| Publication Type: | Journal Article |
| Year of Publication: | 1990 |
| Authors: | Heidweiller, J, Zweers, GA |
| Journal: | The Condor |
| Volume: | 92 |
| Issue: | 1 |
| Date Published: | 1990 |
| ISBN Number: | 00105422 |
| Keywords: | Estrildidae, Lonchura, Lonchura striata, Poephila, Poephila guttata, Taeniopygia, Taeniopygia guttata |
| Abstract: | Two kinds of drinking behavior were studied by film and radiogram analysis of tip down drinking Zebra Finches (Poephila guttata) and tip up drinking Bengalese Finches (Lonchura striata) which use similar scooping tongue motions to carry water into the mouth. Water transport through the pharynx differs: the Zebra Finch uses a scooping motion of the larynx that reoccurs in every motion cycle, while the beak is kept down. The Bengalese Finch elevates the head allowing water to flow downward due to gravity and pharyngeal properistalsis. Extensive analyses show the anatomy of the species to be highly similar. The Zebra Finch is able to drink by a double scoop mechanism, because--unlike the Bengalese Finch--reflexes for glottis closure and esophageal peristalsis are used. Integration of these reflexes and a shift in timing of the larynx-scoop has modified tip up into tip down drinking. Thus, tip down is more complex than tip up drinking, since here actions from different cycles and patterns are integrated in one motion cycle. Increased kinematic complexity is, apart from any historical scenario, an argument that tip down is derived from tip up drinking in Estrildidae. An evolutionary scenario is presented in which developments of scooping anatomical elements are seen as preadaptations. These developed by selection on elements serving the highly specialized kind of feeding on seeds of Gramineae under high predator pressure in open fields, and allowed a wide secondary extension of the feeding area. |
| URL: | http://www.jstor.org/stable/1368379 |
| Short Title: | The Condor |
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