PHI 314 GVSU Vocal Pitch vs Gular Sac Case Female Frigatebirds Project Summary

  

IMPORTANT: Max 150 words

The summary is a

brief

description of the project were the question and hypothesis are explicit. It mentions where is carried out and what species are used. It also provides a short statement why this study is important.

(The project is attached below)

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Vocal Pitch vs. Gular Sac: Which is More Attractive to Female Frigatebirds?
Introduction
Frigatebirds are unique aquatic birds that are known for their bright red chests, which determine
the “indications of their [body] condition and testosterone dependency.” (Iezhova et al., 2007).
While their red gular sacs are very eye-catching, males “produce a rapid warble vocalization that
forms a prominent part of their courtship display.” (Juola & Searcy, 2011). This is our question
for our project: Do the male’s drumming sound and vocal pitch enhance attractiveness more than
the inflation of the gular sac for a successful courtship? We hypothesized that female
frigatebirds will be more attracted to higher pitch drumming sounds in males rather than the
inflation of the gular sac, since a higher pitch is used to communicate more effectively when
defending territory and displaying good body condition. We predicted that when a female
frigatebird chooses a male bird with a high pitch drumming sound as mating partner, it means
that male bird is in a good body condition.
Methods
The species that we will use for our research study is the Fregata magnificens. The study site
will be the Key West National Wildlife Refuge. This experimental, observational research design
will rely on statistical analysis to prove or disprove the hypothesis. The controls for this research
study will be the selection of male frigatebirds with significantly bigger gular sacs and those that
produce high pitched sounds from their gular sacs. The sample size was calculated using the
following statistical analysis since the population of the birds in the study area is unknown:
.
The data will be analyzed by coding and conducting a sample t-test using the independent and
dependent variables at a significance level of alpha (0.05). The descriptive analysis will be used
for this research study. The null hypothesis is there will be no difference between the mating
process between the male frigatebirds with bigger gular sacs and those that can produce high
pitched drumming sounds. The alternative hypothesis is that male frigatebirds’ high pitch
drumming sounds are more attractive than the size of the gular sac.
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Expected Results
We expect to find that female frigatebirds are more likely to mate with male frigatebirds that
produce high pitched sounds from their gular sacs compared to those who have bigger gular sacs.
Their inflated gular pouch may be the first thing female frigatebirds may observe, but “visual
size assessment might not be straightforward since viewing angle, male posturing, and proximity
affect and obscure perceived size.”(Dearborn, 2002. Madsen, 2004.). In other words, this
“preference by females of a given species translates into reproductive benefits for those females”
(Alcock, 2016).
Intellectual Merit
This project depicts our curiosity and intent to obtain reliable data that will help provide
additional data in this field of research. It is a novel project that hopes to explore transformative
concepts that will help us understand the tendencies of Frigata magnificens. species better.
Frigatebirds are the most prominent species known for their gular sacs, but there is not much
research about whether vocal pitch may play a more significant role in mate attractiveness than
the gular sac’s appearance itself (Chastel 2005. Juola, 2010) . With this well-organized
observational study, we can open the discussion on how other secondary sex characteristics
contribute more to mating success than just gular sacs.
Broader Impacts
Many people possess very limited knowledge about not only frigatebirds but other “gular sac
birds” as well. Our research study will contribute to more findings revolving around mating
success in bird species, specifically those with gular sacs. Gular sacs may be a primary
secondary sexual trait for one species, whereas another species will put more emphasis on vocal
pitch to attract mates, like the frigatebirds. Our research will help us not only understand the “not
so researched” species, but also how the species is different or similar to other bird species with
prominent features.
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References
Iezhova, T. A., Madsen, V., Mercade, C., Osorno, J. L., Sanchez, M., & Valkiūnas, G.
(2007). Testosterone levels and gular pouch coloration in courting magnificent frigatebird
(Fregata magnificens): variation with age-class, visited status, and blood parasite
infection. Hormones and Behavior, 51(1), 156-163.
Juola, F. A., & Searcy, W. A. (2011). Vocalizations reveal body condition and are
associated with visual display traits in great frigatebirds (Fregata minor). Behavioral
Ecology and Sociobiology, 65(12), 2297-2303.
Juola, F. A. (2010). Mate choice is a sexually dimorphic marine bird, the great
frigatebird (Fregata minor) (Doctoral dissertation, University of Miami).
Chastel, O., Barbraud, C., Weimerskirch, H., Lormée, H., Lacroix, A., & Tostain, O.
(2005). High levels of LH and testosterone in a tropical seabird with an elaborate
courtship display. General and Comparative Endocrinology, 140(1), 33-40.
Madsen, V., Balsby, T. J., Dabelsteen, T., & Osorno, J. L. (2004). Bimodal signaling of a
sexually selected trait: gular pouch drumming in the Magnificent Frigatebird. The
Condor, 106(1), 156-160.
Alcock, J. (2016). Avian Chapter 9 Mating and Social Behavior. Handbook of Bird
Biology, 313.
Dearborn, D. C., & Ryan, M. J. (2002). A test of the Darwin–Fisher theory for the
evolution of male secondary sexual traits in monogamous birds. Journal of Evolutionary
Biology, 15(2), 307-313.
Lee, G. (2000). The Birds of Paradise. Rapa Nui Journal: Journal of the Easter Island
Foundation, 14(4), 4.

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