نتایج جستجو برای: new wintering population
تعداد نتایج: 2458768 فیلتر نتایج به سال:
Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, ...
Migratory bird needs must be met during four phases of the year: breeding season, fall migration, wintering, and spring migration; thus, management may be needed during all four phases. The bulk of research and management has focused on the breeding season, although several issues remain unsettled, including the spatial extent of habitat influences on fitness and the importance of habitat on th...
The feces of 212 sandhill cranes (Grus canadensis) collected in central New Mexico from October 1982 to January 1983 and from October 1983 to January 1984 were examined to determine the prevalence of coccidial oocysts. One hundred forty-five granulomatous nodules from the viscera of 64 cranes and samples of lung, small intestine, and large intestine from 58 birds were examined by light and tran...
A 4-yr study using 217 cows/yr (3/4 Red Angus, 1/4 Simmental) evaluated effects of calving date and wintering system on cow and calf performance from birth to harvest. Cows were assigned to 1 of 5 treatments: 1) March (Mar) calving cows wintered on native range, 2) Mar calving cows wintered on corn residue, 3) June (Jun) calving cows wintered on native range, 4) Jun calving cows wintered on cor...
During the winter months, humpback whales Megaptera novaeangliae prefer warm and shallow regions, and these habitat preferences have been linked to reproductive status and success. Central North Pacific humpback whales winter in the main Hawaiian Islands (MHI), with peak densities occurring in late March. The Hawaiian Archipelago extends over 1800 km to the northwest of the MHI and includes a n...
-Migration of Spruce Grouse was observed in southwestern Alberta from 1970 to 1975 in a population of grouse that included both migratory and resident birds. Migrants comprised 39% of this population; these individuals migrated each year regardless of weather conditions. Migration occurred from mid-February to late May and from early September to midDecember. More females than males were migrat...
Kleptoparasitism in birds has been the subject of much research, and the Bald Eagle (Haliaeetus leucocephalus) is a known kleptoparasite. It has been reported to pirate ducks captured by Peregrine Falcons (Falco peregrinus), but ours is the first study to examine the effect of kleptoparasitic Bald Eagles on the kill rate of shorebird-hunting Peregrines and indirectly on a population of Dunlins ...
The Mid-Continent Population of the lesser snow goose, which breeds in the eastern and central Canadian Arctic and sub-Arctic, and winters in the southern United States and northern Mexico has increased 5–7% annually from the late 1960s to the mid-1990s, largely because of increased survival in response to an agricultural food subsidy. The rise in numbers complements the increased use of nitrog...
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