Home About us Contact
|
Home About us Contact | ||
|
|
||
Food Provisioning (food + provisioning)
Selected AbstractsRelative influence of male and female care in determining nestling mass in a migratory songbirdJOURNAL OF AVIAN BIOLOGY, Issue 5 2010Kirk W. Stodola Biparental care is common in birds, with the allocation of effort being highly variable between the sexes. In most songbird species, the female typically provides the most care early in the breeding cycle with both parents providing care when provisioning young. Food provisioning should be directly related to offspring quality; however, the relative influence each parent has on offspring quality has rarely been assessed at the nest level. Consequently, we were interested in assessing the relative influence male and female provisioning has on one measurement of offspring quality, nestling mass, in the black-throated blue warbler Dendroica caerulescens. Over a six year period, 2003,2008, we collected information on average nestling mass per brood on day 6 of the nestling cycle and parental provisioning rates on day 7 of the nestling cycle from 182 first brood nests on three different study plots. We found that average nestling mass was directly related to male provisioning rate, while it was not related to female provisioning rate. On the other hand, estimated biomass provisioned had little influence on average nestling mass, calling into question its utility in assessing parental quality. Finally, there was some indication that parental influence on average nestling mass was dependent on the other parent's provisioning rate, suggesting that parents work in concert to influence nestling quality. [source] Control of fledging age in Leach's Storm-Petrel, Oceanodroma leucorhoa: chick development and prefledging mass lossFUNCTIONAL ECOLOGY, Issue 1 2005R. A. MAUCK Summary 1Leach's Storm-Petrel (Oceanodroma leucorhoa) chicks accumulate fat through most of the nestling period, near the end of which they typically weigh 50,100% more than their parents. Much of this excess mass is lost abruptly prior to leaving the nest and fledging itself marks the termination of parental care. 2In this study, we evaluated the hypothesis that the onset of the prefledging mass loss period coincides with the end of the development period and the completion of structural growth. 3We characterized the pattern of prefledging mass loss and the timing of fledging with respect to a point (T), based on wing growth, at which structural development stops. Variation in T suggested that development rate is partially influenced by parental food provisioning, particularly early in the nestling period (age 16,20 days) just prior to the onset of rapid primary feather growth. 4The timing of mass loss and fledging in relation to T suggested that prefledging mass loss begins upon completion of wing growth and that fledging occurs after chicks have reached a mass compatible with sustained flight. Thus, the time to fledging is positively correlated with nestling mass at the end of the development period. 5The prefledging period of mass loss is a unique phase of anorexia placed between parental feeding and self-feeding in the life of the young petrel. [source] Rearing conditions determine offspring survival independent of egg quality: a cross-foster experiment with Oystercatchers Haematopus ostralegusIBIS, Issue 2 2006MARTIJN VAN DE POL Variation in rearing conditions, due either to parental or to environmental quality, can result in offspring of different quality (e.g. body condition, immune function). However, evidence is accumulating that egg size and composition can also affect offspring quality. In Oystercatchers Haematopus ostralegus, high-quality rearing conditions result in a higher quantity as well as quality of offspring. This is thought to be caused by increased parental food provisioning to the chicks in high-quality environments. However, variation in egg quality between rearing conditions could also affect the quantity and quality of offspring. Determining the mechanism and ontogeny of quality differences is important in unravelling the causes of variation in reproductive success. To disentangle the effects of egg quality, and quality of the rearing conditions, on the future survival of offspring, we cross-fostered complete clutches between nests. When reared under conditions of similar environmental quality, chicks originating from eggs laid in low-quality environments survived as well as chicks originating from eggs laid in a high-quality environment. However, chicks reared in high-quality environments survived twice as long as chicks reared in low-quality environments, independent of the environmental quality in which the eggs were laid. This suggests that variation in the future survival of offspring is primarily caused by differences in environmental and/or parental quality, with no clear effect of egg quality (size). [source] Effects of food abundance and predictability on body condition and health parameters: experimental tests with the Hooded CrowIBIS, Issue 4 2002Camilla Acquarone It has been shown that small passerines can counteract variability of food resources by actively regulating their body reserves through an increase of mass. However, the effects of food predictability on body mass regulation and other body parameters, such as immune functions, in larger species have been little studied. To analyse the response of the Hooded Crow Corvus corone to food abundance and predictability, we performed three experiments with controlled food provisioning under laboratory conditions. Body mass, TOBEC (total body electrical conductivity) lean mass index, blood parameters and immune organ masses were measured at the beginning and end of a 15-day period. In the first experiment, the food release was predictable (same amount each day) but the quantity of food delivered to five groups of birds varied (37, 75, 100, 150 or 300 g/day). Low food levels induced a greater decrease in mass accompanied by an increase in erythrocyte sedimentation rate. In the second experiment, the same average quantity of food (100 g) was supplied according to either predictable or unpredictable (random) schedules. In this case, the crows lost more mass, and their erythrocyte sedimentation rate increased when food was unpredictable. In the third experiment, the same average quantity of food (150 g) was supplied according to either a predictable schedule or two schedules with different levels of variability. The group with a low level of variability did not differ from the control, while the group with a highly variable feeding schedule lost more mass. In this group, the higher mass loss was associated with greater variation of the erythrocyte sedimentation rate and a reduced Phytohaemagglutinin index of immunocompetence and haematocrit value. The results of experiments 2 and 3 contrast with findings in other passerines, which increase their mass when food availability is unpredictable. It appears that a body mass decrease in the Hooded Crow can be induced by a reduction of either food abundance (exp. 1) or food predictability (exp. 2, 3), and it is accompanied by a worsening of health state. [source] Behavioural responses to ectoparasites: time-budget adjustments and what matters to Blue Tits Parus caeruleus infested by fleasIBIS, Issue 3 2002Frédéric Tripet Blue Tit nests are often heavily infested by fleas, which feed on the incubating female and the nestlings. Depending on habitat quality, the drawing of blood by fleas reduces offspring quality, or it is compensated by an increase in food provisioning by the adults and may reduce their future reproduction. Given these fitness costs, tits are expected to have evolved behavioural responses enabling them to remove, destroy or minimize the contact with fleas. To identify these traits, we video-recorded the changes in frequency and duration of the hosts' potential anti-flea behavioural defences in nests experimentally infested with low and high flea densities. We also investigated whether flea load affected the number of male feeds delivered to incubating females, and whether the parents increased their rate of food provisioning to the nestlings equally at high flea density. Flea density significantly affected the nest sanitation and sleeping behaviour of Blue Tit females but had no significant effect on grooming. Female Blue Tits increased the frequency but decreased the duration of bouts of these behavioural traits, and hence their time-budgets, based on per hour duration of behaviour, were not significantly affected by flea density. High flea density reduced nestling weight at the early nestling stage but these costs were fully compensated by an increase in female feeding effort. Males did not increase their frequency of food provisioning to incubating females nor to nestlings in heavily infested nests. The results are discussed in the light of parasite-mediated selection on host behaviour and the reciprocal host selection on flea life-history and behavioural traits. [source] Sex-specific food provisioning in a monomorphic seabird, the common guillemot Uria aalge: nest defence, foraging efficiency or parental effort?JOURNAL OF AVIAN BIOLOGY, Issue 1 2009Chris B. Thaxter Sexual differences in food provisioning rates of monomorphic seabirds are well known but poorly understood. Here, we address three hypotheses that attempt to explain female-biased food provisioning in common guillemots Uria aalge: (1) males spend more time in nest defence, (2) females have greater foraging efficiency, and (3) males allocate a greater proportion of foraging effort to self-maintenance. We found that males spent no more time with chicks than females but made longer trips and travelled further from the colony. There was extensive overlap between sexes in core foraging areas, indicating that females were not excluding males from feeding opportunities close to the colony. However, as a result of their longer trips, the total foraging areas of males were much greater than those of females. There was no difference between sexes in overall dive rate per hour at sea, in behaviour during individual dives or in a number of other measures of foraging efficiency including the frequency, depth and duration of dives and the dive: pause ratio during the final dive bout of each trip, which was presumably used by both sexes to obtain prey for the chick. These data strongly suggest that sexes did not differ in their ability to locate and capture prey. Yet males made almost twice as many dives per trip as females, suggesting that males made more dives than females for their own benefit. These results support the hypothesis that female-biased food provisioning arose from a difference between sexes in the allocation of foraging effort between parents and offspring, in anticipation of a prolonged period of male-only post-fledging care of the chick, and not from differences in foraging efficiency or time spent in nest defence. [source] Repeatability of chick growth and food provisioning in Manx shearwaters Puffinus puffinusJOURNAL OF AVIAN BIOLOGY, Issue 5 2005Catherine M. Gray In animals that produce few offspring during their lifetime, the ability to raise high-quality offspring through the provision of parental care is particularly important for individual fitness. In this paper, we use repeatability analysis of data from two separate time-periods, in the 1970s and the 1990s, to examine parental and environmental effects on chick growth and food provisioning in a long-lived seabird, the Manx shearwater Puffinus puffinus. We test the hypothesis that asymptotic body masses of chicks are most strongly influenced by an individual's genotype, with growth rates intermediate and food provisioning rates most strongly affected by environmental conditions during growth. Peak body masses of chicks raised by the same parents showed significant repeatability in both samples, whereas mass growth rates up to the attainment of peak mass showed significant repeatability only in the 1970s. Several different measures of food provisioning by parents showed no individual consistency in either time-period, in keeping with our predictions. Food provisioning rate was a major determinant of annual variation in chick growth, and so it may seem surprising that Manx shearwaters showed repeatable patterns of chick growth but not of food provisioning, and several possible explanations for this pattern are discussed. [source] How different provisioning strategies result in equal rates of food delivery: an experimental study of blue tits Parus caeruleusJOURNAL OF AVIAN BIOLOGY, Issue 4 2002Fabrizio Grieco Food provisioning in birds requires a considerable amount of time and usually has to be traded-off against other parental and non-parental activities. I investigated experimentally the rate at which blue tit Parus caeruleus parents deliver food to their brood after a change in food availability. The main argument behind this study is that parents enjoying an additional food source may use less time for self-feeding and therefore use more time for food provisioning. This could increase the rate at which food is brought to the nest. However, a prey choice model that takes the energetic needs of the parent into account allows for the possibility that the food-supplemented parents would deliver the same amount of food by increasing prey size (through an increase in prey selectivity) and reducing visit rate. The field data indicate that the parents changed provisioning strategy when food-supplemented: they fed the chicks natural food less frequently, but brought larger larvae. On the whole, delivery rate of natural food was the same or lower than in controls. The results suggest that food-supplemented parents used the time saved to increase their degree of food selectivity. When the gains from an increased delivery rate are not worth the increased costs (mainly resulting from an increased visiting rate), the parent with low energetic need may increase selectivity to provide the same amount of food to the brood as the unmanipulated parent, but at a lower cost. [source] Macaque,human interactions and the societal perceptions of macaques in SingaporeAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2009John Chih Mun Sha Abstract Humans and long-tailed macaques (Macaca fascicularis) interface in several locations in Singapore. We investigated six of these interface zones to assess the level of conflict between the two species. We observed macaque-to-human interactions and distributed questionnaires to residents and visitors of nature reserves. We observed an average of two macaque-to-human interactions per hour at the sites, which included affiliative or submissive behaviors (46.9%), aggression (19.1%), taking food and other items (18.5%) searching bins, cars, and houses (13.4%), and nonaggressive contact (2.1%). Two-thirds of interactions occurred when a human was carrying food or food cues, and one-quarter occurred when a human provoked macaques. Only 8% of interactions occurred without a clear human-triggered context. Our interview showed one-third of respondents experienced nuisance problems from macaques. They had items taken from them (50.5%) and received threats (31.9%). Residents reported more nuisance problems than visitors, and their perceptions toward macaques differed. Residents were more aware of the consequences of food provisioning and that there were regulations against feeding. Residents fed macaques less and held more negative sentiments toward macaques. Nearly half of the interviewed people held neutral attitudes toward macaques and only 26.2% of respondents thought conflict with macaques warranted urgent action. Nearly two-thirds of the respondents supported education programs to ameliorate human,macaque conflict, and less than 15% supported removing or eradicating macaques. 87.6% felt that it is importance to conserve and protect macaques. Our results show that human,macaque conflict exists in Singapore, but that it may not be severe. Human behavior is largely responsible for macaque-to-human interactions, and thus could be lessened with management of human behavior in interface zones (i.e. restrict food carrying and provocation). Moreover, our interviews shows people living in Singapore value macaques, do not wish them entirely removed, prefer education-based solutions, and consider conservation and protection of them important. Am. J. Primatol. 71:825,839, 2009. © 2009 Wiley-Liss, Inc. [source] Interactions between visitors and Formosan macaques (Macaca cyclopis) at Shou-Shan Nature Park, TaiwanAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2009Minna J. Hsu Abstract Ecotourism involving feeding wildlife has raised public attention and is a controversial issue, especially concerning nonhuman primates. Between July 2002 and April 2005, the behavior of monkeys and tourists was collected through scan samplings, focal samplings and behavior samplings at the Shou-Shan Nature Park located in Taiwan's second largest city,Kaohsiung. In addition, the number of tourists and monkeys was counted in different hours and places within the park. Four hundred visitors were interviewed using a questionnaire to gather data on sex, age, purpose and frequency of visit to the park. The number of tourists was significantly higher during weekends than in weekdays in all locations. Humans dominated in the initiation of interspecies interactions,the overall ratio of human-initiated and monkey-initiated interactions was 2.44:1. Human,monkey conflicts accounted for only 16.4% of the total interactions (n=2,166), and adult human males and adult male macaques participated in higher rates than other age/sex groups in these conflicts. Visitors showed more affiliative behavior (15.9%) than agonistic behavior (8%) toward the macaques. In response to visitors' threat or attack, the Formosan macaques mostly showed submissive behavior with bared teeth, squealed or ran away to avoid confrontation (69.1%),only few responded with counteraggression (18.7%). This study for the first time provided evidence that food provisioning increased both the frequency and duration of aggression among Formosan macaques (P<0.001). During food provisioning, the average frequency and the duration of agonistic events of macaques were more than 4 times higher compared with those without food provisioning. The average frequency of food provision by tourists was 0.73,times/hr,more than twice the incident that monkeys grabbed the food from tourists (0.34,times/hr). If people refrain from feeding monkeys and destroying the city park's natural vegetation, monkeys can be used to educate public about nature conservation in an urban setting. Am. J. Primatol. 71:214,222, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||