Vocal mimicry

What is vocal mimicry? Vocal mimicry occurs when an individual learns a sound from another species or the environment. It differs from other animal vocalisations such as bird song or human speech, as these are learned from members of the same species (conspecifics). Parrots are the most renowned mimics, with reports of their talents dating back at least to the early 1500s with Henry VIII of England's pet African grey parrot, Psittacus erithacus, which mimicked his servants' voices.

Impact of saltmarsh disturbance on seed quality of Sarcocornia (Sarcocornia quinqueflora), a food plant of an endangered Australian parrot

The article presents a study which evaluates the impact of saltmarsh perturbation on seed quality of Sarcocornia which is a food for the endangered Orange-bellied parrot in Australia. It notes the significant impact of grazing on the energy and availability of Sarcocornia seeds in saltmarshes and indicates that graze-free saltmarshes with regular inundation provide the highest potential for Sarcocornia seed availability. Further, the substantial factor of soil characteristics and salinity of flood water and inundation on the seed production of Sarcocornia is also discussed.

Ultraviolet vision, fluorescence and mate choice in a parrot, the budgerigar Melopsittacus undulatus

As in many parrots, the plumage of the budgerigar Melopsittacus undulatus reflects near-ultraviolet (UVA) wavelengths (300-400 nm) and exhibits UVA-induced fluorescence. However, there have, to our knowledge, been no tests of whether the yellow fluorescence observed under intense UVA illumination has any role in signalling. Four experiments were carried out on wild-type budgerigars, where the presence and absence of UV reflectance and fluorescence were manipulated using filters. Few studies have attempted to separate the contribution of UV reflectance to plumage hue as opposed to brightness or distinguish between a role in sexual as opposed to social preferences. However, our first experiments show that not only do females consistently prefer UV-reflecting males, but also that the observed preferences are due to removal of UV affecting the perceived hue rather than brightness. Furthermore, we found no effect Of the light environment on male response to females, suggesting that the female preferences relate to plumage colour per se. Whilst UV reflectance appears important in heterosexual choice by, females, it has no detectable influence on same-sex association preferences. The results from the second series of experiments suggest that enhancement of the budgerigar's yellow coloration through fluorescence has no effect on male attractiveness. However, the fluorescent plumage may play a role in signalling by virtue of the fact that it absorbs UVA and so increases contrast with nearby UV-reflecting plumage. Our study provides convincing evidence that UV reflectances can play a role in mate choice in non-passerines, but no evidence that the yellow fluorescence observed under UVA illumination is itself important as a signal.

Parrot interpreter : representation, extinction and the electronic information environment

Carter discusses insights and ideas on and about parrots, based on his book of the same name. Parrot understanding is an understanding of the critical role noise plays in binding man together, and in relating to the external world whose resistance to translation is not a source of anxiety but a phenomenon respectfully to embrace. Moreover, the most remarkable thing about parrot is not perhaps that it speaks but that it listens.

Coloration and colour vision in a parrot ring species

Ring species, in which reproductively isolated forms are connected by a chain of intermediate populations, provide valuable insights into the maintenance of trait variability, divergence in sympatry, and the how small changes can lead to species level differences. The parrot Platycercus elegans of eastern Australia is highly variable in plumage coloration in the wild, ranging from pale yellow to deep crimson in the chest, rump and head. It has been suggested as the only known parrot ring species worldwide, and one of less than ~25 ring species amongst all organisms. We test hypotheses for the information signalled by the colour variation, and for the maintenance of the variability.

Hope for resurrecting a functionally extinct parrot or squandered social capital? Landholder attitudes towards the Orange-bellied Parrot (Neophema chrysogaster) in Victoria, Australia

In early 2010, after 27 years of recovery effort, the orange-bellied parrot (OBP; Neophema chrysogaster) was expected to be extinct in the wild within a few years. Shortly before the imminent wild extinction became evident, we surveyed landholders (114 responses of 783 surveys delivered) in part of the main non-breeding area, according to three classes of modelled habitat suitability ('high', 'medium', and 'low'). Predictions of the habitat models appear to correlate with landholder perceptions of the presence of OBP habitat on private land, thus the models appear a tractable way to identify key stakeholders worthy of priority consultation in relation to habitat works. Landholders were sympathetic to wetlands and birds, including OBPs (89.4% were aware of OBPs). Most indicated that they would be upset if the OBP went extinct and agreed that critical habitat should be protected; 80.7% were prepared to consider changes to the way they managed their land to benefit the species, and sought more information on how they could do so (64.0%). This study suggests that the habitat model usefully identified key stakeholders and the OBP enjoyed high awareness, concern, and engagement among many stakeholders, shortly before the species was considered functionally extinct. The maintenance of landholder support is likely to be critical if future attempts are made to reintroduce the species to the wild.

Ground-based survey methods both overestimate and underestimate the abundance of suitable tree-cavities for the endangered Swift Parrot

Most cavity-dependent species select tree-cavities with a narrow range of characteristics so that only a small subset of available cavities may be suitable for any species. Most surveys for tree-cavities are done from the ground using binoculars to reduce effort, but this technique is prone to error. These errors are likely to contribute to the loss of the cavity resource when used to inform conservation efforts for cavity-dependent species. The Swift Parrot (Lathamus discolor) is an endangered migratory bird threatened by ongoing removal of cavity-bearing trees by production forestry. We climbed trees with cavities used for nesting by Swift Parrots and determined that they prefer cavities with small entrances, deep chambers and wide floors. Such cavities are rare and occur in large trees that support higher than average numbers of tree-cavities. Importantly, cavities used by Swift Parrots were also likely to be both overestimated and underestimated using ground-based surveys, and without calibration by climbing, the size and direction of survey error could not be determined. We conclude that the most effective way to gain detailed information about the characteristics and abundance of tree-cavities is to climb a representative sample of trees to calibrate ground-based methods for a specific ecosystem.

Is there variation in the response to contact call playbacks across the hybrid zone of the parrot Platycercus elegans?

Learned vocal signals could be important in the formation of prezygotic isolation between two hybridising taxa. This study examined whether vocal variation in the parrot Platycercus elegans facilitates the separation of individuals from two subspecies, P. e. elegans (CR) and P. e. flaveolus (YR). CR and YR have very different plumage coloration, respectively deep crimson and pale yellow, but hybridise where they meet creating an intermediate population (WS). In a factorial design playback experiment, we conducted 108 playback trials on three focal populations (YR, WS, CR), in and around this area of hybridisation, to test if they respond differently to contact calls from their own or another population. We also analysed whether differences in acoustic variables of the stimulus calls predicted the response to the call. We did not find any indication that individuals from the three focal populations responded differently to calls sampled from their own or another subspecies. We did find an effect of two of the five acoustic variables that we used to describe and classify contact calls from the three source populations. Specifically, duration of the stimulus call positively affected the response from individuals from WS and negatively the response from CR, and CR responded more to stimulus calls with a lower peak frequency. Overall, we found no indication that acoustic variation in contact calls on a subspecies level is involved in maintaining plumage colour differences between P. e. elegans and P. e. flaveolus subspecies.

How does nest box temperature affect nestling growth rate and breeding success in a parrot?

Climate change is predicted to affect many species by reducing range, habitat suitability and breeding success. Cavity-nesting species, already threatened by deforestation and declining natural hollows, may be particularly at risk because they are limited in nest-site location, and climatic alterations may further reduce usability of natural cavities. It is therefore essential to determine how cavity-users may be affected. We recorded internal nest box temperatures and modelled the relationships of four temperature parameters (relating to mean temperature, variability in temperature, low temperature extremes and high temperature extremes) with breeding success and nestling growth in an Australian cavity-nesting parrot, the Crimson Rosella (Platycercus elegans). We found that less extreme low temperatures resulted in heavier nestlings; however, higher mean temperatures tended to result in lighter nestlings. Greater temperature variability tended to reduce fledging success; however, no temperature variables had a clear effect on clutch size or hatching success. Our findings indicate that there may be a complex relationship between nestling growth and temperature, and although less extreme cold temperatures may benefit nestlings, continued increases in mean temperature and variability may have negative consequences.