| .יטנלטא ןורועסי(24 | ||||||||||
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.עוסשה ובנזב ונממ לדבנ ןטקה ןורועסיהמ לודג :יטנלטא ןורועסי .ההכ ויפנכ תיתחתו רתוי ריהב ויפנכ סיסב ,רופא-ןבל ותש .ינצפוקו ינותלקע ופועמ .םיצע ישרוש דיל ילוח ןורדמ לע םייא יפוחמ קוחר ןנקמ ,יתשביה ףדמה לעמ סנכתמ םיתיעל םיסוניקואו םימי ולודיג תיב .רידנ ףרוח רקבמ ץראב | ||||||||||
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Subspecies and Distribution.
O. o. leucorhoa N Pacific from Japan through Kuril and Aleutian Is to Alaska, california, Canada to Iceland, Faeroe Is and Norway. O. o. chapmani San Benito and Coronados Is, off Mexico. O. o. socorroensis islets by Guadalupe Is, off Mexico. O. o. cheimomnestes Guadalupe Is. | ||||||||||
Descriptive notes.19-22 cm; 45 g, wingspan 45-48 cm. Wings long and narrow, with sharp carpal bend; forked tail.Differs from other white-rumped species in combination of fairly well marked upperwing bar reaching forward to leading edge of wing, and less white looking rump due to dark median stripe. Some Pacific birds have dark rump. Juvenile can have even more prominent upperwing bar. Races separated on size and colour of rump. HabitatMarine and pelagic; often in areas of convergence or upwelling, or over continental shelf, rarely coming near land except at colonies.Breeds on offshore islands on high ground or slopes, usually among rocks but also in soft soil betwiin tree roots. Food and FeedingMainly small fish, squid, planktonic crustaceans and offal.Prey caught on thewing by dipping and skimming, or snatched from surface. May fed both night and day.Sometimes follows marine mammals, feeding on left overs or facces. Breeding.Starts May in N Atlantic; at Guadalupe Is (Mexico) different subspecies breed in summer and winter. Colonial; nests in burrows or rocks crevices, nest someimes lined with grass and twigs1 egg; incubation 41-42 days, with stints of 3 days; chicks blueish grey down, brooded for 5 days; fledging 63-70days. Sexual maturity at 5 years. known to have reached 24 years old in wild. Movements.N populations migrate S into tropics; N Atlantic birds occur S to South Africa and occasionally reach Indian Ocean.Pacipic birds apparently winter mostly in equatorial zone of E Pacific. Several records from Australia and New Zealand; behaviour strongly suggesting possible breeding at Chatham Is. Status and ConservationNot globally threatend. Widespread and abundant, with total population of at least 10,000,000 birds: 4,000,000 in Alska, 1,000,000 at over 40 sites in British Columbia.Israel.In Israel subspecies O. l. leucorhoa. Accidental winter visitor. |
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