| inducing whole-assemblage change by experimental manipulation of habitat structure. | 1. habitat structure long has been identified as a primary factor influencing local assemblage composition. most evidence has been in the form of correlations of species occurrence and assemblage composition over a range of habitats, with experimental verification of relationships being relatively uncommon because of the difficulties of enacting precise manipulations of habitat structure. 2. fallen timber (also known as coarse or large woody debris) is one of the few habitat-structural elements ... | 2007 | 17584369 |
| chlamydial diversity and predictors of infection in a wild australian parrot, the crimson rosella (platycercus elegans). | members of the chlamydia genus are known to cause disease in both humans and animals. a variety of other species in the order chlamydiales are increasingly being discovered and emerging as potential pathogens, yet there are scarce data on the diversity, prevalence and impacts of these pathogens in wild birds. to address this gap, we investigated which chlamydiales species are present in a wild population of a common australian parrot, the crimson rosella (platycercus elegans). we collected cloac ... | 2020 | 32603529 |
| does human-induced habitat modification influence the impact of introduced species? a case study on cavity-nesting by the introduced common myna (acridotheres tristis) and two australian native parrots. | introduced species pose a major threat to biodiversity across the globe. understanding the impact of introduced species is critical for effective management. many species around the world are reliant on tree cavities, and competition for these resources can be intense: threatening the survival of native species. through the establishment of 225 nest boxes, we examined the relationship between tree density and the abundance and nesting success of three bird species in canberra, australia. the com ... | 2013 | 23716011 |
| phylogenetic analysis of beak and feather disease virus across a host ring-species complex. | pathogens have been hypothesized to play a major role in host diversity and speciation. susceptibility of hybrid hosts to pathogens is thought to be a common phenomenon that could promote host population divergence and subsequently speciation. however, few studies have tested for pathogen infection across animal hybrid zones while testing for codivergence of the pathogens in the hybridizing host complex. over 8 y, we studied natural infection by a rapidly evolving single-strand dna virus, beak a ... | 2014 | 25225394 |
| a non-invasive method to assess environmental contamination with avian pathogens: beak and feather disease virus (bfdv) detection in nest boxes. | indirect transmission of pathogens can pose major risks to wildlife, yet the presence and persistence of wildlife pathogens in the environment has been little studied. beak and feather disease virus (bfdv) is of global conservation concern: it can infect all members of the psittaciformes, one of the most threatened bird orders, with infection often being lethal. indirect transmission of bfdv through contaminated nest hollows has been proposed as a major infection source. however, data on whether ... | 2020 | 32566393 |
| beak and feather disease virus (bfdv) prevalence, load and excretion in seven species of wild caught common australian parrots. | pathogens pose a major risk to wild host populations, especially in the face of ongoing biodiversity declines. beak and feather disease virus (bfdv) can affect most if not all members of one of the largest and most threatened bird orders world-wide, the psittaciformes. signs of disease can be severe and mortality rates high. its broad host range makes it a risk to threatened species in particular, because infection can occur via spill-over from abundant hosts. despite these risks, surveillance o ... | 2020 | 32609774 |
| avihepadnavirus diversity in parrots is comparable to that found amongst all other avian species. | avihepadnaviruses have previously been isolated from various species of duck, goose, stork, heron and crane. recently the first parrot avihepadnavirus was isolated from a ring-necked parakeet in poland. in this study, 41 psittacine liver samples archived in poland over the last nine years were tested for presence of parrot hepatitis b virus (phbv). we cloned and sequenced phbv isolates from 18 birds including a crimson rosella, an african grey parrot and sixteen ring-necked parakeets. phbv isola ... | 2013 | 23411008 |
| feather mites of the genera <i>dubininia</i> and <i>cacatualges</i> (acari: xolalgidae) associated with parrots (aves: psittaciformes) of the old world. | this paper gives a systematic revision of feather mites of the genera dubininia vassilev, 1958 and cacatualges dabert, badek and skoracki, 2007 (xolalgidae: ingrassiinae) associated with parrots (aves: psittaciformes) of the old world. five new species are described: cacatualges probosciger sp. n. from probosciger aterrimus (gmelin) (cacatuidae) from new guinea, dubininia charmosynae sp. n. from charmosyna pulchella gray gr (psittaculidae) from new guinea, d. micropsittae sp. n. from micropsitta ... | 2017 | 28610269 |
| complex patterns of food allocation in asynchronously hatching broods of crimson rosellas. | in birds, asynchronous hatching typically leads to lower growth and survival of last-hatched chicks. however, all crimson rosella platycercus elegans, chicks grow at the same rate, although first-hatched chicks can be as much as seven times heavier than last-hatched chicks at the end of hatching. we examined the delivery and distribution of food to 18 rosella broods by videotaping feeds and simultaneously recording mass changes in the nestbox using a digital balance. parents visited the nest inf ... | 1999 | 10202083 |
| phylogenetic analysis of the australian rosella parrots (platycercus) reveals discordance among molecules and plumage. | relationships and species limits among the colourful australian parrots known as rosellas (platycercus) are contentious because of poorly understood patterns of parapatry, sympatry and hybridization as well as complex patterns of geographical replacement of phenotypic forms. two subgenera are, however, conventionally recognised: platycercus comprises the blue-cheeked crimson rosella complex (crimson rosella p. elegans and green rosella p. caledonicus), and violania contains the remaining four cu ... | 2015 | 26021439 |
| intraspecific geographic variation in rod and cone visual pigment sensitivity of a parrot, platycercus elegans. | variation in wavelength sensitivity among subspecies is unknown among vertebrates. the parrot platycercus elegans has extreme plumage variation between subspecies ranging from pale yellow to crimson which, with differences in background colour and light environment between subspecies, makes it a good candidate for the evolution of within-species differences in vision. we report differences in visual pigments between populations of p. elegans from two subspecies, providing the first known support ... | 2017 | 28128324 |
| is it benign or is it a pariah? empirical evidence for the impact of the common myna (acridotheres tristis) on australian birds. | there is widespread concern over the impact of introduced species on biodiversity, but the magnitude of these impacts can be variable. understanding the impact of an introduced species is essential for effective management. however, empirical evidence of the impact of an introduced species can be difficult to obtain, especially when the impact is through competition. change in species abundance is often slow and gradual, coinciding with environmental change. as a result, negative impacts on nati ... | 2012 | 22808210 |
| host heterozygosity and genotype rarity affect viral dynamics in an avian subspecies complex. | genetic diversity at community, population and individual levels is thought to influence the spread of infectious disease. at the individual level, inbreeding and heterozygosity are associated with increased risk of infection and disease severity. host genotype rarity may also reduce infection risk if pathogens are co-adapted to common or local hosts, but to date, no studies have investigated the relative importance of genotype rarity and heterozygosity for infection in a wild, sexually reproduc ... | 2017 | 29042596 |
| food allocation in crimson rosella broods: parents differ in their responses to chick hunger. | food allocation in many asynchronously hatching bird species favours large, competitively superior chicks. in contrast, food is usually distributed equally within broods of crimson rosellas, platycercus elegans, implying that parents do not simply feed the most competitive chick. we used two temporary removal experiments to manipulate hunger of: (1) individual first- or last-hatched chicks, or (2) the whole brood. when only a single chick was hungry, parents compensated fully and chicks gained t ... | 2000 | 10792929 |
| where and when does a ring start and end? testing the ring-species hypothesis in a species complex of australian parrots. | speciation, despite ongoing gene flow can be studied directly in nature in ring species that comprise two reproductively isolated populations connected by a chain or ring of intergrading populations. we applied three tiers of spatio-temporal analysis (phylogeny/historical biogeography, phylogeography and landscape/population genetics) to the data from mitochondrial and nuclear genomes of eastern australian parrots of the crimson rosella platycercus elegans complex to understand the history and p ... | 2008 | 18664434 |
| avian retinal oil droplets: dietary manipulation of colour vision? | avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. cones contain an oil droplet, rich in carotenoid pigments (except vs/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: platycercus ... | 2010 | 19939843 |
| dispharynx nasuta (nematoda:acuariidae) infection causing proventricular lesions and death in three captive rosellas (psittaciformes:psittacidae). | two adult male crimson rosellas (platycercus elegans) and an adult female eastern rosella (platycercus eximius) were found dead in their cages in a private aviary in march 2009, april 2010, and february 2010, respectively, without premonitory signs. their postmortem examination showed pectoral muscle atrophy and a distended proventriculus. the proventricular mucosal surface was covered with a gelatinous, whitish material, where a large number of nematode parasites identified as dispharynx nasuta ... | 2011 | 22946392 |
| learned vocal variation is associated with abrupt cryptic genetic change in a parrot species complex. | contact zones between subspecies or closely related species offer valuable insights into speciation processes. a typical feature of such zones is the presence of clinal variation in multiple traits. the nature of these traits and the concordance among clines are expected to influence whether and how quickly speciation will proceed. learned signals, such as vocalizations in species having vocal learning (e.g. humans, many birds, bats and cetaceans), can exhibit rapid change and may accelerate rep ... | 2012 | 23227179 |
| avian pox in crimson rosellas (platycercus elegans) in southern australia. | poxviral infection was identified in a crimson rosella presented to the australian wildlife health centre (victoria) in 2002, and from a second crimson rosella in 2008. both cases were characterized by proliferative lesions on non-feathered skin. routine histopathology identified intra-lesional epidermal changes consistent with those caused by poxvirus. electron microscopy confirmed the presence of poxvirus in inclusions in the first case, and genetic analysis of dna extracted from both cases fo ... | 2013 | 23581441 |
| how parrots see their colours: novelty in the visual pigments of platycercus elegans. | intraspecific differences in retinal physiology have been demonstrated in several vertebrate taxa and are often subject to adaptive evolution. nonetheless, such differences are currently unknown in birds, despite variations in habitat, behaviour and visual stimuli that might influence spectral sensitivity. the parrot platycercus elegans is a species complex with extreme plumage colour differences between (and sometimes within) subspecies, making it an ideal candidate for intraspecific difference ... | 2013 | 24259259 |
| do glucocorticoids or carotenoids mediate plumage coloration in parrots? an experiment in platycercus elegans. | conspicuous coloration can indicate phenotypic quality, and may reflect exposure or vulnerability to stress, or access to essential nutrients such as pigments. although the production of pigmented colours is well understood, much less is known about how structural colours are affected by physiological state. in this study, we tested whether glucocorticoids (corticosterone) predicted expression of plumage coloration in an australian parrot, the crimson rosella (platycercus elegans). parrots provi ... | 2019 | 31002829 |
| seasonal fluctuation of beak and feather disease virus (bfdv) infection in wild crimson rosellas (platycercus elegans). | understanding patterns of pathogen emergence can help identify mechanisms involved in transmission dynamics. beak and feather disease virus (bfdv) poses a major threat world-wide to wild and captive parrots. yet data from wild birds on seasonal fluctuations in prevalence and infection intensity, and thereby the potential high-risk times for virus transmission, have been lacking. we screened wild crimson rosellas (platycercus elegans) for bfdv in blood and cloacal swabs. prevalence in blood sampl ... | 2020 | 32398741 |