Some aspects of wildlife and wildlife parasitology in New Zealand Part 3/3 Part three: Kiwis and aspects of their parasitology Kiwis are unique and unusual in many ways. For a comprehensive and detailed review of the biology and status of the various kiwi species, the paper by Sales (2005) in the reading list is recommended. There are five (or 6) recognised species: the North Island Brown Kiwi (Apteryx mantelli), the Great Spotted Kiwi (Apteryx haastii), the Little Spotted Kiwi (Apteryx owenii), the Okarito Brown Kiwi ( Rowi ) (Apteryx rowi) and the Tokoeka (Apteryx australis) which some consider includes two species making six in total. All of them are classified as threatened and two as nationally critical with fewer than 150 birds remaining. Apart from the Little Spotted Kiwi which survives in predatorfree sanctuaries and the Rowi which has benefited from intensive predator control in its habitat, all other species are continuing to decline despite the major conservation efforts. In 1991, the Department of Conservation launched the Kiwi Recovery Programme (currently costing about NZ$12 million a year) to try to stop and reverse the decline in kiwi populations. There is a similar but smaller Kakapo Recovery Programme aimed at saving this unique flightless parrot from extinction. Left: a North Island Brown Kiwi chick: Right: another Brown kiwi chick sleeping off an anaesthetic. Both kiwi were patients in the New Zealand Wildlife Health Centre. Injured & sick kiwis are frequently brought to the Centre for treatment. Photographs by courtesy of the New Zealand Wildlife Health Centre, Massey University. All kiwis are flightless and nocturnal, roosting and nesting in burrows, generally in forest; they feed mainly on earthworms and other invertebrates which they locate by scent & sound while probing in the leaf litter and topsoil on the forest 20
floor with their long beaks. A kiwi s nostrils are close to the tip of the beak. Females lay very large eggs for their body size, usually two eggs in a clutch. In two species the males alone incubate the eggs after the first week but in the others incubation is shared. More research and recovery work has been done on the North Island Brown kiwi than the other species. Part of the Recovery Programme, particularly centred on the North Island Brown Kiwi, is a scheme known as Operation Nest Egg, managed by the Department of Conservation and supported by a major bank and public donations. Essentially this involves removing eggs from burrows, incubating them until the chicks hatch and then raising them in a protected environment until they reach a weight of about 1-1.2 kg. In some areas, the programme also involves capturing wild 2-3 week-old chicks as they are independent of their parents from hatching, and rearing them in the same way. At this weight they can be released into the wild with a muchimproved chance of survival to adulthood as they are considered big enough to fight off a stoat or ferret if attacked. Stoats & ferrets are the predators that kill the most kiwi chicks (as well as other birds); uncontrolled domestic dogs are also a serious problem in some places. Removal of an egg often results in repeat laying. A very high success rate is achieved by both methods and the various groups involved have released hundreds of kiwis into the wild. The only major disease problem encountered during rearing of the chicks was coccidiosis. Outbreaks of severe diarrhoea occurred often leading to deaths; large numbers of coccidial oocysts were found in the faeces. As coccidiosis had never been observed in kiwis in the wild and there was no record of oocysts in the faeces of wild birds, there was a question as to whether the species of coccidia involved were from other bird species. However, sporulation of the oocysts revealed two or three morphological types all of which were species of Eimeria (Charleston, unpublished). As species of Eimeria are highly host-specific this suggested that the coccidia were almost certainly specific to kiwis. More faecal samples from wild adult kiwis were examined and small numbers of oocysts were found in some, supporting the conclusion that the outbreaks were caused by coccidia that occur naturally in kiwis. Now that the cause of the problem in the rearing facilities has been identified, the infection is controlled by management and anticoccidial drugs. It is not known if clinical coccidiosis occurs in young kiwis in the wild but, as the population density is very low, it is probably rare. These kiwi coccidia are currently the subject of a research programme led by Kerri Morgan in the Wildlife Health Centre at Massey University, here in Palmerston North. Detailed retrospective studies of tissues from infected kiwi are in progress to identify developmental stages of the coccidia; these have revealed at least two types of schizont (meront) in the intestine, coccidial stages in the liver of about one third of birds examined and renal coccidia in about 20%. Molecular studies to characterise the DNA of the different species are also 21
in progress. Separating out the species is particularly difficult as experimental infections are impossible. So far the work has not reached the stage of publication except as conference abstracts. The relationship of the species to other Eimeria spp. whose DNA has been defined will be very interesting given the long evolutionary history of kiwi isolated on their island home. Some other interesting protozoal parasites have been found in kiwis. About ten years ago during routine blood sampling of some healthy North Island Brown Kiwi chicks captured for rearing, protozoa were observed in both erythrocytes and leucocytes in stained blood smears. Those in the erythrocytes were found to belong to the genus Babesia and subsequently named Babesia kiwiensis (Peirce et al. 2003 in the reading list). The birds were also infested with ticks, Ixodes anatis; this is an endemic species commonly found on kiwis (and other land birds) and is likely to be the vector. This is the only naturally occurring Babesia species recorded in New Zealand. It is not known if it infects other kiwi species or if it is significant to health, although most species infecting birds are not. Species of Babesia infecting mammals are not established in New Zealand as there are no suitable tick vectors. The protozoa found in the leucocytes were identified as a species of Hepatozoon and later named H. kiwii. This may also be transmitted by Ixodes anatis and it is the first species of Hepatozoon reported in New Zealand birds. Given the evolutionary history of kiwis, it will again be interesting to see how these two protozoa relate to those found in other places. One other endemic bird tick (Ixodes eudyptidis) and the only tick found on farm animals (Haemaphysalis longicornis - an introduced species), have also been found on North Island brown kiwi; it is not known if they transmit any parasites to kiwi. There is a single record of Plasmodium in a North Island Brown kiwi but it is not known which species it was or the significance of the infection. Plasmodium infections have been recorded in a wide variety of endemic, native and introduced birds in New Zealand, many of the records being incidental observations on blood samples. Little work has been done on these infections and although some have been identified as introduced species of Plasmodium, the identity of most of those recorded is uncertain. There are a number of endemic culicine mosquitoes in New Zealand so it would not be surprising if it was found that there are undescribed endemic species of Plasmodium as well. There are numerous records of other parasites from kiwis but very little is known about most of them. Kiwis are hosts to at least five species of feather mites; several of these have been found on more than one species of kiwi so they do not appear to be host specific. Kiwis are also host to eight species of chewing lice, belonging to two genera, with four species of each. Little is known about 22
their distribution in New Zealand, and their evolutionary relationships with other lice do not appear to have been studied. A surprisingly large variety of helminths have been recorded from kiwis including nine nematode species. Some of these are clearly introduced and not endemic kiwi parasites such as Toxocara cati, the common parasite of cats, and Porrocaecum ensicaudatum which is common in some introduced passerines. Others, however, including a species of Cyrnea (Spiruridae) and one of Heterakis do appear to be unique to kiwis but nothing is known of their biology or their significance to health. There are a number of records of cestodes in kiwis and, although they have often been given names, their true identity is not known. Avian cestodes are notoriously difficult to identify and almost impossible when the specimens are fragmentary and poorly preserved as is often the case in post mortem specimens. One trematode, Lyperosomum megacotylosum, has been found in the intestine of North Island Brown kiwi but nothing is known of its biology. It will be obvious that there is plenty of work that could be done on parasites of kiwis and this is equally true for parasites of other endemic bird species about which we generally know even less. But studying their parasites and other infectious diseases is not only difficult but also not a priority except where it becomes clear that they are threatening the health or survival of the host. Research funding is very limited and the reality is that the emphasis is mainly on conserving the host species. As a parasitologist, I would argue that conserving the parasites is just as important as conserving the hosts! However, for most non-parasitologists concerned with the conservation of host species, being concerned about conserving the parasites is difficult to accept as all infectious organisms, including parasites, are regarded as potentially harmful to their hosts and to be eliminated if possible, particularly when releasing birds into new environments! With highly endangered species, this is entirely understandable and perhaps the parasites will survive anyway as therapeutic agents are rarely 100% effective all the time. But in recent years it has become clear that parasites have important influences on host evolution and are an integral part of the host s natural environment. It would be good if more consideration could be given to the parasites and their relationship with their hosts after all, their evolutionary history also spans millions of years and is no less interesting than that of their hosts. 23
For more information, some suggestions for further reading: On the geological and evolutionary history of New Zealand, see: Gibbs, G.: Ghosts of Gondwana: The history of life in New Zealand : Craig Potton Publishing, 2006. On the extinct bird life and other aspects of New Zealand s natural history see: www.terranature.org On Kiwi biology, see: Sales, J. The endangered kiwi a review Folia zoologica 54: 1-20 (2005). On the discovery of Babesia and Hepatozoon in kiwis, see: Peirce, M. A., Jakob-Hoff, R. M. and Twentyman, C. 'New species of haematozoa from Apterygidae in New Zealand'. Journal of Natural History 37: 15, 1797-1804, (2003). On general conservation issues in New Zealand and related topics see also the Department of Conservation s website: www.doc.govt.nz For a list of helminth and protozoan parasites of kiwis see: McKenna, P.: An Updated Checklist of Helminth & Protozoan parasites of Birds in New Zealand. WebmedCentral PARASITOLOGY 2010 1 (9); WMC00705 For a review of ectoparasites of kiwis see: Heath, A.C.G. A review of ectoparasites of Apteryx spp. (kiwi) in New Zealand, with new host records, and the biology of Ixodes anatis. Tuhinga 21: 147-159 (2010). Tony Charleston Some aspects of wildlife and wildlife parasitology in New Zealand Part 1: Some background to New Zealand and its natural history (3/2011) Part 2: The arrival of humans (1/2012) Part 3: Kiwis and aspects of their parasitology (2/2012) 24