No special efforts were made to collect ectoparasites from the owls, but a few specimens of fleas and lice were collected. I am indebted to Miss Clay, of the Department of Entomology of the British Museum of Natural History for identifying the louse, which was Philopterus cursitans (Nitzsch 1861), a species found on A. noctua in Europe also. Dr Karl Jordan, of the Zoological Museum, Tring, kindly identified the flea, Ceratophyllus gallinae (Schrank 1803).
The intestine and caeca of 24 birds were opened and their contents examined for endoparasites. The only one found was an extremely slender nematode worm, kindly identified for me by Dr Bayliss, of the British Museum, as Capillaria tenuissima (Rudolphi, 1803). Of these 24 birds, 9 had no parasites, 9 had them in the caeca only, 5 had them in the intestine only, and 1 had them in both, a solitary one in the intestine and many in the caeca. The caeca of owls are large and are peculiar in having the closed end expanded into a pear-shaped sac. They usually have dark coloured glutinous contents,
unlike that of the intestine. The caeca only were examined in 20 owls, of which 6 contained nematodes. Infections were not very heavy. The 6 infected intestines contained only 15 worms, while 15 pairs of infected caeca contained 135 worms. This nematode is normally found in A. noctua in Europe. Two specimens of the Morepork, Ninox novaeseelandiae were also examined.*
It is interesting to find that while the introduced bird has only its introduced parasites, the native owl contained a cestode and two species of nematodes, one a Capillaria sp.
Though the numbers are not large enough to be conclusive there is a suggestion that the nematode is more common in the bush districts of South Otago and Southland than in the more open and drier Central Otago and Canterbury. Five birds were received from the Cromwell district and seven from localities in Canterbury. The intestine and caeca of two and the caeca only of the rest were examined and none contained nematodes. As will be seen from the figures given above, among the 32 southern birds examined, one individual out of every three had the parasites in its caeca.
In Europe the owl is known to be the host of certain Haemosporidia. No special attempt was made to look for the presence of these, but the blood of one or two specimens was examined. No blood parasites were noticed.
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[Footnote] * It should be noted that neither of these Moreporks met its death because of the investigation. One was found dead and the other was killed in mistake for a Little Owl on the ground that it destroyed native birds.