Beginners' zoology . Fig. 318. — Aftekyx. of New Zealand. Size of a hen, wings and tailrudimentary, feathers hair-like. In dust ? Dust helps to remove old oil. At what seasonhave birds the brightest feathers? Why? Have you ever. -^??^^^S-^v^;^ Fig. 319.— Golden, Silver, and Noble Pheasants, males. Order?(Key, p. 177.) Ornaments of males, brightest in season of courtship, are due tosexual selection (Figs. 321-7-9, 333). seen evidence of the moulting of birds? Describe themoulting process (page 120). BIRDS 175 Adaptations forFlying. — Flightis the most diffi-cult and energy-consuming meth-od of
Beginners' zoology . Fig. 318. — Aftekyx. of New Zealand. Size of a hen, wings and tailrudimentary, feathers hair-like. In dust ? Dust helps to remove old oil. At what seasonhave birds the brightest feathers? Why? Have you ever. -^??^^^S-^v^;^ Fig. 319.— Golden, Silver, and Noble Pheasants, males. Order?(Key, p. 177.) Ornaments of males, brightest in season of courtship, are due tosexual selection (Figs. 321-7-9, 333). seen evidence of the moulting of birds? Describe themoulting process (page 120). BIRDS 175 Adaptations forFlying. — Flightis the most diffi-cult and energy-consuming meth-od of movingfound among ani-mals, and care-ful adjustment isnecessary. Forbalancing, theheaviest musclesare placed at thelower and centralportion of the are the flyingmuscles, and in somebirds (humming birds)they make half of theentire weight. Teethare the densest of ani-mal structures; teethand the strong chew-ing muscles requiredwould make the headheavy and balancingdifficult; hence the chewing apparatus istransferred to the heavy gizzard near thecentre of gravity of the body. The birdsneck is long and excels all other necks inflexibility, but it is very slender (althoughapparently heavy), being inclosed i
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
