42
Unfortunately, selected albatross species like the Laysan albatross ( Phoebastria
immutabilis ) were intensively hunted for feathers that were used as in the manufacture of women’s hats as well as of down. According to archaeological excavations,
these birds were also important part of the human diet in the area of the settlement
of Aleut and Eskimos (Brooke 2004 ).
Recently, the styles of the bird’s hovering, intermittent fl ight and locomotion
have great potential to inspire the future design of autonomous fl ying vehicles
(Tobalske 2010 ). Therefore, studies on seabird wing design (Norberg 1995 ), loadings and shapes (Warham 1977 ), as well as their structural mechanics (Habib 2010 ),
determine the current science in terms of bioinspiration and bionics.
Wings and Diving
Because the optimum design of the propulsive organs is different for the two media
(air and water), which differ substantially in density and buoyancy, an intermediate
adaptive stage probably would involve a loss of effi ciency in each medium as the
price of adequacy in the other (Raikow et al. 1988 ). Diving petrels, auks, penguins
use their wings for propulsion under water. However, propulsion underwater can be
also provided by feet as it was observed for fi sh-eating ducks, loons, cormorants, or
grebes. These foot-propelled divers are generally slower than wing-propelled divers.
The most extreme underwater adaptations occur in penguins. The limb and its
skeleton are fl attened, and the wing is reduced in surface area by the loss of differentiated fl ight feathers, patagia, and the alula. The shoulder joint and the extrinsic muscles of the wing are functionally specialized, and the limb is relatively rigid as joint
mobility is restricted. In all, the wing is converted to a “fl ipper” similar in external
form to those of other aquatic tetrapods (Raikow et al. 1988 ). Maximum diving
depths of some seabirds are amazing (Adams and Walter 1993 ; Prince et al. 1994 ).
For example, predators of pelagic fi sh in southern African waters, the pursuit diving
Cape Cormorant ( Phalacrocorax capeis ) and African Pengui ( Spheniscus demersus )
are capable of diving to depths of 92 m and 130 m, respectively (Burger 1991 ).
Studies of underwater propulsion indicate that alcids employ a different method
from that of penguins (Watanuki et al. 2006 ). In alcids, the manus stays in the fl exed
position during the propulsive stroke, in which the wing moves down and backward
in a rowing action. In penguins the manus is extended, and the wing rotated so the
leading edge is lower than the trailing edge in the downstroke. This entails little
caudal movement from the wing, and the upstroke can then be used to generate
thrust as well (see for review Raikow et al. 1988 ).
Detailed analysis of the wing propulsion during deep diving by Brünnich’s
guillemots ( Uria lomvia ) was recently reported by Watanuki and co-authors. “At the
start of descent, the birds produced frequent surges (3.2 Hz) against buoyancy during
both the upstroke and the downstroke to attain a mean speed of 1.2–1.8 m/s; close
to the expected optimal swim speed. As they descended deeper, the birds decreased
the frequency of surges to 2.4 Hz, relaying only on the downstroke” (Watanuki et al.
2003 ). However, “during their ascent, they stopped stroking at 18 m depth, after
which the swim speed increased to 2.3 m/s. This may be due to increasing buoyancy
1 Introduction
Unfortunately, selected albatross species like the Laysan albatross ( Phoebastria
immutabilis ) were intensively hunted for feathers that were used as in the manufacture of women’s hats as well as of down. According to archaeological excavations,
these birds were also important part of the human diet in the area of the settlement
of Aleut and Eskimos (Brooke 2004 ).
Recently, the styles of the bird’s hovering, intermittent fl ight and locomotion
have great potential to inspire the future design of autonomous fl ying vehicles
(Tobalske 2010 ). Therefore, studies on seabird wing design (Norberg 1995 ), loadings and shapes (Warham 1977 ), as well as their structural mechanics (Habib 2010 ),
determine the current science in terms of bioinspiration and bionics.
Wings and Diving
Because the optimum design of the propulsive organs is different for the two media
(air and water), which differ substantially in density and buoyancy, an intermediate
adaptive stage probably would involve a loss of effi ciency in each medium as the
price of adequacy in the other (Raikow et al. 1988 ). Diving petrels, auks, penguins
use their wings for propulsion under water. However, propulsion underwater can be
also provided by feet as it was observed for fi sh-eating ducks, loons, cormorants, or
grebes. These foot-propelled divers are generally slower than wing-propelled divers.
The most extreme underwater adaptations occur in penguins. The limb and its
skeleton are fl attened, and the wing is reduced in surface area by the loss of differentiated fl ight feathers, patagia, and the alula. The shoulder joint and the extrinsic muscles of the wing are functionally specialized, and the limb is relatively rigid as joint
mobility is restricted. In all, the wing is converted to a “fl ipper” similar in external
form to those of other aquatic tetrapods (Raikow et al. 1988 ). Maximum diving
depths of some seabirds are amazing (Adams and Walter 1993 ; Prince et al. 1994 ).
For example, predators of pelagic fi sh in southern African waters, the pursuit diving
Cape Cormorant ( Phalacrocorax capeis ) and African Pengui ( Spheniscus demersus )
are capable of diving to depths of 92 m and 130 m, respectively (Burger 1991 ).
Studies of underwater propulsion indicate that alcids employ a different method
from that of penguins (Watanuki et al. 2006 ). In alcids, the manus stays in the fl exed
position during the propulsive stroke, in which the wing moves down and backward
in a rowing action. In penguins the manus is extended, and the wing rotated so the
leading edge is lower than the trailing edge in the downstroke. This entails little
caudal movement from the wing, and the upstroke can then be used to generate
thrust as well (see for review Raikow et al. 1988 ).
Detailed analysis of the wing propulsion during deep diving by Brünnich’s
guillemots ( Uria lomvia ) was recently reported by Watanuki and co-authors. “At the
start of descent, the birds produced frequent surges (3.2 Hz) against buoyancy during
both the upstroke and the downstroke to attain a mean speed of 1.2–1.8 m/s; close
to the expected optimal swim speed. As they descended deeper, the birds decreased
the frequency of surges to 2.4 Hz, relaying only on the downstroke” (Watanuki et al.
2003 ). However, “during their ascent, they stopped stroking at 18 m depth, after
which the swim speed increased to 2.3 m/s. This may be due to increasing buoyancy
1 Introduction