Tropical hornbills (Aceros cassidix, Aceros undulatus, and Buceros hydrocorax) use ballistic transport to feed with their large beaks

Abstract

The most common and plesiomorphic mechanism of food transport in tetrapods is lingual-based. Neognathous birds use this mechanism for exploiting a large diversity of food resources, whereas paleognathous birds use cranioinertial mechanism with or without tongue involvement. Food transport in three hornbills' species (Aceros cassidix, A. undulatus, and Buceros hydrocorax) is defined by a ballistic transport mechanism. Only one transport cycle is used for moving the food from the tip of the beak to the pharynx. The tongue never makes contact with the food nor is it used to expand the buccal cavity. In hornbills, filmed through high-speed video, time to food release occurred between 0.11 and 0.16 sec before time to maximum gape. The ballistic curves show similar patterns. Maximum gape angle is significantly different between the three species. Each species show a different kinematic and motor pattern of head movements associated with ballistic transport. In A. undulatus, head rotation follows a continuous pattern similar to that reported earlier in toucans. A. cassidix rotates head downward at the time of maximum gape to permit food to reach the pharynx without touching the mandible. B. hydrocorax elevates the head along the transport cycle to avoid contact with the food to the cavity of the upper beak. Selection of large food items in the diet may explain the evolutionary trend of using ballistic transport in the feeding behavior of hornbills, which play a key role in tropical forest ecology by dispersing seeds.

Evolution and function of anterior cervical vertebral fusion in tetrapods

“…The syncervical is thought to aid in supporting a relatively large head that is equipped with a casque in many species (Kemp, 2001). The skulls of hornbills and toucans weigh relatively the same, however, and both groups use a ballistic method of feeding (Baussart et al, 2009;Seki, Bodde & Meyers, 2010;Baussart & Bels, 2011), yet toucans are not known to have specialized adaptations in their cervical vertebrae. In some of the casqued species, a behaviour involving head-to-head combat has been observed, called 'casque-butting' or 'aerial jousting' along with locking of the bills, called 'bill grappling' (Cranbrook & Kemp, 1995;Kinnaird, Hadiprakarsa & Thiensongrusamee, 2003;Kasambe, Charde & Yosef, 2011).…”

Morphofunctional study of the tongue in the domestic duck (Anas platyrhynchos f. domestica, Anatidae): LM and SEM study

“…Sometimes neognathous birds use catch and throw mechanism, but it is used only during ingestion of large food particles and still requires complex movements of hyolingual apparatus. The exception among neognathous birds is toucan, hornbills and southern cassowary in which develops the so-called ballistic transport (Baussart et al 2009; Baussart and Bels 2011; Harte et al 2012). …”

Determination of hematological and serum biochemical values and detection of Chlamydophila psittaci antibodies in captive hornbills at the Ninoy Aquino Parks and Wildlife Nature Center

“…[27] Triglyceride concentrations for all hornbills lie within the standard range of value of 38.0-211.0 mg/dl for Aceros and 73.0-178.0 mg/dl for Anthracoceros that gives the researchers a good idea about the balance between the Aceros and Anthracoceros' bi-directional transference of adipose and blood glucose that excludes the Hornbill from the risk of coronary artery diseases and stroke. [28] High-density lipoprotein (HDL) concentrations in the bloodstream of the hornbills had values ranging from 56.39 to 77.21 mg/dl, 59.86-87.66 mg/dl, and 68.83 mg/dl for Tarictic hornbill, Rufous hornbill, and Palawan hornbill, respectively. Normal concentrations of HDL would result in a better LDL or bad cholesterol scavenging that could help the avians in keeping endothelial walls clean from plaques and reprocessing bad cholesterol in the liver.…”