DOCSLIB.ORG

Multiple Sexual Ornaments in Satin Bowerbirds: Ultraviolet Plumage and Bowers Signal Different Aspects of Male Quality

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Multiple Sexual Ornaments in Satin Bowerbirds: Ultraviolet Plumage and Bowers Signal Different Aspects of Male Quality Behavioral Ecology Vol. 14 No. 4: 503–509 Multiple sexual ornaments in satin bowerbirds: ultraviolet plumage and bowers signal different aspects of male quality Ste´phanie M. Doucet and Robert Montgomerie Department of Biology, Queen’s University, Kingston, Ontario K7L 3N6, Canada Much attention has been devoted to understanding the evolution of elaborate male ornaments and how they may signal male quality. However, the evolution of multicomponent sexual signals remains poorly understood, and past research on this type of signaling has been largely theoretical. Satin bowerbirds, Ptilonorhynchus violaceus, are polygynous, are sexually dichromatic, and construct sexually selected display structures (bowers): a model system for investigating the evolution and signal function of multiple sexual signals. We studied the interrelationship between bower features, plumage coloration, and indicators of male quality in this species. To do this, we located the bowers of male satin bowerbirds in rainforest in Queensland, Australia, and quantified bower quality. We captured the male bower owners and used reflectance spectrometry to objectively measure the plumage coloration of several body regions. We measured various indicators of male health and condition, including the intensity of infection from ectoparasites and blood parasites. Bower quality and male ultraviolet plumage coloration were significantly correlated. By using multiple regression analyses, we show that bower quality predicts ectoparasite load and body size, whereas ultraviolet plumage coloration predicts the intensity of infection from blood parasites, feather growth rate, and body size. Our findings support the multiple messages hypothesis of multicomponent signals: Female satin bowerbirds should assess both male and bower features to choose the highest quality mates. Key words: bowerbirds, bowers, honest advertisement, multiple ornaments, parasites, plumage color, sexual selection, structural colors. [Behav Ecol 14:503–509 (2003)] laborate, secondary sex traits are often presumed to on different time scales (daily for bowers and yearly for E communicate aspects of male quality to discriminating plumage color), these multicomponent sexual signals may females (Andersson, 1994). In many species, elaborate sexual reveal different aspects of male quality (Johnstone, 1995b; displays involve several distinct signals such as plumage Møller and Pomiankowski, 1993), and females may thus ornamentation, song, and display behavior. Some theoretical obtain useful information from evaluating all components of models have shown that, under certain circumstances, species male display. could evolve multiple quality-revealing sexual ornaments In satin bowerbirds, individual variation in the quality of ( Johnstone, 1995a), but other models propose that honest bower construction, the numbers and types of decorations advertising should favor a single most-revealing signal at the adorning the bower platform, and age-correlated features of expense of others ( Johnstone, 1996; Schluter and Price, 1993). courtship song are known to influence female choice of Despite some theoretical consideration ( Johnstone 1995a, copulation partners, as measured by male mating success 1996; Schluter and Price, 1993), the evolution of multiple (Borgia, 1985b; Lofredo and Borgia, 1986). In contrast to quality-indicating sexual ornaments has received little empir- other features of the sexual display of male satin bowerbirds, ical support (for exceptions, see Johnstone, 1995b). In many the structurally based iridescent plumage of males has species, the evolution of more than one sexual signal can be received less attention, even though this species is highly more accurately attributed to Fisherian arbitrary selection sexually dichromatic and plumage ornamentation is a prom- (Fisher, 1958; Møller and Pomiankowski, 1993; Pomian- inent feature of male courtship display. Recent studies of kowski and Iwasa, 1993), signal amplification (Hasson, other bird species have shown that structural plumage 1989), enhanced signal detection (Rowe, 1999), or to distinct coloration can honestly signal condition (Doucet, 2002; signals intended for different receivers (Pryke et al., 2001a,b). Keyser and Hill, 1999), male quality (Keyser and Hill, 2000), In satin bowerbirds, Ptilonorhynchus violaceus, males clear and viability (Sheldon et al., 1999). Thus plumage coloration display courts, build bowers (elaborate structures constructed may be a quality-indicating mechanism in male satin bower- from twigs), and decorate the bower platform with a variety of birds and may function as a key component of a complex, colorful natural and human-manufactured objects (see multimodal sexual signal of male quality. In the present study, Marshall, 1954). Females of this species observe male court- we investigated how multicomponent sexual signals can ship from within the bower avenue, and the sexual display of potentially reveal male quality in this species by studying the courting males incorporates song mimicry, ritualized pranc- relationship between male plumage coloration, bower fea- ing, and brilliant plumage coloration. Because different tures, and various indicators of male health and condition. components of the male satin bowerbird’s display will vary METHODS Address correspondence to S.M. Doucet, who is now at the This study was conducted from September–December 2000 in Department of Biological Sciences, 331 Funchess Hall, Auburn a 700-ha study area in Mount Baldy State Forest, Queensland, University, Auburn, AL 36849, USA. E-mail: [email protected]. Australia (17°309 S, 145°309 E). The dominant habitat was Received 3 April 2002; revised 3 September 2002; accepted 21 rainforest with a sharp transition to wet sclerophyll forest at September 2002. the northeastern edge of our study area. We located 12 satin Ó 2003 International Society for Behavioral Ecology bowerbird bowers in our study area by listening for male 504 Behavioral Ecology Vol. 14 No. 4 dicular to the feather surface. All spectral measurements are expressed as the proportion of light reflected relative to that reflected from a Spectralon white standard, an almost perfect reflector. We measured plumage reflectance on four body regions for each individual: wing coverts, breast, mantle, and rump, taking five readings from each region and moving the probe by at least 5 mm between readings. We restricted spectral analyses to wavelengths from 300–700 nm, as most birds are sensitive to ultraviolet (UV) wavelengths (300–400 nm; Cuthill et al., 2000), and 700 nm is likely the upper limit of the vertebrate visual spectrum (Jacobs, 1981). We summarized reflectance data by calculating five color variables: total brightness, UVV-brightness, UVV-chroma, con- trast, and hue. We calculated total brightness as the mean of reflectance values, in 1-nm intervals, from 300–700 nm (Andersson, 1999; Endler, 1990); this measurement thus gives the mean proportion of incident light that is reflected from the feather surface in the bird-visible range of wavelengths. Similarly, we calculated UVV-brightness as the mean of reflectance values in the UV–violet region of the spectrum (300–420 nm; Andersson et al., 1998), in which peak Figure 1 reflectance occurred in all males. As a measure of spectral sat- Representative reflectance spectrum (average of rump, mantle, breast, and wing coverts) for one adult male satin bowerbird. This uration, we calculated UVV-chroma as the proportion of total individual was chosen because its plumage color was closest to the reflectance occurring in the UV–violet region of the spec- mean for the color variables we calculated across all individuals trum. We calculated contrast as the difference between the sampled. maximum and minimum reflectance across the 300–700-nm range, such that higher contrast indicates a more intense color (Keyser and Hill, 1999, 2000). Given the simple, advertisement calls, usually given near bowers, and systemat- unimodal shape of adult male satin bowerbird reflectance ically searching for active display sites. We assessed bower spectra (Figure 1), contrast is likely a reliable estimate of color quality by evaluating bower construction and quantifying the intensity in this species. Finally, to approximate hue, we used number of decorations used. Two observers independently the wavelength at which maximum reflectance was reached, evaluated four features of bower construction—overall sym- a commonly used index of spectral location (see Keyser and metry of the structure, stick size, stick density, and overall Hill, 1999, 2000; Sheldon et al., 1999). quality of construction—each on a scale from one (poor) to We also calculated an overall ornamental color score using four (excellent). We calculated a bower quality score for each principal components analysis (PCA). We first calculated the bower as the sum of these measures averaged between the two mean of each color variable for each body region on each observers. Similar indices of bower quality have been shown to male. We then performed a PCA by using the mean total correlate with mating success in several species of bowerbird brightness, UVV-chroma, contrast, and hue averaged over the (Borgia, 1985b; Borgia and Mueller, 1992; Lenz, 1994; Uy and four regions of each male studied. The first principal Borgia, 2000). To assess the extent of bower decoration, we component (PC1) from this analysis explained 46% of the regularly visited bowers from mid October to late November variation in color among males, with total brightness,
Load more

Recommended publications
  • Variation in Bower Decorating Style Among Male Bowerbirds
    Proc. Nati. Acad. Sci. USA Vol. 83, pp. 3042-3046, May 1986 Population Biology Animal art: Variation in bower decorating style among male bowerbirds Amblyornis inornatus (cultural rnlsson/geographic variadon/behavior) JARED DIAMOND Physiology Department, University of California Medical School, Los Angeles, CA 90024 Contributed by Jared Diamond, December 30, 1985 ABSTRACT Courtship bowers of the bowerbird Ambly- BACKGROUND ornis inornatus, the most elaborately decorated structures Bowers are avenues, huts, or towers of sticks decorated with erected by an animal other than humans, vary geographically objects such as fruits, flowers, mushrooms, and stones. and individually. Bowers in the south Kumawa Mountains are Males often hold a decoration in their bill while displaying to tall towers of sticks glued together, resting on a circular mat of a female, and experiments confirm that bower structure and dead moss painted black, and decorated with dull objects such decorations influence females' choice of mate (7). Whereas as snall shells, acorns, and stones. Bowers in the Wandamen males are polygynous and contribute nothing to the female Mountains are low woven towers covered by a stick hut with an after copulation, females perform the whole effort ofbuilding entrance, resting on a green moss mat and decorated with a nest and rearing the young. Species comparisons show that colorful objects such as fruits, flowers, and butterfly wings. male bowerbirds with duller ornamental plumage build fan- Young males build simpler bowers, and adult males differ cier bowers (4, 8). Thus, during bowerbird evolution the among themselves. Experiments with poker chips of seven female's attention has been transferred from ornaments ofthe colors offered as decorations showed that individual birds male's body to those ofhis bower.
    [Show full text]
  • Nest, Egg, Incubation Behaviour and Parental Care in the Huon Bowerbird Amblyornis Germana
    Australian Field Ornithology 2019, 36, 18–23 http://dx.doi.org/10.20938/afo36018023 Nest, egg, incubation behaviour and parental care in the Huon Bowerbird Amblyornis germana Richard H. Donaghey1, 2*, Donna J. Belder3, Tony Baylis4 and Sue Gould5 1Environmental Futures Research Institute, Griffith University, Nathan 4111 QLD, Australia 280 Sawards Road, Myalla TAS 7325, Australia 3Fenner School of Environment and Society, The Australian National University, Canberra ACT 2601, Australia 4628 Utopia Road, Brooweena QLD 4621, Australia 5269 Burraneer Road, Coomba Park NSW 2428, Australia *Corresponding author. Email: [email protected] Abstract. The Huon Bowerbird Amblyornis germana, recently elevated to species status, is endemic to montane forests on the Huon Peninsula, Papua New Guinea. The polygynous males in the Yopno Urawa Som Conservation Area build distinctive maypole bowers. We document for the first time the nest, egg, incubation behaviour, and parental care of this species. Three of the five nests found were built in tree-fern crowns. Nest structure and the single-egg clutch were similar to those of MacGregor’s Bowerbird A. macgregoriae. Only the female Huon Bowerbird incubated. Mean length of incubation sessions was 30.9 minutes and the number of sessions daily was 18. Diurnal incubation constancy over a 12-hour day was 74%, compared with a mean of ~70% in six other members of the bowerbird family. The downy nestling resembled that of MacGregor’s Bowerbird. Vocalisations of a female Huon Bowerbird at a nest with a nestling
    [Show full text]
  • Male Courtship Vocalizations As Cues for Mate Choice in the Satin Bowerbird (Ptilonorhynchus Violaceus)
    MALE COURTSHIP VOCALIZATIONS AS CUES FOR MATE CHOICE IN THE SATIN BOWERBIRD (PTILONORHYNCHUS VIOLACEUS) CHRISTOPHER A. LOFFREDO AND GERALD BORGIA Departmentof Zoology,University of Maryland,College Park, Maryland 20742 USA AI3STRACT.--MaleSatin Bowerbirds(Ptilonorhynchus violaceus) court femalesat specialized structurescalled bowers. Courtship includes a complexpattern of vocalizationsin which a broad-band,mechanical-sounding song is followed by interspecificmimicry. We studiedthe effect of male courtshipdisplays on male mating successin Satin Bowerbirds.Data from 2 yearsof field researchshowed low between-maledifferences in mechanicalcomponents of courtshipsong and high variability betweenmales in mimeticsinging. Older malessang longer and higher-qualitybouts of mimicry than did youngermales. In one year, courtship song featureswere correlatedwith male mating success.The resultssuggest that female SatinBowerbirds use male courtship vocalizations in their mate-choicedecisions. We discuss hypothesesabout assessment of male age and dominancefrom courtshipvocalizations and suggestthat thesesongs have evolvedas a result of selectionfor male displaycharacteristics that provide femaleswith information about the relative quality of prospectivemates. Re- ceived27 June1985, accepted20 September1985. MALESatin Bowerbirds(Ptilonorhynchus vio- ingnessto copulateor by flying away. Given laceus)build specializedstructures called bow- the complexity of male display and the atten- ers that are used as sites for courting females tion femalespay to displayingmales,
    [Show full text]
  • Chapter 18 Evolution of Reproductive Behavior (1St Lecture)
    Chapter 18 Evolution of reproductive behavior (1st lecture) The Satin Bowerbird has an unusual courtship ritual Male constructs an female elaborate “avenue” bower, contaiing colorful objects that he has collected. When a female arrives, he performs a energetic dance while emitting a medley of male buzzes, screeches and imitations of other bird songs. The female assesses the male based on: bower attributes, the male’s dance, and location of the bower If the female decides to mate with him, then she will enter his bower, copulate, and fly away, never to see him again. She will incubate her eggs and raise young on her own. The male will continue in this manner across the 8-month breeding season, mating with as many females as possible. The design of the bower varies greatly, both among and within species Playhouse bower Different populations of Amblyornis inoratus construct different types of bower, perhaps reflecting different “aesthetic tastes” of females within each population Maypole bower Evolutionary relationships among 14 of the 19 species of bowerbird, based on similarities in their mitochondrial cytochrome b gene Note that 2 bowerbird species share the ancestral trait of not building a bower Maypole builders Presumably, the hypothetical species Y built a Avenue simple bower. builders The ensuing adaptive radiation illustrates a fantastic example of divergent evolution What are the features of the bowerbird courtship ritual that represent evolutionary conundrums? The males make absolutely no parental investment Each male mates multiple
    [Show full text]
  • Molecular Evolution and Functional Characterization of the Visual Pigment Proteins of the Great Bowerbird (Chlamydera Nuchalis) and Other Vertebrates
    Molecular Evolution and Functional Characterization of the Visual Pigment Proteins of the Great Bowerbird (Chlamydera nuchalis) and Other Vertebrates by Ilke van Hazel A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Ecology and Evolutionary Biology University of Toronto © Copyright by Ilke van Hazel 2012 Molecular Evolution and Functional Characterization of the Visual Pigment Proteins of the Great Bowerbird (Chlamydera nuchalis) and Other Vertebrates Ilke van Hazel Doctor of Philosophy Department of Ecology and Evolutionary Biology University of Toronto 2012 Abstract Visual pigments are light sensitive receptors in the eye that form the basis of sensory visual transduction. This thesis presents three studies that explore visual pigment proteins in vertebrates using a number of computational and experimental methods in an evolutionary framework. The objective is not only to identify, but also to experimentally investigate the functional consequences of genetic variation in vertebrate visual pigments. The focus is on great bowerbirds (Chlamydera nuchalis), which are a model system in visual ecology due to their spectacular behaviour of building and decorating courtship bowers. There are 4 chapters: Chapter 1 introduces background information on visual pigments and vision in birds. Among visual pigment types, the short-wavelength-sensitive (SWS1) pigments have garnered particular interest due to the broad spectral range among vertebrates and the importance of UV signals in communication. Chapter 2 investigates the evolutionary history of SWS1 in vertebrates with a view toward its utility as a phylogenetic marker. Chapter 3 investigates SWS1 evolution and short-wavelength vision in birds, with particular focus on C.
    [Show full text]
  • Miscellaneous Notes on the Bowerbirds Chlamydera Cerviniventris and C
    AUSTRALIAN 6 BIRD WATCHER AUSTRALIAN BIRD WATCHER 1989, 13, 6-19 Miscellaneous Notes on the Bowerbirds Chlamydera cerviniventris and C. lauterbachi (Ptilonorhynchidae) in Papua New Guinea by C.B. FRITH and D.W. FRITH 'Prionodura', Paluma via Townsville, Queensland 4816 Summary Nests, a nestling and three bowers of the Fawn-breasted Bowerbird Chlamydera cerviniventris are described, and observations of parental nest attendance reported. Nests, eggs and bowers of Lauterbach's Bowerbird C. lauterbachi are described and observations of male and female behaviours at a bower reported. First descriptions of nestling, fledgling and juvenile Lauterbach's Bowerbird are given. The location of nests relative to bowers and seasonality of nesting of the Fawn-breasted and Lauterbach's Bowerbirds are reviewed. Introduction The four or five Chlamydera bowerbird species (Ptilonorhynchidae) are unlike the other fourteen, forest-dwelling, species in that they inhabit only open drier habitats of riverine forests, open woodlands, grasslands and adjacent forest edges (Donaghey et al. 1985). They are all members of the 'avenue' bower building group but differ from Sericulus and Ptilonorhynchus species, in which males are brightly coloured, by being dull and cryptically sexually monomorphic or very nearly so (Gilliard 1969). Least known of the Chlamydera species are Lauterbach's Bowerbird C. lauterbachi endemic to central and north-eastern New Guinea, and the Fawn-breasted Bowerbird C. cerviniventris of north-western Cape York Peninsula, Australia, and coastal central and eastern New Guinea and the eastern Vogelkop (Cooper & Forshaw 1W7) . Other than descriptions of bowers, some male displays and nest and eggs, little is known of nesting habits and nest dispersion relative to bower locations in Lauterbach's and Fawn-breasted Bowerbirds (Peckover 1969, Cooper & Forshaw 1W7).
    [Show full text]
  • Birds of New Guinea Field Guide (Beehler Et Al
    © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. Introduction The New Guinea Region Our region of coverage follows Mayr (1941: vi), who defined the natural region that encompasses the avifauna of New Guinea, naming it the “New Guinea Region.” It comprises the great tropical island of New Guinea as well as an array of islands lying on its continental shelf or immediately offshore. This region extends from the equator to latitude 12o south and from longitude 129o east to 155o east; it is 2,800 km long by 750 km wide and supports the largest remaining contiguous tract of old-growth humid tropical forest in the Asia-Pacific (Beehler 1993a). The Region includes the Northwestern Islands (Raja Ampat group) of the far west—Waigeo, Batanta, Salawati, Misool, Kofiau, Gam, Gebe, and Gag; the Aru Islands of the southwest—Wokam, Kobroor, Trangan, and others; the Bay Islands of Geelvink/Cenderawasih Bay—Biak-Supiori, Numfor, Mios Num, and Yapen; Dolak Island of south-central New Guinea (also known as Dolok, Kimaam, Kolepom, Yos Sudarso, or Frederik Hendrik); Daru and Kiwai Islands of eastern south-central New Guinea; islands of the north coast of Papua New Guinea (PNG)—Kairiru, Muschu, Manam, Bagabag, and Karkar; and the Southeastern (Milne Bay) Islands of the far southeast—Goodenough, Fergusson, Normanby, Kiriwina, Kaileuna, Wood- lark, Misima, Tagula/Sudest, and Rossel, plus many groups of smaller islands (see the endpapers for a graphic delimitation of the Region).
    [Show full text]
  • An Inverse Relationship Between Decoration and Food Colour Preferences in Satin Bowerbirds Does Not Support the Sensory Drive Hypothesis
    ANIMAL BEHAVIOUR, 2006, 72, 1125e1133 doi:10.1016/j.anbehav.2006.03.015 An inverse relationship between decoration and food colour preferences in satin bowerbirds does not support the sensory drive hypothesis GERALD BORGIA*† & JASON KEAGY† *Department of Biology, University of Maryland, College Park yDepartment of Behavior, Ecology, Evolution and Systematics Program, University of Maryland, College Park (Received 20 September 2005; initial acceptance 25 October 2005; final acceptance 30 March 2006; published online 26 September 2006; MS. number: A10246) Male bowerbirds collect and decorate their bowers with coloured objects that influence female choice. A recent version of the sensory drive hypothesis claims that female food colour preferences have driven the evolution of female preferences for the colour of male display traits. This hypothesis predicts a positive correlation between male display and food colour preferences. A positive correlation between food and decoration preferences could also arise because of sensory biases built into bowerbirds or the environment. Here we test hypotheses that (1) male and female satin bowerbirds show well-defined food colour prefer- ences, (2) these preferences correlate with independently assessed preferences for bower decorations, and, in a cross-species comparison, (3) food items were used as the first bower decorations. We found that male and female satin bowerbirds, Ptilonorhynchus violaceus, preferentially use long wavelength and were colours as food items. Male decoration preferences were biased towards colours of short wavelength and were negatively correlated with food colour preferences. Our reconstruction of ancestral character states is most consistent with the hypothesis that the original bower decorations were inedible objects and were thus unlikely to have been dual-use traits that also functioned as food items.
    [Show full text]
  • Evolution of Colorful Display
    COMMENTARY doi:10.1111/j.1558-5646.2007.00051.x EVOLUTION OF COLORFUL DISPLAY Gerald Borgia,1 Brian Coyle, and P. B. Zwiers Department of Biology, University of Maryland, College Park, Maryland 20742-4415 1E-mail: [email protected] Received February 27, 2006 Accepted November 27, 2006 How the displays of bowerbirds have evolved has attracted widespread interest. Endler et al. (2005) analyzed color use in display in a subset of bowerbird species and generalized their results to all bowerbirds. Here we discuss problems with their analysis that calls into question their conclusions. For example, they state that bowerbirds do not use decorations that match their background, but this is not supported by their results. They reconstruct historical patterns of sexual dimorphism in plumage display using questionable methodology. The high lability of these display traits makes these reconstructions unreliable and, using accepted methods and acknowledging the lability problem, we were unable to support their conclusions. Their claim that plumage differences between sympatric species are due to character displacement is not supported by the available data. Their focus is on visual contrast as the cause for display color and we offer additional hypotheses that may contribute to explaining color use. We support studies of spectral analysis of display traits but urge greater care in using this information to reach conclusions about how colorful displays have evolved. KEY WORDS: Character displacement, character-state reconstruction, mate recognition, rapid evolution, sexual selection. Bowerbirds are widely known for their multifaceted sexual dis- logeny suggest the following sequence of events: (1) increase of plays including a bower, bower decorations, and dancing and vo- contrast under sexual selection; (2) onset of increased predation cal elements.
    [Show full text]
  • Animal-Fungal Interactions 1: Notes on Bowerbird's Use of Fungi
    Animal-Fungal Interactions 1: Notes on Bowerbird’s Use of Fungi Todd F. ElliottA* and Peter A. MarshallB A Integrative Studies Department, Warren Wilson College, P.O. Box 9000, Asheville, North Carolina 28815-9000, United States of America B Terra Preta Truffles, P.O. Box 94, Braidwood, New South Wales 2622, Australia * Corresponding author. Email: [email protected] Key words: Bowerbirds, bowers, ornithomycological, mushrooms, fungi, mycophagy Downloaded from http://meridian.allenpress.com/australian-zoologist/article-pdf/38/1/59/1474054/az_2015_032.pdf by guest on 29 September 2021 DOI: http://dx.doi.org/10.7882/AZ.2015.032 Reports of ornithomycological interactions are scattered (Species Fungorum 2015). We found other reports dating across multiple bird families, including: Acanthizidae, back to the 1800s of fungi, black bracket fungi, mushrooms, Alaudidae, Casuariidae, Corvidae, Dromaiidae, and puffballs being used by Amblyornis inornata (Vogelkop Glareolidae, Megapodiidae, Petroicidae, Prunellidae, Bowerbirds), Chlamydera maculata (Spotted Bowerbird), Psittaculidae, Strigopidae, and Upupidae, (Simpson 1998; and Ptilonorhynchus violaceus (Satin Bowerbird), but Simpson 2000; Beever & Lebel 2014). These records unfortunately these reports are too taxonomically vague document fungi as food for birds ranging from Cassowaries to determine what taxa of fungi were involved (Beccari to Siberian Jays; in some cases, fungi may comprise a 1878; Nubling 1921; Marshall 1934, Diamond 1986; seasonally significant portion of birds’ diets (Andreev
    [Show full text]
  • Age-Related Effects of Testosterone, Plumage, and Experience on Aggression and Social Dominance in Juvenile Male Satin Bowerbirds (Ptilonorhynchus Violaceus)
    The Auk 109(3):422-434, 1992 AGE-RELATED EFFECTS OF TESTOSTERONE, PLUMAGE, AND EXPERIENCE ON AGGRESSION AND SOCIAL DOMINANCE IN JUVENILE MALE SATIN BOWERBIRDS (PTILONORHYNCHUS VIOLACEUS) KEN COLLIS AND GERALD BORGIA Departmentof Zoology,University of Maryland,College Park, Maryland 20742, USA ASSTRACT.--Weinvestigated the relationshipbetween age and dominancein the Satin Bowerbird(Ptilonorhynchus violaceus) to understandwhy youngmales delay maturation. Tes- tosteroneimplants were used to experimentallyadvance the expression of adultcharacteristics in juvenile-plumagedmales. Testosterone implants increased both aggression and dominance amongjuvenile-plumaged males. In theyear following implantation, treated males molted intofull adultplumage and maintained their dominance over controls at feedingsites even thoughtheir implants were probably empty. Despite the changesin circulatingandrogens, aggression,and plumagebrought on by the testosteronetreatment of juvenile-plumaged males,age-related differences remained in aggressionand socialdominance between the treatedand untreatedbirds. These age effects are consistentwith the hypothesisthat male experiencein maleaggressive encounters plays an important role in determiningdominance relationshipsand, ultimately, affects the developmentof maleadult-plumaged characters. Received12 September1990, accepted 13 January1992. THEEVOLUTION of exaggeratedmale display still in juvenile plumage(Marshall 1954),they traitscommon in manypolygynous species has do not acquirea full-adult blue plumageuntil attracted
    [Show full text]
  • Novitates No
    AMERIICAN MUSEUM NOV ITATES PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CITY OF NEW YORK DECEMBER 12, 1952 NUMBER 1602 GEOGRAPHIC VARIATION AND PLUMAGES IN AUSTRALIAN BOWERBIRDS (PTILONORHYNCHIDAE) By ERNST MAYR AND KATE JENNINGS INTRODUCTION In view of the great recent interest in the biology of bower- birds, it is surprising how little is known about the taxonomy of the Australian species. The available accounts in the standard works are very confusing, since no difference is made in most of them between synonyms and valid subspecies. Furthermore, a study of individual variation, of the sequence of plumages, and of measurements is badly needed, as information on these matters is woefully inadequate in the existing literature. In fact, we know much more about the New Guinea species than about the most familiar Australian birds. The following account is based on the material in the American Museum of Natural History which includes the Rothschild and Mathews collections. Where this material proved inadequate, additional specimens were borrowed from the United States National Museum, the Chicago Natural History Museum, the Museum of Comparative Zoology, and the Academy of Natural Sciences of Philadelphia (including parts of the Gould Collec- tion). We greatly appreciate the kindness of the curators of these institutions in making this material available. Ailuroedus crassirostris Paykull GREEN CATBIRD The only two Australian subspecies of this Australo-Papuan species are so different from each other that they were listed as 2 AMERICAN MUSEUM NOVITATES NO. 1602 two species in most of the older literature. However, their essential similarity, the agreement of habits, and the basic dif- ference from buccoides (New Guinea), the only other species of the genus, make it evident that crassirostris Paykull, 1815 (=viridis Vieillot, 1817), and maculosus Ramsay, 1875, must be considered as conspecific.
    [Show full text]