Differences in the diet of the male and female tui (Prosthemadera novaeseelandiae: Meliphagidae)

Abstract

Tui are shown to be highly nectarivorous but observations show differences in degree of importance between the three food categories; nectar, fruit and arthropods, according to season. Foraging observations were significantly different for male and female tui during spring and especially during autumn, with males taking more nectar and females taking more arthropods.     

Geographical variation in size of an Australian honeyeater (Aves: Meliphagidae): an example of Bergmann's rule

The singing honeyeater, a nectar-feeding bird, is common throughout most of Australia. There is considerable geographical variation in weight, the heaviest birds (30 g) living at the highest latitudes (35°S) and the lightest birds (19 g) at the lowest latitudes (16°S). Clinal variation in weight is apparently related to climatic factors (e.g. potential evapotranspiration) in accord with Bergmann's rule. The exceptions are populations on islands and peninsulas which are about 13% heavier than those on the adjacent mainland.     

Inter-colony and sex differences in the effects of parental body condition and foraging effort on the brood growth of Adélie penguins

Among colonies with different foraging distances, central-place-foraging seabirds may change their foraging and reproductive efforts. We compared the body condition, meal frequency, and diving behavior of male and female Adélie penguins at two locations: Dumont d'Urville, where there was little sea ice and they foraged in open waters far from the colony; and Syowa, where there was heavy, fast sea ice and they foraged in ice cracks close to the colony. The parental mass decrease rate during the chick-rearing period was similar between colonies and between sexes. A large individual variation in meal frequency positively affected the brood growth rate, but daily underwater time did not. A weak but significant positive effect of body condition on brood growth rate was found only in males at Syowa. It was suggested that males work with better body condition than females. We propose the hypothesis that the regional difference in the distance to the feeding sites and the sex difference in body energy reserve might constrain the capacity to regulate reproductive effort.     

An introductory ecological biogeography of the Australo-Pacific Meliphagidae

Abstract

The Meliphagidae, that can readily be defined on tongue characteristics, are a monophyletic group centred in the Australo-Pacific region, but with one African genus (Promerops). The classification of Salomonsen (1967) allows 38 genera and 170 species in the former region, and one genus with two species in the latter. Australia and New Guinea jointly have 23 genera and 108 species, and constitute the centre of diversity of the group. Endemic genera are concentrated in Australia and New Guinea, and around the periphery of the Pacific part of the range (Sulawesi, Bonins, Marianas, Hawaii, New Zealand). The meliphagids are diversified in body size and bill form. They are basically nectarivores and insectivores, with most species combining the two roles to varying degrees. There is a good general correlation between bill form and way of life. A few species feed on trunks and aerial flycatching is well developed in many. Morphological modification is only minor in these instances and the meliphagids as a group remain rather generalised in bodily proportions. A long period of coevolution with Australian plant elements is shown by meliphagids being the major pollinators of several tree and shrub genera.

The group combines monotypic genera with restricted ranges and wide-ranging genera with many species. Of the latter; Myzomela, Lichema, and Philemon are centred in the tropics, and Meliphaga and Phylidonyris in Australia. Most of these co-occur over a wide area, this being favoured by differences in body size and bill morphology.

Comparison of three kinds of meliphagid communities, two typical continental ones, two of isolated forest outlyers in Australia, and six insular Pacific ones, shows the first to be rich (10 and 11 genera, 21 and 17 species), and the second impoverished (6 and 7 genera, 9 and 12 species). Individual Pacific island groups, however, have only 2–5 genera, and 3–6 species. Genus to species ratios are 0.55–0.64 in the major continental communities, but are 1.0 in New Zealand and Samoa.

Morphological distance between species, measured as the percent difference in size between successive members along a size gradient is 5.4 and 5.5% for wing length and 4.9 and 9.3% for bill length in the two continental communities. It increases to 7.8–14.9, and 11.3–12.7%, respectively, in the isolated forest outlyers of Tasmania and southwestern Australia. The figures are 23.0 and 35.0% for wing and bill length in New Zealand, and 41.0 and 51.0% in Fijian forms. This accords with current theory that in impoverished insular environments, size separation of co-occurring species must be greater.

The marked success of the Meliphagidae in the Australo-Pacific region can be attributed to their versatility and adaptibility, and dual role of insectivore and nectarivore in an area exceptionally rich in nectar-producing trees and shrubs.     

食物对三突花蛛生长发育的影响——Ⅰ.食物对三突花蛛历期和体重的影响

对取食不同食物(棉铃虫Helicoverpa armigera、摇蚊Chironomus sp.、果蝇Drosophilamelanogaster及其组合)的三突花蛛(Misumenops tricuspidatus)历期和体重进行了比较研究。结果表明,取食混合食物的三突花蛛历期缩短、干重增大。     

A role for corticosterone and food restriction in the fledging of nestling White storks

Fledging is a critical period in the life of a bird, notably because at this stage under-development and lack of experience in searching for food may impair survival. The behavioral changes that accompany nest departure are therefore expected to be finely tuned to body condition and growth by endocrine processes. This study examines the possible involvement of corticosterone (CORT) in the stimulation of fledging in White storks through measurement of the changes in its plasma levels in relation to growth, nutritional status and the hatching rank of nestlings. For the first time in nest-bound chicks, we show that fledging is preceded by a marked and progressive 4 fold increase in baseline plasma CORT levels concomitant with an increase in locomotor activity (wing flapping) at the nest. Data on changes in body size, body mass, plasma metabolites and feeding frequency support the view that the increase in plasma CORT was induced by food restriction rather than being endogenously programmed. The timing and intensity of plasma CORT increase was dependent on the hatching rank within a brood, this increase being blunted in the less developed chicks possibly to avoid the impairment of final wing growth. These results show that an increase in plasma CORT as a result of food restriction and through the stimulation of locomotor activity is involved in the control of fledging in White storks. Moreover the CORT increase is adjusted to the hatching rank-related growth status of nestlings.     

Food supply controls the body condition of a migrant bird wintering in the tropics

The hypothesis that migratory bird populations are limited during the non-breeding season is increasingly supported by empirical studies that also suggest consequences that carry-over into subsequent seasons. Although variation in food supply is the best supported explanation for non-breeding season limitation, the ecological mechanisms and physiological consequences are not well understood. We both supplemented and reduced Ovenbird (Seiurus aurocapilla) food availability on replicate plots in Jamaica in each of 3 years to determine the direct role of food in limiting the physical condition of Ovenbirds. Annual variation in rainfall and food supply created a natural experiment in parallel with manipulations. Sex and age-classes of Ovenbirds did not respond differently in terms of body condition to either food manipulation or natural variation in environmental conditions, suggesting that this population is not structured by strong dominance relationships. Ovenbird body mass, fat, and pectoralis muscle shape were positively and predictably related to manipulated food availability. Feather regrowth rate also responded positively to food supplementation and negatively to food reduction in the drier of 2 years. Prior to manipulation, annual variation in body mass corresponded to annual variation in food supply and rainfall, providing additional, correlational evidence of food limitation. Since multiple intercorrelated body condition indices of Ovenbirds responded directly to food supply, and since food supply influenced body condition independently of other habitat features, we argue that food is a primary driver of non-breeding season population limitation. Moreover, since these effects were observed during the late non-breeding period, when individuals are preparing to migrate, we infer that food availability likely initiates carry-over effects.     

Honeyeater ecology: An introduction

Abstract

Nectar-feeding birds are often used for testing quantitative models but most of this work has been done on groups in the Northern Hemisphere and only recently have workers turned their attention to honeyeaters (Meliphagidae). Predictions of upper size limits derived from North America appear inappropriate and possible reasons for this are discussed. One; the suggested evolutionary links between nectar-feeding birds and their flowers, may not be as close for honeyeaters but further work is needed. Other aspects such as research on community and social relationships among honeyeaters appears rewarding but little is known.

We caution workers on expecting agreement with wide generalisations in any topic because of known variability in movements and diet in different areas and for different individuals.     

Effects of stochastic food deprivation on energy budget,body mass and activity in Swiss mice

When small animals are faced with an unpredictable food supply,they can adapt by altering different components of their energy budget such as energy intake,metabolic rate,rate of non-shivering thermogenesis(NST)or behaviour.The present study examined the effect of stochastic food deprivation(FD)on body mass,food intake,resting metabolic rate(RMR),NST and behaviour in male Swiss mice.During a period of 4 weeks' FD,animals were fed ad libitum for a randomly assigned 4 days each week,but were deprived of food ...     

Invertebrate predator-prey body size relationships: an explanation for upper triangular food webs and patterns in food web structure?

Summary It has been suggested by Cohen and Newman (1985) that many of the patterns in published food webs can be derived from a stochastic model in which the species are arranged in a trophic hierarchy (the cascade model). We suggest that, if predators are larger than their prey, a trophic hierarchy can be generated on the basis of body size Empirical evidence from the literature shows that there is a positive relationship between predator and prey size for a range of invertebrates and that predators are usually larger than their prey. Using experimental data on an aquatic food web we show that body size can lead to the type of trophic hierarchy used in the cascade model, suggesting that many food web patterns may be a product of body size. This conclusion is discussed with respect to the limitations of the food web data and the relationship between static and dynamic models of web structure.     

In vivo effects of Manduca sexta allatostatin and allatotropin on larvae of the tomato moth, Lacanobia oleracea

Abstract. Injection of Manduca sexta allatotropin (Manse-AT) into fifth or sixth stadium larval Lacanobia oleracea had no significant effect on larval growth, development or food consumption, compared to control injected insects. In contrast, injection of M. sexta allatostatin (Manse-AS) into fifth stadium larvae resulted in a retardation of growth, reduction in feeding and increased mortality, compared to control injected insects, but had no effect on non-feeding (day 7) sixth instar larvae. Results suggest that Manse-AS is not acting on the corpora allata (CA) to inhibit Juvenile Hormone (JH) synthesis to produce the observed effects, but most likely by its myoinhibiting action on the foregut. Inhibition of foregut peristalsis by Manse-AS in vivo appears to suppress feeding, resulting in increased mortality. Foregut peristalsis may be inhibited by the intact peptide or a deletion peptide produced by cleavage of Manse-AS by haemolymph enzymes, because Manse-AS (5-15) also inhibits muscle contractions in the foregut in vitro .     

Biogeographic variation of food habits and body size of the America puma

Summary The puma (Felis concolor) has the most extensive range of any terrestrial mammal in the Western Hemisphere, covering over 100° latitude. Food habits of different puma subspecies vary with latitude. Subspecies from temperate habitats generally eat larger prey and specialize on a smaller number of prey taxa, whereas, in tropical habitats, they prey on smaller, more varied prey. In North America, ungulates (primarily deer) represented 68% of the puma's diet by frequency of occurrence. Mean weight of vertebrate prey (MWVP) was positively correlated (r=0.875) with puma body weight and inversely correlated (r=-0.836) with food niche breadth in all America. In general, MWVP was lower in areas closer to the Equator. Patterns of puma prey selection are probably influenced by prey availability and vulnerability, habitat characteristics, and potential competition from the jaguar (Panthera onca).     

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test

Density dependence plays a key role in life-history characteristics and population ecology of large, herbivorous mammals. We designed a manipulative experiment to test hypotheses relating effects of density-dependent mechanisms on physical condition and fecundity of North American elk (Cervus elaphus) by creating populations at low and high density. We hypothesized that if density-dependent effects were manifested principally through intraspecific competition, body condition and fecundity of females would be lower in an area of high population density than in a low-density area. Thus, we collected data on physical condition and rates of pregnancy in each experimental population. Our manipulative experiment indicated that density-dependent feedbacks affected physical condition and reproduction of adult female elk. Age-specific pregnancy rates were lower in the high-density area, although there were no differences in pregnancy of yearlings or in age at peak reproduction between areas. Age-specific rates of pregnancy began to diverge at 2 years of age between the two populations and peaked at 6 years old. Pregnancy rates were most affected by body condition and mass, although successful reproduction the previous year also reduced pregnancy rates during the current year. Our results indicated that while holding effects of winter constant, density-dependent mechanisms had a much greater effect on physical condition and fecundity than density-independent factors (e.g., precipitation and temperature). Moreover, our results demonstrated effects of differing nutrition resulting from population density during summer on body condition and reproduction. Thus, summer is a critical period for accumulation of body stores to buffer animals against winter; more emphasis should be placed on the role of spring and summer nutrition on population regulation in large, northern herbivores.     

Size of ornament is negatively correlated with baseline corticosterone in males of a socially monogamous colonial seabird

The Goymann–Wingfield model predicts that glucocorticoid levels in social animals reflect the costs of acquiring and maintaining social status. The crested auklet is one of the few avian colonial species where a mutual ornament in males and females is used in both sexual and aggressive displays. Previous studies of the crested auklet support the notion that the crest ornament is a badge of status in this species. Here, we examined the relationship between the crest ornament size and the adrenocortical function in breeding crested auklets. Crest length was negatively correlated with corticosterone at baseline in males, but not in females. Baseline corticosterone in females (but not in males) was negatively correlated with body condition index. Although male and female crested auklets are monomorphic in their ornamental traits, our results suggest that the socially mediated physiological costs associated with status signaling may differ between the sexes.     

Carrying food items to cover for consumption: the behavior of ten bird species feeding under the risk of predation

Summary In earlier work (Lima et al. 1985; Lima 1985), we found that gray squirrels (Sciurus carolinensis) and black-capped chickadees (Parus atricapillus) when exploiting a patch of food in the open often carried individual food items to protective cover for consumption. Their tendency to carry (i) decreased as distance of the patch from cover increased, and (ii) increased as size of the available food items increased. A simple model indicated that this behavior was consistent with a trade-off between efficient foraging and predation risk. Maximal feeding efficiency was achieved by always eating at the patch, whereas minimal time exposure to predators was achieved by carrying all items to cover for consumption. Because predation-riskrelated trade-offs are likely to be of importance in the determination of feeding behavior, we surveyed the behavior of 10 bird species feeding under similar conditions to assess both the generality of the above results and the adequacy of some simple assumptions concerning the assessment and perception of predation risk.We observed considerable interspecific variability in behavior. Of the 10 species studied, 4 behaved in a manner similar to the squirrels and chickadees. Five other species showed an increased tendency to carry with larger items but no clear tendency to decrease carrying from longer distances. The one remaining species exhibited neither behavioral trend.The model that predicted squirrel and chickadee behavior failed to account for all observed behavior. The behavior of all species, however, was influenced by predation risk, and the discrepancy between theory and observation most likely reflects shortcomings of the model. These discrepancies indicate that other factors, in addition to exposure time, may be of significance in the perception of predation risk by several (or all) of the species studied. Of particular importance may be a distance-dependent probability of escaping attack. Other results indicate that predation risk may influence handling times via aspects of the digestive process.     

Cold-induced vasodilatation of finger and maximal oxygen consumption of young female athletes born in Hokkaido

To determine whether there is a direct correlation between endurance capacity and cold tolerance, maximal oxygen consumption (VO₂max), and cold-induced vasodilatation (CIVD), we measured these factors in 14 young female athletes born in Hokkaido, Japan's northernmost island. We determined the VO₂max by a standard incremental test on a cycle ergometer and measured the oxygen consumption (VO₂) by means of the Douglas-bag method. We determined the CIVD reaction by measuring the skin temperature of the left middle finger during immersion in cold water at 0°C for 20 min. The athletes showed significant positive correlations between VO₂max, expressed as l/min, and CIVD as well as other peripheral cold tolerance indexes (resistance index against frostbite and CIVD index). The body weight VO₂max (VO₂max/kg body weight) failed to correlate significantly with either the CIVD or with other cold tolerance indexes. These results suggest that CIVD in females may depend on factors other than those determined in this study, in addition to the functional spread of the vascular beds in peripheral tissues, including striated muscle; it is known that the size and the vascular bed in this tissue are affected by exercise training and that this results in the elevation of VO₂max and VO₂max/kg body weight.