Dianne H. Brunton

Regeneration of the Heart in Diabetes by Selective Copper Chelation

Heart disease is the major cause of death in diabetes, a disorder characterized by chronic hyperglycemia and cardiovascular complications. Although altered systemic regulation of transition metals in diabetes has been the subject of previous investigation, it is not known whether changed transition metal metabolism results in heart disease in common forms of diabetes and whether metal chelation can reverse the condition. We found that administration of the Cu-selective transition metal chelator trientine to rats with streptozotocin-induced diabetes caused increased urinary Cu excretion compared with matched controls. A Cu(II)-trientine complex was demonstrated in the urine of treated rats. In diabetic animals with established heart failure, we show here for the first time that 7 weeks of oral trientine therapy significantly alleviated heart failure without lowering blood glucose, substantially improved cardiomyocyte structure, and reversed elevations in left ventricular collagen and beta(1) integrin. Oral trientine treatment also caused elevated Cu excretion in humans with type 2 diabetes, in whom 6 months of treatment caused elevated left ventricular mass to decline significantly toward normal. These data implicate accumulation of elevated loosely bound Cu in the mechanism of cardiac damage in diabetes and support the use of selective Cu chelation in the treatment of this condition.

The effects of nesting stage, sex, and type of predator on parental defense by killdeer (Charadrius vociferous): testing models of avian parental defense

SummaryTwo models predicting the temporal patterns of parental investment in offspring defense over the nesting cycle were tested. The first is based on offspring age, the other on the vulnerability of offspring to predation. Both models make very similar predictions for altricial species after eggs have hatched, i.e., increases in intensity of parental defense until fledging. For precocial species, however, the post-hatching predictions of each model are different: the offspring age model predicts a continued increase in defense intensity, while the vulnerability model predicts a decline. I examined the temporal patterns of parental defense of a precocial shorebird, the killdeer (Charadrius vociferus), and determined which model was supported. Killdeer responses to human and natural predators were observed. Killdeer were less willing to leave the nest, responded most intensely, and displayed closest to a potential predator around hatching. Defense intensity increased from early to late incubation as predicted by the offspring age model. However, after hatching killdeer parental defense declined for both males and females, thus supporting the vulnerability model for this stage. Males and females responded significantly differently to all types of predators. Males took greater risks, remained on the nest longer, defended offspring more intensely, and displayed closer to the predator than females at the approach of a potential predator. Responses to natural predators depended on the type of predator and the approach made by the predator; a greater range of defense behavior was used for predators approaching on the ground compared to aerial predators. In general, killdeer responses to humans were more intense and less variable than their responses to natural predators. This was most likely because the human intruder approached nests and chicks more directly and closer than natural predators.

Life history traits and food supplementation affect productivity in a translocated population of the endangered Hihi (Stitchbird, Notiomystis cincta)

We studied the effect of food supplementation, female age and clutch order on productivity in a translocated species. Food supplementation increased clutch size from 3.9 to 4.4 (average) eggs per nesting attempt, and more than doubled fledging and recruitment success. Supplemented females started a second clutch 9 days sooner after fledging first clutch chicks than unfed females. During second clutches, supplemented females incubated the eggs for a shorter period of time (15.2 days vs. 16.8). Older females laid larger clutches (4.6 vs. 3.7 eggs) than yearlings and incubated second clutch eggs for a shorter period (15.4 vs. 16.6 days). Females laid more eggs in first clutches (4.2 vs. 3.8 eggs), and those eggs took approximately 30% longer to lay than eggs in second clutches. The successful maintenance of hihi populations on the available islands may be dependent on the permanent provision of supplemental food at nest sites.

Optimal Colony Size for Least Terns: An Inter-Colony Study of Opposing Selective Pressures by Predators

, I compared breeding success and causes of nesting failure for Least Terns Sterna antillarum nesting in 11 colonies ranging from 2 to 606 nests in Connecticut, USA. Although the percentage of nests lost due to predation decreased with increasing colony size, the relationship between colony size and the impact of predators varied with the type of predator. A significant positive correlation was observed between colony size and nest loss due to Black-crowned Night-Herons (Nycticorax nycticorax). In contrast, a significant negative correlation was observed between colony size and nest loss duc to small mammals, Herring Gulls (Larus argentatus), and American Crows (Corvus brachyrhnchos). Thus, colonies of approximately 150 nests appear to be large enough for low impacts by small mammals, gulls, and crows, but small enough to be relatively unattractive to Black-crowned Night-Herons. Nest losses and chick mortality were significantly higher during 1988, mainly the result of increased levels of Black-crowned Night-Heron predation on large colonics. Overall, both hatching and fledging success of Least Terns did not increase with increasing colony size, although all colonies with fewer than 10 nests failed completely. Hatching and fledging success did not correlate with increasing nesting synchrony or increasing nest density during either year. However, nesting synchrony showed a significant negative correlation with both hatching success during both years and fledging success during 1988. Thus, less synchronous colonies showed a tendency to be more successful.

Sexual differences in reproductive effort: time-activity budgets of monogamous killdeer, Charadrius vociferus

Abstract By measuring the time allocated to various reproductive and somatic activities it was possible to look at differences in the strategies of the sexes for killdeer, a monogamous species. Killdeer time-activity budgets supported the general hypothesis that males and females maximize fitness in different ways. Males allocated more time than females to mating activities: mate attraction and territorial defence. However, the parental roles of the sexes were not those predicted for a monogamous species; males allocated more time than females to parental activities throughout a nesting attempt. Males appeared to be less time-constrained, and better able to perform parental activities. Females allocated more time to foraging than did males. It is suggested that the amount of time females allocated to parental activities is limited by the high energy demands of egg production. Further, high nest-failure rates may select for females maintaining good condition for re-nesting. The costs of desertion for killdeer were considerable. Adult removal experiments supported the hypothesis that two parents were necessary for successful reproduction. No individuals managed to raise offspring alone successfully. Lone males, however, were able to hatch chicks while females were not. The need for continuous parental attentiveness may results in selection for biparental care for killdeer.

The success of using trained dogs to locate sparse rodents in pest-free sanctuaries

Context. Better techniques to detect small numbers of mammalian pests such as rodents are required both to complete large-scale eradications in restoration areas and to detect invaders before they become abundant or cause serious impacts on biodiversity. Aims. To evaluate the ability of certified rodent dogs (Canis familiaris) to locate Norway rats (Rattus norvegicus) and mice (Mus musculus) or their scent trails at very low densities in field conditions. Methods. We experimentally tested two rodent dogs by releasing small numbers of laboratory rats and mice in a 63 ha rodent-free forest sanctuary and then determining if the dogs and their handlers could find the rodents and their scent trails. We divided the enclosure into two halves, east and west of the midpoint, and alternated releases daily between the two areas to minimise residual scent between consecutive trials. Radio-tagged rats or mice were released a total of 96 times at random locations that were unknown to handlers, followed for 50–100 m, then caught and either placed in hidden cages at the end of the scent trail or removed from the forest. Handlers and their dogs had up to 6 h to search for rodents. Key Results. Despite the extremely low density of rodents in the effective research area of 32 ha, both dogs were highly successful at finding rodents, together locating 87% of rats and 80% of mice. Handlers reported few false positive detections. We found that well-trained dogs can effectively cover 30–40 ha of steep forested habitat in half a day (6 h). Conclusions. Despite the limitations of our study design, we conclude that well-trained rodent dogs may be able to locate wild rodents at low densities in forest situations. Implications. Our results support the ongoing use of certified dogs to detect rodent survivors and invaders in conservation areas in New Zealand and elsewhere. Additional research is required to trial dogs on experimentally released wild rodents and to compare the cost-effectiveness of dogs with other detection methods.

First report of beak and feather disease virus (BFDV) in wild Red-fronted Parakeets (Cyanoramphus novaezelandiae) in New Zealand

Abstract Psittacine beak and feather disease (PBFD) is a highly infectious and potentially fatal viral disease of parrots and their allies caused by the beak and feather disease virus (BFDV). Abnormal feather morphology and loss of feathers are common clinical symptoms of the disease. PBFD also damages the lymphoid tissue and affected birds may die as a result of secondary bacterial or fungal infections. The disease is therefore of concern for conservation biologists and wildlife managers, as it is immunosuppressive and can become an additional threatening factor among critically endangered psittacines. We conducted a PCR-based screening for BFDV in a wild population of the Red-fronted Parakeet (Cyanoramphus novaezelandiae) on Little Barrier Island, New Zealand, during a translocation of this species. Fifty-four parakeets were captured and feather samples collected for molecular screening. We detected BFDV DNA from 15 individuals, but only two showed external signs attributable to PBFD, namely abnormal feather morphology or colouration, loss of feathers and haemorrhagic feathers. Our survey represents the first positive identification of BFDV in wild New Zealand endemic psittacines and confirms the risk of spread of the virus between wild populations within this global hotspot of endemic psittacine diversity.

The song structure and seasonal patterns of vocal behavior of male and female bellbirds (Anthornis melanura

The bellbird (Anthornis melanura) is a honeyeater endemic to New Zealand, which uses song to defend breeding territories and/or food resources year round. Both sexes sing and the song structure and singing behavior have not yet been quantified. The number of song types, spectral structure, repertoire size, and singing behavior of male and female bellbirds was investigated for a large island population. Song types differed between the sexes with males singing a number of structurally distinct song types and females producing song types that overlapped in structure. Singing behavior also differed between the sexes; males often sung long series of songs while females sung each song at relatively long and variable intervals. Singing by both sexes occurred year round but the frequency of male and female singing bouts showed contrasting seasonal patterns. The frequency of female singing bouts increased as the breeding season progressed, whereas male singing bouts decreased. In contrast to almost all studied passerines, female bellbirds exhibited significant singing behavior and sung songs of complex structure and variety that parallel male song. These results provide a quantitative foundation for further research of song in bellbirds and in particular the function of female vocal behavior.

The effects of translocation‐induced isolation and fragmentation on the cultural evolution of bird song

Understanding the divergence of behavioural signals in isolated populations is critical to knowing how certain barriers to gene flow can develop. For many bird species, songs are essential for conspecific recognition and mate choice. Measuring the rate of song divergence in natural populations is difficult, but translocations of endangered birds to isolated islands for conservation purposes can yield insights, as the age and source of founder populations are completely known. We found significant and rapid evolution in the structure and diversity of bird song in North Island saddlebacks, Philesturnus rufusater, in New Zealand, with two distinct lineages evolving in < 50 years. The strong environmental filters of serial translocations resulted in cultural bottlenecks that generated drift and reduced song variability within islands. This rapid divergence coupled with loss of song diversity has important implications for the behavioural evolution of this species, demonstrating previously unrecognised biological consequences of conservation management.

Bioacoustic distances between the begging calls of brood parasites and their host species: a comparison of metrics and techniques

A variety of bioacoustics distance metrics have been used to assess similarities in the vocalizations of different individuals. Here, we provide a detailed analysis of several acoustic similarity indices, some of which have been developed with the specific aim of characterizing the sensory coding of auditory stimuli. We compare different approaches through the analysis of begging calls of several passerine species and specialist brood parasitic cuckoos that putatively evolved to mimic their hosts. The different bioacoustics distances did not provide consistently correlated similarity patterns, implying that they are sensitive to different sound features. However, the encoded spectrogram alignment method was correlated with all other acoustic distance metrics, suggesting that this method provides a consistent approach to use when the perceptually salient sound parameters are unknown for a particular species. Our analyses confirm that statistical similarity of begging calls can be detected in a New Zealand pair of host and specialist parasite species. We also show detectable similarity in two other Australasian host–parasite pairs and another New Zealand system, but to a more limited extent. By examining phylogenetic patterns in the begging call diversity, we also confirm that specialist cuckoos have evolved to mimic the begging calls of their hosts but host species have not co-evolved to modify their calls in response to begging call similarity by the parasite. Our results illustrate that understanding the function and mechanism of behavioral copying and mimicry requires statistically consistent measures of similarity that are related to both the physical aspects of the particular display and the sensory basis of its perception.