![\"<p>Alejandro](\"https:\/\/today.uconn.edu\/wp-content\/uploads\/2011\/04\/Guevara_lg.jpg\")
<\/a>Now, a UConn graduate student in ecology and evolutionary biology in the College of Liberal Arts and Sciences has proven this theory false. Using high-speed, high-definition video, Alejandro Rico-Guevara has shown that instead of using this mechanism, known as capillary action, hummingbird tongues instead trap fluids by dramatically changing their shape.<\/p>\n
Rico-Guevara published his results today in the scientific journal Proceedings of the National Academy of Sciences.<\/em><\/p>\n \u201cHummingbirds are tiny, fast, and they feed on flowers, which are hard to see into,\u201d says Rico-Guevara. These three factors prevented scientists from closely observing hummingbird feeding until the advent of modern technology.<\/p>\n In the early 19th century, biologists proposed that hummingbirds drank nectar from flowers using capillary action, the passive process of a fluid rising into a narrow tube because of forces attracting the liquid to the tube\u2019s solid internal surface. The idea was at first controversial, says Rico-Guevara. But in part because it was so difficult to test, the theory was eventually accepted.<\/p>\n Fast-forward about 150 years, and biologists were using computer programs to model what they saw in nature. Using the capillary action theory, a group of scientists predicted that hummingbirds should prefer thin, watery nectar to thicker fluids. This finding, says Rico-Guevara, made him skeptical, since many birds in fact prefer thicker nectars.<\/p>\n \u201cThe challenge was: How do you determine what\u2019s going on if you can\u2019t see inside the bird\u2019s mouth?\u201d says associate professor Margaret Rubega, Rico-Guevara\u2019s Ph.D. advisor, who worked with him on this paper.<\/p>\n \u201cWe didn\u2019t want to just accept what was written,\u201d adds Rico-Guevara. \u201cCapillary action seemed possible, but it couldn\u2019t be the whole story.\u201d<\/p>\n So Rico-Guevara set about testing the theory on 30 species of hummingbirds, many in the Andes Mountains of his native Colombia. He used high-speed video to record hummingbirds feeding from nectar feeders with clear walls so that he could observe their tongues as they drank.<\/p>\n What he found was very different than the previous theory predicted. Rico-Guevara observed that when in contact with a fluid, the tubes separate from each other, appearing much like a snake\u2019s forked tongue. The tubes expand to expose tiny elongate fringes that trap nectar and then retract, pulling the fluid with them into the bird\u2019s mouth.<\/p>\n Rico-Guevara thinks that this new concept could be more far-reaching than just hummingbirds \u2013 it\u2019s possible that others of the more than 200 types of nectar-feeding birds with similar tongues also use this process. If so, this could change the way ecologists think about the behavior, ecology, and evolution of these birds.<\/p>\n Additionally, the researchers point out, this novel fluid-gathering process could be useful to engineers. A feature of this mechanism, says Rubega, is that it requires no energy on the part of the bird; all movements are spurred by changes in pressure and molecular interactions between the bird\u2019s tongue and the surrounding fluids. This method could be instructive for creating low-energy fluid trapping and transporting instruments.<\/p>\n Since it\u2019s not every day that a Ph.D. student debunks a 180-year-old scientific hypothesis, Rico-Guevara says that his own reaction to his findings has been mostly positive, but at times nerve-wracking.<\/p>\n \u201cI\u2019m starting to tell my colleagues about this, and it\u2019s kind of scary,\u201d he says. \u201cBut it\u2019s also super exciting.\u201d<\/p>\n A study using high-speed video showed that hummingbird feeding doesn\u2019t work as previously thought.<\/p>\n","protected":false},"author":37,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"wds_primary_category":0,"wds_primary_series":0,"wds_primary_attribution":0,"footnotes":""},"categories":[1,70],"tags":[],"magazine-issues":[],"coauthors":[63],"class_list":["post-34185","post","type-post","status-publish","format-standard","hentry","category-uncategorized","category-video"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-06-17 01:52:52","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/34185","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/users\/37"}],"replies":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/comments?post=34185"}],"version-history":[{"count":5,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/34185\/revisions"}],"predecessor-version":[{"id":43305,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/34185\/revisions\/43305"}],"wp:attachment":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media?parent=34185"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/categories?post=34185"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/tags?post=34185"},{"taxonomy":"magazine-issue","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/magazine-issues?post=34185"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/coauthors?post=34185"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}<\/a><\/a><\/a>