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Marokas, Vakarų Sachara http://forum.birdlife.lt/viewtopic.php?f=24&t=734 |
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Autorius: | Miilda [ 2011-04-10 18:38 (Sek) ] |
Pranešimo tema: | Marokas, Vakarų Sachara |
Vasario 2-16 d. buvau Maroke ir Vakarų Sacharoje stebėti paukščių. Tai buvo viena iš geriausių mano paukštinėjimosi kelionių. Keliavome tryse (aš ir du anglai ). Iš viso nuvažiavome apie 7 000 km, stebėjome virš 220 paukščių rūšių ir nakvojome tik 6 naktis viešbutyje, visos kitos naktys buvo praleistos važiuojant ir miegant mašinoje. Dvi dienas praleidome dykumoje Vakarų Sacharoje. Toks įtemptas keliavimo būdas suteikė mums galimybę pamatyti beveik visas rūšis, kurias norėjome. Visa kelionė man kainavo tik apie 2 000 Lt (lėktuvo bilietai apie 850 Lt (Ryanair, Kaunas-Londonas-Agadiras ir atgal), automobilio nuoma apie 160 svarų sterlingų ir visas kita (maistas, benzinas, nakvynė (viešbučio trivietis kambarys mums trims kainavo tik apie 40 Lt!). Čia gana smulkiai yra aprašyta visa mūsų kelionė (anglų k.): http://birdforum.net/showthread.php?t=196337 O čia yra šiek tiek mano darytų nuotraukų. Kokybė nėra stebuklinga, kadangi tai buvo mano pirmasis fotografavimo bandymas: Pirmoji dalis: https://picasaweb.google.com/miildas/Mo ... uzigeTqkwE# Antroji dalis: https://picasaweb.google.com/miildas/Mo ... LStzPqz6AE# |
Autorius: | Edmundas4 [ 2011-11-05 09:55 (Šeš) ] |
Pranešimo tema: | Re: Marokas, Vakarų Sachara |
Sveiki visi. Kad nepriklonuoti temų rašysiu į tą pačią. Buvau Maroke, Feso mieste. Mačiau įdomų reiškinį. Vakare prieš temstant virš miesto susirinkdavo šimtai čiurlių, iš pradžių aukštai, vėliau leisdavosi žemyn. Visas senamiestis aptvertas aukšta siena kurioje kas metras skylės10x10 cm. Tai čiurliai lysdavo nakvoti į tas skyles, net mušdavosi dėl vietos. Anksti ryte vėl pakildavo į dangų ir dingdavo iš miesto. Ir taip kartojosi tris dienas. Tai kaip tas teiginys, kad čiurliai visą laika praleidžia ore. Gal kas pakomentuos. |
Autorius: | Egle [ 2011-11-05 10:22 (Šeš) ] |
Pranešimo tema: | Re: Marokas, Vakarų Sachara |
Edmundai, o iš kur ištraukėt teiginį, kad čiurliai visą laiką praleidžia ore? Aš tai tokio negirdėjau . Čiurliai nelabai gali pakilt nuo žemės, taigi nevaikšto žeme, bet dėl viso laiko ore... Paukštis juk kažkur turi nakvoti, neskraidys gi visą naktį . |
Autorius: | Povilas [ 2011-11-05 10:27 (Šeš) ] |
Pranešimo tema: | Re: Marokas, Vakarų Sachara |
Čiurlių "miegas" skrydyje gana įdomus klausimas: http://www.sciencedaily.com/releases/20 ... 113243.htm Dar viena ištrauka iš straipsnio: Niels C. Rattenborg "Do birds sleep in flight?", Naturwissenschaften (2006) 93: 413–425 "Candidates for sleep in flight Common swift Of all the birds thought to sleep in flight, perhaps the common swift (Apus apus) has received the most attention. The idea that swifts spend the night on the wing arose from observations of swifts ascending into the sky above their colony after sunset and descending the following morning (Edwards 1887; Masson 1930; Weitnauer 1952, 1954, 1960; Lack 1956). Although collisions with and observations from airplanes showed that swifts did, in fact, fly at night (Weitnauer 1952, 1954–1956; Lack 1956), it was not until Weitnauer used radar to track swifts throughout the night that aerial roosting was confirmed (Weitnauer 1960, 1980; Bruderer and Weitnauer 1972). Nevertheless, these radar studies were unable to determine whether individual birds flew for an entire night or the number of consecutive nights spent in flight. Recently, Tarburton and Kaiser (2001) used radio tracking to follow individual swifts in flight for periods up to two consecutive nights before loosing the signal. The birds participating in aerial roosting were primarily prebreeders; breeding adults roosted, and presumably slept, in the nest box and only engaged in aerial roosting toward the end of the fledging period. Although the tracking of prebreeders was discontinuous, due to temporary signal loss, all but one of the pre-breeders tracked were always encountered while in flight, regardless of whether it was day or night. The exceptional individual roosted at night on a building, a behavior rarely observed at this study site. Even fledglings typically departed from the nest for the first time after sunset and spent their first night outside the nest in flight. In other reports, recently fledged juveniles have been found roosting on foliage or other substrates more often than adults, however (Holmgren 2004). Nonaerial roosting occurs primarily during low ambient temperatures, suggesting that juveniles are more energetically vulnerable than adults, and therefore, more likely to resort to non-aerial roosting, presumably a less energetically expensive behavior than aerial roosting. Although there is substantial evidence showing that pre-breeding adult common swifts often spend the night in flight, the average and maximum length of time spent in continuous flight remains unknown. In conjunction with the results from tracking studies, the fact that observations of nonbreeding birds roosting terrestrially are noteworthy suggests that aerial roosting is the typical nocturnal behavior for common swifts, at least during the breeding season. Aerial roosting may also occur in other species of swifts, but the evidence is not as substantial as that for the common swift (reviewed in Holmgren 2004). The evidence for sleep in flying common swifts, however, is circumstantial, depending solely on the notion that if swifts must sleep, such sleep must occur on the wing. Aside from spending the night in flight, perhaps, the only other piece of evidence for sleep in flight comes from a radar study of the flight patterns of common swifts at night. Bäckman and Alerstam (2002) tracked individual swifts flying at night for periods up to 1 h. In general, the swifts flew into the wind, a flight pattern that reduced displacement from the colony. Interestingly, the swifts’ orientation oscillated with a period of 1–16 min, around the direct heading into the wind, a flight pattern expected under wind speeds lower than the swifts’ lowest flight speed, assuming that the swifts’ goal was to remain over the colony. However, this oscillation occurred at all wind speeds, including those higher than the swifts’ flight speed. Bäckman and Alerstam (2002) suggest that this flight pattern may reflect oscillations in the level of alertness, possibly related to sleep in flight. Weaving from left to right of the direct heading may result from a sensory bias related to flying alternately with only the left or right eye open. Indeed, pigeons flying with one eye occluded tend to veer toward the side with the open eye (Prior et al. 2004)." |
Autorius: | Egle [ 2011-11-05 10:47 (Šeš) ] |
Pranešimo tema: | Re: Marokas, Vakarų Sachara |
Povilai, labai įdomus tekstas, ačiū . Bet ir iš šio teksto išplaukia, kad čiurliai gali ir dažnai praleidžia naktį ore, bet lygiai taip pat nakvoja ir "normaliai". Be to, klausimas Edmundui: ar visi jūsų matyti čiurliai buvo Apus apus, o gal buvo ir kitos čiurlių rūšys? |
Autorius: | Edmundas4 [ 2011-11-05 13:45 (Šeš) ] |
Pranešimo tema: | Re: Marokas, Vakarų Sachara |
Matyti buvo [b]apus melba[/b] |
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