title: How seabirds plunge-dive without injuries.
abstract: In nature, several seabirds (e.g., gannets and boobies) dive into water at up to 24 m/s as a hunting mechanism; furthermore, gannets and boobies have a slender neck, which is potentially the weakest part of the body under compression during high-speed impact. In this work, we investigate the stability of the bird's neck during plunge-diving by understanding the interaction between the fluid forces acting on the head and the flexibility of the neck. First, we use a salvaged bird to identify plunge-diving phases. Anatomical features of the skull and neck were acquired to quantify the effect of beak geometry and neck musculature on the stability during a plunge-dive. Second, physical experiments using an elastic beam as a model for the neck attached to a skull-like cone revealed the limits for the stability of the neck during the bird's dive as a function of impact velocity and geometric factors. We find that the neck length, neck muscles, and diving speed of the bird predominantly reduce the likelihood of injury during the plunge-dive. Finally, we use our results to discuss maximum diving speeds for humans to avoid injury.
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
authors.forename: Brian
authors.initials: B
authors.lastname: Chang
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
authors.forename: Matthew
authors.initials: M
authors.lastname: Croson
authors.affiliation: National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; Setor de Ornitologia, Museu Nacional, Universidade Federal do Rio de Janeiro, São Cristóvão, Rio de Janeiro RJ 20940-040, Brazil.
authors.forename: Lorian
authors.initials: L
authors.lastname: Straker
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
authors.forename: Sean
authors.initials: S
authors.lastname: Gart
authors.affiliation: National Museum of Natural History, Smithsonian Institution, Washington, DC 20560.
authors.forename: Carla
authors.initials: C
authors.lastname: Dove
authors.affiliation: North Carolina Museum of Natural Sciences, Raleigh, NC 27601.
authors.forename: John
authors.initials: J
authors.lastname: Gerwin
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; sunnyjsh@vt.edu.
authors.forename: Sunghwan
authors.initials: S
authors.lastname: Jung
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D004242:Diving / Q000502:physiology*; D055119:Elastic Modulus; D005247:Feeding Behavior / Q000502:physiology*; D006801:Humans; D008953:Models, Anatomic; D014867:Water
chemical_list: D014867:Water
keywords: buckling; diving; injury; seabirds; water entry