Sunbird Species Research Articles

Group display in the socially monogamous Northern Double-collared Sunbird (Cinnyris reichenowi)

Several sunbird species (Nectariniidae) exhibit group display, but the function of this behaviour still remains unclear. We test two hypotheses (reproductive tactic and joint territory defence) to explain the function of this behaviour using data gathered on Northern Double-collared Sunbirds (Cinnyris reichenowi) from the Cameroon Mountains. Sunbirds exhibited group display throughout the breeding cycle. Groups of birds were mainly comprised of neighbouring pairs aggregated at territory boundaries. The frequency of group displays varied significantly among individuals and over the breeding cycle, with the highest frequency during the pre-breeding period and the lowest during egg-laying (∼female's fertile period). Time spent on group display was significantly longer at the end of breeding. Off-territory forays were recorded for both males and females, males significantly increased the time spent on these forays during incubation. Extra-pair copulations were recorded only in five cases for females (4%) suggesting that most off-territory forays were motivated by feeding on nectar in neighbouring territories. Therefore, we suggest that the behaviour is used for joint territory defence rather than as an information centre for choosing mates for extra-pair copulations. Its function for choosing primary mates is also unlikely, because group displays were mainly observed in complete pairs.

Sunbirds hover at flowers of Salvia and Lycium

Sunbirds usually perch when visiting flowers for nectar and only rarely hover. Except for three studies of sunbirds visiting introduced plants in South Africa and India as well as a native plant in Cameroon, there have been no quantitative studies of sunbird hovering behaviour. Here I present detailed observations of foraging behaviour in two sunbird species (Malachite Sunbird Nectarinia famosa and Southern Double-collared Sunbird Cinnyris chalybeus) at flowers of three Salvia species (Salvia africana-lutea, S. lanceolata and S. africana-caerulea; Lamiaceae) and one natural hybrid as well as Lycium afrum (Solanaceae) in South Africa. The birds not only perched, but also hovered (up to 28% of total visits) and sometimes hover-clasped (up to 3%). Other birds only rarely (Karoo Prinia Prinia maculosa) or never hovered during flower visits. These observations indicate that the foraging behaviour of specialist passerine nectarivorous birds overlaps with that of hummingbirds more than was previously thought.

Breeding Biology of An Afrotropical Forest Understory Bird Community In Northeastern Tanzania

Abstract Many aspects of the breeding biology of Afrotropical forest birds are poorly known. Here we provide a description based on the monitoring of 1461 active nests over eight breeding seasons about one or more aspects of the breeding biology for 28 coexisting understory bird species on the Amani Plateau in the East Usambara Mountains, Tanzania. Mean nest height and mean distance of nest from forest edge varied widely among species with most species constructing nests across a broad vertical and forest edge to interior gradient. However, there were important exceptions with all sunbird species and several dove and waxbill species constructing nests in close proximity to the forest edge. For 17 common species for which we recorded two or more active nests, mean clutch size across species was 1.9 eggs per clutch, the lowest site-specific mean clutch size yet reported for a tropical forest bird community. For nine bird species, a subset of the 17 common species, length of breeding season, defined as the d...

Food selection by avian floral visitors: an important aspect of plant-flower visitor interactions in West Africa

Community-level studies have shown that plant–pollinator interactions are much more generalized than previously expected. Consequently, many authors have questioned the significance of phenotypic complementarity between plants and pollinators and abundance effects in pollination interactions. Here, we compare the behaviour of three sunbird species feeding on the nectar of five plant species in afromontane vegetation. We studied the feeding behaviour with and without consideration of plant abundance (i.e. diet selectivity and diet composition, respectively). The aims of the study were to estimate: (1) how relative resource abundance influences flower selectivity; (2) the degree of phenotypic matching; and (3) whether different plant resource assessment methods give different answers to this question. The results showed that, although sunbirds frequently feed on both morphologically adapted and nonadapted plants, food selectivity data are consistent with the hypothesis of phenotypic complementarity. Moreover, we found that the type of plant abundance measurement can change conclusions in some cases, as individual plants differ in their growth habits and nectar production. This effect was most obvious for the assessment of selectivity of the northern double-collared sunbird (Cinnyris reichenowi) and for Hypoestes aristata, a plant producing inflorescences composed of a large number of small flowers possessing small amounts of nectar per flower (a high abundance of flowers, but a low abundance of nectar relative to the remaining plant community).

Dependence on sunbird pollination for fruit set in three West African montane mistletoe species

Abstract:Theory predicts that not all plant species will be equally affected by disruption to their pollinator mutualisms because traits such as breeding system and mutualism strength can affect their response. We investigated these traits in three species of Afromontane mistletoe Globimetula braunii, Agelanthus brunneus and A. djurensis in Ngel Nyaki Forest Reserve, Nigeria, to test whether the traits were reliable indicators of relative reproductive success and could be used to predict relative vulnerability to pollinator loss. For each mistletoe species, insect and bird visitors were identified during a 160–240-min observation period of 4–10 plants and their roles in flower opening and fruit set were investigated using exclusion experiments applied to 250–500 flowers. We found that all three mistletoes are self-compatible but not capable of autonomous self-fertilization. The pollinator assemblage comprised four species of sunbird (Cyanomitris spp., Cinnyris spp.) and a small social wasp (Vespinae). None of the mistletoes requires birds for flower opening: G. braunii flowers self-opened in the absence of pollinators, whereas insects opened both Agelanthus spp. Irrespective of flower opening, each mistletoe species requires sunbirds for effective pollination and fruit set. Only G. braunii demonstrated pollen limitation (pollen limitation index = 0.504) which may be an early indication of mutualism breakdown. We suggest that mistletoes be considered as indicators of habitat condition and functioning within Afromontane forest ecosystems.

Foraging Behavior and Coexistence of Two Sunbird Species in a Kenyan Woodland

We investigated the mechanism of coexistence of the rare Amani Sunbird (Hedydipna pallidigastra) and the widespread Collared Sunbird (H. collaris), within Brachystegia woodland in the Arabuko-Sokoke Forest, Kenya. We compared how prey abundance and search strategies affect resource exploitation by the two species. We used foraging theory to direct our measures of feeding activities as influenced by sunbird species, tree species and foraging height. We evaluated invertebrate abundance among tree species at different heights within trees. The Collared Sunbird primarily used the understory, and the Amani Sunbird primarily used the upper-canopy. Overall, the rate of prey attacks per flight of the Amani Sunbird was 2.8 times greater than that of the Collared Sunbird. The Amani Sunbird, however, used increased search and attack rates in the understory compared with the mid- and upper-canopies, but the Collared Sunbird foraged similarly throughout all strata. We hypothesize that the increased foraging rate of the Amani in the understory reflects increased foraging costs due to interference from the Collared Sunbird in that stratum. Furthermore, the Collared Sunbird exploits rich patches by moving frequently from place to place. The Amani Sunbird forages slowly, with reduced travel rates, and with a greater number of prey captures within a patch. Arthropod density did not differ among the vegetative strata, but was higher in Brachystegia spiciformis and Hymenaea verrucosa than in six other tree species. We hypothesize that the Amani Sunbird appears dependent upon continued tall B. spiciformis trees within the canopy of the Arabuko-Sokoke Forest.

Food niche differentiation in two syntopic sunbird species: a case study from the Cameroon Mountains

Closely related bird species can coexist in areas of range overlap due to differentiation of their ecological niches. If coexisting species have similar habitat requirements, separation of food niches presumably plays a crucial role. Theoretically, two possible food niche separation scenarios are possible: (1) use of different food resources or (2) temporal differences in feeding activity. We examined these mechanisms by investigating the feeding habits of two short-billed sunbirds (Cinnyris reichenowi and C. bouvieri) coexisting locally in the Bamenda Highlands, NW Cameroon. Daily feeding activity in both species showed a similar pattern, with two peaks (0800–0900 hours and 1500–1600 hours, respectively) and a prominent decrease in activity between 1100 and 1400 hours. However, the studied species clearly differed in their exploitation of plant resources. C. bouvieri mostly visited Lobelia columnaris, while C. reichenowi regularly visited three plant species, namely, Hypericum revolutum, Hypoestes aristata and Impatiens sakerana, with the most time spent at the second species. Such resource partitioning was probably caused by interspecific aggressive behaviour, since C. bouvieri actively repelled C. reichenowi from Lobelia columnaris plants, forcing C. reichenowi to feed on other plant species.

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Ecology![Figure][1] Cyanomitra oritis feeding on Impatiens sakeriana . CREDIT: STEPAN JANECEK New World hummingbirds and Old World sunbirds are both adapted for feeding on nectar. They share specialized traits, such as an elongated bill and a small body size. Hummingbirds, however, have become famous for their ability to hover indefinitely in front of flowers, whereas sunbirds seem less able or inclined to do so. Following on a recent study that demonstrated that African sunbirds can hover when challenged to feed from an invasive, hummingbird-pollinated New World plant ( Nicotiana glauca ), Janecek et al. have examined the pollination system of the native African plant Impatiens sakeriana, which displays a suite of characteristics common to plants that attract hovering birds: red flowers, a long flower spur, high nectar production, and an absence of nearby perching structures as is usually observed in sunbird-pollinated plants. The reproductive ecology of this plant has been a conundrum. It had been hypothesized that it evolved to be pollinated by a now-extinct hovering bird; in this species' absence, it would have to be either self- or insect-pollinated. The authors used exclusion and germination experiments along with observations to demonstrate that these plants are not capable of self-pollination and are not pollinated by insects. Further, they showed that two species of African sunbirds ( Cyanomitra oritis and Cinnyris reichenowi ) will both perch and hover at I. sakeriana flowers. Nevertheless, C. reichenowi , when perching, pierces the sides of flowers to drink the nectar, resulting in lower seed production. Therefore, the authors suggest that the distinctive flower morphology of I. sakeriana has evolved in order to induce birds to hover, instead of perch, and thus to enforce a fair trade of nectar for pollination. Oikos 119 , 10.111/j.1600-0706.2010.08612.x (2010). [1]: pending:yes

Nocturnal pectoral tuft display in the malachite sunbird

Diurnal birds generally sleep during the hours of darkness. Most male southern African sunbirds have pectoral tufts, although the function of these is not always understood. We examined nocturnal tuft display in male malachite sunbirds (Nectarinia famosa) and found that they display their pectoral tufts almost continuously throughout the night, whilst asleep. We suggest the possible function of this behaviour and suggest that these tufts might be a deterrent to predators, as they look like ‘eyes’ in the dark. A review of the use and occurrence of pectoral tufts in southern African sunbird species is also discussed. We suggest the ‘anti-predator’ hypothesis be investigated further.

Nocturnal Pectoral Tuft Display in the Malachite Sunbird

Diurnal birds generally sleep during the hours of darkness. Most male southern African sunbirds have pectoral tufts, although the function of these is not always understood. We examined nocturnal tuft display in male malachite sunbirds (Nectarinia famosa) and found that they display their pectoral tufts almost continuously throughout the night, whilst asleep. We suggest the possible function of this behaviour and suggest that these tufts might be a deterrent to predators, as they look like ‘eyes’ in the dark. A review of the use and occurrence of pectoral tufts in southern African sunbird species is also discussed. We suggest the ‘anti-predator’ hypothesis be investigated further.

Floral visitors of <i>Ananas comosus</i> in Ghana: A preliminary assessment

Ananas comosus var comosus (L.) Merr. is the third most important tropical fruit in the world production and the leading foreign exchange earner among fresh fruits exported from Ghana. A survey was conducted in pineapple farms in the Central region of Ghana to identify floral visitors and their activities on the flowers. Nectar concentration and energetics and effect of floral visitors on fruit production were determined. Fourteen species of butterflies and one ant species were the main insect floral visitors as well as four species of sunbirds. The mean nectar concentration was 23.3% (± 0.39, SE) and pollination limitation did not significantly affect fruit yield (weight: p = 0.285; length: p = 0.056; width: p= 0.268). The study showed that butterflies, ants and sunbirds are the main floral visitors on A. comosus. However their visits did not results in pollination and fruit production was not affected in any way by floral visitation. Still, it was found that A. comosus provides an important nectar resource for its foragers. Even if pollination is not crucial in pineapple cultivation, it is still essential in pineapple breeding programs to promote genetic diversity and conservation.

Description of a new species of Haemoproteus (Haemosporidia, Apicomplexa) from an Orange-tufted Sunbird Nectarinia osea

AbstractHaemoproteus osea sp. nov. is described from the blood of Nectarinia osea, sunbird species, endemic to Israel and the Red Sea zone of Arabia. Infection was found only in one out of 44 birds, in Eilat, at the north end of Gulf of Aqaba; level of parasitaemia was 0.07%. Young gametocytes adhere alongside the nucleus. The gametocytes extend alongside the erythrocyte nucleus, filling the entire space to the erythrocyte envelope and only slightly impose over the tip of the erythrocyte nucleus. Mean nuclear displacement ratio is 0.75. H. osea differs from H. sequeirae Tendeiro, 1947 in having the microgametocyte cytoplasm blue staining, similarly to the macrogametocyte, rather than reddish white, and also in causing less evident displacement of the erythrocyte nucleus.

Hyper-specialization for long-billed bird pollination in a guild of South African plants: the Malachite Sunbird pollination syndrome

A large diversity of floral morphological types exists within the bird pollination syndrome in the Cape Floral Region of South Africa. Here we focus on species with tubular flowers and ask: “Do differences in tube length among plant species correspond to differences in bill length among the birds that serve as pollinators?” To answer this question, we observed 1669 bird–plant interactions at thirteen bird-pollinated plant species across a spectrum of tube lengths. Only three nectar feeding bird species pollinated the focal plant species. The relatively short-billed species were the Southern Double-collared Sunbird ( Cinnyris chalybea) and Orange-breasted Sunbird ( Anthobaphes violacea); the only long-billed species was the Malachite Sunbird ( Nectarinia famosa). We found that the groups of plant species pollinated by the long- and short-billed birds differed significantly in floral tube length. Short-billed sunbirds nevertheless often robbed long-tubed flowers by piercing the corolla, and there was a significant difference in floral tube length among those species that were robbed, and those that were pollinated by short-billed sunbirds. The presence of territorial Malachite Sunbirds depressed robbing rates by short-billed sunbirds at long-tubed flowers. In turn, the absence of Malachite Sunbirds from short-tubed plant species might be explained by the observed positive correlation between tube length and nectar volume. Together, these data suggest that there is a subset of the bird-pollinated plants at the Cape that are pollinated solely by the long-billed Malachite Sunbird, a pollination service irreplaceable by the more abundant, short-billed sunbird species. To extrapolate this finding to a greater subset of species in the Cape Floral Region, we measured flowers on herbarium specimens of all tubular putatively bird-pollinated plants. We find that floral tube length has a bimodal distribution with 37 Cape species potentially dependent on pollination by Malachite Sunbirds.

Development of ten highly polymorphic microsatellite markers for Sunbirds (Aves: Nectariniidae) with broad cross-amplification utility in at least eight species

We describe the isolation of ten microsatellite loci from the Rwenzori Double-collared Sunbird using an enrichment protocol. All loci were variable with the number of alleles ranging from 5 to 13, and observed heterozygosity ranging from 0.500 to 0.929. Nine of these loci were screened on a panel of seven additional Sunbird species from three genera. All nine were successfully amplified and remained highly variable. Given 10–15% sequence divergence among these species in the mtDNA ND2 gene, our results suggest that these markers will work broadly across most members of the species rich bird family Nectariniidae.

Response of avian nectarivores to the flowering of Aloe marlothii: a nectar oasis during dry South African winters

In southern Africa, Aloe marlothii flowers during the dry winter season and offers copious dilute nectar to a variety of birds. Avian abundance and community composition were monitored at an A. marlothii forest at Suikerbosrand Nature Reserve, South Africa. Sampling occurred during two summer months (February–March) when no flowers were present, and six months (May–October) that spanned the winter flowering. We hypothesized that an influx of occasional nectarivores to the A. marlothii forest during flowering would lead to significant changes in the avian community. Overall bird abundance increased 2–3 fold at the peak of nectar availability (August). We recorded 38 bird species, of 83 species detected during transects, feeding on A. marlothii nectar; this diverse assemblage of birds belonged to 19 families, including Lybiidae, Coliidae, Pycnonotidae, Sylviidae, Cisticolidae, Muscicapidae, Sturnidae, Ploceidae and Fringillidae. Surprisingly, only two species of sunbird (Nectariniidae) were observed feeding on A. marlothii nectar, and both occurred in low abundance. We predicted that competition for nectar resources would be high, but few aggressive inter- and intra-specific interactions occurred between birds while feeding on inflorescences. During peak flowering, insect feeders (insectivores, omnivores, nectarivores) fed on nectar during the cold morning when insect activity was low, whilst non-insect feeders (frugivores and granivores) fed on nectar in the middle of the day. Our study highlights the importance of A. marlothii nectar as a seasonal food and water source for a diverse assemblage of occasional nectarivores.

Molecular evolution in space and through time: mtDNA phylogeography of the Olive Sunbird ( Nectarinia olivacea/obscura) throughout continental Africa

This study constitutes the first investigation of the phylogeographic structure of a forest bird distributed throughout the montane and lowland forest biomes of Africa. The key objective was to investigate the importance of Pleistocene climatic cycles on avian diversification across Africa. The Olive Sunbird is a relatively large polytypic sunbird widely distributed throughout evergreen, montane and coastal forests in Africa. Recently, it was split into two species, the Eastern Olive Sunbird ( Nectarinia olivacea) and the Western Olive Sunbird ( Nectarinia obscura), based on morphological grounds. Analyses of a 395 bp fragment of the mtDNA NADH subunit 3 gene with flanking tRNA sequences, from 196 individuals of N. olivacea and 86 from N. obscura indicate that genetic divergence levels are low (1.0–2.4%) across some 9000 km, from Ghana in the northwest of Africa to KwaZulu-Natal in eastern South Africa. Neither currently recognized Olive Sunbird species were monophyletic using either parsimony or likelihood tree-building methods. Φ ST values suggested that there was less variation partitioned among species than between most neighboring regions. Genetic diversity within the N. olivacea/obscura complex was dominated by three star-like phylogenies linked to each other by a single mutational step and two subnetworks (IV and V) separated from the core star-like phylogenies (subnetworks I, II, and III) by five to six mutational steps. The dominant evolutionary mechanism shaping genetic variation within the N. olivacea/obscura complex as identified by nested-clade analyses, appears to be one of range expansion possibly out of East Africa associated with a period of forest expansion during the mid-Pleistocene, some 1.1–0.7 million years ago. Mismatch profiles suggested that secondary contact has occurred between eastern and western lineages within the Ufipa Escarpment and possibly Zimbabwe, as well as between eastern lineages in the Kenyan Highlands and northern Eastern Arc Mts.

Biologie de la reproduction de Aloe mayottensis (Liliaceae), une espèce endémique de l'île Mayotte (Océan Indien)

A particularly interesting aspect of the study of organisms in insular environments is plant reproduction and the interaction of plants with their pollinators. Differences in composition between the fauna and flora of continental and island populations, combined with their geographical isolation, have frequently driven rapid evolution in colonizing populations. In particular, floral traits and compatibility systems tend to favour autogamy in response to a paucity of pollinators in the environment. In this context we investigate the origins of the reproductive biology of Aloe mayottensis Berger, a lily endemic to the island of Mayotte. We show that this species is pollinated by the island's endemic sunbird species, and has floral traits and a reproduction system that favour allogamy. Our results show that A. mayottensis is a protandrous and partially self-compatible species. Analysis of stigmatic pollen load shows that stigma received a mean of 56 crossed pollen grains and 62.2 selfed pollen grains per stigma. Study of visitation rates of plants and flowers by the sunbird showed that there is daily variation in the activity of this pollinator, and that males are more active than females.Key words: Aloe mayottensis, floral biology, Lomatophyllum, Nectarinia, bird pollinization, sunbirds, Oceanic islands, Mayotte.

Effects of tsetse targets on mammals and birds in Kasungu National Park, Malawi

Possible effects on wildlife of targets baited with an attractive odour (acetone), impregnated with deltamethrin and used to control tsetse flies (Glossina morsitans morsitans), were investigated in the Kasungu National Park, Malawi. Mammals and birds were censused simultaneously along transects in 'Miombo' woodland or 'Dambo' grassland/mixed woodland, with and without targets. Mammals were also monitored by surveys of their spoor on experimentally cleared plots (5 m in diameter) and a target relocation experiment was conducted when the targets were removed from the test transects and transferred to the controls. Significantly fewer small antelopes (e.g. common Duiker Sylvicapra grimmia) were detected in plots along transects with targets (tests) than along control transects. The presence of targets affected the frequency of occurrence of antelopes, suids and large herbivores in the experimental plots, but small carnivores, monkeys, rodents and hares were unaffected. A conclusion of the relocation experiment was that the deltamethrin-impregnated cloth was responsible for the observed effects and not the acetone. A total number of 23 species of birds meeting a criterion for their abundance in the areas surveyed were selected for detailed analyses. Lower indices in the test areas than in the controls were recorded for 15 of these 23 species in the Dambos and for 10 of 21 species in the Miombo woodland. Matched paired comparisons revealed significantly lower numbers in the test areas than in the controls in both habitats only for black-headed Oriole Oriolus larvatus, but for Grey Lourie Corythaixoides concolor, little bee-eater Merops pusillus, fork-tailed Drongo Dicrurus adsimilis and combined data on three species of sunbirds in the Dambos. The black-eyed bulbul Pycnonotus barbatus had significantly lower numbers in the tests than in the controls in Miombo woodland. The numbers of three species of dove were higher in the tests than in the controls in both habitats, significantly so for the Cape turtle dove Streptopelia capicola, and numbers of the Flappet Lark Mirafra rufocinnamomea were significantly higher in the tests than in the controls in Dambos. The results are discussed in the light of previous studies on environmental effects of tsetse control, including effects of tsetse targets on pollinators especially non-target horseflies.

New Aethopyga Sunbirds (Aves: Nectariniidae) from the Island of Mindanao, Philippines

We describe a new species of sunbird, Aethopyga linaraborae, known from Mt. Mayo, Mt. Puting Bato, and Mt. Pasian, all part of an isolated range of mountains in eastern Mindanao, Philippines. It occurs commonly in mossy forest from about 1,200 m and above. We also describe a new subspecies of Apo Sunbird, Aethopyga boltoni tibolii, known from Mt. Busa and Mt. Matutum of southern Mindanao, where it is found in mossy forest above 1,000 m.

Bird pollination in South African species ofSatyrium (Orchidaceae)

Field observations showed that three South African orchid species,Satyrium carneum, S. coriifolium andS. princeps, are pollinated by sunbirds. Foraging sunbirds insert their bills into the labellum chamber of the flowers and suck nectar from the labellum spurs with their tongues. The column overarches the entrance to the labellum and pollinaria become affixed to the upper mandible of the bill. Birds often attempt to remove pollinaria by rubbing their bills against a branch, but are mostly unsuccessful due to the large plate-like viscidia which attach the pollinaria very firmly to the bill. Other modifications for bird pollination in theseSatyrium species may include the red, carmine or orange colour of the flowers, sturdy inflorescence stems used for perching and large amounts of dilute nectar in the spurs. EachSatyrium species was pollinated by several species of sunbird, and despite some differences in flowering time, occasional hybrids occur at a site whereS. carneum andS. coriifolium share the same sunbird pollinators.