نتایج جستجو برای: clutch assembly
تعداد نتایج: 129523 فیلتر نتایج به سال:
Life-history theory predicts that parents produce the number of offspring that maximizes their fitness. In birds, natural selection on parental decisions regarding clutch size may act during egg laying, incubation or nestling phase. To study the fitness consequences of clutch size during the incubation phase, we manipulated the clutch sizes during this phase only in three breeding seasons and m...
within a population, the sizes of eggs and clutches vary, and the combination of both determines a female’s reproductive investment. we investigated females’ investment in clutches of the Chilean Swallow (Tachycineta meyeni) at the southern limit of its range, where it breeds in an extreme climate. we analyzed variation in clutch, egg and yolk size in relation to the female’s condition, date of...
Elevated nitrite and microcystin concentrations co-occur during degradation of Microcystis blooms and are toxic to aquatic organisms. We studied the relative and combined effects of these on Daphnia obtusa life-history. Nitrite and microcystin-LR treatments were: 0, 1, 3 mg L(-1) and 0, 10, 100, 300 μg L(-1), respectively. Experiments were factorial with 12 treatment combinations. Incubations w...
The parasitoid wasp genus Achrysocharoides (Eulophidae) is unusual in that many of its species lay male and female eggs in single-sex clutches. The average clutch size of female broods is always greater than that of male broods, and in some species male clutch size is always one. We constructed models that predicted that severely egg-limited wasps should produce equal numbers of male and female...
Traits such as clutch size vary markedly across species and environmental gradients but have usually been investigated from either a comparative or a geographic perspective, respectively. We analyzed the global variation in clutch size across 5,290 bird species, excluding brood parasites and pelagic species. We integrated intrinsic (morphological, behavioural), extrinsic (environmental), and ph...
AnsTn.Kr. -The breeding biology of Eurasian Nuthatches (Sitta europaea asiatica) was studied in 1986-1990 in two habitats, riparian and upland forests, in the Magadan region, northeastern Siberia. Clutch sizes and breeding success averaged 6.49 eggs and 57.5%, respectively, and varied among years. Habitat influenced clutch size but not numbers of young fledged from successful nests. Within seas...
Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests,...
The breeding biology of Western and Semipalmated Sandpipers was studied for four years near Nome, Alaska. Despite a short breeding season and a putatively invariant clutch size, there were seasonal declines in the fecundity of both sandpiper species. Most females produced only one clutch ( > 98%), but often laid fewer than four eggs (7.6-34.5% of first nests). Clutches of 2-3 eggs were initiate...
A novel multi-fingered exoskeleton haptic device using passive force feedback has been proposed by the authors. The haptic device solves the conventional problems of previously developed master-slave systems with force feedback, such as oscillations, complex structures and complicated control algorithm. However, some problems still remain in the conventional passive elements. In the present pap...
To study the energetic costs of incubation in relation to clutch size, clutch sizes were manipulated and the metabolic rate of female great tits, Parus major (Linnaeus), during nocturnal incubation (MR(inc)) was measured using mobile oxygen analysers. Individuals were measured on consecutive nights while incubating their own or manipulated clutches. The experiment was performed under field cond...
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