Partitioning of nectar sources in an Australian honeyeater community

Feeding by honeyeaters was found to maintain nectar at low levels at three sites studied on Kangaroo Island in May-June 1978. The productivity of nectar at a site and position in a dominance hierarchy appeared to determine which bird species used each site. Correa was the main nectar source in the poorest area and produced 0.05 kJ m^?2 per day. The small eastern spinebill was the most abundant honeyeater. The purple-gaped honeyeater also occurred but fed mostly on honeydew. The medium sized New Holland honeyeater was common and territorial in the second area, where Banksia marginata and B. ornata inflorescences and Adenanthos flowers produced 0.7 kJ m^?2 of nectar per day. Spinebills and crescent honeyeaters also visited flowers and were sometimes chased by New Holland honeyeaters. The richest site was a flowering Eucalyptus cosmophylla tree (5.1 kJ m^?2 of nectar per day). A red wattlebird, the largest honeyeater, held a territory in part of this tree and chased other honeyeaters from the territory. New Holland, crescent and purple-gaped honeyeaters fed on flowers in other parts of the tree. The spinebill was absent. We conclude that nectar was partitioned along a spectrum of rich to poor sources. Larger more aggressive species used and sometimes defended the richest sources while the smaller birds used the poorer sources.     

Morphological relationships of passerine birds from Australia and New Guinea in relation to their diets

Beak, wing, leg and intestinal lengths, and gizzard widths, were all significantly related to body mass in 51 honeyeater species from Australia, 48 honeyeater species from New Guinea and 31 purely insectivorous passerine bird species from Australia. The nectar-feeding honeyeaters had smaller gizzards and intestines than wholly insectivorous birds of comparable size, although their wing and leg lengths did not differ; New Guinean and Australian honeyeaters were similar in these respects. Overall, honeyeaters had longer beaks than pure insectivores. Among Australian honeyeaters, those genera consuming more nectar than insects had longer beaks than the less nectarivorous, more insectivorous genera. Indeed, the latter group had beaks comparable in length to wholly insectivorous birds. All morphological differences revealed were attributable to known differences in diet.     

Nectar utilization and pollination by Australian honeyeaters and insects visiting Calothamnus quadrifidus (Myrtaceae)

Nectar availability in Calothamnus quadrifidus flowers was studied at Wongamine Nature Reserve in late spring (November). Despite some overnight depletion by moths and other invertebrates, more nectar was present in flowers at dawn than at the preceding dusk. Significant nectar depletion occurred within a few hours after dawn, mainly due to foraging by two honeyeater species. Lichmera indistincta and Phylidonyris nigra. Thereafter, nectar availability was maintained at relatively low levels, principally because of foraging by honeyeaters and honey bees. Apis mellifera, that became active during the warmer part of the day. Although individual honeyeaters consumed more nectar than A. mellifera, honey bees were so abundant that their total impact was greater than that of either honeyeater species for much of the day. Transfer of C. quadrifidus pollen between flowers is necessary in order to achieve a high level of seed set, as the flowers appear to be protandrous. Honeyeaters appeared to be considerably more significant pollen vectors than A. mellifera.     

Seasonal changes in the abundance and body condition of honeyeaters (Meliphagidae) in response to inflorescence and nectar availability in the New England National Park,New South Wales

Seasonal changes in numbers and body condition of honeyeaters were examined over 2 years in the New England National Park, New South Wales, Australia. Nectar availability measured as inflorescence density and nectar production were also recorded. In the main study site, the abundance of six of the seven most common species of honeyeater was significantly correlated with inflorescence density. However, honeyeater numbers were not significantly correlated with daily energy productivity. Unlike most honeyeater communities, the New England community was dominated numerically by the Eastern Spinebill, the smallest of the most common species present. Among the most common species, the duration of time a species was recorded in the area was negatively, but not significantly, correlated with its size. All species examined showed similar seasonal changes in body condition, with the highest bodyweights and fat deposits recorded in winter.     

Seasonal changes in a honeyeater assemblage in Banksia woodland near Perth,Western Australia

Abstract

Honeyeaters were the most numerous birds in banksia woodland near Perth, Western Australia, throughout the year. Numbers were greatest in a Banksia littoralis swamp, but only during those few months when it contained large amounts of nectar. In the surrounding woodland, numbers were lower but fairly constant during the year. This reflects the smaller amounts of nectar produced throughout the year, by the overlapping flowering patterns of several Banksia and Adenanthos species.

Large and medium-sized honeyeaters (wattlebirds and New Holland Honeyeaters) and flocking silvereyes dominated the swamp when it flowered. In contrast, small honeyeaters (spinebills and Brown Honeyeaters), many of whom were highly territorial residents, comprised the majority of the woodland assemblage throughout the year. These observations support a model based upon aggressive defence of rich nectar sources by the larger honeyeater species, and more efficient exploitation of dispersed flowers by smaller honeyeaters.     

Sustained and delayed noisy miner suppression at an avian hotspot

To mitigate the impact of noisy miners Manorina melanocephala on Australia’s woodland birds, there is a need to identify locations where noisy miner suppression can be affordable, sustainable and facilitate woodland bird recovery. In 2017, we suppressed noisy miners from the Goulburn River, NSW for at least three months. During this period, six pairs of critically endangered regent honeyeaters nested in the treatment area. In 2018, we continued monitoring the original noisy miner treatment area, which was expanded to include our 2017 control area, and established a new control area downstream. In 2019, the removal effort was again expanded to include the 2018 control area. In the 2017 treatment area, noisy miners remained suppressed up to 27 months post‐removal. Their numbers here were lower 1 year after the initial cull than in the week after it. In the 2018 and 2019 treatment areas, noisy miner abundance was significantly lower after respective culls than at all pre‐removal periods. In 2018, around 20 vulnerable painted honeyeaters occupied the 2018 treatment area. In 2019, two regent honeyeater pairs nested in and at least 40 painted honeyeaters occupied the treatment area. Songbird abundance increased within seasons and also up to a year following noisy miner removal, and plateaued thereafter. We show how, in strategic locations, a week of noisy miner suppression each spring can sequentially create ever‐larger landscapes where noisy miner impacts on threatened woodland birds are minimal.     

Ecomorphological constraints imposed by the kidney component measurements in honeyeater birds inhabiting different environments

The histological renal anatomy of 10 species of honeyeaters was examined quantitatively, using stereology. The kidneys of five species of predominantly wet zone inhabiting birds: the western spinebill Acanthorhynchus superciliosus , White-checked honeyeater Phylidonyris nigra . New Holland honeyeater Phylidonyris novaehollandiae , little wattlebird anthochaera chrysoptera and red wattlebird Anthochaera carunculata , were compared to five predominantly arid zone inhabiting birds: the grey-fronted honeyeater Meliphaga plumula , white-plumed honeyeater Meliphaga penicillata , white-fronted honeyeater Phylidonyris albifrons , spiny-checked honeyeater Acanthogenys rufogularis and yellow-throated miner Manorina flarigula. The kidneys were asymmetrical, with the left kidney being larger than the right kidney. Kidney mass was directly proportional to body mass (coefficient of correlation, r =+0·95), as was kidney volume to kidney mass (r =+1·0). Wet zone honeyeaters generally and a higher percentage and absolute volume of renal cortex, whilst arid zone honeyeaters generally had a significantly higher percentage and absolute volume of renal medulla. There were few differences between species, in either the percentage or absolute volume or luminal surface area of nephron components within the cortex. Within the medulla, wet zone honeyeaters generally had a higher percentage and absolute luminal surface area of collecting ducts, whilst arid zone honeyeaters had a higher percentage and absolute surface area of capillaries. This may be due to factors such as variations in diet and climate between habitats resulting in differences in honeyeater renal morphology which enable arid zone birds to conserve water and wet zone birds to conserve ions more efficiently.     

Honeyeater population changes in relation to food availability in the Jarrah forest of Western Australia

The numbers of honeyeaters present at particular sites in the Jarrah forest varied significantly from month to month, with peak abundance occurring between May and September. Numbers also varied from site to site, depending upon the major plant species present. Honeyeater abundance was not limited by arthropod availability, but in many instances was closely correlated with the availability of nectar, particularly that produced by Dryandra sessilis. Large honeyeaters, such as Anthochaera chrysoptera and Phylidonyris novaehollandiae, were generally most abundant at times and sites of greatest nectar production. Small honeyeaters, such as Acanthorhynchus superciliosis, were never abundant but were present for most of the year. The production of nectar between October and December was such that more honeyeaters could have been supported than were actually present. Low numbers at these times can be explained in terms of reduced foraging efficiency that would have resulted from more widely dispersed flowers, and the possible availability of more rewarding nectar resources at other sites.     

Honeyeater foraging: A test of optimal foraging theory

Honeyeaters (Meliphagidae) were observed foraging for nectar from Lambertia formosa inflorescences, each of which has seven flowers. The frequency distribution of numbers of flowers probed per visit to an inflorescence was found to be bimodal, with one peak at two and the other at seven. It is hypothesized that this frequency distribution results from a rule of departure from inflorescences that maximizes the net rate of energy gain. Patterns of nectar distribution were determined for a large sample of inflorescences. In addition the extent to which the honeyeaters re-probe flowers during a visit to an inflorescence was estimated. From these data and from field measurements of the times required by the honeyeaters to perform the various foraging behaviours, computer simulations of honeyeater foraging were constructed. These simulations led in turn to optimal frequency distributions of numbers of flowers probed per inflorescence that were bimodal but had peaks at 1 and 7 instead of 2 and 7. Although the observed and predicted behaviour were consequently similar, the difference between them was nevertheless significant. This difference could have been due to the birds' transient occupancy of the study area.     

Mutualistic interdependence between mistletoes (Amyema quandang), and spiny-cheeked honeyeaters and mistletoebirds in an arid woodland

The mutualism involving mistletoes (Amyema quandangj, spiny-cheeked honeyeaters (Acan-thagenys rufogularis) and mistletoebirds (Dicaeum hirundinaceum) was studied in arid woodland in South Australia between 1980 and 1984. Plants and birds were locally interdependent: mistletoes supplied a continuous resource of fruits or nectar that sustained permanent populations of pollinators (honeyeaters) and dispersers (honeyeaters and mistletoebirds). The reproductive phenology of Amyema quandang was central to the interactions. Amyema quandang flowered in winter and annual fruit crops overlapped so that ripe fruit was continuously available. Spiny-cheeked honeyeaters obtained most of their energy requirements from mistletoe nectar in winter and mistletoe fruit in summer. Higher honeyeater densities were sustained by flowering in winter. Mistletoebirds were present in low density throughout the year and subsisted on a diet of mistletoe fruit and a few insects. The reproductive strategy of A. quandang probably evolved in response to the pollination and dispersal service provided by honeyeaters in inland Australia. Neither spiny-cheeked honeyeaters nor mistletoebirds have adaptations resulting from evolutionary interactions with A. quandang. The high specificity of their mutualism is a result of: (i) the abundance of A. quandang in relation to other nectar and fruit producing plants in the community: (ii) the year-round production by A. quandang of the primary source of fruit or nectar for honeyeaters and mistletoebirds: (iii) the facultative specialization of both birds on A. quandang; and (iv) the reluctance or inability of other frugivorous birds in the community to consume A. quandang fruit.     

Pollinator visits to floral colour phases of Fuchsia excorticata

Abstract

Fuchsia excorticata is a gynodioecious tree (endemic to New Zealand) which is pollinated by honeyeater birds. Red, tubular flowers are common among bird-pollinated plants, and the tubular flowers of F. excorticata change colour from green to red. The purpose of the present study was to describe the timing of the colour change, dropping of the floral tube, and nectar production of F. excorticata and to determine how bellbirds (Anthornis melanura) and two introduced species of nectar robbers (Zosterops lateralis and Bombus sp.) respond to the different colour phases.

Floral tubes fell off about 11 days after anthesis in both sexes, with colour change occurring on about Day-4 for female trees and on about Day-5 for hermaphrodite trees. Green-phase hermaphrodite flowers produced significantly more nectar/day than did green-phase female flowers, while red-phase flowers did not produce nectar in either sex. All three floral visitors studied preferentially visited green-phase flowers and virtually ignored the nectarless flowers in the red phase. These results contrast with the general association between red, bird-pollinated flowers and the presence of a nectar reward. We suggest that the non-migratory habit of the New Zealand honeyeaters and the lack of native insect visitors to this species may account for this anomalous green-to-red colour change.     

Asymmetrical competition between the bell miner (Manorina melanophrys,Meliphagidae) and other honeyeaters: evidence from Southeastern Victoria,Australia

Summary The Bell Miner (Manorina melanophrys, Meliphagidae) is a medium-sized, colonial and co-operatively breeding honeyeater. Recent works show that the Bell Miner presents clear patterns of interspecific competition involving aggressive behaviour against many honeyeaters (Meliphagidae) and other bird species (Loyn et al. 1983; Clarke 1984). Nevertheless, those works have been based on short-term (1 year or less) studies only, and none of them have studied the effect territorial defence has on Bell Miners' fitness. We show how the population of honeyeaters decreased over 7 years at the Sir Colin Mackenzie Zoological Park (Southeastern Victoria, Australia). The decrease of honeyeaters in the study site was correlated with a local increase in the Bell Miner population which has been expanding since at least 1983. This process presumably led to the spatial zonation of Bell Miners and honeyeaters observed at present, while other passerine species show no sensitivity to either the invasion of Bell Miners in the recent past or to the present spatial distribution of the Bell Miner population. Finally, we show that Bell Miner reproductive activity is not affected by their interaction with competitors, which leads us to conclude that the interaction between the Bell Miner and other honeyeaters would be better described as asymmetrical competition.     

Interspecific competition in Australian honeyeaters—depletion of common resources

Many species of honeyeaters and other nectar-feeding birds occur in most habitats in South Australia. They frequently feed on nectar of the same species of plants. A succession of species of plants provide nectar for birds throughout the year. Nectar is most abundant in winter and early spring and least abundant in summer and autumn. There is more nectar per flower and more flowers in winter and spring. Nectar is often depleted by honeyeaters, and sometimes other visitors (silvereyes, lorikeets and insects) between December and May. It is at times reduced to a level at which it is uneconomical for some species to exploit. There are seasonal movements of honeyeaters into areas of abundant nectar and out of these areas when nectar becomes scarce. Breeding coincides with peak abundance of nectar. Diversity of honeyeaters is probably maintained by an interaction of two types of competition, exploitation and interference. The larger species use the richest sources of nectar and aggressively exclude the smaller species (interference) whereas the smaller species can use poorer sources of nectar because their energy requirements are less (exploitation).     

Patterns of bird species richness and composition on islands off Arnhem Land,Northern Territory,Australia

The bird faunas of the adjacent Wessel and English Company island chains were sampled at two scales (0.25 ha quadrats and entire islands). Ninety‐six species were recorded from 226 quadrats, with the most frequently recorded species being mistletoebird Dicaeum hirundinaceum, brown honeyeater Lichmera indistincta, silver‐crowned friarbird Philemon argenticeps, bar‐shouldered dove Geopelia humeralis, northern fantail Rhipidura rufiventris and yellow white‐eye Zosterops lutea. At the quadrat scale, vegetation type was a major determinant of the abundance of individual species (and hence species composition), species richness and total bird abundance. Bird species composition and richness at the quadrat scale was also significantly affected by island isolation (particularly the amount of land within 20 km of the island perimeter). Island size had no effect on quadrat‐scale richness or total abundance. However, the abundance of 10 of the 38 most frequently recorded individual species was significantly related to island size, in most cases even when the comparison was restricted to similar habitats. The most striking cases were rufous fantail Rhipidura rufifrons, mangrove golden whistler Pachycephala melanura, brown honeyeater and yellow white‐eye, which were all significantly more abundant on smaller islands. One hundred and seventy‐one species were recorded from the 62 islands sampled. There was a very tight relationship between island size and the number of terrestrial species (73% of deviance explained) and of all species (84% of deviance explained). This relationship was improved (marginally) when isolation was included in the model. Ordination of islands by their terrestrial bird species composition was related to island size and isolation, and suggested an erratic species composition on small islands.     

The organization of a honeyeater community in an unpredictable environment

The honeyeater community of an open-layered forest was studied in the New England National Park over a 2.5 year period. Various aspects of honeyeater behaviour (aggression, social and foraging) were examined during transects and by use of time-budgets. Time-budgets were used to estimate the daily energy requirements for each species. Since nectar availability in the study area was variable, the energy produced per day by the nectar sources was occasionally insufficient to meet the daily energy demands of the honeyeater community. No strong spatial partitioning of the nectar resources by the birds was found. Use of the resources appeared to be based primarily on dominance interactions (interspecific aggression), with the larger species tending to dominate the smaller ones. Smaller species survive in the area because of their behavioural attributes and greater foraging efficiency which enables them to use the sparse supply of nectar on poor days. Temporal gradients in nectar richness may be just as important as spatial gradients in permitting the coexistence of species which use the same resource in the same habitat. Most of the results from this study fail to support the predictions made elsewhere concerning the organization of communities in unpredictable environments.     

Bills and tongues of nectar-feeding birds: A review of morphology,function and performance,with intercontinental comparisons

The bills and tongues of nectar-feeding birds differ from continent to continent. The major differences are that: (i) the tongues of A Australian honeyeaters are broader any more fimbricated at the tip than the bifurcated tongues of sunbirds and hummingbirds; (ii) the bills of hummingbirds are more uniformly narrow and taper less markedly towards their tips than those of sun-birds and honeyeaters; and (iii) bill curvatures are generally greater for sunbirds and honey-creepers than for hummingbirds. A variety of hummingbirds has straight or even slightly upturned bills, while bills for all sunbirds, honeycreepers and honeyeaters are decurved to some extent. Despite differences in tongue morphology, hummingbirds, sunbirds and honeyeaters extract nectar at a similar range of rates, averaging approximately 40 γL s^?1 from ad libitum feeders, and 1–15 γL^?1 from flowers. All tongues collect nectar by capillarity, with licking rates of 6–17 s^?1. Licking behaviour has been little studied, although speeds of licking respond to changes in sugar concentration and corolla length. The tongues of honeyeaters are broad, and may need to be brush-tipped in order to allow capillary collection of nectar. Brush-tipped tongues can cover large surface areas on each lick, and may allow honeyeaters to exploit nectar and honeydew that is thinly spread over large surface areas. Bill lengths of nectarivorous birds are similar in all regions, though species of hummingbird have the shortest and longest bills. Bill lengths largely determine the range of floral lengths that can be legitimately probed. Maximum floral lengths exceed bill lengths, since hummingbirds, sunbirds and honeyeaters protrude their tongues beyond the tips of their bills. Rates of nectar extraction, however, decline rapidly once the floral length exceeds bill length. Decurved bills may have evolved in honeyeaters and sunbirds to enable perching birds to reach flowers at the ends of branches more easily. Consistent differences in bill length between the sexes suggest that males and females may exploit different floral resources or different proportions of the same resources. For honeyeaters and sunbirds, males have longer bills than females, but the reverse is true for many hummingbirds.     

The impact of Tropical Cyclone Larry on bird communities in fragments of the endangered rainforest Type 5b

Abstract Bird surveys were conducted to assess the impact of a severe cyclone on bird communities in three fragments of the endangered rainforest Type 5b on the Atherton Tablelands of far north Queensland. Bird communities were surveyed using timed area searches in three sites in each of the three fragments and were undertaken prior to and following Tropical Cyclone Larry. Cyclone Larry caused short‐term changes in the abundance of some species of birds in Type 5b rainforest fragments. Two weeks after the storm, in two of three fragments surveyed, abundance of the frugivorous wompoo fruit‐dove (Ptilinopus magnificus) and figbird (Sphecotheres viridis) had decreased while the omnivorous Macleay's honeyeater (Xanthotis macleayana) and Lewin's honeyeater (Meliphaga lewinii) decreased in abundance in all three locations. Most insectivorous species increased in some sites and decreased in others following Cyclone Larry. Rapid recovery of bird communities to approximately their pre‐cyclone state after only 7 months appeared to reflect the capacity of species to either modify their foraging behaviour, switch foods, or to move within or between fragments or to other food sources in the landscape.     

Generous-like flowers: nectar production in two epiphytic bromeliads and a meta-analysis of removal effects

Animal-pollinated angiosperm plants that respond positively to nectar removal by replenishment invest energy that can entail a reproductive cost. We investigated whether or not nectar removal stimulates replenishment in two hummingbird-pollinated bromeliad species. Nectar replenishment rates were also assessed by removing nectar from manually pollinated flowers because pollination events might be used as signals to save energy by preventing allocation to post-pollination nectar production. Then we synthesized the current understanding of nectar removal effects by reviewing existing published studies with a meta-analysis. The magnitude and significance of estimated nectar removal effects and factors associated with variation in size and direction of nectar removal effects were elucidated with the meta-analysis. We found that both Tillandsia species strongly respond to repeated nectar removal by producing >3 times additional nectar. Nectar secretion patterns were not altered by pollination (stigmatic pollen deposition) and we found no evidence of nectar reabsorption. Although the effect size varied widely across systems and/or environmental conditions, the meta-analysis showed that nectar removal had overall a positive effect on nectar replenishment (mainly among species inhabiting wet tropical habitats such as Tillandsia), and a negative effect on the secretion of additional sugar, suggesting that those plants are resource limited and conservative in the secretion of additional sugar.Electronic Supplementary Material Supplementary material is available for this article at     

The exploitation of floral nectar in Eucalyptus incrassata by honeyeaters and honeybees

Summary During October and November, 1977, a study of nectar production and nectarivore foraging in Eucalyptus incrassata was conducted at Wyperfeld National Park in south-eastern Australia in order to evaluate the extent to which introduced honeybees (Apis mellifera) compete with native honeyeaters for floral nectar. Data on nectar production, nectar availability, ambient air temperature and the numbers of visiting honeyeaters and honeybees were collected. Most of the daily nectar production in E. incrassata occurs early in the morning when temperatures are too low for insects to forage. In addition, insects, particularly honeybees, are unable to exploit nectar in the youngest flowers because the stamens are clustered tightly around the style. As a result of these temporal and structural characteristics of the flowers, honeyeaters are able to harvest most of the nectar. Honeybees potentially have access to 35–47% of the average daily production of floral nectar in E. incrassata and actually harvest considerably less. These data show that E. incrassata flowers are adapted to restrict insect foragers despite their superficially unspecialized appearance. Eight forest and woodland eucalypts do not have a flower stage which excludes insects and the significance of this difference is discussed.     

Composition of the pollinator community,pollination and the mating system for a shrub in fragments of species rich kwongan in south-west Western Australia

In this study we investigate the composition of the potential honeyeater pollinator community, patterns of honeyeater visitation, pollination and the mating system in a range of population fragments for the bird-pollinated mixed mating system shrub Calothamnus quadrifidus R.Br. Specifically, we aimed to answer the following questions. For smaller and more isolated population fragments are honeyeater species lost from the pollinator community, patterns of visitation different, levels of pollination lower and rates of selfing, biparental inbreeding and correlated paternity higher. The composition of the honeyeater community was similar across population fragments and there was no relationship between the abundance of birds and population fragment size. Honeyeaters were most commonly observed visiting numerous inflorescences within single plants in all populations, but as population fragments became larger movements between plants were more commonly observed. Our observations of honeyeater visitation were generally consistent with our measurements of pollination and patterns in the mating system across population fragments. We found no significant relationship between population fragment size and levels of pollination. Mating system studies showed outcrossing rates (t _m) comparable to those found in other bird-pollinated Myrtaceae, and ranged from 0.54 to 0.90 across populations. Outcrossing rates were not significantly correlated with log population size, but correlations of outcrossed paternity indicate a clear trend from low correlated paternity in larger populations to significantly higher correlated paternities in smaller populations. As a consequence mating in small populations will occur between much smaller groups of plants, and this may affect population fitness in subsequent generations.