Philesturnus Carunculatus Research Articles

Some matchmaking advice when translocated immigrants are a population's last hope

Some matchmaking advice when translocated immigrants are a population's last hope

Differential patterns of diversity at microsatellite, MHC, and TLR loci in bottlenecked South Island saddleback populations

Differential patterns of diversity at microsatellite, MHC, and TLR loci in bottlenecked South Island saddleback populations

Mutual Wattle Ornaments in the South Island Saddleback (Philesturnus carunculatus) Function as Armaments

AbstractMany birds have ornamental traits that are expressed in both sexes. Wattles—colorful fleshy structures that hang from the lower bill—are frequent among birds, but remain poorly understood and are generally presumed to be under sexual selection. The South Island saddleback (Philesturnus carunculatus) is an endangered bird endemic to New Zealand in which both males and females possess wattles. We used behavioral observations, morphological measures, and a playback experiment to investigate the role of wattles in saddlebacks during territorial encounters. Wattles were monomorphic when controlled for body mass, and became engorged with blood in both sexes during visual displays. In a playback experiment using male song, wattle engorgement was significantly associated with territorial intrusions in males but not in females. However, female wattle engorgement was significantly more likely during playback experiments in the absence of their mate, suggesting wattles are used in territorial defense by both sexes. The markedly similar use of wattles by both males and females in visual displays as a response to territorial intrusions supports the hypothesis that these elaborate structures function in part as armaments.

Investigation of mortalities associated with Salmonella spp. infection in wildlife on Tiritiri Matangi Island in the Hauraki Gulf of New Zealand

CASE HISTORY: Salmonellosis was suspected as the cause of death in eight wild animals on Tiritiri Matangi Island, in the Hauraki Gulf of New Zealand, between November and September 2011, including three hihi (Notiomystis cincta), a tuatara (Sphenodon punctatus), a masked lapwing (Vanellus miles novaehollandiae), and a saddleback (Philesturnus carunculatus). An outbreak investigation to identify the source and distribution of infection was undertaken over the summer of 2011–2012. CLINICAL AND LABORATORY FINDINGS: Surveillance of five species of forest bird (n=165) in December 2011 returned a single positive result for Salmonella spp. Environmental sampling of 35 key water sources and hihi supplementary feeding stations conducted in December 2011 and March 2012 returned isolates of S. enterica subspecies houtenae and S. enterica serovar Saintpaul from a stream, a dam and a supplementary feeding station. The same serotypes were identified in tissue samples collected from post mortem specimens of the affected birds, and their similarity was confirmed by pulsed-field gel electrophoresis. DIAGNOSIS: Mortality in wildlife associated with infection with S. enterica subspecies houtenae and S. enterica serovar Saintpaul. CLINICAL RELEVANCE: This is the first detection of these Salmonella spp. from wild birds in New Zealand. Our study highlights how active surveillance in response to observed disease emergence (here mortalities) can provide important insight for risk assessment and management within populations of endangered species and inform risk assessment in translocation planning.

A new genus and two new species of feather lice (Phthiraptera: Ischnocera: Philopteridae) from New Zealand endemic passerines (Aves: Passeriformes).

The first descriptions of New Zealand endemic feather lice belonging to the Brueelia-complex (Phthiraptera: Ischnocera: Philopteridae) are given. The new genus Melibrueelia and new species M. novaeseelandiae are described, illustrated and compared with morphologically close taxa within the complex. The type host of M. novaeseelandiae is the tui, Prosthemadera novaeseelandiae (Gmelin, 1788), and an additional host is the bellbird, Anthornis melanura (Sparrman, 1786) (Passeriformes: Meliphagidae), both endemic to New Zealand. Also, the new species Brueelia callaeincola is described and illustrated from four endemic bird species belonging to two endemic genera and an endemic family: Philesturnus carunculatus (Gmelin, 1789) (the type host), Ph. rufusater (Lesson, 1828), Callaeas cinerea (Gmelin, 1788) and C. wilsoni (Bonaparte, 1851) (Passeriformes: Callaeidae). Brief discussions on possible evolutionary histories of the new taxa are included.

Avian malaria in New Zealand

Avian malaria parasites of the genus Plasmodium have the ability to cause morbidity and mortality in naïve hosts, and their impact on the native biodiversity is potentially serious. Over the last decade, avian malaria has aroused increasing interest as an emerging disease in New Zealand with some endemic avian species, such as the endangered mohua (Mohua ochrocephala), thought to be particularly susceptible. To date, avian malaria parasites have been found in 35 different bird species in New Zealand and have been diagnosed as causing death in threatened species such as dotterel (Charadrius obscurus), South Island saddleback (Philesturnus carunculatus carunculatus), mohua, hihi (Notiomystis cincta) and two species of kiwi (Apteryx spp.). Introduced blackbirds (Turdus merula) have been found to be carriers of at least three strains of Plasmodium spp. and because they are very commonly infected, they are likely sources of infection for many of New Zealand's endemic birds. The spread and abundance of introduced and endemic mosquitoes as the result of climate change is also likely to be an important factor in the high prevalence of infection in some regions and at certain times of the year.Although still limited, there is a growing understanding of the ecology and epidemiology of Plasmodium spp. in New Zealand. Molecular biology has played an important part in this process and has markedly improved our understanding of the taxonomy of the genus Plasmodium. This review presents our current state of knowledge, discusses the possible infection and disease outcomes, the implications for host behaviour and reproduction, methods of diagnosis of infection, and the possible vectors for transmission of the disease in New Zealand.

Differences in vocalisations, morphology and mtDNA support species status for New Zealand saddleback Philesturnus spp

Appropriate definitions of species limits are critical for scientific study and conservation management. Many subspecies of birds are defined on the basis of phenotypic variation. However, it has been suggested that following close examination many of these subspecies will be recognised as good species. North Island (NI) (Philesturnus rufusater) and South Island (SI) saddlebacks (P. carunculatus) differ in plumage and apparent vulnerability to introduced predators and, until recently, were considered subspecific. Here, we formally compare vocalisations, morphology and mtDNA between NI and SI saddlebacks. We show significant differences in male song and chatter calls which are fundamental saddleback vocalisations. A discriminant analysis correctly allocated 90% of birds based on significantly larger tarsus, weight and wing measurements in SI saddlebacks relative to NI saddlebacks. Finally, molecular data show c. 5% sequence divergence in mtDNA between the two groups. We concur with previous work elevating NI and SI saddleback to full species.

Characterization of MHC class II B polymorphism in bottlenecked New Zealand saddlebacks reveals low levels of genetic diversity

The major histocompatibility complex (MHC) is integral to the vertebrate adaptive immune system. Characterizing diversity at functional MHC genes is invaluable for elucidating patterns of adaptive variation in wild populations, and is particularly interesting in species of conservation concern, which may suffer from reduced genetic diversity and compromised disease resilience. Here, we use next generation sequencing to investigate MHC class II B (MHCIIB) diversity in two sister taxa of New Zealand birds: South Island saddleback (SIS), Philesturnus carunculatus, and North Island saddleback (NIS), Philesturnus rufusater. These two species represent a passerine family outside the more extensively studied Passerida infraorder, and both have experienced historic bottlenecks. We examined exon 2 sequence data from populations that represent the majority of genetic diversity remaining in each species. A high level of locus co-amplification was detected, with from 1 to 4 and 3 to 12 putative alleles per individual for South and North Island birds, respectively. We found strong evidence for historic balancing selection in peptide-binding regions of putative alleles, and we identified a cluster combining non-classical loci and pseudogene sequences from both species, although no sequences were shared between the species. Fewer total alleles and fewer alleles per bird in SIS may be a consequence of their more severe bottleneck history; however, overall nucleotide diversity was similar between the species. Our characterization of MHCIIB diversity in two closely related species of New Zealand saddlebacks provides an important step in understanding the mechanisms shaping MHC diversity in wild, bottlenecked populations.

Coccidia species in endemic and native New Zealand passerines

New Zealand native passerines are hosts to a large variety of gastrointestinal parasites, including coccidia. Coccidian parasites are generally host-specific, obligate intracellular protozoan parasites. In passerine birds, members of the genus Isospora are most common. Under natural conditions, these parasites seldom pose a threat, but stressors such as quarantine for translocation, overcrowding, or habitat changes may cause an infection outbreak that can severely affect wild populations. Although coccidia are important pathogens and have caused mortalities in kiwi (Apteryx spp.) and hihi (Notiomystis cincta), their prevalence, epidemiology, life cycles, and taxonomic relationships are still widely unknown in native New Zealand songbirds. Over a period of 3years (2007-2009), we examined 330 fecal samples of six native passerine species: tui (Prosthemadera novaeseelandiae), North Island saddleback (Philesturnus carunculatus rufusater), North Island robin (Petroica longipes), silvereye (Zosterops lateralis), and fantail (Rhipidura fuliginosa). The overall prevalence by flotation of coccidian infection in the New Zealand bird species examined was 21-38%, 21% in North Island robin, 38% in tui, and 25% in saddleback. Similar to prior studies in other countries, preliminary sequencing results suggest that coccidia in passerines in New Zealand are members of the family Eimeriidae, unlike the phenotypically similar genus Cystisospora of mammals. Using molecular methods, we identified at least five new genetically distinct Isospora species in the examined birds (three in tui and one each in saddlebacks and North Island robins).

PRESENCE AND SEASONAL PREVALENCE OF PLASMODIUM SPP. IN A RARE ENDEMIC NEW ZEALAND PASSERINE (TIEKE OR SADDLEBACK, PHILESTURNUS CARUNCULATUS)

The conservation and management of Saddlebacks (Philesturnus carunculatus) and other New Zealand birds, currently relies on the translocation of individuals to predator-free sites. Avian malaria has been identified as one of the diseases to be tested for prior to translocations in New Zealand, with the aim of translocating disease-free individuals. We describe avian malaria lineages and their seasonal prevalence in 2007-2008 in Saddlebacks from Mokoia Island, a source of birds for translocations, and investigate their pathogenicity. Three lineages of avian malaria were found at low prevalence (≤10.6%) and parasitemia (all but one infection were below 1/10,000 erythrocytes), typical of chronic infections. Two lineages clustered with previously identified lineages of Plasmodium relictum and one with a lineage of Plasmodium (Huffia) elongatum. Prevalence of malaria infection was higher in the spring with no significant difference in prevalence between juvenile and adult birds. We found no effect of stress on infections or any indication of pathogenicity.

The phylogenetic analysis of avipoxvirus in New Zealand

Avipoxvirus is known to be endemic in New Zealand and it is a cause of ongoing mortalities in the endangered black robin and shore plover populations. There is no information on the strains of avipoxvirus occurring in New Zealand and their likely origin or pathogenicity. This study was designed to identify the phylogenetic relationships of pathogenic avipoxvirus strains infecting introduced, native, and endemic bird species in New Zealand. Avipoxvirus 4b core protein gene was detected in tissue samples from 25/48 birds (52.1%) from 15 different species in New Zealand. Bootstrap analysis of avipoxvirus 4b core protein gene revealed that the New Zealand avipoxvirus isolates comprised of three different subclades. The majority of New Zealand avipoxvirus isolates (74%) belonged to A1 subclade which shared 100% genetic similarity with the fowlpox HPB strain. An isolate from a wood-pigeon (kereru) belonged to subclade A3, displaying 100% sequence homology to albatrosspox virus. An additional group, isolated from two shore plovers and one South Island saddleback, grouped within subclade B1 and presented 99% sequence homology to European PM33/2007 and Hawaiian HAAM 22.10H8 isolates. The results suggest that a variety of New Zealand bird species are susceptible to avipoxvirus infection, that there are more than two distinctive avipoxvirus subclades in New Zealand, and that the most prevalent A1 strain may have been introduced to New Zealand through introduced avian hosts such as passerines or poultry.

Concurrent avian malaria and avipox virus infection in translocated South Island saddlebacks (Philesturnus carunculatus carunculatus)

CASE HISTORY: Outbreaks of mortality in South Island saddlebacks (Philesturnus carunculatus carunculatus) that had been translocated to two offshore islands in the Marlborough Sounds of New Zealand were investigated during the summer of 2002 and 2007. Both outbreaks were associated with a severe decrease in numbers of saddlebacks of up to 60% of approximately 200 birds. CLINICAL AND PATHOLOGICAL FINDINGS: Many of the surviving birds were in poor condition, and had skin lesions on the legs and head. Necropsy showed pale liver and lungs, and a swollen spleen. Histopathology revealed schizonts resembling Plasmodium spp. within the cytoplasm of many hepatocytes and splenic histiocytes. The skin lesions consisted of epithelial proliferations containing numerous Bollinger bodies typical of avipox virus (APV) infection. Two different APV were isolated, using PCR, from two different birds exhibiting skin lesions. Each isolate had 100% sequence homology with APV members from either Clade A or Clade B. In addition, PCR analysis revealed that the Plasmodium elongatum present in infected birdsbelonged to a strain that was endemic in the population of North Island saddlebacks (Philesturnus carunculatus rufusater). DIAGNOSIS: Concurrent infections with Plasmodium spp. haemoparasites and APV were identified as the likely cause of death in the birds examined. CONCLUSIONS AND CLINICAL RELEVANCE: Although the Plasmodium spp. identified is thought to be endemic to saddlebacks in New Zealand, the affected birds were likely to be immunocompromised by concurrent APV infection or through lack of genetic diversity. Both the introduced mosquito Culex quinquefasicatus and the native mosquito Culex pervigilans are likely vectors for both these diseases, and the provision of water supplies less favourable to mosquito-breeding is recommended.

Microclimate of Natural Cavity Nests and Its Implications for a Threatened Secondary-Cavity-Nesting Passerine of New Zealand, the South Island Saddleback

Secondary-cavity-nesting birds occur widely throughout the world, but little information is available on the benefits of the nest's microclimate for such species, particularly for those using natural cavities. We investigated the influences of microclimate on a threatened secondary-cavity-nesting passerine, the South Island Saddleback (Philesturnus carunculatus carunculatus). Our aims were to determine whether (1) saddlebacks select tree cavities with microclimates less variable than those of other tree cavities in their surrounding territory, (2) whether structural aspects of tree cavities translate into certain microclimate characteristics, and (3) if less frequently used sites not in tree cavities (e.g., cavities in banks or in vegetation) have thermal properties similar to those of tree-cavity nests. We found that the saddleback's tree-cavity nests were more stable in temperature, more insulated against cold, and did not change temperature as rapidly as the ambient air or unused tree cavities. Regression analysis showed that of structural characteristics of tree cavities examined, only one, entrance width, was significantly associated with an aspect of microclimate (minimum temperature). Additionally, we found that regardless of cavity type the thermal properties of saddleback nest cavities were similar. These results indicate that saddlebacks likely select nest cavities with less variable thermal properties that are potentially beneficial, and future studies experimentally manipulating the variability of microclimate may be fruitful in determining the effect of microclimate on reproductive success. Nevertheless, this study is one of the first to demonstrate microclimate as a factor determining selection of natural nest cavities over available unused cavities.

Rapid recovery of an island population of the threatened South Island Saddleback Philesturnus c. carunculatus after a pathogen outbreak

The small size of many island populations of endangered birds, together with their high density, low genetic diversity and naivety to introduced pathogens, may render them vulnerable to disease epidemics. Such an outbreak occurred in an isolated population of threatened South Island Saddleback Philesturnus c. carunculatus on Motuara Island, New Zealand. In 2002, the population dropped from ~130 birds to ~60 birds, apparently from an outbreak of systemic coccidiosis. However, within three years the population had recovered to > 130 individuals. This appears to be the carrying capacity of the island as areas left vacant after the crash were re-occupied by the end of the third year. Reproductive success of saddlebacks was similar across the three years following the crash and there were no significant differences in clutch size, nesting success or fledgling mass as the population increased. In contrast, feather mite loads increased and leucocyte counts changed significantly in both adult and nestling saddlebacks as the population recovered, suggesting higher population densities may reduce immunocompetence. Although reproductive success did not appear directly affected by population size, our observations indicate increased levels of stress at high densities could render saddlebacks susceptible to recurring disease outbreaks.

Genetic monogamy in two long‐lived New Zealand passerines

High rates of extra‐pair paternity (EPP) can be relatively common in passerines whereas low rates or absence of EPP are often associated with taxa that are long‐lived and exhibit obligatory paternal care. We examined EPP in an under‐represented category: passerine species with relatively long life spans (or low annual mortality rates). Specifically, we studied EPP in New Zealand saddlebacks Philesturnus carunculatus and robins Petroica australis, two species with unusually low annual mortality rates (6.5–11% and 10–20% respectively). No EPP (0%) was detected in saddlebacks (39 pairs, 202 offspring) and only one case of EPP (1.9%) was detected in robins (54 pairs, 198 offspring). Genetic monogamy in these passerine species supports the hypothesis that low annual mortality rates play an important role in explaining variation in rates of EPP across species.

Assessing the ecological application of lasergrammetric techniques to measure fine-scale vegetation structure

In the study of habitat use by animals, it is important to sample vegetation structure or the degree of cover at different heights or in vegetation strata. Commonly-used techniques to estimate vegetation cover (e.g. point height intercept) are time-consuming and can be especially subjective in tall forest environments. We investigated the application of a Terrestrial Laser Scanner (TLS) to quantify forest structure, in terms of evenness and functional diversity. We also explored the suitability of the developed lasergrammetric technique (LGT) in the monitoring of nest site preferences of translocated populations of New Zealand endemic birds, the South Island saddleback ( Philesturnus carunculatus) and the New Zealand robin ( Petroica australis). At an acquisition rate of up to 6000 points per second and with an estimated error of less than 2 cm, the LGT technique utilises terrestrial scanners that allow collection and processing of field data rapidly and precisely. Further, LGT is able to account for small structural elements such as minor branches, leaves and vine stems. The derived measures (mean height of canopy (MCH), indices of structural evenness ( E var) and functional diversity ( FD var)) can quantified vertical variations in vegetation density but appeared highly dependent on the vertical scale of measurement. When applied to an ecological case study, results suggested that the LGT method provides complementary quantitative estimates to summary methods when assessing vegetation structure for micro-scale studies. However, further validations of the LGT accuracy are needed more specifically in relation to density of obstructing vegetation and when used in the measuring of small vegetative objects and total biomass estimates. The development of new software packages that easily convert large amounts of three-dimensional data collected using laser scanners, into a form ready for biostatistical analysis, also is strongly encouraged.

No evidence for loss of genetic variation following sequential translocations in extant populations of a genetically depauperate species

Repeated population bottlenecks can lead to loss of genetic variation and normally should be avoided in threatened species to preserve evolutionary potential. We examined the effect of repeated bottlenecks, in the form of sequential translocations, on loss of genetic variation in a threatened passerine, the saddleback (Philesturnus carunculatus carunculatus), a species that has recovered from a remnant population with historically low levels of genetic variation. Although a slight but nonsignificant loss of alleles may have occurred between the first-order translocation and the extirpated source population, first-, second-, and third-order translocated populations had very similar levels of genetic variation to each other. The most obvious difference among the seven island populations appeared to lie in allele frequencies with little or no loss of alleles among extant populations. Although sequential translocations are known to cause loss of variation in genetically diverse species, our study indicates that genetically depauperate species may be less sensitive to loss of genetic variation through founder events presumably because the few remaining alleles are well represented in founding individuals. These results show that ancient bottlenecks may have a long-term effect on genetic variation, to the extent that contemporary population bottlenecks may leave no appreciable genetic signature. Our results suggest that subjecting genetically depauperate endangered species to sequential translocations could be used to rapidly establish new populations without further eroding genetic variation.

Factors affecting the survival of founding individuals in translocated New Zealand Saddlebacks Philesturnus carunculatus

Successful founders of new populations may represent a non‐random sample of potential founding individuals. Using a recent Saddleback Philesturnus carunculatus translocation as a natural experiment, we related morphology, parasite load and genetic variation of translocated individuals to subsequent survivorship to assess the traits of successful founders. We also included capture location and holding time in our models to account for variables particular to translocations. Generalized linear model results suggest that, in addition to capture location, poor body condition (males) and the presence of ectoparasites (females) significantly reduced survivorship. Despite recent claims in the literature, we found no evidence that genetic variation was associated with survivorship or parasite load.

A new endemic family of New Zealand passerine birds: adding heat to a biodiversity hotspot

The results of phylogenetic analysis of two molecular datasets sampling all three endemic New Zealand ‘honeyeaters’ (Prosthemadera novaeseelandiae, Anthornis melanura and Notiomystis cincta) are reported. The undisputed relatedness of the first two species to other honeyeaters (Meliphagidae), and a close relationship between them, are demonstrated. However, our results confirm that Notiomystis is not a honeyeater, but is instead most closely related to the Callaeidae (New Zealand wattlebirds) represented by Philesturnus carunculatus in our study. An estimated divergence time for Notiomystis and Philesturnus of 33.8 mya (Oligocene) suggests a very long evolutionary history of this clade in New Zealand. As a taxonomic interpretation of these data we place Notiomystis in a new family of its own which takes the name Notiomystidae. We expect this new phylogenetic and taxonomic information to assist policy decisions for the conservation of this rare bird.

Successful island reintroductions of New Zealand robins and saddlebacks with small numbers of founders

Populations established with a small number of founders are thought to have a high risk of extinction due to Allee effects, demographic stochasticity, inbreeding and reduced genetic variation. We tested whether the initial number of birds released was related to persistence in reintroductions of saddlebacks (Philesturnus carunculatus) and robins (Petroica australis) to New Zealand offshore islands. Data were analysed for 31 populations that had been observed for at least 3 years since reintroductions. The numbers released ranged from 5–188. Most of the populations (26) survived and grew, including five from less than 15 founders, and four out of the five extinctions were attributable to introduced mammalian predators. The number of individuals released did not significantly affect extinction probability. The ability of these small releases to establish populations can be attributed to the closed nature of the islands (allowing birds to find mates), low mortality rates following release and high growth rates at low density. Stochastic simulation models based on data from two reintroduced populations suggested that populations with four founders (two male, two female) would have a negligible chance of extinction through demographic stochasticity and would be able to grow even if there were high rates of egg failure through inbreeding.