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

2. Introduction Mate Selection
Reproductive signals
Typically, females are considered “choosers”, males are “displayers”
Preconceived notion used by many researchers (Green & Madjidian, 2011)
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

3. 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

4. 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.

5. 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.

6. 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)

7. 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

8. 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

9. 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)

10. 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

11. 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

12. 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

13. 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)

14. 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”

15. 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?

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