Meeting Abstract

103.6  Wednesday, Jan. 7  Evolutionary Insights About Hummingbirds’ Serrate Tomia RICO-G., A.; Univ. of Connecticut alejandro.rico@uconn.edu

For many years it has been believed that the minute serrations on the tomia (cutting edges of the beak) of hummingbirds serve in the capture of small arthropods. This belief most likely exists because the serrate tomia resemble similar structures that function in prey capture as described in previous studies (e.g. scopate, denticulate and lacerate tomia) of other species. To date, however, there has been no test of this hypothesis about the function of serrate tomia in hummingbirds. I examined the bills of over 1000 specimens representing 189 species and 98 genera of hummingbirds, in 7 museum research collections. My results contradicted the idea that serrate tomia are used for arthropod capture. Additionally, recent data suggest that the tomia might not play a critical role in capturing flying arthropods, because they are mainly caught in the bill base rather than in the tip. Interestingly, hummingbirds share similar bill serrations with their old world counterparts, sunbirds, which are also nectarivores. This evolutionary convergence in tomial serrations suggests a new hypothesis about their function. Here, I propose a new biophysical model to describe the nectar intake mechanism in hummingbirds. In this model, the serrate tomia are used to fully extract any previously gathered nectar that remains on the tongue, allowing all of the liquid to be retained inside the bill. This mechanism works in conjunction with other structures in the interior of the beak in order to enhance nectar intake. This research highlights the necessity to develop further research on the evolutionary convergences of nectarivorous birds.