Investigation of a mortality cluster in wild adult yellow-eyed penguins (Megadyptes antipodes) at Otago Peninsula, New Zealand.

We investigated an epidemic mortality cluster of yellow-eyed penguins (Megadyptes antipodes) that involved 67 moribund or dead birds found on various beaches of the Otago Peninsula, New Zealand, between 21 January and 20 March 2013. Twenty-four carcases were examined post-mortem. Histological lesions of pulmonary, hepatic and splenic erythrophagocytosis and haemosiderosis were found in 23 of 24 birds. Fifteen birds also had haemoglobin-like protein droplets within renal tubular epithelial cells. Despite consistent histological lesions, a cause of death could not be established. Virology, bacteriology and molecular tests for avian influenza, avian paramyxovirus-1, avipoxvirus, Chlamydia psittaci, Plasmodium spp., Babesia spp., Leucocytozoon spp. and Toxoplasma gondii were negative. Tissue concentrations of a range of heavy metals (n = 4 birds) were consistent with low level exposure, while examination of proventricular contents and mucus failed to detect any marine biotoxins or Clostridium botulinum toxin. Hepatic concentrations of total polycyclic aromatic hydrocarbons (PAHs) (n = 5 birds) were similar to background concentrations of polycyclic aromatic hydrocarbons previously found in yellow-eyed penguins from the South Island of New Zealand, but there were significantly higher concentrations of 1-methylnapthelene and 2-methylnapthelene in the birds found dead in this mortality cluster. The biological significance of this finding is unclear. A temporal investigation of the epidemic did not indicate either a common source or propagative epidemic pattern. Although our investigation did not definitively implicate a toxic or infectious agent, we could not rule out causes such as toxic marine organisms or mycoplasmosis. Further investigations should therefore by carried out in the event of future mortality clusters.

Extra-intestinal coccidiosis in the kiwi (Apteryx spp.).

Despite significant conservation intervention, the kiwi (Apteryx spp.) is in serious population decline. To increase survival in the wild, conservation management includes rearing of young birds in captivity, safe from introduced mammalian predators. However, an increase in density of immunologically naïve kiwi increases the risk of exposure to disease, including coccidia. Intestinal coccidiosis has recently been described in the kiwi, and although extra-intestinal coccidiosis was first recognized in kiwi in 1978, very little is known about this disease entity. This study used archived histological tissues and reports from routine necropsies to describe the pathology of naturally occurring extra-intestinal coccidiosis. At least 4.5% of all kiwi necropsied during 1991 to 2011 (n=558) were affected by extra-intestinal coccidiosis, and it is estimated that it caused death in 0.9 to 1.2% of kiwi in the study group. Four forms were recognized: renal, hepatic, and, less commonly, splenic and pulmonary. At necropsy, renal coccidiosis was associated with miliary white streaks and foci through the kidneys, renomegaly, and renal pallor or congestion. Renal meronts and gametocytes were confined to the distal convoluted tubules and collecting ducts, and were associated with renal tubular necrosis and tubular obstruction. Hepatic miliary pinpoint foci were present throughout the hepatic parenchyma associated microscopically with macromeronts measuring 304×227 µm. In two cases, clusters of splenic meronts were identified, and a similar lesion was identified in the pulmonary interstitium of another case. Juvenile, captive kiwi were most often affected with extra-intestinal coccidiosis, illustrating an increased expression of disease with population manipulation for conservation purposes.

Malaria parasites (Plasmodium spp.) infecting introduced, native and endemic New Zealand birds.

Avian malaria is caused by intracellular mosquito-transmitted protist parasites in the order Haemosporida, genus Plasmodium. Although Plasmodium species have been diagnosed as causing death in several threatened species in New Zealand, little is known about their ecology and epidemiology. In this study, we examined the presence, microscopic characterization and sequence homology of Plasmodium spp. isolates collected from a small number of New Zealand introduced, native and endemic bird species. We identified 14 Plasmodium spp. isolates from 90 blood or tissue samples. The host range included four species of passerines (two endemic, one native, one introduced), one species of endemic pigeon and two species of endemic kiwi. The isolates were associated into at least four distinct clusters including Plasmodium (Huffia) elongatum, a subgroup of Plasmodium elongatum, Plasmodium relictum and Plasmodium (Noyvella) spp. The infected birds presented a low level of peripheral parasitemia consistent with chronic infection (11/15 blood smears examined). In addition, we report death due to overwhelming parasitemia in a blackbird, a great spotted kiwi and a hihi. These deaths were attributed to infections with either Plasmodium spp. lineage LINN1 or P. relictum lineage GRW4. To the authors' knowledge, this is the first published report of Plasmodium spp. infection in great spotted and brown kiwi, kereru and kokako. Currently, we are only able to speculate on the origin of these 14 isolates but consideration must be made as to the impact they may have on threatened endemic species, particularly due to the examples of mortality.

Bilateral coxofemoral degenerative joint disease in a juvenile male yellow-eyed penguin (Megadyptes antipodes).

A juvenile, male, yellow-eyed penguin (Megadyptes antipodes) with abnormal stance and decreased mobility was captured, held in captivity for approximately 6 weeks, and euthanized due to continued clinical signs. Radiographically, there was bilateral degenerative joint disease with coxofemoral periarticular osteophyte formation. Grossly, the bird had bilaterally distended, thickened coxofemoral joints with increased laxity, and small, roughened and angular femoral heads. Histologically, the left femoral articular cartilage and subchondral bone were absent, and the remaining femoral head consisted of trabecular bone overlain by fibrin and granulation tissue. There was no gross or histological evidence of infection. The historic, gross, radiographic, and histopathologic findings were most consistent with bilateral aseptic femoral head degeneration resulting in degenerative joint disease. Although the chronicity of the lesions masked the initiating cause, the probable underlying causes of aseptic bilateral femoral head degeneration in a young animal are osteonecrosis and osteochondrosis of the femoral head. To our knowledge, this is the first reported case of bilateral coxofemoral degenerative joint disease in a penguin.

MUCOPOLYSACCHARIDOSIS II (MPS II) IN A FREE-LIVING KAKA (NESTOR MERIDIONALIS) IN NEW ZEALAND.

A lysosomal storage disease, identified as a mucopolysaccharidosis (MPS), was diagnosed in a free-living Kaka (Nestor meridionalis), an endemic New Zealand parrot, which exhibited weakness, incoordination, and seizures. Histopathology showed typical colloid-like cytoplasmic inclusions in Purkinje cells and many other neurons throughout the brain. Electron microscopy revealed that storage bodies contained a variety of linear, curved, or circular membranous profiles and electron-dense bodies. Because the bird came from a small isolated population of Kaka in the northern South Island, a genetic cause was deemed likely. Tandem mass spectrometry revealed increased levels of heparan sulfate-derived disaccharides in the brain and liver compared with tissues from controls. Enzymatic assays documented low levels of iduronate-2-sulfatase activity, which causes a lysosomal storage disorder called MPS type II or Hunter syndrome. A captive breeding program is currently in progress, and the possibility of detecting carriers of this disorder warrants further investigation.

Pruritic facial dermatitis in a population of free-living stitchbirds.

From September 2001 to February 2005, observations of an island population of the New Zealand stitchbird (Notiomystis cincta) revealed a progressive feather-losing dermatitis, which developed during the breeding season around the birds' eyes, base of the bill, and ventral neck. The lesions were significantly more likely to develop in males (96%) than females (51%), with males exhibiting a more severe form of the condition at the end of the breeding season. Histology from a dead bird revealed the presence of ovoid burrowing mites within the lesions, and isolation of mites from skin crusts of a live bird were identified as Knemidocoptes spp. Although other factors might be involved in the expression of the condition, Knemidocoptes appears to be a likely causative agent in the development of skin lesions in this population.

DIPHTHERITIC STOMATITIS IN YELLOW-EYED PENGUINS (MEGADYPTES ANTIPODES) IN NEW ZEALAND.

Diphtheritic stomatitis is a seasonal disease that has been recognized as a syndrome in Yellow-eyed Penguin ( Megadyptes antipodes ) chicks in New Zealand for >10 yr. It was present in about 50% of 234 chicks examined since 2002 and is characterized by a thick serocellular exudate in the oral cavity of 1-4-wk-old chicks. The syndrome includes inanition, weight loss, and death in many affected birds. Microscopically, the lesions varied in severity. Most affected chicks had severe, locally extensive, ulcerative stomatitis with large amounts of exudate containing numerous bacteria; a smaller number had mild focal lesions with smaller amounts of exudate and bacteria. Although Corynebacterium amycolatum has been consistently isolated from the oral lesions, it was also present in the oral cavity of 34% of normal adult penguins and their chicks and is not known to possess diphtheritic toxins. A primary viral pathogen was therefore suspected, and intracytoplasmic inclusion bodies were occasionally seen in oral mucosal epithelial cells. No herpesvirus DNA was detected with PCR. Avipoxvirus DNA and an unidentified virus-like agent were detected in some early oral lesions, but could not be confirmed in subsequent testing. Electron microscopy on early affected epithelium with intracytoplasmic inclusion bodies was unrewarding. Our findings raise the possibility that the disease is caused by an unknown primary virus infection followed by secondary Corynebacterium invasion, but this requires confirmation. The means of transmission has not been established but insect vectors are suspected.

Traumatic ventriculitis following consumption of introduced insect prey (Hymenoptera) in nestling hihi (Notiomystis cincta).

Nestling mortality in the endangered and endemic Hihi, also called Stitchbird (Notiomystis cincta), was studied over the 2008-09 breeding season at Zealandia-Karori Sanctuary, Wellington, New Zealand. Histopathology showed traumatic ventriculitis in seven of 25 (28%) dead nestlings. Single or multiple granulomas centered on chitinous insect remnants were found lodged within the gizzard mucosa, muscle layers, and ventricular or intestinal serosa. The insect remnants were confirmed as bee or wasp stings (Hymenoptera) using light and electron microscopy. Bacteria or yeasts were also found in some granulomas, and death was due to bacterial septicemia in four cases. Endemic New Zealand birds are likely to lack evolutionary adaptations required to safely consume introduced honey bees (Apis mellifera) and vespulid wasps (Vespula germanica [German wasp], and Vespula vulgaris [common wasp]). However, these insects are attracted to feeding stations used to support translocated Hihi populations. As contact between bees, wasps, and the endemic fauna of New Zealand seems inevitable, it may be necessary to minimize the numbers of these introduced insects in areas set aside for ecologic restoration.

Evaluation of the pathogenicity of avipoxvirus strains isolated from wild birds in New Zealand and the efficacy of a fowlpox vaccine in passerines.

Avipoxvirus (APV) infection is a highly contagious disease of birds and has been reported in more than 200 bird species, affecting both domesticated and free-ranging birds around the world. In New Zealand, at least three different strains of Avipoxvirus (APV) have been identified in a range of bird species.The pathogenicityof two APV strains isolated from wild birds in New Zealand, representing subclade A1 and subclade B1 were compared in zebra finches (Taeniopygia guttata). The efficacy of fowlpox vaccine at preventing clinical disease in passerines was also evaluated. Twenty-five zebra finches were divided into five groups (I-IV and a control group). Birds from Groups II and IV were vaccinated using fowl poxvirus vaccine prior to challenge. Subsequently two groups (I and II) were inoculated with a silvereye isolate (A1) and the other two groups (Group III and IV) were inoculated with a blackbird isolate (B1). Both inocula were previously propagated in chicken fibroblast cell culture. Birds in the control group were inoculated with sterile PBS. Skin thickness at the inoculation sites was measured and the development of additional skin lesions was monitored. Antibody development was measured by ELISA pre- and post virus inoculation. Both APV strains caused either swelling or hyperplasia at the inoculation site of non-vaccinated birds (4/5 in Group I and 5/5 in Group III). The swelling was milder and no foot lesions were observed in vaccinated birds before or after challenge with the silvereye or blackbird APV strains. These findings indicated that the fowlpox vaccine provided safe and appropriate protection for zebra finches exposed to the two wild APV strains and suggest that the vaccine has the potential to be used where APV threatens the captive management or translocation of endangered passerines.

The anatomy of the bill tip of kiwi and associated somatosensory regions of the brain: comparisons with shorebirds.

Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip organs and associated somatosensory brain regions are likely a result of similar ecological selective pressures, with inter-specific variations reflecting finer-scale niche differentiation.

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.

Facial bristle feather histology and morphology in New Zealand birds: implications for function.

Knowledge of structure in biology may help inform hypotheses about function. Little is known about the histological structure or the function of avian facial bristle feathers. Here we provide information on morphology and histology, with inferences for function, of bristles in five predominantly insectivorous birds from New Zealand. We chose species with differing ecologies, including: brown kiwi (Apteryx mantelli), morepork (Ninox novaezealandae), hihi (Notiomystis cincta), New Zealand robin (Petroica australis), and New Zealand fantail (Rhipidura fuliginosa). Average bristle length corrected for body size was similar across species. Bristles occurred in distinct groups on different parts of the head and upper rictal bristles were generally longest. The lower rictal bristles of the fantail were the longest possessed by that species and were long compared to bristles of other species. Kiwi were the only species with forehead bristles, similar in length to the upper rictal bristles of other species, and the lower rictal bristles of fantails. Herbst corpuscles (vibration and pressure sensitive mechanoreceptors) were found in association with bristle follicles in all species. Nocturnal and hole-nesting birds had more heavily encapsulated corpuscles than diurnal open-nesting species. Our results suggest that avian facial bristles generally have a tactile function in both nocturnal and diurnal species, perhaps playing a role in prey handling, gathering information during flight, navigating in nest cavities and on the ground at night and possibly in prey-detection. These differing roles may help explain the observed differences in capsule thickness of the corpuscles.

A new prey-detection mechanism for kiwi (Apteryx spp.) suggests convergent evolution between paleognathous and neognathous birds.

Kiwi (Apterygidae: Apteryx spp.) are traditionally assumed to detect their soil-dwelling invertebrate prey using their sense of smell. The unique position of the nares at the tip of the bill and the enlarged olfactory centres in the brain support this assumption. However, studies designed to show the importance of olfaction in prey-detection by Apteryx have provided equivocal results. Another family of probing birds, the Scolopacidae, detect their buried prey using specialised vibration and pressure-sensitive mechanoreceptors embedded in pits in the bill-tip. We found that aspects of the foraging patterns of Apteryx mantelli are like those of scolopacid shorebirds, suggesting that Apteryx may be using a similar prey-detection mechanism. We examined specimens of all five Apteryx species and conducted a morphological and histological examination of the bill of A. mantelli. We discovered that Apteryx possess an arrangement of mechanoreceptors within pits similar to that in Scolopacidae species and may therefore be able to localise prey using a similar vibrotactile sense. We suggest that this sense may function in conjunction with, or be dominant over, olfaction during prey-detection. The Apterygidae and the Scolopacidae are members of the two different super-orders of birds: the Paleognathae and the Neognathae, respectively. Therefore we cite the similar bill-tip anatomy of these two families as an example of convergent evolution across a deep taxonomic divide.

Sub-lingual oral fistulas in free-living stitchbirds (Notiomystis cincta).

Sub-lingual oral fistulas are a consistently observed lesion affecting the New Zealand stitchbird (hihi: Notiomystis cincta). This lesion, which has not been reported in other species, is usually only recognized when the tongue protrudes below the bird's mandible from a hole in the oral-cavity floor. In this study, we surveyed the prevalence of oral fistulas in a free-living population of stitchbirds on Tiritiri Matangi Island in 2002, 2003 and 2005. Between surveys, individuals with a fistula were caught and the progress of their lesion was monitored. The majority of birds with a fistula had a small localized lesion alongside the edge of the mandible without the tongue protruding. Oral fistulas were generally not associated with any reduction in the bird's condition or productivity, but if the tongue consistently deviated through the fistula it affected nectar-feeding efficiency. No fistulas were found in nestlings, but 9% to 10% of adult birds had some form of oral fistula, suggesting that it developed after fledging. Repeated measurement of birds showed that the size of the fistulas did not progress beyond the formation of the initial hole unless the tongue protruded. This protrusion resulted in continuous rubbing and erosion of the oral cavity floor and, ultimately, the mandible itself. Histopathology confirmed that fistulas occur in the thinnest part of the floor of the oral cavity, at the attachment point of the skin to the mandible. Despite long-term monitoring of this population, the formation of an oral fistula has never been observed and its aetiology remains elusive.

Development of the lung of the brushtail possum, Trichosurus vulpecula.

The developing lung of the brushtail possum, Trichosurus vulpecula, was studied by light microscopy, and transmission electron microscopy was used to study the morphology of the conducting airways in the adult. Bronchi did not extend beyond the hilus of each of the six lobes of the lung, and lobules were supplied by major bronchioles. By 105 days post partum, bronchi and bronchioles were fully formed, coinciding with the emergence of mucosal associated lymphoid tissue (MALT), which preceded alveolar maturation by approximately 20 days. In the adult lung, goblet cells were rarely observed in the mucosal epithelium of bronchi, whereas Clara cells were present in the mucosa of all airways, increasing proportionately as the conducting and respiratory portions narrowed distally. Although the airways of the possum lung have a poorly developed mucociliary blanket, this may be compensated for by the large numbers of Clara cells and adequate supply of MALT.