OF WASHINGTON, VOLUME 44, NUMBER 2, JULY 1977 219 coverslip method was 36% to 61%. Accumu- 95% in 48 hours. This is, however, a higher lated recovery by gravity pan flotation at 2, 4, range of recovery than was found with the al- 8, 16, 24 and 48 hours was 15, 27, 39, 44, and ternate methods investigated, and does not 51% (SD 2.01) respectively. Forty-eight-hour require elaborate equipment or constant atten- gravity pan flotation, without intervening agi- tion. tation, yielded only 12% of the total oocysts so that the range of recovery was 12% to 56%. GARY MCCALLISTER Recovery by gradient centrifugation was 69% Division of Biological Sciences (SD 1.56). The range was 52% to 73%. Mesa College Wassal and Denham reported 100% recov- Grand Junction, Colorado 81501 ery of Nematodirus ova after 3 hours and Vet- terling reported 100% recovery of coccidian LARI M. COWGILL oocysts at the rate of 1 man hr/1, whereas with Department of Zoology the Seinhorst method the maximum recovery of Brigham Young University Eimeria tenella oocysts ranged from 81% to Provo, Utah 84602 Research Note Helminth Parasites of Hooded Mergansers, Lophodytes cucullatus (L.), from Ontario The mergansers as a group are cosmopolitan latus from Ontario and constitutes the first de- in their distribution (Scott, 1968, A Coloured tailed study of the parasite fauna of this host. Key to the Waterfowl of the World, Wildfowl The viscera of 32 L. cucullatus (9 adults Trust, London, 91 p.). Three species are fre- and 23 immatures) were collected by hunters quently found in the Nearctic: the common during September and October, 1974 at two merganser, Mergus merganser (L.), the red- locations in Ontario: Cache Bay, Lake Nipis- breasted merganser, M. senator (L.), and the sing (46°22'N, 79°59'W) and Long Point, hooded merganser, Lophodytes cucullatus Lake Erie (42°40'N, 80°10'W). All material (L.). The latter is restricted to this region was deep frozen and examined at a later date (Kortright, 1967, The Ducks, Geese, and using conventional parasitological techniques, Swans of North America, Stackpole Co., Har- which included separating the various organs risburg, Pa. and Wildl. Mgmt. Inst., Washing- so that they could be examined individually, ton, D.C., 476 p.). The parasite fauna of M. and washing the gut contents through a screen merganser and M. senator is well known (vide with a 250-m/x mesh to collect the parasites. Lapage, 1961, Parasitology 51: 1-109; Mc- Techniques employed in the preparation of all Donald, 1969a, U.S. Fish. Wildl. Scrv. Spec. parasites prior to identification were listed by Sci. Eep. Wildl. 125, 333 p.; 1969b, ibid. 126, Andrews and Threlfall (1975, Proc. Helmin- 692 p.) However, little work has been done thol. Soc. Wash. 42: 24-28). Specimens of on that of L. cucullatus. The majority of works all the parasites recovered have been placed in which this species is mentioned are qualita- in the collection of the junior author. Infec- tive and not quantitative in approach, Lapage tions are recorded as prevalence (i.e., percent (1961, op. cit.) and McDonald (1969a, b, op. of birds infected) and intensity (i.e., average cit.) having provided host-parasite and para- number of helminths per infected individual). site-host lists, respectively, and bibliographies. Twenty species of parasites (excluding Ces- The present study was undertaken to deter- toda) were recovered from the host species mine the helminth fauna, if any, of L. cucul- during the present study, of which 17 were Copyright © 2011, The Helminthological Society of Washington 220 PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY Table 1. Helminths of 32 hooded mergansers from Ontario. Prevalence Intensity/infected bird Most common No. ( % ) birds location Parasite infected average range in bird* Diplostomum mergi Dubois, 1932f 4 (13) 6 1-13 3 (b) Tylodelphys com/era (Mehlis, 1846) ft 1 (3) 4 4 3 (a), 4 Apatemon gracilis (Rudolphi, 1819) 10 (31) 5 1-14 3 (a) Cotylttrus cornutus (Rudolphi, 1808)§ 15 (47) 8 1-28 3 (a) Cotylunts erraticus (Rudolphi, 1809 )§ 6 (19) 12 1-41 3 (a) Notocotylus attenuatus (Rudolphi, 1809)§ 2 (6) 3 1-4 3 (c), 5 Echinostoma revolutum (Froelich, 1802 )§ 4 (13) 2 1-4 3, 4 Echinoparypliium recurvatum (Linstow, 1873 )§ 6 (19) 2 1-5 3 (c) Echinoparypliium alegans (Looss, 1899 )§ 1 (3) 4 4 3 (b) Microphallus primas (Jagerskiold, 1908 )§ 2 (6) 2 1-2 3 (c) Prosthogonimus cuneatus (Rudolphi, 1809 )§ 14 (44) 3 1-2 4, 6, 7 Zygocotyle lunata (Diesing, 1836 )§ 1 (3) 1 1 3 (c) Psilostomum sp.§ 9 (28) 8 2-27 3 Stcphanoprora mergi Cannon, 1938§ 1 (3) 4 4 3 (c), 4 Capillara anatis ( Schrank, 1790 ) § 9 (28) 4 1-15 3 (cV, 5 Tetrameres sp. ( gravid female ) § 1 (3) 1 1 1 Streptocara crassicauda (Creplin, 1829) 2 (6) 2 1-2 2 Streptocara formosensis Sugimoto, 1930§ 4 (13) 1 1 2 Polymorphic cucullatus Van Cleave and Starrett, 1940 1 (3) 1 1 3 (c) Corynosoma constrictum Van Cleave, 1918§ 1 (3) 2 2 3 (c) * 1, provcntriculus wall; 2, below gizzard lining; 3, small intestine, (a) anterior, (b) mid, (c) posterior; 4, large in- testine; 5, caeca; 6, Bursa of Fabricius; 7, cloaca. § New host record. f New host/North American record. t New record for A n a t i d a e . new host records, two were new records for in Newfoundland. However, it should be noted North America, and one was a new record for that the results presented herein do not repre- the Anatidae. Among those collected were 14 sent the whole picture with regard to the species of Trematoda (12 genera), four of "normal" parasite burden of L. cucullatus due Nematoda (three genera), and two of Acan- to several factors. Firstly, most host specimens thocephala (two genera) (Table 1). Twenty- (97%) were collected in one location on the eight (87%) of the birds were infected. The same day within four hours of each other. Psilostomum sp. that was recovered did not fit Hosts examined by Turner and Threlfall (1975, the description of any of the known species op. cit.) and Bishop and Threlfall (1974, op. and will be described in the future. Cestodes cit.) were taken in several areas. Secondly, were recovered from 14 (44%) of the birds the hosts collected during this study were taken examined. The majority of specimens were too during the period of fall migration and at no poorly preserved to make exact determinations other time of the year. Buscher (1965, J. of numbers or species. However, it was pos- Wildl. Mgmt. 29: 772-781) studied the sea- sible to identify Schistocephalus solidus (Muel- sonal dynamics of helminth populations of ler, 1776) in six (19%) of the birds, two three species of anatids and provided evidence Hymenolepis spp. in seven (22%) of the birds, that there is a change in the parasite burden of and unidentified cestodes in two (7%). a host at different times of the year. The number of parasite species recovered Prior to this study nine species of helminths from hosts during the present study—range had been recorded from this host (vide Mc- 1-9 (mean 3) per infected bird—closely ap- Donald, 1969b, op. cit.) (three of Trematoda, proximates those found by Turner and Threl- four of Cestoda, one of Nematoda, and one of fall (1975, Proc. Helminthol. Soc. Wash. 42: Acanthocephala). Perhaps the reason that few 157-169), who reported 20 species of hel- parasite species have previously been recovered minth in Anas crecca L. (range 1—7, mean 2) is that in the past relatively few hosts were and 18 in Anas discors L. (range 1—8, mean 2) examined thoroughly. The sample size was from eastern Canada, and Bishop and Threlfall not large enough to compare statistically the (1974, Proc. Helminthol. Soc. Wash. 41: 25- helminth burdens of adults (9) with immatures 35), who recovered 23 helminth species (range (23). However, the data point to the im- 1—13, mean 8) from Somateria mollissima (L.) mature birds being more frequently infected Copyright © 2011, The Helminthological Society of Washington OF WASHINGTON, VOLUME 44, NUMBER 2, JULY 1977 221 and having a higher intensity of infection Council of Canada for the grant (NB.CC- than the adults. Buscher (1965, op. cit.) sug- A3500) to Dr. Threlfall which funded the field gested that this is probably because the young work. We thank Mr. Harry G. Lumsden and birds had not developed an age immunity to Dr. Robert M. Alison of the Ontario Ministry parasite infections. Also the feeding habits may of Natural Resources for help while the senior differ between the age classes; until a study author was in Ontario. This work would not of the stomach contents has been done this have been possible without the help of Peter can not be proven conclusively. Bain, Bill Maclntyre, Trevor Alcock, and many It is interesting to note that during this study other residents of Cache Bay, Ontario who col- one species of parasite, Microphallus primas, lected the majority of the host specimens. which is known to have a marine intermediate host (Deblock and Pearson, 1969, Ann. P a r a - GEOFFREY A. BAIN sitol. 44: 391-414) was recovered. Godfrey Dept. of Zoology (1966, The Birds of Canada, Queen's Printer, University of Western Ontario Ottawa, 428 p.) and Kortright (1967, op. cit.) London, Ontario both report L. cucullatus as being found infre- N6A 5B7 quently in areas of salt water; where it has been recorded from the marine habitat, it was WILLIAM THRELFALL during the winter. To date no evidence has Dept.