Aggressive responses to playback of solos and duets in a Neotropical antbird

Duetting behaviour is a unique form of animal communication that occurs in many diverse taxa in the animal kingdom. Hypotheses for the function of duets can be grouped into two broad categories to explain why individuals coordinate with their partner\u27s songs to create duets: (1) duets are cooperative displays where pair members have a shared goal, such as joint resource defence, and (2) duets are conflicting displays where pair members have different goals, such as guarding against divorce or extrapair copulations. To distinguish between cooperative versus conflicting functions of vocal duets, we conducted a playback experiment to 40 breeding pairs of barred antshrikes, Thamnophilus doliatus. We broadcast five playback treatments to territorial pairs of birds: solos of males and females, duets created by males responding to female songs and by females responding to male songs, and a heterospecific control. We categorized subjects\u27 behaviour in terms of vocal and physical responses. Male vocal and physical responses were significantly higher towards conspecific stimuli than towards heterospecific stimuli. Males tended to show more vocal responsiveness towards duet stimuli, although this tendency was not significant. We observed a similar pattern for female vocal responses. However, for physical responses, females showed significantly more intense responses towards female solo stimuli than towards any other conspecific treatment, suggesting that female antshrikes perceive rival females as an especially intense threat. Our results provide some support for a joint resource defence function for duetting in this species, while the high intrasexual aggression observed between females may indicate a form of mate guarding. © 2011 The Association for the Study of Animal Behaviour

Vocal behaviour of Barred Antshrikes, a Neotropical duetting suboscine bird

Despite the high biodiversity that characterizes the tropics, we know little about the behaviour of most tropical birds. Antbirds (Thamnophilidae) are a biodiverse family of more than 200 species found throughout Central and South America, yet their ecology and behaviour are poorly known. In this study, we provide the first detailed description of the vocalizations and vocal behaviour of Barred Antshrikes (Thamnophilus doliatus), a widespread Neotropical suboscine passerine. We studied 38 territorial pairs in a population in Costa Rica from 2008 to 2010, using field recordings and observations to quantify their vocalizations and vocal behaviour. Males and females produced similar songs consisting of rapidly repeated chuckling notes. Several aspects of their songs distinguish the sexes: male songs were longer in duration, contained more syllables, and were lower in pitch. Males had a higher song output than females, but within song bouts males and females sang at similar rates. Barred Antshrike song output varied daily, with the highest song output occurring at dawn. Song output also varied seasonally, with increased song output occurring during the breeding period. Males and females combined songs to create duets, overlapping the terminal portion of their mate\u27s song. Most duets were created by females responding to male songs (84 %), and the rest by males responding to female songs. The timing of duet responsiveness varied between the sexes; males responded more quickly to their partner\u27s song (1. 6 s) than females (2. 0 s). This detailed account of the vocalizations and vocal behaviour of a population of Barred Antshrikes creates a foundation for future comparative studies of antbirds. Our study highlights similarities and differences in the behavioural patterns of tropical birds and contributes to our understanding of the function of vocal duets and the vocal behaviour of antbirds. © 2012 Dt. Ornithologen-Gesellschaft e.V

The Responses of Duetting Antbirds to Stereo Duet Playback Provide Support for the Joint Territory Defence Hypothesis

In multiple animal taxa, including many birds and primates, members of mated pairs produce coordinated acoustic displays known as duets. By observing the behaviour of territorial animals as they respond to playback-simulated duets of rivals, we can gain insight into the behavioural significance of vocal duets. Playback experiments, however, have been conducted across a very narrow range of duetting animals. Furthermore, many studies have been conducted with single-speaker playback, whereas stereo-speaker playback offers more spatially realistic simulation of duets. Moreover, by evaluating the reactions of animals to separate loudspeakers broadcasting male and female duet contributions, we can study the interactions of both males and females with same-sex vs. opposite-sex rivals. We used a paired experimental design to broadcast duet stimuli through a single-speaker and a stereo-speaker apparatus to 30 pairs of duetting barred antshrikes Thamnophilus doliatus in Costa Rica. Our goals were (1) to evaluate whether territorial antbirds respond more aggressively to male vs. female duet components and (2) to assess aggressive responses of antbirds towards single-speaker vs. stereo-speaker playback. Neither males nor females differentiated between the loudspeaker simulating the male vs. female duet contribution during stereo-speaker playback trials. Barred antshrikes displayed significantly stronger responses to stereo-speaker playback compared with single-speaker playback. Males displayed stronger playback responses than females with closer, quicker and more vocal responses. These results provide evidence for a joint resource defence function of antbird duets given that pairs responded together with equivalent intensity to male and female simulated intruders. This is the first study to show that although duetting is an aggressive territorial signal, birds do not necessarily respond to sex-specific components of duets. Our results support the idea that spatially realistic stereo presentation of duet stimuli is critical for experimental duet research. © 2013 Blackwell Verlag GmbH

Impact of tertiary Gleason pattern 5 on prostate cancer aggressiveness: Lessons from a contemporary single institution radical prostatectomy series

Objective: To better evaluate tertiary Gleason pattern reporting and to evaluate the impact of tertiary Gleason pattern 5 (TP5) on prostate cancer pathological features and biochemical recurrence at our large single institution. Methods: We retrospectively reviewed 1962 patients who underwent radical prostatectomy (RP) for prostate cancer; TP5 was reported in 159 cases (8.1%). Men with Gleason score (GS) 7 and GS 8 disease were divided into subgroups with and without TP5, and histopathological features were compared. Multivariate analyses were conducted to assess the impact on TP5 on biochemical-free survival (BFS). Results: Tumors possessing GS 3 + 4 with TP5 were more likely to exhibit extraprostatic extension (EPE) and had a larger tumor diameter (TD) than GS 3 + 4 alone. GS 3 + 4 with TP5 was also associated with positive surgical margins (SM), seminal vesicle involvement (SVI), and higher pre-operative prostate-specific antigen (PSA) values, but without statistical significance. GS 4 + 3 with TP5 more commonly presented with EPE, positive SM, SVI, and greater TD and pre-operative PSA level than GS 4 + 3 alone. In multivariate analysis, Gleason score, EPE, and TP5 were overall independent risk factors for PSA recurrence in this cohort. Additionally, GS 4 + 3 with TP5 was associated with shorter time to recurrence versus GS 4 + 3 alone. Conclusion: Our results emphasize the importance of TP5 and suggest that criteria for tertiary pattern reporting in prostate cancer should be standardized. Further studies are needed to evaluate the role of tertiary patterns in prognostic models