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

Riegert, Jan; Antczak, Marcin; Fainová, Drahomíra; Blažková, Pavla

doi:10.1016/j.beproc.2013.12.006

Cited by 8 publications

(5 citation statements)

References 34 publications

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“…, Riegert et al . ). Instead, C. oritis displays a similar pattern of trapline foraging to that found in highly specialized hermit hummingbirds (Feinsinger & Colwell ).…”

Section: Discussionmentioning

confidence: 97%

Sunbird hovering behavior is determined by both the forager and resource plant

Padyšáková

Janeček

2016

Biotropica

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The long-standing paradigm that pollination systems adapted to hovering birds evolved only in the New World was recently challenged by the discovery of hovering pollination by Old World specialized passerine pollinators. This raises the possibility that hovering pollination may evolve more easily than previously believed, given sufficient selective pressure on plant traits, on nectarivory, or both. We observed foraging behavior by the sunbird Cyanomitra oritis at flowers of the native Old World plant Impatiens sakeriana. We measured the length of pedicels and peduncles (PedPed length), which can make the flowers difficult to reach while the bird perches on the stem, and determined if it influenced sunbird hovering or perching at a flower. Detailed analyses of video recordings showed that sunbirds only hovered at flowers with a long PedPed, whereas they employed both foraging modes when an adequate perch was available. A hovering sunbird could deplete nectar in a shorter time than a perching one. The frequency of visits was not greater at flowers with longer PedPed or with more open I. sakeriana flowers in the vicinity. Our study provides evidence that sunbird behavior does not follow simple energetic models, and that some sunbird pollination systems in the Old World resemble highly specialized hummingbird systems in the New World much more than expected, especially the overall adaptation of the system to bird hovering.

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“…, Riegert et al . ). Instead, C. oritis displays a similar pattern of trapline foraging to that found in highly specialized hermit hummingbirds (Feinsinger & Colwell ).…”

Section: Discussionmentioning

confidence: 97%

Sunbird hovering behavior is determined by both the forager and resource plant

Padyšáková

Janeček

2016

Biotropica

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“…Most sunbird species are sexually dimorphic, whereby males have bright iridescent colours and females mostly dull, unstructured melanin-based plumage. For display, sunbirds select highly visible places exposing themselves to direct sunlight [35]. If iridescent feathers have higher photothermal absorption than unstructured melanin-based plumage, male sunbirds might be exposed to greater solar heat loads than females, particularly under high intensities of solar radiation.…”

Section: Introductionmentioning

confidence: 99%

Enhanced photothermal absorption in iridescent feathers

Rogalla

Patil

Dhinojwala

et al. 2021

J. R. Soc. Interface.

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The diverse colours of bird feathers are produced by both pigments and nanostructures, and can have substantial thermal consequences. This is because reflectance, transmittance and absorption of differently coloured tissues affect the heat loads acquired from solar radiation. Using reflectance measurements and heating experiments on sunbird museum specimens, we tested the hypothesis that colour and their colour producing mechanisms affect feather surface heating and the heat transferred to skin level. As predicted, we found that surface temperatures were strongly correlated with plumage reflectivity when exposed to a radiative heat source and, likewise, temperatures reached at skin level decreased with increasing reflectivity. Indeed, nanostructured melanin-based iridescent feathers (green, purple, blue) reflected less light and heated more than unstructured melanin-based colours (grey, brown, black), as well as olives, carotenoid-based colours (yellow, orange, red) and non-pigmented whites. We used optical and heat modelling to test if differences in nanostructuring of melanin, or the bulk melanin content itself, better explains the differences between melanin-based feathers. These models showed that the greater melanin content and, to a lesser extent, the shape of the melanosomes explain the greater photothermal absorption in iridescent feathers. Our results suggest that iridescence can increase heat loads, and potentially alter birds' thermal balance.

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“…, Riegert et al . ). Additionally, the majority of species are sexually dimorphic in both body size and plumage coloration: males are larger and exhibit colourful iridescent plumage patches (either year‐round or seasonally), whereas females are generally drab (Fry et al .…”

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confidence: 97%

Variation in sperm morphology among Afrotropical sunbirds

Omotoriogun

Laskemoen

Rowe

et al. 2015

Ibis

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Birds show considerable variation in sperm morphology. Closely related species and subspecies can show diagnostic differences in sperm size. There is also variation in sperm size among males within a population, and recent evidence from passerine birds suggests that the coefficient of inter‐male variation in sperm length is negatively associated with the level of sperm competition. Here we examined patterns of inter‐ and intra‐specific variation in sperm length in 12 species of sunbird (Nectariniidae) from Nigeria and Cameroon, a group for which such information is extremely limited. We found significant variation among species in sperm total length, with mean values ranging from 74 μm to 116 μm, placing these species within the short to medium sperm length range for passerine birds. Most of this variation was explained by the length of the midpiece, which contains the fused mitochondria and is an important structure for sperm energetics. Relative midpiece length was negatively correlated with the coefficient of inter‐male variation in sperm total length across species, suggesting that sperm competition may have selected for greater midpiece length in this group. We also mapped sperm lengths onto a time‐calibrated phylogeny and found support for a phylogenetic signal in all sperm length components, except head length. A test of various evolutionary or tree transformation models gave strongest support for the Brownian motion model for all sperm components, i.e. divergences were best predicted by the phylogenetic distance between lineages. The coefficients of inter‐male variation in sperm total length indicate that sperm competition is high but variable among sunbird species, as is the case with passerine birds at large.

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

Cited by 8 publications

References 34 publications

Sunbird hovering behavior is determined by both the forager and resource plant

Sunbird hovering behavior is determined by both the forager and resource plant

Enhanced photothermal absorption in iridescent feathers

Variation in sperm morphology among Afrotropical sunbirds

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