In the column “Since You Asked,” Contributing Editor Julie Craves answers readers’ questions about birds and bird behavior. Her column appears in every issue of BirdWatching. Here’s a question from the August 2016 issue:
What is the purpose of the huge bills of hornbills? – Dan Ware, Durham, North Carolina
Hornbills have large, usually de-curved bills, with which they can deftly pluck fruit — like toucans in the New World. Most hornbills also eat insects and small animals, and use their bills to snatch and subdue prey.
Hornbill beaks have a distinct feature called a casque, which can range from a subtle ridge along the top of the bill to a knob or a large bulky structure. Casques are covered with keratin and usually hollow, reinforced by bony struts. Some are dull, while others become yellow, orange, or red after the bird applies oils wiped from the preen gland. Casques can add strength or counterweight to the bills (handy when chiseling in bark or hard soil) or act as sound chambers to augment vocalizations. Because casques are typically larger in males and may take years to reach full size, it is believed that they signal sexual maturity or status.
Populations of a number of hornbill species are declining, primarily due to habitat loss. Some are hunted for food or for their casques, which are used for decorations. Helmeted Hornbill, found in Southeast Asia, is particularly valued for its solid casque, which can be carved like ivory. – Julie Craves
About Julie Craves
Julie is supervisor of avian research at the Rouge River Bird Observatory at the University of Michigan Dearborn and a research associate at the university’s Environmental Interpretive Center. She writes about her research on the blog Net Results, and she maintains the website Coffee & Conservation, a thorough resource on where coffee comes from and its impact on wild birds.
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