| י240) שחף כספי | ||||||||||
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:שחף כספי . השכיח והנפוץ מבין השחפים הגדולים . ראשו וצוארו לבנים, צבע גבו משתנה בין גווני הצבע האפור . קצות כנפיו שחורים לבנים , גופו מוצק וראשו גדול. מקורו גדול . חזק וצהוב בקצה הלסת התחתונה כתם אדום . העין צהובה ומסביבה טבעת אדומה . צבע הרגלים משתנה אצל התת מינים השונים מצהוב לורוד בית גידולו חופים או בקרבתם, לעיתים בפני היבשת ליד אגמים . או מקוי מים גדולים. אוכל כל וסתגלן . בארץ נודד אקראי נדיר ביותר ... ואת השחף ... ויקרא י"א, 16 | ||||||||||
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Subspecies and Distribution.
L. a. smithsonianus North America. Winters S to Central America L. a. argenteus Iceland, Faeroes, British Is and W France to W Germany. Winters S to N Iberia. L. a. argentatus Denmark and Fenno-Scandia, to E Kola Peninsula. Winters mostly in N and W Europe. L. a. vegae NE Siberia. Winters S to China. םםםםםםםםםםםםםםםםםםםםםםםםםםםםםםםםםםם םםםםםםםםםםםםםםםםםםםםםםםםםםםםםםםם | ||||||||||
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Descriptive notes.
55-65 cm, 750-1500 g, wingspan 135-145 cm. Large gull with powerful bill. White head, underparts and tail, mantle and apperwings grey, varying from pale to dark grey. Black wingtips with a white spotted pattern. Bill yellow, with red gonydeal spot. Legs and feet pink, but yellowish on some N Baltic birds. Iris pale yellow, with orange to yellowish red orbital ring. Races differ mainly in size, in tone of mantle and upperwing, and in exact pattern of primary tips, but quite variable. Even within Netherlands artenteus mantle color varies among colonies from light to dark grey, and the darkest mantled birds from Norway argentatus are comparable to the lightest mantled L. fuscus graellsii from Bretain. NE Asian vegae is large, heavy-billed, with a darker mantle. Subspecies argenteus generally smallest and palest, and subspecies smithsonianus intermediate bitwiin argenteus and argentatus . Minimal hybridization with L. fuscus. Habitat. Breeding habitats very varied, coastal cliffs and stacks, rocky and grassy islands, sandy beaches, gravel bars, salt marshes, and buildings. After breeding season coastal and near-coastal areas, also inland, at large lakes and reservoirs, on fields and at rubbish dumps. Food and Feeding. Omnivorous and highly opportunistic, feeds extensively on fish, earthworms, crabs, and other marine invertebrates, taken alive or found dead. Huge numbers scavenge at rubbish dumps, fishing wharves and sewage outfalls. Frequently follows fishing boats. Preys on birds, and their eggs and chicks. Flocks sometimes prey on fatigued migrant passerines, particularly those struggling to land into a wind. Feeding methods very varied include walking on mudflas, plunge diving and surface-dipping. Breeding. May-Jun. Colonies of dozens to thousands of pairs. With increased population, aggression and cannibalism increased. Bulky nest of grass and vines, on ground, cliff sedge or roof, usually sheltered in vegetation. 2-3 eggs, incubation 29 days. Chick buff grey above with large blackish spots, well defined on head, buffy white below, with black throat spot. Chick growth rate declined as population density increased. First breeding at 3-7 years. Movements. North birds are migratory, and may leapfrog over S breeders. Winters as far S as West Indies and Central America, but in Palearctic usually only to Iberia. Finnish breeders move short distances, most remaining in Baltic. Many N European birds winter in S North Sea. some of those breeding in NE Asia remain well N in winter, but many migrate, wintering as far E as coasts of South China Sea. Status and Conservation. Not globally threatened. on of themost abundant coastal birds in North America and Europe. Israel. In Israel subspecies L. a. argenteus. Sreaggler. |
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