Art. XXXVII.—Observations on certain External Parasites found upon the New Zealand Huia (Neomorpha acutirostris Gould) and not previously recorded.
[Read before the Wellington Philosophical Society, 7th September, 1920; received by Editor, 23rd November, 1920; issued separately, 8th August, 1921.]
In the course of compiling a table of measurements of the skin of a female specimen of the New Zealand huia (Neomorpha acutirostris Gould) formerly contained in the collection of Sir Walter L. Buller and now in my possession I detected upon the inner side of one of the large orange-coloured wattles which form so characteristic a feature at either side of the base of the bill of this bird a number of small wart-like excrescences which with the aid of a hand-lens proved to be a species of parasite belonging to the Ixodidae. The ticks, five in number, were scattered over the surface of the wattle, 2 mm. to 3 mm. separating the individuals, and so strongly were the mandibles embedded in the skin that considerable force was required to detach them. Although they were in a very shrunken and unsatisfactory condition for study, I was enabled by careful preparation to secure the specimens so that the identity of the species could be correctly established without question; and Mr. Cecil Warburton, of the Quick Laboratory,
New Museums, Cambridge, to whom I had entrusted them for identification, has with his usual generosity and kindness furnished me with the following notes as the result of his examination:—
“One of the ticks is Haemaphysalis leachi Audouin, and the others Hyalomma aegyptium (Linn.). The result is surprising … neither of them is a true Australasian tick, but H. leachi has been in Australia a long time. H. aegyptium, however, we thought had only recently reached there from Africa. Both ticks are common in India…. Was the bird by any chance kept alive in some aviary there before dying and being preserved? … If it acquired the ticks in its native habitat we shall have to revise our views as to the quite recent introduction of these species into Australasia.”
Fortunately, full and conclusive details bearing upon the origin and history of this identical huia's skin are available. The Indian theory we have to dismiss, for the skin formed one of the originals in a series of specimens collected jointly by Sir Walter L. Buller and Captain Mair on the Patitapu Range (some twenty miles from Masterton) on the 9th October, 1883, as recorded by Buller in his Supplement to the Birds of New Zealand. Sixteen specimens were then secured, and any doubt as to its being a New-Zealand-killed example may safely be set aside as invalid.
Another theory, however, strongly favouring the Indian origin of these parasites, may be traced directly to a period contemporary with the introduction of the mina (Acridotheres tristis) into New Zealand in the year 1875, and if the facts I have collected may be accepted as correct the introduction of the ticks Haemaphysalis leachi and Hyalomma aegyptium would likewise date approximately from that period. The strongest evidence we possess for supposing that the Indian mina acts as a host for both of these ticks is based upon the occurrence of examples of Hyalomma aegyptium in the larval phase upon a female of this bird from Burma, and eggs and an adult of Haemaphysalis leachi found upon a male shot in the Calcutta Botanical Gardens. Unfortunately, the remote probability of ever again meeting with the huia in a living state does not tend to assist in the successful prosecution of these inquiries; I am, however, awaiting the result of an examination of specimens of the mina living in New Zealand, which friends in Wellington and Hawke's Bay are kindly instituting on my behalf. Evidence as to the most probable means by which these ticks were transmitted to the huia may be gathered from the related experiences of early observers of the invasion by the mina of the particular areas of country comprising the huia's only known habitat in New Zealand. The aggressiveness of the imported foreigner led to many rival conflicts, during which a ready means of infection must have occurred. More retiring in its nature, the huia must have suffered severe and possibly fatal punishment from these attacks. Of this the late Mr. Taylor White was a frequent observer on his estate at Wimbledon, Patangata, Hawke's Bay, where the huia some twenty-years ago was not uncommon.
Instances are known in which the pugnacious mina has been a leading factor in expatriating certain of the endemic bird fauna of many of the oceanic islands into which it has been introduced. For instance, Henry Palmer, when collecting in the Sandwich Islands, records in his diary how this species is “very numerous and very harmful to the native birds”; and, again, MM. Alphonse Milne-Edwards and E. Oustalet attributed the extinction of the native starling (Fregilupus varius) in Bourbon to the mina introduced by Poivre in 1755.
The food of the huia largely consists of insects occurring among ground-herbage, more particularly a species of Coleoptera, the larva of which burrows in dead timber; and in searching for this food the bird is again liable to become infested by at least one of the species of ticks under discussion, for Mr. C. W. Howard records (Ann. Transvaal Museum, vol. 1, 1908, p. 104) how unfed adults of Hyalomma aegyptium “may be frequently found moving about the ground or hidden under bark of trees,” and there is no reason to doubt that a similar habit may also have been acquired by this species in New Zealand. Although we are without direct evidence, it is probable that Haemaphysalis leachi may be found in similar surroundings. From a date beginning about 1880 the huia, at all times an uncommon bird, seemed rapidly to decrease in numbers. This decrease and ultimate disappearance have given rise to much speculation, and it is possible that the persecution to which it has been subject by Maori hunters, the mercenary collector, and introduced animals cannot alone be called upon to account for its regrettable extinction. The question is raised as to whether we have not to recognize yet another of those disastrous factors by which the balance of nature has in this particular instance been disturbed through the introduction of these parasites into New Zealand, where they were previously unknown.
The specimen from which I collected the ticks under discussion had the wattles appreciably smaller and more shrunken than in any other example of the species I have at various times examined. Owing, however, to a distinct reduction in the length of the bill, and sundry white edgings to the under tail-coverts, I had looked upon this particular specimen as an immature bird Professor E. Ehlers has, however, gone to some length (Abh. Ges. Gotting., Bd. xxxix, pp. 35–43, 1894) in an endeavour to show that the length of the bill has no bearing upon the age of the individual.
We possess abundant evidence of the destruction caused by members of the Ixodidae in spreading disease and death among the animals they attack. A species of Argas has been know to infest fowls in South Africa, and to occasion so much loss of blood that the fowls die in great numbers. It has also been a subject for conjecture if the endemic New Zealand quail really owes its extinction altogether to the prevalence of bush and grass fires, and to the persecution of sportsmen and introduced carnivorous animals.
The two species of tick to which I have here directed attention are widely distributed throughout Africa, and Hyalomma aegyptium is also recorded from southern Europe, and ranges through Asia Minor to Persia and adjoining countries as far as China. Their hosts include almost all domestic and wild animals, numerous birds, and a tortoise. Haemaphysalis leachi transmits the distemper or malignant jaundice of dogs.
We have long known that the huia has been subject to attack from an endemic parasite belonging to the Mallophaga, but I am not aware if the identity of the species has ever been established, or if its specific characters are known. Every skin of Neomorpha that I have examined reveals the presence of the louse, by the great number of egg-cases, or nits, attached to the bases of the feathers, particularly in the orbital region; I have counted as many as ten of these nits attached to a single very small feather. The perfect insect I have never seen.