezuela. PARTICIPANTS: Graduate student Judith Scarl successfully submitted and defended her dissertation and was awarded the degree of PhD on this project. We initiated collaborations with Dr. Virginia Sanz at the Instituto Venezolano de Investigacion Cientifica (Venezuela) and Dr. Steve Beissinger (Univ Calif Berkeley) to radio-track dispersing green-rumped parrotlet fledglings in Venezuela. This study will complement our own and those of Dr. Sanz and Dr. Beissinger respectively. Cornell University Undergraduate students Nick Sly and Christina Masco worked on this project in the field in Venezuela and in our laboratory this year. This provided both with training in the methods of behavioral ecology and bioacoustics. TARGET AUDIENCES: This study provides information that is proving useful for wild parrot management in the sites studied (Costa Rica, Australia, and Venezuela). All field data are shared with local wildlife biologists. The research is aimed at identifying the functions of vocal mimicry in wild parrots and thus at solving a major scientific puzzle of interest to both biological theorists and the lay public. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The ontogeny of contact calls and their relationship to early begging calls in parrotlets is now fully defined. There are 5 basic stages that are quite similar to those described for captive budgerigars. Initial examinations of similarities between the contact calls of genetic vs foster parents suggests no clear genetic effects. However, this year's additional large sample will need to be analyzed before any definitive conclusions can be drawn. Early analyses of counter-warbling between parrotlet pairs suggests that both syntax and themes may be present in these exchanges. This is similar to findings of Dr. Tim Wright on duets in Yellow-naped Amazon parrots. The studies by Dr. Scarl demonstrated the ability of both wild conures and galahs to identify the sex of calling conspecifics even when both sexes produce the same call types. In addition, her published and in press work demonstrates that the two sexes in galahs each respond differently to production of the same call type depending upon the sex of the caller. These findings demonstrate considerable subtlety in how wild parrots communicate despite a limited number of call types. Dr. Scarl also demonstrated that galahs, like conures, adjust their contact calls during exchanges with conspecifics in ways that appear to facilitate negotiations about flock fusion and subsequent flock leadership.
Publications
- Balsby, T.J.S. and J.C. Scarl. 2008. Sex specific responses to vocal convergence and divergence of contact calls in Orange-Fronted Conures (Aratinga canicularis). Proceedings of the Royal Society of London, B, 275:2147-2154.
- Russello, M.A., Saranathan, V., Buhrman-Deever, S., Eberhard, J., and Caccone, A. 2007. Characterization of polymorphic microsatellite loci for the invasive monk parakeet (Myiopsitta monachus). Molecular Ecology Notes 7:990-992.
- Buhrman-Deever, S.C., E.A. Hobson, and A.D. Hobson. 2008. Individual recognition and selective response to contact calls in foraging brown-throated conures, Aratinga pertinax. Animal Behaviour 76:1715-1725.
- Patricelli, G.L., M.S. Dantzker, and J.W. Bradbury. 2008. Acoustic directionality of red-winged blackbird (Agelaius phoeniceus) song relates to amplitude and singing behaviours. Animal Behaviour 76:1389-1401.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: This year's research efforts focused on Venezuela where we are taking advantage of 30 prior research on a banded population of Green-rumped Parrotlets. This population uses artificial nest boxes (set up to promote nesting success in this species in the wild). We have outfitted a number of these nestboxes with tiny video cameras and microphones and recorded all vocalizations made by parents (inside or outside the nest) and offspring. We have also been able to perform repeat vocal signal playback experiments to the same mated pairs, an achievement that was difficult with our prior studies in Costa Rica where the parrots are much more itinerant. Finally, we had swapped eggs between nests to determine whether the individual signatures in contact calls that we have found in all parrot species studied to date are acquired through genetic effects via the parents, provision of possible templates by the parents and learned, and/or by fledgling experimentation. The intensive recording
of calls within the nest coupled with video to identify which fledgling made which call should provide some exciting answers to this question which has never been studied in wild parrots before. We also conducted a shorter field season in Costa Rica where we continued capturing single wild conures for short periods and using playbacks to determine whether individuals respond more to calls emitted by males, by females, by the same sex, or by different sexes. Dissemination was promoted by the PI's giving of seminars on the parrot research to Elmira College undergraduates interested in pursuing behavioral ecology research and teaching as a career.
PARTICIPANTS: Jack Bradbury (PI): oversaw all projects on parrot vocal communication Thorsten Balsby (Postdoctoral Fellow, Cornell University): Worked with PI on vocal communication of Orange-fronted Conures in Costa Rica; Karl Berg (Graduate Student, Cornell University): Oversaw field work in Venezuela on Green-rumped Parrotlets; Judith Scarl (Gradute Student, Cornell University): Oversaw field work in Australia on Galahs; Beatrice Mao (Undergraduate, Cornell University): Helped analyze field recordings of parrots from Costa Rica; Matt Halley (Undergraduate, Cornell University): Worked in field in Venezuela with Karl Berg
Impacts
A major finding arising from our Costa Rica studies this year is that wild Orange-fronted Conures, which have morphologically identical sexes, respond differentially to calls from males and females depending on whether the responder is a male or female. This implies that despite the significant differences among individuals of both sexes in their contact call fine structure, there are markers that indicate to other conures whether the caller is a male or a female. Statistical analyses suggest that the relative durations of the three parts of the contact calls may be one component that differs between the two sexes. Playback experiments in future seasons will test this idea. A parallel finding came out of the Galah work in Australia: these parrots also appear able to discriminate between male and female callers even when these are out of sight and at some distance. The importance of gender roles other than incubation remains largely unstudied in parrots and our new
findings provide the first tools for exploring these issues.
Publications
- Buhrman-Deever, S.C., A.R. Rappaport, and J.W. Bradbury. 2007. Geographic variation in contact calls of feral US populations of the monk parakeet. The Condor 109:389-398.
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Progress 01/01/06 to 12/31/06
Outputs
Field studies were undertaken in 2006 in Costa Rica, Venezuela, and Australia. The Costa Rica studies included an extensive series of playbacks to each of Orange-fronted Conures and White-fronted Amazon parrots to see how often and well wild birds would mimic changes in call type. We also built on the prior year's evidence that double calls in Conures might announce subsequent changes in call type during negotiations between flocks. We compared the degree of subsequent type matching by wild flocks given playbacks that either included or omitted double calls before call type changes. Finally, we collected extensive samples on the call type variation exhibited by birds when alone versus when in a negotiation with conspecifics. In Venezuela, we initiated a parallel study on calls of wild Green-rumped parrotlets using an existing marked population that largely breeds in nest boxes. This site provides an unusual opportunity to monitor the calls of known individuals over
time, compare calls of the two sexes, and characterize the acquisition of individual signature calls by nestlings. This first season was devoted to characterizing the vocal repertoire, showing that this species, like our other study species, exhibits individual call signatures, and undertaking an initial series of playback experiments to determine whether mates could respond differentially to each other's calls. In Australia, our planned studies of paternity in galah parrots were undermined by a severe drought. However, the remaining field work was highly successful. We recorded extensively to characterize gender differences in calls, and used playbacks to determine whether gender of sender and/or receiver affected responses to these calls. We also performed an extensive set of playbacks at nest sites to discriminate between alternative functions of the heraldic display. Here in Ithaca, analysis and write-up of the Brown-headed conure study (undertaken on the island of Bonaire in
prior years) is nearly complete with 6 publications to be submitted to peer-reviewed journals in 2007.
Impacts
This study continues to identify both parallels and differences between the usage of vocal mimicry by parrots and humans. It also provides regular data to the host countries that can be used for conservation of wild parrots.
Publications
- Bradbury, J.W. and T. Balsby. 2006. The mystery of mimicry. Psittascene 18:8-11.
- Cortopassi, K.A. and J.W. Bradbury. 2006. Contact call diversity in wild orange-fronted parakeet pairs, Aratinga canicularis. Anim. Behav. 71:1141-1154.
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Progress 01/01/05 to 12/31/05
Outputs
Field work in Costa Rica this year focused on the post-breeding and early wet season behavior of two species: the Orange-fronted Conure and the White-fronted Amazon. Our cumulative knowledge of the vocal repertoire of the Orange-fronted Conure suggested a series of playback and interaction studies that were very successful. These birds often give contact calls in pairs. One project involved careful examination of the first and second calls in such pair for relative similarity in vocal structure, and a series of playbacks to see whether wild birds respond more to the first or the second of dual calls. A second project examined responses of wild flocks to different types of warbler calls. A third used birds of known sex to determine whether contact calls differ between male and female in any consistent manner for this species. A fourth series of playbacks continued to examine the degree to which wild birds modify their own contact calls to match, or alternatively become
more divergent from a playback call. Another part of the Costa Rica team radio-tracked 20 successive White-fronted Amazon parrots to determine stability of night roost sites, composition of foraging groups, home range, and diet. With the completion of the Bonaire field studies in the prior season, this year was spent analyzing nutritional and toxin contents of wild parrot foods, performing statistical analyses of playback experiments, and characterizing social dynamics. The Galah parrot work in Australia also turned in an excellent field season. Given the difficulty of accessing natural nesting holes, 100 nest boxes were installed throughout the study site (with full permission by Australian authorities). Major concerns this year were a) to obtain larger samples of male versus female contact calls, b) obtain parental and offspring DNA samples to determine paternity of nestlings, and c) determination of functions of different parts of the repertoire using playbacks.
Impacts
This study continues to identify both parallels and differences between the usage of vocal mimicry by parrots and humans. It also provides regular data to the host countries that can be used for conservation of wild parrots.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
During this last year, the field studies of wild parrots in Costa Rica and the island of Bonaire continued as planned, and two additional parrot species, and field sites, were added to the project. The 5-month Costa Rica field project focused first on types of calls that are used during the breeding season by Orange-fronted Conures, (a species studied intensively to date in the non-breeding season), and then concentrated on playback experiments and interactions between wild flocks and short-term captive White-fronted Amazon parrots during their non-breeding period. Both phases of the field season were highly successful, and the research team is currently analyzing all of the data collected over the period. The Bonaire team, studying a related Conure species, focused on identifying natural foods of the parrots, assessing their nutritional and toxicity values, and quantifying the degree to which foraging flocks did or did not advertise their current food plants to
over-flying flocks. They also used the short-term captive method to record a wide variety of soft or rare call types that are difficult to detect and record in free-flying birds. A related project was initiated on vocal repertoires of feral monk parakeets in the United States. This species, originally from Argentina, is a likely taxonomic relative of Conures, and has markedly similar call patterns. Recordings of flight calls were obtained this year from feral populations in New York City, Long Island, Connecticut, Florida, Louisiana, and Texas. Initial analysis shows striking divergence in call patterns between these sites, and even between different communal roosts at the same site, reflecting again the role of cultural learning in the acquisition of wild parrot vocal signals. Finally, we initiated a project on vocal communication in wild galahs, a species of Australian parrot that also exhibits vocal repertoires similar to the Neotropical species. The focus here is on identifying
subtle sexual and individual differences in flight calls that are used both for individual recognition, and as mechanisms by which the ostensibly mated pairs initiate divorce or extra-pair matings. How sexual selection operates in birds with long term pair bonds has been little studied, and vocal signals appear to be the major mechanism by which this can be mediated in wild parrots. The initial season went very well with the location of numerable active nests, extensive banding of the study population, repeated recordings from birds of known identity and sex, and initial radio-tracking to monitor movements of birds both as a pair and as singletons.
Impacts
This study continues to identify both parallels and differences between the usage of vocal mimicry by parrots and humans. It also provides regular field data to the host countries that is used for conservation of parrots.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
The project, whose goal is to understand the functional significance of vocal mimicry in wild parrots, continued on two fronts: north-western Costa Rica and the island of Bonaire. In both sites, we continued to use array recording, interactive playback, short-term holding of wild-caught captives in aviaries where they could interact with passing flocks, and radio-tracking to test hypotheses about alternative functions of vocal mimicry and vocal learning in parrots. The major findings of this year were a) verification that interactions between playbacks and wild flocks were similar in both sequence and function to exchanges between real birds on both sides of the exchange, and b) that wild flocks actively select which other passing flocks to recruit to local food finds.
Impacts
This study continues to identify both parallels and differences between the usage of vocal mimicry by parrots and humans. It also provides regular field data to the host countries that is used for conservation of parrots.
Publications
- Bradbury, J.W. 2003. Vocal communication in wild parrots. In: Animal Social Complexity: Intelligence, Culture and Individualized Societies. F.B.M. DeWaal and P. L. Tyack, eds. Harvard University Press, Cambridge MA,, pp. 293-316.
- Wright, T.F., K.A. Cortopassi, J.W. Bradbury, and R.J. Dooling. 2003. Hearing and vocalizations in the conure Aratinga canicularis. J. Comp. Psychol. 117:87-95.
- Vehrencamp, S.L., A. Ritter, M. Keever, and J. W. Bradbury. 2003. Responses to playback of local versus distant contact calls in the Orange-Fronted Conure (Aratinga canicularis). Ethology 109:37-54.
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Progress 01/01/02 to 12/31/02
Outputs
Our study of the function of mimicry in wild parrot vocal signals added two new species to our list of examined taxa. The White-fronted Amazon parrot was examined in Costa Rica using array recording of birds interacting with experimental playbacks, and through ad lib recording during foraging, night roost aggregation, early morning foraging group formation, and midday playtime. The goal was to define the vocal repertoire and find those call types that showed any evidence of short-term or longer-term mimicry. These parrots were extremely responsive to interactive playbacks, and wild birds could be kept vocalizing to the speaker for hours. This provides an extremely exciting opportunity to test a number of hypotheses about how wild parrots use their extensive vocal repertoires and when vocal copying is important. During this first season on this species, we were able to demonstrate that most calls given by mated pairs are duets, that females typically initiate the
duets, and that males end them with characteristic call types. There appears to be a major excess of unmated males following the breeding season, making our playbacks of female calls particularly attractive to unmated males. Unmated males interacted with speaker playbacks of female calls by imitating the type of call emitted by our speaker, and by intercalating their calls between ours to produce pair-like duets. We also undertook this year a study of the Brown-throated Parakeet in the Caribbean. This species occurs throughout northern South America, but has invaded each of the nearby islands (Curacao, Aruba, Bonaire, and Margarita). We surveyed each of these islands and two mainland poulations to determine how contact calls varied both as a function of founding populations and current habitat. We then began a longer term study on the island of Bonaire examining the degree to which wild flocks mimic each other's contact calls in the process of fusing foraging flocks. Because Bonaire
is a very dry island, food is sparse and this allows us to manipulate food patches to determine what calls foragers give when they do or do not invite passing flocks to join them. This work complements earlier studies in Costa Rica on another member of the same genus that also suggested the importance of contact call modification in mediating group fission/fusion events.
Impacts
This study examined the degree to which individual variation in learned vocalization in wild parrots parallels similar processes in humans. It also provides critical data for management and conservation of wild parrot populations.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
The study of wild parrot vocalizations continued this year in both the field and in the lab analyses.We tackled two different issues this year. The first used video and sound recording equipment at Orange-fronted Parakeet nests in Costa Rica to assay variability in loud contact calls of known individuals through the breeding season. We also implanted tiny video cameras and microphones inside nest cavities to monitor the calls and behaviors of wild nestlings. Results indicate that adult pairs at the nest show much higher levels of contact call variation than has been seen in either short term captives or foraging birds in the non-breeding season. Several hypotheses for this greater variability are being examined. The second undertaking, also in Costa Rica, was an extensive series of interactive playbacks of contact calls to overflying wild Parakeets. Currrent analysis is examining the degree to which wild respondents use different parts of their vocal repertoires when
answering a playback and vary the structure of any of their calls during interactive exchanges. Pilot playbacks to three other sympatric species of parrots were undertaken with positive and exciting results. Interactive playback appears to be a very powerful technique for studying vocal communication in wild parrots.
Impacts
This study examines the degree to which individual variation in learned vocalization in wild parrots parallels similar processes in humans. It also provides critical data for management and conservation of wild parrot populations.
Publications
- Bradbury, J. W., Cortopassi, KA and Clemmons, J. R.. 2001. Geographical variation in the contact calls of Orange-fronted Conures. The Auk 118:958-972.
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Progress 01/01/00 to 12/31/00
Outputs
Two field trips to Costa Rica were mounted in 2000 (the first field season of the award) to pursue studies on the functions of vocal learning in wild Orange-fronted Parakeets. Current work focuses on the most conspicuous call in these birds' repertoires: the loud contact call. The first field trip sought recordings of single pairs at their nests during the breeding season. The goal was to determine how many different call signatures were produced by each individual bird in nature, and whether these differed between and within mated pairs. During the second trip, two successive groups of 5-6 wild birds captured from the same flock were held in an aviary for several weeks and responses to playbacks of natural and manipulated calls were used to determine whether birds discriminated between local and distant populations, members of same vs different flocks, and members of same vs different family group. Analyses of the field data undertaken subsequently indicate that most
wild birds have a favored signature call, but each can also produce a few rare alternatives. No evidence was found for convergence of the calls of mated pairs as has been suggested in domesticated parrots. Results also showed significantly higher responses of short-term captives to calls recorded from local populations when compared to calls from more distant sites. Birds also responded preferentially to non-captive family members.
Impacts
Both sexes of parrots can learn new vocal signals throughout life and are thus better models for human language than most songbirds. The functions for vocal learning remain unknown in wild parrots. This study seeks to understand how parrots use this ability in the wild and whether there are useful parallels with human language.
Publications
- Bradbury, J.W. and Vehrencamp, S.L. 2000. Economic models of animal communication. Anim. Behav. 59:259-268.
- Cortopassi, K.A. and Bradbury, J.W. 2000. The comparison of harmonically rich sounds using spectrographic cross-correlation and principal coordinates analysis. Bioacoustics 11:89-127.
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Progress 01/01/99 to 12/31/99
Outputs
In the 5.5 months since this project began, the PI and staff have assembled the critical field equipment and software to undertake the first field trip to Costa Rica in February 2000. This trip will focus on recordings of and playbacks to nesting wild parrots to see whether each wild bird has its own contact call or shares those of its mate or neighbors. Playbacks will determine which variants in calls are salient to wild birds. A second field trip June/July 2000 will relocate the same birds post-nesting to see if calls have changed with new social affiliations, monitor nestling dispersal, and determine whether nesting location affects subsequent post-nesting home ranges.
Impacts
This study examines the degree to which individual variation in learned vocalization in parrots parallels similar processes in humans. It also provides critical data for management and conservation of wild parrots.
Publications
- No publications reported this period
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