Social Modulation of Courtship Behaviors in Songbirds Abbie Patik Department of Zoology and Physiology Program in Neuroscience University of Wyoming

Introduction Mate Selection Reproductive signals Typically, females are considered “choosers”, males are “displayers” Preconceived notion used by many researchers (Green & Madjidian, 2011) http://www.ncanimals.org/information.html http://bna.birds.cornell.edu/bna/species/425/galleries/photos/md-sage-grouse-greater-male http://www.carlmaples.com/photos_for_sale/Colorado_Deer_1986.html Species must be selective when it comes to mates – you want a mate that is able to produce numerous, viable offspring. Potential mates demonstrate reproductive signals/displays In many cases, the nature of these displays demonstrates their genetic, and therefore physical, superiority Ex. – plumage in peacocks, puffing/dancing rituals in sage grouse, large antlers deer -Green and Madjidian’s (2011) article reviews numerous studies on sexual selection and found that research in this field is in a bit of a rut. Researchers have preconceived notions about who initiates and then who reacts to sexual selection Females are choosers and males are displayers  they just strut their stuff and hope any female picks them as a mate

Songbirds Songbirds are ideal for studying attraction displays Male song is primary means of mate attraction Our research questions: Do males play a role in shaping their mate selection by modulating song performance? Do males change their song different degrees in the presence of different females? Songbirds are ideal for studying attraction displays because male song is a primary means of attracting a female. In many species, including the finches we study, males sing but females do not – reinforcing notion that males display as best they can while females choose. My research investigated the alternative idea that males play a role in shaping the selection of their mate by modulating their song performance. To further examine that, I tested whether males may change their songs to different degrees in the presence of different females, which would indicate a role for male mate choice in performance of reproductive signals

Methods 19 male Bengalese finches (Lonchura striata domestica) Sound and video recorded in soundproof chamber alone Each male recorded with 6 different females, one hour each Recorded them alone to get a baseline song Recorded with 6 females, each for one hour. The cages were divided so that the males and females could see, smell and hear each other but could not physically interact.

Sound and Video Recordings Differentiate between : songs and calls directed (D) and undirected (U) songs Directed = sung towards/at female Undirected = sung alone or away from female Only directed songs used for analysis All sound recordings were viewed to differentiate between songs and calls. Songs were marked for differentiation between directed and undirected songs using videos Directed = songs sung towards/at the female present (clear behavioral direction)  males puff up chests, bob their heads and are clearly trying to get a female’s attention Undirected = songs sung alone or not towards female Only directed songs were used for analysis - According to Sakata et al. (2008) the acoustic structure of notes is much more variable from one undirected song to the next, and there is not as much variation for directed songs, which is why we want to use them.

Song Analysis Males who sang > 8 songs to > 2 females were used for analysis (12 males) 8 songs randomly selected from the full hour 15 songs randomly selected from singing alone, used as baseline Choose males that sang to at least 2 females to get a comparison  don’t know if his song is changing unless we have females to compare When scoring songs we numbered them (did not use letters)

Song Analysis Song note sequence was scored Choose males that sang to at least 2 females to get a comparison  don’t know if his song is changing unless we have females to compare

Song Analysis cont. Analyzed note transitions Note transitions revealed complexity of song sequence (entropy) Transition entropy = ∑ pi* log2 (pi) (Sakata et al., 2008) Pi = probability of each transition show the transition percentages from one note to the next – y-axis is preceding note, x-axis is following note

Do all males behave the same? No! Not every male sang to every female Males behave differently towards different females Not all males sang to every female… give examples – one male sang at least 8 songs to 1 female, no songs to 2 females, and less than 8 songs to 3 females. Not behaving the same towards every female But…(next slide)

Randomly selected songs with female were not different than those performed alone When we looked at the differences in entropy values, there doesn’t seem to be much difference between him with a female and him alone.. This graph, do males change at all? It doesn’t seem so… For 8 randomly selected songs throughout the hour, entropy values did not differ significantly between directed and undirected songs Counterintuitive Indicates that males do not change their song around females --We thought if changed at all, would likely be most evident at first, so analyzed a subset The introduction of a female may initiate a change in song – we looked at first 3 songs R2 = 0.90

Changes are evident in early songs Looking at first 3 is closer to what Sataka et al. did… Tried looking at just the first 3 songs that a male sang to a female Results were different Entropy values are significantly lower for directed than undirected Indicates that male changes his song around a female immediately following introduction Entropy decreases – less variability, more precise R2 = 0.43

Early and late songs were different We also looked to see if the first 3 songs differed in entropy from the 8 random songs, and this graph indicates that the first 3 are lower overall than the random 8. R2 = 0.46

Male Song Differs by Female 8 Random songs First 3 songs Each dot represents a female that a male sang to If the song entropy value is the exact same as the undirected/alone song, then the marks would all line up along the 100% mark. Coefficient of variation – how big range is compared to 100%, t-test, null hypothesis is that the variance is 0 (means that male did NOT change his song around different females)

Conclusions Males play an important role in mate selection Males modulate song in the presence of a female Changes revert to their original song within one hour Males modulate song differently around different females Suggests males prefer certain females over others Males play an important role in mate selection Not just the “performers”

Future Research Testing effects of song changes on female preference Do females prefer song sung earlier? Do females prefer song directed in which they were the receivers? Female preference revealed by behavioral display (wing flaps, calls, copulation solicitation, etc.) Work will be conducted during Summer 2011 Females teach the male… cooperative mate selection?

Thank you for your time! Acknowledgements Dr. Jonathan Prather EPSCoR Fawn Pickard NASA Zach Coburn INBRE