JULY, 1963] HELMINTHOLOGICAL SOCIETY 173 Whether the Rates

JULY, 1963] HELMINTHOLOGICAL SOCIETY 173

Whether the rates of increase would become inversely related at some later time or whether the apparent inverse relationship between rate of increase and initial population level results from all populations being observed at the "ceiling level," the higher initial populations reaching it earlier and maintaining it while the lower initial populations catch up, remains to be determined. The latter explanation appears more likely, especially in the absence of injury to the host. SUMMARY Scutdlonema brachyurum reproduced well in red clover. The rate of increase of population was directly related to the initial population level during a period of 21 weeks. During a period of 325 days a very high "ceiling level" appeared to have been reached without ill effect on the host. LITERATURE CITED CHAPMAN, R. A. 1958. An evaluation of methods for determining the number of nematodes in soil. U. S. Department of Agriculture Plant Disease Eeptr. 42: 1351-1356. COURSEN, B. W. and W. E. JENKINS. 1958. Host-parasite relationships of the pin nematode, Paratylenchus projcctus, on tobacco and tall fescue. U. S. Depart- ment of Agricultural Plant Disease Eeptr. 42: 865-872. JONES, F. G. W. 1956. Soil Populations of beet eelworm (Heterodera scliaclitli Schm.) in relation to cropping. Ann. Appl. Biol. 44: 25-56. SEINHORST, J. W. 1961. Plant-nematode inter-relationships. Ann. Eev. Microbiol. 15: 177-196. SHER, S. A. 1961. Revision of the Hoplolaiminae (Nematoda) I. Classification of the nominal genera and nominal species. Nematologica 6: 155-169.

Observations on the Nasal Mites of the Eastern Brown-Headed Cowbird (Molothrus ater ater) GORDON MARSTON CLARK* The socially parasitic nesting of cowbirds suggests the possibility that the nestling cowbird may acquire particular parasites from his foster parents and, further, that the foster parents of a cowbird can be predicted by an examination of certain of its parasites. Nasal mites should be ideal tools for this purpose. They are true endopara- sites, spending their entire lifetime within the nasal turbinates and respira- tory system of the host. They are generally quite specific, at least to the family level, in their acceptance of bird hosts, and they are highly adapted for their parasitic existence and cannot live for long outside of the turbinates. In addition, nasal mites commonly are spread by parent birds in the process of feeding their young. Current, limited knowledge indicates that coAvbirds do not support nasal mites normally found in non-icterid foster parents (Strandtinann and Fur- man, 1956) and that certain populations of cowbirds are infested with nasal mites infrequently, if at all (Clark, 1960). MATERIALS AND METHODS This paper re-explores this question by an examination of 208 eastern brown-headed cowbirds (Molotlirus a. ater) which include samples taken from icterid roosts at Montgomery, Alabama, in January 1960 (20 birds), Han- over, Pennsylvania, on February 26, 1960 (50 birds), March 22, 1960 (50 -Bureau of Sport Fisheries and Wildlife, Patuxent Wildlife Research Center, Laure?, Maryland. Present address: Rocky Mountain Laboratory, Hamilton, Montana.

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Copyright © 2011, The Helminthological Society of Washington JULY, 1963] HELMINTHOLOGICAL SOCIETY 175 birds), and February 14, 1962 (88 birds). These cowbirds were killed during trapping operations at the roosts and returned to the laboratory where the nasal turbinates were searched for mites with a stereomicroscope. All of the mites recovered from each bird were mounted in Hoyer's medium on a single slide so that a later count of the species and numbers of mites recovered from each bird could be made. RESULTS The genera Paraneonyssus, Ptilonyssus and Sternostoma of the family Ehinonyssidae and the genus Boydaia of the family Speleognathidae Avere found in these birds (Table I). The rate of infestation by all types of nasal mites ranged from 15 per cent in the sample taken at Hanover on February 14, 1962, to 55 per cent in the Montgomery sample. The most common genus was Paraneonyssus (8% to 30%), followed by Boydaia (2% to 30%), Ptilo- tmssus (2% to 15% and Sternostoma (0% to 2%). Double infestations, ranged from 0% to 20%, and consisted of three instances of Boydaia plus Paraneonyssus and two instances of Boy da-it plus Ptilonyssus, The following species of mites were represented: Paraneonyssus icteridius Strandtmann and Furman, 1956; Ptilonyssus sp.; Sternostoma- cryptorhyn- chiim Berlese and Trouessart, 1889; Boydaia quiscali Clark, 1960; and Boydaia sturnri Boyd, 1948. The number of nasal mites recovered from each infested bird ranged from 1 through 19 in single infestations, with an average of 3.4 mites per bird. In double infestations, the total mites per bird ranged from 3 through 18, with an average of 9.6 mites per bird (Table II). DISCUSSION The majority of the nasal mites recovered from the cowbirds in this study are species normally found in icterid birds. None has previously been re-

Table 2.—Numbers of nasal mites in the various genera carried by individual infested birds Number Number of birds in each sample Birds in Avith number of mites indicated Sample Sample Mite Genera in brackets Montgomery Paraneonyssus 1(1) 2(2) 1(4) Hanover, 2/26/60 2(1) 2(2) 1(3) 1(4) 1(8) 1(9) Hanover, 3/22/60 2(1) 1(2) 1(4) 1(9) Hanover, 2/14/62 3(1) 2(2) 1(4) 1(19)

Montgomery 20 Boydaia KD K3) Hanover, 2/26/60 50 1(1) Hanover, 3/22/60 50 1(2) 1(4) Hanover, 2/14/62 2(1) 2(2) Hanover, 3/26/60 50 Ktcrnostoma 1(3) Montgomery 20 Boydaia + 1(373.; IP.) 1(1223.; 6P.) Hanover, 2/14/62 88 Paraneonyssus 1(523.; 6P.) Montgomery 20 Boydaia + 1(273.; IP.) 1(613.; 5P.) Ptilonyss'its

Copyright © 2011, The Helminthological Society of Washington 176 PROCEEDINGS OF THE [VOL. 30, No. 2 ported from the eastern brown-headed cowbird (Strandtmann and Wharton, 1958). Paraneonyssus ictcridius has been recovered from the California cowbird, the meadowlark (Sturnella magna), the yellow-headed blackbird, the common red-winged blackbird, the tri-colored blackbird, Bixnver's blackbird, and the common grackle (Strandtmann and Fiirman, 1956). Botjdaia quiscali is normally found in grackles and redwings. 7?. ft turn i is a parasite of the starling, although we have also found it in grackles. Sternostoma cryptorliynclium is a parasite of the house sparrow (Furman, 1957). The species of Ptilonyssus recovered from cowbirds in this study appears new. It has not been found by us in other icterids, and is not conspecific with any others of this g'enus which we have recovered from local passeriform birds. Friedmann (1929) states that the birds most frequently parasitized by the cowbird in New York State are the red-eyed vireo, redstart, yellow warbler, chipping' sparrow, and song' sparrow, followed by the warbling vireo, yellow- throated vireo, chestnut-sided warbler, phoebe, veery, and wood thrush. Although the frequency may differ slightly in the southeastern states, it is apparent that the cowbird does not commonly lay a high percentage of its eggs in the nests of other icterids. It does so occasionally, however, for Fried- mann (1929) stated that cowbird eggs have been reported from the nests of the bobolink, redwing, meadowlark, orchard oriole, and common grackle. Since large numbers of cowbirds apparently are not raised by other icterids, the high incidence of nasal mites in cowbirds reported in this paper suggests that cowbirds become infested at an advanced age, through close association with other icterids and starlings at the winter roosts. The occurrence of Sternostoma crijptorhynclmm, normally a parasite of the house sparrow, is the only case which indicates that cowbirds may occasionally be infested by nasal mites by non-icterid foster parents. These results generally agree with the observation of Strandtmann and Furman (1956) that in cowbirds the host specificity of nasal mites is operative even in the face of ample oppor- tunities for cross transmission of parasites. SUMMARY An examination of four populations of eastern brown-headed cowbirds for nasal mites showed that as high as 55% may be infested by a total of five species of mites. These were Paraneonyssus ictcridius; Ptillonyss-us sp.; Sternostoma cryptorliynclmm ; Boydaia quiscali and Boydaia sturni. The single occurrence of Sternostoma cryptorliynclium, a normal parasite of the house sparrow, was the only indication in 208 birds examined that cowbirds may be infested with nasal mites by non-icterid foster parents. LITERATURE CITED CLARK, GORDON MARSTON. 1960. Three new nasal mites (Acarina: Speleognath- idae) from the gray squirrel, the common grackle, and the meadowlark in the United States. Proc, Helm. Soe. Wash., 27: 103-110. FRIEDMANN, HERBERT. 1929. The Cowbirds. Charles C. Thomas, Baltimore, Md., 421 pp. FURMAN, DEANE P. 1957. Revision of the genus Sternostoma Berlese and Troues- sart (Acarina: Ehinonyssidae). Hilgardia, 26: 473-495. STRANDTMANN, B. W. and D. P. FURMAN. 1956. A new species of mite, Para- neonyssus ictcridius, from the nasal cavities of blackbirds. Pan-Pac. Entom., 32: 167-174. anc] G. \y. WHARTON. 1958. A manual of mesostigmatid mites parasitic on vertebrates. Contribution $4, The Institute of Acarology. Univer- sity of Maryland, College Park.