1. Birdie Rap Battles: Interactive Playback Reveals the Vocal Complexity of Territorial Titmice
Tannyr Lamica, Kathryn Sieving
Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL
Introduction
Results
Animal vocalization research helps us understand the links between vocal and social complexity and how to better understand the origins of our own language (Krams et al., 2012).
Birds in order Passeriformes (songbirds) are known for complex and melodious calls. The tufted titmouse (Baeolophus bicolor), a member of family Paridae, has such extreme vocal complexity they may have a proto-language.
Because of the species’ abundance, “talkative” nature, and formation and defense of territories by the males, tufted titmice afforded me the opportunity to probe the limits of its song diversity; previous work has had to do with their anti- predator calls (Hetrick & Sieving, 2011; Sieving et al.,2010).
I found that individuals averaged 4.8 call types and 3.6 unique call types per individual. The average for the true number of unique call types that individuals could produce was 7.244, and I estimated 120 total call types possible for the population (Fig. 1). Length of time replying did not necessarily predict level of potential call type diversity, but the longest responder had the highest estimated true call diversity with call types. There was no strong correlation between bout number and call type diversity (R^2= ).
These 4 spectrograms show 3 (first 3 starting at the left) variants of non-aggressive song calls and 1 (last picture to the right) aggressive call that we call “soft song”.
Conclusions
Figure 2. Observed number of call types according to each sample (individual bird) in blue compared to estimated number of call types possible for each sample in orange.
Approach
Since males escalate their repertoire when facing a conspecific aggressive breeding competitor, I hypothesized that interactive playback sampling would generate more variety of song types than we currently know about (Mcgregor et al., 1992).
Interactive playback draws out complexity.
There is a lot of individual variation in repertoire complexity.
Even song repertoire has high vocal complexity, which has not been previously tested.
Methodology
Future Work
I sampled 10 individuals on the University of Florida campus using a Marantz pmd660 recorder, Sennheiser ME67 shotgun microphone, and portable speaker using interactive playback vocalization sampling between March 30th and April 28th 2016.
I processed and categorized recordings (using Adobe Audition) according to bout number, call type (note and syntax combination), and frequency of aggressive calls (previously determined from unpublished research and from observations) for each individual.
Lastly, I estimated number of call types per individual, number of call types unique to each individual, unused call types per individual, and estimate of true call type diversity per individual (using EstimateS). I then extrapolated the samples using rarefaction to estimate total number of call types for the population.
Is vocal complexity linked to survival, mating success, etc.?
Experimentally demonstrate tufted titmouse soft song.
Sample and analyze populations of titmice in their natural habitats and compare urban/suburban and natural populations.
References
Hetrick, S. A., & Sieving, K. E. (2011). Antipredator calls of tufted titmice and interspecific transfer of encoded threat information. Behavioral Ecology,23(1), doi: /beheco/arr160
Krams, I., Krama, T., Freeberg, T. M., Kullberg, C., & Lucas, J. R Linking social complexity and vocal complexity: a parid perspective. Philosophical Transactions of the Royal Society B: Biological Sciences, 367(1597),
Mcgregor, P. Dabelsteen, T., Shepherd, M., & Pedersen, S. (1992). The signal value of matched singing in great tits: evidence from interactive playback experiments. Animal Behaviour, 43, Doi: / (92)90012-x
Sieving, K. E., Hetrick, S. A., & Avery, M. L. (2010). The versatility of graded acoustic measures in classification of predation threats by the tufted titmouse Baeolophus bicolor : exploring a mixed framework for threat communication. Oikos,119(2), doi: /j x
Acknowledgements
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Figure 1. Number of titmouse call types observed to 10 samples and estimated according to rarefaction if 100 samples were taken, bound by 95% confidence intervals.
I would like to thank Dr. Sieving for her expert advice and support in this project and Sarah Obaid for her assistance in the EstimateS analysis. I would also like to thank the University Scholars Program for their financial support.