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- All Subjects: Birds
- Creators: Alcock, John
Description
Colorful ornaments in animals often serve as sexually selected signals of quality. While pigment-based colors are well-studied in these regards, structural colors that result from the interaction of light with photonic nanostructures are comparatively understudied in terms of their consequences in social contexts, their costs of production, and even the best way to measure them. Iridescent colors are some of the most brilliant and conspicuous colors in nature, and I studied the measurement, condition-dependence, and signaling role of iridescence in Anna's hummingbirds (Calypte anna). While most animal colors are easily quantified using well-established spectrophotometric techniques, the unique characteristics of iridescent colors present challenges to measurement and opportunities to quantify novel color metrics. I designed and tested an apparatus for careful control and measurement of viewing geometry and highly repeatable measurements. These measurements could be used to accurately characterize individual variation in iridescent Anna's hummingbirds to examine their condition-dependence and signaling role. Next, I examined the literature published to date for evidence of condition-dependence of structural colors in birds. Using meta-analyses, I found that structural colors of all three types - white, ultra-violet/blue, and iridescence - are significantly condition-dependent, meaning that they can convey information about quality to conspecifics. I then investigated whether iridescent colors were condition-dependent in Anna's hummingbirds both in a field correlational study and in an experimental study. Throughout the year, I found that iridescent feathers in both male and female Anna's hummingbirds become less brilliant as they age. Color was not correlated with body condition in any age/sex group. However, iridescent coloration in male Anna's hummingbirds was significantly affected by experimental protein in the diet during feather growth, indicating that iridescent color may signal diet quality. Finally, I examined how iridescent colors were used to mediate social competitions in male and female Anna's hummingbirds. Surprisingly, males that were less colorful won significantly more contests than more colorful males, and colorful males received more aggression. Less colorful males may be attempting to drive away colorful neighbors that may be preferred mates. Female iridescent ornament size and color was highly variable, but did not influence contest outcomes or aggression.
ContributorsMeadows, Melissa (Author) / McGraw, Kevin J. (Thesis advisor) / Rutowski, Ronald L (Committee member) / Sabo, John L (Committee member) / Alcock, John (Committee member) / Deviche, Pierre (Committee member) / Arizona State University (Publisher)
Created2012
Description
In the U.S., less than 20 percent of wildlife strikes are reported, which leaves a large portion of incidents unaccounted for. Although wildlife strikes at airports often go unreported, since the early 1990's the number of wildlife strikes has increased five-fold and the number of damaging strikes has increased 1.5-fold. Goals for this project include determining if biological and landscape variables are good predictors of wildlife strikes. We define response variables as the number of reported wildlife strikes per 10,000 airport operations. We studied seven major airports around Phoenix, Arizona and 30 large airports in the western U.S. In the Phoenix metro valley, airports varied from having 0.3 strikes per year per 10,000 operations to having 14.5 strikes from 2009 to 2013. We determined bird richness by using the citizen-science database "eBird,"and measured species richness within a 15 kilometer area of each airport. Species richness between hotspots ranged from 131 to 320. Seasonal differences were determined using an analysis of variance (ANOVA) analysis for the seven Phoenix metro airports as well as the 30 western U.S. airports. Our results showed that there was a seasonal difference in wildlife strikes in the majority of our airports. We also used land use data from CAP LTER to determine any environmental factors such as vicinity to water or fence line located within five kilometers from airports using ArcGIS. These results are important because they are helpful in determining the factors influencing wildlife strikes based on the number of strikes reported.
ContributorsSalaki, Logan (Co-author) / Montgomery, Brett (Co-author) / Bateman, Heather (Thesis director) / Niemczyk, Mary (Committee member) / Barrett, The Honors College (Contributor)
Created2015-05