Cormorant in Japan catching fish for humans note

Cormorant in Japan catching fish for humans (note string on neck to prevent swallowing) www. viewimages. com/Search. aspx? mid=3320439&epmi d=1&partner=Google Locomotion in Birds III: Swimming & Diving

Source: http: //www. oaklandzoo. org/atoz/video 22. html Swimming on the Surface • Swimming - aquatic birds (like Tufted Ducks) typically have: – low specific gravity (lightweight so very buoyant) – feathers with lots of barbules (less permeable) – well-developed uropygial gland – webbed feet – often much stored fat (buoyancy, energetics)

Swimming Below the Surface Anhinga sunning, near Ft. Myers, Fla • Anhinga swimming • http: //www. youtube. com/watch? v=o 2 s_D 040 OLA

Diving and swimming underwater • Birds that frequently dive and swim, such as grebes, cormorants, & loons, have: – relatively high specific gravities (heavier, less buoyant) – feet located well back on body for better propulsion and maneuvering underwater – and/or smaller wings that permit 'flying' underwater (e. g. , scoters, petrels, murres (video of Thick-billed Murres 'flying' underwater), and, of course, penguins -see the Adelie Penguin in 2 slides)

Pelican Diving

Adelie Penguin Source: http: //www. bionik. tu-berlin. de/intseit 2/xs 2 pinfi. html

• A) Bubbles in the wake of a Pigeon Guillemot (Cepphus columba) swimming horizontally, indicating intermittent thrust on downstroke • B) Wing positions during horizontal swimming by a Common Murre, as drawn from films taken at 32 frames/sec. Sequence is from left to right and top row to bottom row. Angle of attack of the wings suggests substantial lift during the upstroke (From: Lovvorn 2001) Swimming Underwater

Why Swimmers Have Small Wings I • Researchers believe small wings reduce drag underwater and are better suited for swimming • No concrete evidence • Studying the effects of wing area is difficult; crossspecies studies never give fair comparisons • Bridge (2004) studied the effect of altered wing size on Common Guillemots (Uria aalge) and Tufted Puffins (Fratercula cirrhata) during their brief molting periods (assumed molt = smaller wing = better swimming)

Wing-molt stages of a Tufted Puffin • Approximations of the percentage of intact wing area with the wing loosely extended are listed for each molt stage (Bridge 2004)

Why Swimmers Have Small Wings II: Puffin Swimming • Bridge (2004) used video cameras at Sea. World California mounting one camera in viewing window, and the other above the pool pointing straight down. • Plotted movement in 3 dimensions, calculated dive speed angle of descent • Found that wing molt had an adverse effect • During molt, the birds swam a shorter distance with each flap, and energy output, measured as work per flap, also reduced, especially when both primary and secondary feathers were missing • http: //www. youtube. com/watch? v=f. OM 6 Gwpr 2 r. I puffin

Why Swimmers Have Small Wings III • If reduced wing areas don’t improve diving/swimming ability, why has natural selection favored small, pointed wings in many aquatic birds? • Adept at high-speed, long-distance flight, essential for rapid movement between habitats - good • Small, pointed wings cannot generate lift at low speed, so rapid vertical takeoffs impossible – a problem? • Not a big problem for most diving birds because open aquatic habitats prevent close approach by undetected predators • When slow down to land, small wings stall easily, lose lift - good • High-speed hard landings more acceptable on water than on land • Aquatic habitats relax constraints on small, pointed wings. • -- Jane Qiu, Journal of Experimental Biology

Great Cormorant feathers have a regular and highly waterproof central part whereas the distal region is irregular and wettable. A ventral feather is shown (From: Grémillet et al. 2005). Double-crested Cormorants, Chatham, Cape Cod

Foot-propelled locomotion • When submerged, Great crested Grebes (Podiceps cristatus) swim with synchronized foot strokes, wings closely folded against the body • During the power stroke, the feet move from a cranial and ventrolateral position to a caudal and dorsomedial position relative to the body. • The mean swimming speed varied from 0. 7 - 1. 2 meters/sec (Johansson and Norberg 2001).

Foot Propulsion • Dorsal (left) & lateral (right) frames of a diving grebe • The dorsal view recorded after reflection from a mirror Photo source: http: //www. copyright-freepictures. org. uk/animals/birds/90 -great-crested-grebe. htm

One rude penguin