SHORT COMMUNICATIONS 423 ties (Walters 1990). This insistance on soli- DU PLESSIS,M. A. AND J. B. WILLIAMS. 1994. Com- tary roosting is not only expensive in terms munal cavity-roosting in Green Woodhoopoes: consequences for energy expenditure and the sea- of cavity construction, but is also extremely sonal pattern of mortality. Auk 111:292-299. costly for those group members, usually ju- FRAZIER, A. AND V. NOLAN. 1959. Communal roosting veniles, lacking access to their own roost hole. by the Eastern Bluebird in winter. -Banding Such supernumerary individuals are generally 30:219-226. forced to roost in the open (J. Walters, pers. KENDEIGH, S. C. 1961. Energy of conserved by comm.) where they are exposed to ambient roosting in cavities. Wilson Bull. 73: 140-147. KNORR, 0. A. 1957. Communal roosting of the Pyg- temperatures, precipitation, wind, and preda- my Nuthatch. Condor 59:398. tors. This suggests that, for the Red-cockaded LIGON. J. D. 1993. The role of phylogenetic history in Woodpecker, the costs of roosting communal- the evolution of contemporary avian mating and pa- ly within a cavity outweigh not only the costs rental care systems. Cum Ornithol. lO:l-46. of solitary roosting, but also the general ben- LIGON, J. D. AND S. H. LIGON. 1978. The communal efits of cavity roosting. social system of the Green Woodhoopoe in Kenya. Living Bird 17:159-197. SWINGLAND,I. R. 1977. The social and spatial organ- ACKNOWLEDGMENTS zation of winter communal roosting in Rooks (Car- Thanks to Rana Creek Ranch for allowing me ac- vus frugilegus). J. Zool. (Lond.) 182509-534. cess to their Acorn Woodpeckers and to Walter Ko- WEATHERHEAD,I? J. 1983. Two principal strategies of enig, Jeff Walters, and an anonymous reviewer for avian communal roosts. Am. Nat. 121:237-243. comments on the manuscript. Financial support was WEATHERHEAD,F! J. AND D. J. HOYSAK. 1984. Domi- provided by a NSF postdoctoral fellowship and NSF nance structuring of a Red-winged Blackbird grants to W. D. Koenig. roost. Auk 101551-555. WILLIAMS, J. B., M. A. DU PLESSIS,AND W. R. SIEG- LITERATURE CITED FRIED. 1991. Green Woodhoopoes (Phoeniculus purpureus) and obligate cavity-roosting provide a DU PLESSIS, M. A., W. W. WEATHERS, AND W. D. Ko- test of the thermoregulatory insufficiency hypoth- ENIG. 1994. Energetic benefits of communal esis. Auk 108:285-293. roosting by Acorn Woodpeckers during the non- ZELENY, L. 1977. Song of hope for the bluebird. Nat. breeding season. Condor 96:631-637. Geog. 151:854-865.

Wilson Bull., 110(3), 1998, pp. 423-425

Anting by an (Cinclus mexicanus)

Sophie A. H. Osborn ’

ABSTRACT.-Anting behavior has been recorded known to consume , my observation does not ap- in over 200 birds, yet its purpose remains unresolved. pear to lend support to either the molt-irritation or the Here I report an observation of anting in an aquatic food preparation hypotheses for this species. Received , the American Dipper (Cinclus mexicanus). 5 Dec. 1997, accepted 26 March 1998. The dipper was seen ants onto its remiges in a process known as “active” anting. Numerous hy- potheses exist for why birds , including controlling ectoparasites, inhibiting the growth of fungi or bacte- Anting behavior, in which a bird exposes ria, soothing skin irritated during the molting period, its and possibly skin to ants or other and removing toxic prior to food con- pungent substances (Whitaker 1957, Simmons sumption. Because of the timing and nature of the dip- 1966, Clayton and Vernon 1993), has been pers’ anting episode and the fact that dippers are not documented sporadically in the literature and its purpose remains unresolved. Although it is

I Div. of Biological Sciences, Univ. of Montana, observed infrequently, anting has been record- Missoula, MT 59812; ed in more than 200 avian species (see Gros- E-mail: [email protected]. kin 1950, Whitaker 1957, Potter 1970, Dun- 424 THE WILSON BULLETIN l Vol. 110, No. 3, September 1998 can 1976, Hendricks 1980, Post and Browne Smith). Both genera spray formic acid and are 1982), most of which have been . known to be used by anting birds (Groskin To date, only one record exists for anting in 1950). From my observation position, I could an aquatic species (Creutz 1952), the Eurasian not be certain whether the dipper was select- Dipper (Cilzclus cinclus). Here, I report an in- ing Formica neorujibarbis exclusively, or cident of anting in the American Dipper (Cin- whether it also selected one or more of the clus mexicanus), North Americas’ only truly Camponotus spp. that may have been attracted aquatic passerine. to the swarming Formica ants. All ants were I observed an adult American Dipper anting collected approximately one month after the on Blodgett Creek (elevation 1370 m), near observation, because high water prevented my Hamilton, Montana, on 12 July 1997. Just pri- being able to access the log any earlier. or to anting, the bird was engaged in two ae- The anting I observed conforms to descrip- rial chases and attacks with another dipper. At tions of “active” anting wherein a bird ac- 09:50 MST, the dipper flew to the end of a tively preens ants into its , as opposed downed log that was partially submerged in to “passive” anting in which birds settle on water across the stream from its nest. There, ants and allow them to crawl into their plum- it pecked into a hole (7.5 X 13.2 cm), where- age (Whitaker 1957, Potter 1970). Unlike upon numerous ants began to emerge. The many birds that have been described as anting dipper then picked up an ant and, holding its “frenetically” (Clayton and Vernon 1993) or right wing open, applied it with a preening while in apparent “ecstasy” (Ivor 1956), even motion to the ventral portion of its wing. The falling over in the process, the dipper I ob- entire process was then repeated, with the dip- served appeared to ant calmly, looking much per picking up a total of approximately 15 as though it were merely preening. ants. The bird concentrated its efforts primar- Numerous hypotheses exist for why birds ily on the axillary and secondary regions of ant. Anting may help control ectoparasites its right wing. It appeared to insert each ant (Groskin 1950, Simmons 1966) inhibit the near the base of the remiges and then to preen growth of fungi and owing to the an- down toward the tips. Several ants were ap- tibiotic nature of ant secretions (Ehrlich et al. plied to the base of the secondaries or sec- 1986), soothe skin irritated by rapid ondary coverts and into the axillaries without replacement during the molting period (Potter a downward preening motion. I may have 1970, Potter and Hauser 1974), or be a means overlooked anting of the birds’ primaries be- of removing toxic formic acid prior to food cause it was several seconds before I recog- consumption (Judson and Bennett 1992). My nized the dippers’ unusual alternation of peck- anting observation occurred prior to the dip- ing at ants and preening as anting behavior. pers’ presumed molting period and therefore Only one ant appeared to be used for each does not appear to lend support to the hy- preening bout and each ant appeared to be pothesis that anting is closely correlated with held among the feathers for only a few sec- feather replacement (Potter 1970, Potter and onds. I was not able to determine whether the Hauser 1974). American Dippers have been dipper consumed or discarded the ants after recorded molting only between July and Sep- using them. The anting bout was conducted in tember (Bent 1948, Sullivan 1973). Dippers full sunlight and lasted l-2 minutes. The bird molt after the dispersal of their young and un- did not vocalize while anting. dergo a brief molt-induced flightless period Ants that were later collected from inside (Sullivan 1965, 1973). The dipper I observed the hole in the log were identified as Formicu was still feeding its fledglings, which had left neorujibarbis (Emery). I suspect that the dip- the nest three days earlier. Dippers continue per was using this species for its anting bout to feed fledglings up to two weeks before the because it initially pecked into the hole nu- young disperse (Sullivan 1973). The anting merous times and then began picking up the dipper still retained all its remiges and rectri- ants as soon as they emerged. However, two ces and showed no obvious signs of having other species of ants were collected from the begun its molt. However, without having the immediate vicinity of the hole, Camponotus bird in hand, I could not confirm whether it vicinus (Mayr) and Camponotus laevigatus (E had started replacing its body feathers. Be- SHORT COMMUNICATIONS 425 cause dippers molt symmetrically (Sullivan CLAYTON, D. H. AND J. G. VERNON. 1993. Common 1973), the dipper I observed presumably Grackle anting with lime fruit and its effect on would have anted both wings if its anting bout ectoparasites. Auk 1 lo:95 l-952. CREUTZ, G. 1952. Einemsen (“anting”) bei Cinch. was correlated with feather replacement. Ant- J. Omithol. 93:174. ing birds frequently have been seen altemat- DUNCAN, S. 1976. Anting by a Scarlet Tanager and ing wings during bouts of anting (e.g., Wenny two Blue Jays in Massachusetts. Bird-Banding 1998). Although the female Eurasian Dipper 47:73. observed by Creutz (1952) in Germany anted EHRLICH, F? R., D. S. DOBKIN, AND D. WHEYE. 1986. the ventral and dorsal sides of both wings, it The adaptive significance of anting. Auk 103:835. did so in early April (in 1939), well before its GROSKIN, H. 1950. Additional observations and com- molt. Creutz was unable to identify the ob- ments on “anting” by birds. Auk 67:201-209. ject(s) with which the Eurasian Dipper anted. HALSTED, J. A. 1988. American Dipper nestlings par- Because dippers are not known to consume asitized by blowfly larvae and the northen fowl mite. Wilson Bull. 100:507-508. ants (Kingery 1996), it is also unlikely that HENDRICKS, P 1980. Anting by Common Crows. J. the American Dipper I observed was anting as Field Ornithol. 51:177-178. a means of food preparation. To my knowl- IVOR, H. R. 1956. The enigma of bird anting. Nat. edge, no information exists on ectoparasites, Geog. 110: 105-l 19. fungal pathogens, or bacterial infections of JUDSON, 0. P AND A. T. D. BENNE~. 1992. Anting‘ ’ dippers. However, dipper nestlings and nests as food preparation: formic acid is worse on an are known to be parasitized by ectoparasites empty stomach. Behav. Ecol. Sociobiol. 31:437- such as the northern fowl mite (Ornithonyssus 439. sylviarum; Halstead 1988). A nestling dipper KINGERY, H. E. 1996. American Dipper (Cinclus mex- of fledging age I found dead in the nest (4 icanus). In The birds of North America, no. 229 July 1997) in my study area was heavily in- (A. Poole and E Gill, Eds.). The Academy of Nat- fested with unidentified ectoparasites. Cause ural Sciences, Philadelphia, Pennsylvania; The American Ornithologists ’ Union, Washington, of death was unknown, yet the presence of D.C. ectoparasites suggested that adult dippers POST, W. AND M. M. BROWNE. 1982. Active anting by could become infested by nest and nestling the Yellow-shouldered Blackbird. Wilson Bull. parasites during brooding and/or feeding of 94:89-90. the young. More observations of anting in the POTTER,E. E 1970. Anting in wild birds, its frequency dipper are needed to adequately determine and probable purpose. Auk 87:692-713. whether this aquatic species gains the same POUR, E. E AND D. C. HAUSER. 1974. Relationship possible benefits from anting as do non-aquat- of anting and sunbathing to molting in wild birds. ic passerines. Auk 91:537-563. SIMMONS, K. E. L. 1966. Anting and the problem of ACKNOWLEDGMENTS self-stimulation. J. Zool. (Lond.) 149: 145-162. I am very grateful to R. Lang of the USDA for SULLIVAN, J. 0. 1965. “Flightlessness” in the dipper. identification of the ants and to D. Emlen for preparing Condor 67:535-536. the specimens. I thank B. Walker for translating SULLIVAN, J. 0. 1973. Ecology and behavior of the Creutzs’ (1952) article. Comments from J. Marks, D. dipper, adaptations of a passerine to an aquatic Wenny, and E. Potter substantially improved the manu- environment. Ph.D. diss., Univ. of Montana, Mis- script. This observation was made during a study fund- soula. ed by the USDA Forest Service, Rocky Mountain Re- WENNY, D. 1998. Three-striped Warbler (Badeuterus search Station, Bitterroot Ecosystem Management/Re- search Project, whom I sincerely thank. tristriatus) “anting” with a caterpillar. Wilson Bull. 110:128-131. LITERATURE CITED WHITAKER, L. M. 1957. A resume of anting, with par- BENT, A. C. 1948. Dipper. U.S. Nat. Mus. Bull. 195: ticular reference to a captive Orchard Oriole. Wil- 96113. son Bull. 69: 195-262.