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Results 501 - 550 of 917
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Bicca-Marques Júlio César - - 2005
Birth seasonality in wild neotropical primates has been suggested to increase with latitude as a response to a stronger divergence in high-quality food availability across the year, and a higher between-year predictability at higher latitudes related to temporal differences in photoperiod. In captivity, however, monkeys are fed foods of similar ...
Willis M A - - 2005
The location of distant resources using odor information usually also requires information on the flow of air (or water) through the environment together with the expression of internally programmed steering responses. The orientation responses of virgin male Periplaneta americana L. to wind and the female sex-pheromone component (-)-periplanone-B were video-recorded ...
Zelleke G - - 2005
(1) Four breeding groups of Rhode Island Red and White Leghorn domestic fowl (RIR (female) x RIR (male), RIR (female) x WL (male), WL (female) x RIR (male) and WL (female) x WL (male)) were compared for fertility, hatchability, and their post-insemination sustainability, egg weight loss during incubation and uncovered ...
Dahlin C R - - 2005
Pinyon jays (Gymnorhinus cyanocephalus) have a complex social system that may require a complex communication system. They need to interact with multiple flock members, and they form life-long pair-bonds. We researched whether pinyon jays would selectively vocalize depending on the presence or absence of food and certain flock members. We ...
Boivin Guy - - 2005
Reproduction is a major life-history trait but it has been studied mostly in relation to female reproductive effort. Recently, an ovigeny index using the proportion of oocytes ready to be oviposited at eclosion has been proposed for female insect parasitoids. Here, we propose a spermatogeny index for male parasitoid wasps. ...
Stauffer, Donald J; 1Center ...
The reproductive biology of two species of Africanhornbill, the Black-casqued Hornbill, <i>Ceratogymna</i><i> atrata</i>, and the White-thighed Hornbill,<i> Ceratogymna cylindricus</i>, was investigated over a four-year period (1994–1997) on a 25km<sup>2</sup> site in lowland rainforest in south-central Cameroon. Nesting attempts varied considerably among years, with the percentage of successful nests highest in ...
Lebas Natasha R - - 2005
Nuptial gifts are food items or inedible tokens that are transferred to females during courtship or copulation . Tokens are of no direct value to females, and it is unknown why females require such worthless gifts as a precondition of mating. One hypothesis is that token giving arose in species ...
Both, Christiaan
Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient ...
Visser, Marcel E.
Climate change is apparent as an advancement of spring phenology. However, there is no a priori reason to expect that all components of food chains will shift their phenology at the same rate. This differential shift will lead to mistimed reproduction in many species, including seasonally breeding birds. We argue ...
Stephen Beatty
By examining Western Australian freshwater crayfishes, this thesis aims to further our understanding of how life-history strategies, trophic relationships and disease introductions contribute to the threats posed by introduced species. Reproductive and population biology of two species of freshwater crayfish endemic to Western Australia (the marron Cherax cainii and gilgie ...
Ottosson, Ulf
The Garden Warbler is a classic subject for the study of Palaearctic-African bird migration strategies. Most studies have considered the situation close to the breeding areas, while the African and especially the sub-Saharan part of the species' migration have received comparatively little attention. Here we use autumn and spring ringing ...
Fan Y - - 2005
The German cockroach, Blattella germanica (L.), produces several potent protein aeroallergens, including Bla g 4, a approximately 20 kDa lipocalin. RT-PCR, Northern analyses and in situ hybridization showed that Bla g 4 is expressed only in the adult male reproductive system. Western blotting and ELISA with rBla g 4 antiserum ...
Jackson C - - 2005
The effects of winter food supplementation on reproduction in the seasonally breeding four-striped field mouse Rhabdomys pumilio were investigated at Mountain Zebra National Park in the Eastern Cape Province of South Africa. On both control and supplemented grids, reproductive activity in females was inhibited; no pregnant females were collected and ...
Caro Samuel P - - 2005
Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the first results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy ...
Hassall Mark - - 2005
Armadillidium vulgare differed in growth and survivorship on two field sites. Growth rates were higher at a site with consistently higher quality food than at the other site where less high-quality food was produced and which was less predictably accessible. Survivorship was higher at the second site where temperature fluctuations ...
Schoech Stephan J - - 2004
Food supplementation studies demonstrate the importance of resources in the timing of reproduction. Studies of Florida Scrub-Jays (Aphelocoma coerulescens) found that supplemented jays bred earlier than unsupplemented jays and that protein may play a critical role. In this study, free-living scrub-jays were provided with supplemental diets high in fat and ...
Fietz Joanna - - 2005
The edible dormouse (Glis glis) is a small rodent and an obligate hibernator. Dormice undergo strong fluctuations of reproductive output during years that seem to be timed to coincide with future food supply. This behaviour enables them to avoid producing young that will starve with a high probability due to ...
Séguy M - - 2005
The role of olfaction/olfactory cues on photoperiodic responses was assessed in Malagasy primate, the gray mouse lemur. When exposed to short photoperiod (SP), this primate demonstrates rapid changes in energy balance as adaptive anticipatory response for winter survival. To follow early changes induced by SP exposure, body mass, food intake, ...
Alport Laura J - - 2004
In strepsirrhine primates, the accessory olfactory system plays an important role in intrasexual competition. However, it does not play the same role in most haplorhines. In these primates, the main olfactory system and neocortex may have evolved to serve similar functions as the accessory olfactory system in strepsirrhines. To test ...
Cotton S - - 2004
Stalk-eyed flies are exemplars of sexual selection leading to the evolution of exaggerated male ornaments (eyespan). In Sphyracephala beccarri, there is no evidence for female mate choice for exaggerated male eyespan and only minor sex differences in eyespan. We used S. beccarri to test whether heightened condition dependence only evolves ...
Schjørring Solveig - - 2004
A hermaphroditic individual that prefers to outbreed but that has the potential of selfing faces a dilemma: in the absence of a partner, should it wait for one to arrive or should it produce offspring by selfing? Recent theory on this question suggests that the evolutionary solution is to find ...
Lee Haejin - - 2004
California's climate, typified by winter and spring precipitation and summer drought, is often called a Mediterranean climate, and creates a long period for pollutant build-up. The initial storms of the winter season usually have higher pollutant concentrations, which is called a seasonal first flush. To investigate the existence of a ...
Rödl Thomas - - 2004
Many songbirds in the temperate zones have comparatively short breeding seasons and are migratory. This often implies high breeding synchrony and competition for food, space, and mates. Tropical birds, in contrast, tend to be resident and react more flexibly to a more variable onset of environmental conditions conducive for breeding. ...
Yamanouye N - - 2004
Crotaline snakes store sperm by means of a uterine musculature twisting (UMT). We investigated the influence of plasma levels of estradiol and progesterone and vasotocinase cystine aminopeptidase (CAP) activity on UMT formation and maintenance, and the in vitro uterine reactivity for AVT in Crotalus durissus terrificus in primary or secondary ...
Jan Szyszko
The locomotory activity of both hungry and satiated individuals of Carabus hortensis L. was studied both in pine and beech forest by tracking the beetles by using a portable harmonic radar system. The degree of locomotory activity as well as walking distances was recorded for both males and females. Hungry ...
Nieminen Petteri - - 2004
The arctic fox (Alopex lagopus) is a winter-active inhabitant of the high arctic with extreme fluctuations in photoperiod and food availability. The blue fox is a semi-domesticated variant of the wild arctic fox reared for the fur industry. In this study, 48 blue foxes were followed for a year in ...
Dong C D - - 2004
For the first time, strong evidence is presented to demonstrate that the accumulations of butyltin compounds (BTs) exhibit seasonal variations with respect to their compositions and concentrations in marine fishes. Measurements were made on the benthic ponyfish Leiogenathus splendens and lizardfish Trachinocephalus myops inhabiting the west coast of Taiwan. In ...
Almeida-Santos Selma M - - 2004
Seasonal variations in spermatozoa numbers and in sperm motility along the vas deferens in Crotalus durissus terrificus from southeastern Brazil were analyzed. Our data demonstrate storage and motility of the spermatozoa along the vas deferens throughout the year. This is characteristic of a postnuptial reproductive cycle, usually found in snakes ...
Martínez-Gómez Margarita - - 2004
Rabbits (Oryctolagus cuniculus), like many small mammals, have a marked postpartum estrus, and during the breeding season, are often both pregnant and lactating. We examined reproductive performance and allocation of resources by rabbit mothers with overlapping litters under presumably optimal conditions of unrestricted food, standardized litter size, and young reproductive ...
Moreno-Rueda Gregorio - - 2004
It is known that breeding success in birds declines with an advance in the laying date. In this paper, breeding success diminished with laying date in a house sparrow (Passer domesticus) population breeding in captivity. The principal cause of the cline in breeding success with date was a decrease in ...
ANTHONIE M. A. HOLTHUIJZEN
From 1984 through 1987, we studied aggressive responses of Prairie Falcons (Falco mexicanus) to species intruding into their nesting territories in southwestern Idaho (52 nesting attempts, 613 days, 9,085 hr). Prairie Falcons responded aggressively most frequently to Common Ravens (Corvus corax; 49% of encounters), followed by Red-tailed Hawks (Buteo jamaicensis; ...
Rolff Jens - - 2004
Life-history theory predicts changes in age and size at maturity in response to constraints in animals with complex life cycles. A critical underlying assumption is that only these traits are optimized during ontogeny. However, it is not clear how altered life histories mechanistically translate into survival and fecundity. Here we ...
Pochron Sharon T - - 2005
In the dry season, baboons traveled purposefully to spatially predictable foods that provided a relatively large number of grams per minute of preparation (e.g., economical foods), but not to predictable foods that merely accounted for a large proportion of feeding time (Pochron in Int J Primatol 22:773-785, 2001). In this ...
Lipton Jonathan - - 2004
Much of animal behavior is regulated to accomplish goals necessary for survival and reproduction. Little is known about the underlying motivational or drive states that are postulated to mediate such goal-directed behaviors. Here, we describe a mate-searching behavior of the Caenorhabditis elegans male that resembles the motivated behaviors of vertebrates. ...
Török János - - 2004
Investment into the current reproductive attempt is thought to be at the expense of survival and/or future reproduction. Individuals are therefore expected to adjust their decisions to their physiological state and predictable aspects of environmental quality. The main predictions of the individual optimization hypothesis for bird clutch sizes are: (1) ...
Herzog Harold A - - 2004
OBJECTIVE: To determine whether winning best in show at the annual Westminster Kennel Club Dog Show was associated with a subsequent increase in breed popularity. DESIGN: Analysis of archival data. STUDY POPULATION: Breed-specific numbers of individual purebred puppies registered with the American Kennel Club between 1946 and 2002. PROCEDURE: For ...
Bylund H - - 2004
Feeding and oviposition in the pine weevil Hylobius abietis (Linnaeus) were monitored under laboratory conditions in two long-term experiments lasting over an extended breeding season. Data were also collected from weevils under semi-natural conditions outdoors. In addition, the effects of crowding and starvation were studied in separate experiments. During the ...
Koskela Esa - - 2004
Adaptive bias in sex allocation is traditionally proposed to be related to the condition of mothers as well as to the unequal fitness values of produced sexes. A positive relationship between mother condition and investment into male offspring is often predicted. This relationship was also recently found to depend on ...
Dufaÿ M - - 2004
Because the interests of mutualists are not perfectly aligned, conflicts between partners often arise, rendering mutualism unstable by allowing the evolution of cheating. The dwarf palm Chamaerops humilis is engaged in a nursery pollination mutualism with a specific weevil Derelomus chamaeropsis. In exchange for pollen dispersal, dwarf palms provide pollinators ...
Akunda, Elijah M.W.; Department ...
This paper quantifies the effects of population density and intercropping on the development and growth of nitrogen fixing attributes of soybean and explains how these attributes influence food through yielding process. Information for this study was obtained from a field study conducted over two rainy seasons comprising of the short ...
Rakotoarisoa, Jean Eric; The ...
The endemic Scaly Ground-roller <i>Geobiastes squamigerus</i> was studied during two breeding seasons from October 1997 to January 1999 in Masoala National Park, Madagascar. Several vocalisations were associated with territorial defence, contact, excitement, and aggressiveness towards intruding conspecifics. Of the 269 prey items observed, 71.5% were invertebrates, 7.5% vertebrates, and 21.0% ...
Schlabritz-Loutsevitch Natalia E - - 2004
We developed a system that allows individual feeding of adult baboons, 8-15 years of age, maintained in an outdoor group social environment. The purpose of the system is to allow careful monitoring and control of individual diet. Baboons were housed in two group cages, 16 females and a single male ...
Marler Peter - - 2004
Birdsongs are always part of larger set of sound signals. Every bird uses a repertoire of calls for communication. Calls are shorter and simpler than songs, with a much larger range of functions. Whereas songs are specialized for application in reproduction and territoriality, calls also serve such functions as signaling ...
Pendleton, Frank N
I investigated the effects of spraying deltamethrin for tsetse fly control on bird populations in the Okavango Delta, Botswana. Because deltamethrin has low toxicity to vertebrates, effects on birds would have been indirect and caused by reductions in insect food supplies, not by poisoning. The northern half of the Delta ...
Amrhein Valentin - - 2004
Male songbirds usually sing when they have occupied a territory, but the territory prospecting of non-territorial males is more elusive and has been rarely studied. Here, we simulated newly arriving, non-territorial males by translocating unmated male nightingales (Luscinia megarhynchos) to our study site. We show that territory prospecting of translocated ...
Plaistow Stewart J - - 2004
In most organisms, transitions between different life-history stages occur later and at smaller sizes as growth conditions deteriorate. Day and Rowe recently proposed that this pattern could be explained by the existence of developmental thresholds (minimum sizes or levels of condition below which transitions are unable to proceed). The developmental-threshold ...
Mathevon N - - 2004
Offspring solicit food from their parents by begging behaviours. Studies on birds suggest that these displays are 'honest signals of need' and adults provide food according to the begging level. However, siblings may compete for parental resources and the begging intensity is expected to change with brood size. Here, we ...
Jiggins C D - - 2004
Ecological divergence can cause speciation if adaptive traits have pleiotropic effects on mate choice. In Heliconius butterflies, mimetic patterns play a role in mate detection between sister species, as well as signalling to predators. Here we show that male butterflies from four recently diverged parapatric populations of Heliconius melpomene are ...
Cotton Samuel - - 2004
We used the stalk-eyed fly Cyrtodiopsis dalmanni to examine predictions made by condition-dependent handicap models of sexual selection. Condition was experimentally varied by manipulation of larval food availability. Cyrtodiopsis dalmanni is a highly dimorphic species exhibiting strong sexual selection, and the male sexual ornament (exaggerated eyespan) showed strong condition-dependent expression ...
Ezenwaji, HMG; Fisheries & ...
The biology of the commercially important clupeid, <I>Pellonula leonensis</I>, was studied from May 1998 to March 1999 in the Anambra river. In the atalla fishery of this river, the clupeid was the dominant species in terms of number and weight. Total length (TL) ranged from 3.4 to 8.5 cm and ...
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