Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 80

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 4 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Anatidae
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 4 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Acta Ornithologica
|
1995
|
tom 30
|
nr 2
125-136
Habitat use, feeding, diet composition, changes in body mass and interior indices, time budget, sex ratio and mortality of Mallards wintering in Belarus were investigated in 1980-1992. Counts and individual tagging allowed to reveal in wintering Mallards several functional groups, which use of wintering area was independent. The estimated number of Mallards in every wintering ground depended on food abundance in unfrozen feeding water bodies. The main food of 80% of Mallards wintering in Minsk city district was active silt from sewage plant. 80-90% of Mallards wintering in Lukomlskoe Lake (rural area) fed on Zebra Mussels Dreissena polymorpha. Body mass of Mallards studied increased from October till December and decreased from January till the middle of March (24% in females and 23% in males), and could have negative impact on reproductive success of sedentary Mallards. Time expenditure on flights and swimming decreased and foraging time increased from December till March. Mortality rate fluctuated between 1 and 6% in different winters.
Breeding season timing and breeding success of Tufted Duck were studied on three lakes in the years 1987-1989. Clutch laying began in mid May, earliest in a Black-headed Gull colony, and continued to the first days of July. Clutch size ranged between 3 and 18 eggs ( x = 9.3, SD = 2.8, n = 331) and did not differ significantly between lakes and years. There was a significant reduction in clutch size as the nesting season advanced (from 13.3 eggs in May to 6.3 in July). Nesting losses (25-90% failed nests or clutches) grew as the breeding season progressed. Ducklings came to the water beetween the end of June and the beginning of August. Duckling losses (20-90%) were inversely correlated with nesting failures and due mainly to predation. The investigated populations were characterized by very limited production of young in most lakes and seasons and, as a consequence, by a decline in the population to half that noted in the 1970s.
An examination of specimens of Anas georgica Gmelin (Anatidae) from Región del Bio-Bio and Región del Maule, Chile, revealed the presence of two digenean species reported for the Holartic Region: Australapatemon burti (Miller, 1923) Dubois, 1968 (Strigeidae) and Paramonostomum pseudalveatum Price, 1931 (Notocotylidae). A. burti parasitized ducks from both regions and P. pseudalveatum parasitized only ducks from Región del Bio-Bio. The digeneans were mounted in toto, described and illustrated. The morphology and dimensions of specimens studied correspond with their original descriptions and new morphometrical data and morphological characters are given. The reports of A. burti and P. pseudalveatum in A. georgica represent a new host record and the first record of the genera Australapatemon Sudarikov, 1959 and Paramonostomum Lühe, 1909 from Chile.
New species Drepanidotaenia czaplinskii sp. n. from Netta rufina (Pall.) (Anatidae) is described and figured. The new species differs from the type species of the genus, D. lanceolata, by longer rostellar hooks (0.055-0.060 in D. czaplinskii vs. 0.030-0.037 in D. lanceolata) and a relatively shorter hook blade, in cirrus size and shape, in cirrus sac size and length of vagina. The narrow interpretation of generic diagnosis of Drepanidotaenia (Spassky and Spasskaya 1954) is supported and only two valid species (D. lanceolata, D. czaplinskii) are recognized in this genus.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 4 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.