نتایج جستجو برای: clutch
تعداد نتایج: 2466 فیلتر نتایج به سال:
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...
The hormone melatonin is known to play an important role in regulating many seasonal changes in physiology, morphology and behaviour. In birds, unlike in mammals, melatonin has thus far been thought to play little role in timing seasonal reproductive processes. This view is mainly derived from laboratory experiments on male birds. This study tests whether melatonin is capable of influencing the...
A dynamic model of a manipulative machine for automobile clutch is setup in ADAMS and further analysis is made to an automatic clutch for AMT. Since the engaging process of clutch is complex and related to riding performance and life span of friction plate, it has to be researched intensively using modern control theory. Adaptive control is effective to avoid engine flameout, which guarantees s...
A recent study proposed that incubation behaviour (i.e. type of parental care) in theropod dinosaurs can be inferred from an allometric analysis of clutch volume in extant birds. However, the study in question failed to account for factors known to affect egg and clutch size in living bird species. A new scaling analysis of avian clutch mass demonstrates that type of parental care cannot be dis...
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