Floating and Swimming in Passerines

FLOATING AND SWIMMING IN PASSERINES

StevenSpeich and M. Allen Speich

A recent controversyinduced us to submit our observationsand experimentson the survivalvalue and mode of swimmingby small passefine birds. Schemer (1969) observed a Willow Warbler (Phylloscopustrochilus) spreading its wingsand tail when floatingin water and concluded that the behavior enabled the bird to stay afloat. However,Jackson (1970) questionedwhether this behavior was not "... merely part of the swimmingmovement..." and correctly pointed out that air trappedin the featherswas sufficient to keep a bird afloat without the spreadingof the wingsand tail. Our observationsof floating Cliff Swallows(Petrochelidon pyrrhonota), Barn Swallows (Hirundo rustica), and House Sparrows (Passer domesticus)suggest that even the passivespreading of the wingsand tail aids in survival. There are but a few examplesin the literatureof passefinesusing their wings for swimming. In addition to the Dipper (Cinclus mexicanus),which actively usesits wingsin swimmingunder water and occasionallyon the surface,the followingpasse fines have been observedsurface-swimming: Bank Swallow (Riparia riparia; Stoner, 1928 and 1936); Barn Swallow(Jackson, 1970); Catbird (Dumetella carolinensis;Petrides, 1942); Robin (Turdus migratorius; Broun, 1943); Willow Warbler(Schemer, 1969); HouseSparrow (Hickling, 1950; Creutz, 1953); and EuropeanTree Sparrow(Passer montanus; Hickling, 1950). Apparently all of the above passefines,possibly excludingthe Dipper, employ what is describedas the "butterfly" stroke (Jackson,1970) to propel themselvesacross the water. This strokein birds is analogousto the movementsof the armsby man in performingthe "butterfly." We now add four more passefine speciesthat swim using the "butterfly" stroke. B. Deuel (pets. comm.) observedin September 1969 at Malheur National Wildlife Refuge, Harney Co., Oregon, a Long-billedMarsh Wren (Telmatodytespalustn's} that fell into the water. The floating bird immediately swam to shore and dimbed onto a bank. The bird was picked up and placedon a branch,where it sat with its feathersfluffed for fifteen minutesbefore flying away. In July 1965 at the Desert National Wildlife Range, Clark Co., Nevada, Deuel (pets. comm.) saw a Tree Swallow (Iridoprocne bicolor} fall into the water while skimmingthe water surfaceand Calif. Birds3: 65-68, 1972 65 SWIMMING PASSERINES then swim towardsshore. On 27 April 1970 we startleda nestling Black Phoebe {Sayornisnigricans} in a highway culvert near Clarks- ville, E1 Dorado Co., California. It fluttered from its nest and landed six feet from shore in a stagnantpool, where it floated on outstretchedwings for thirty secondsbefore swimmingto shore.On approximately 25 occasionsbetwen 1967 and 1970 we observed individual Cliff Swallowsthat fell into water during both day and night banding operationsat breedingcolonies. These mishapswere mainly in concreteculverts beneath highways.The behaviorof the adult birds in water varied. During nocturnal banding operations individualadults often floated with spreadwings and tail for several minutes until retrievedby banders.However, some birds swamabout erraticallyand then restedfor shortperiods. During the day, downed birds generallytried to swim out of the culvert,using the "butterfly" stroke, to a nearby bank or emergentobject. If the water was moving,the downedbirds usuallydrifted passivelyout of the culvert and then swamto safety. On the afternoon of 4 July 1970 we examined swallow nests under a wooden bridge near Minden, DouglasCo., Nevada.Irrigation water three to four feet deep in a canal fifteen feet wide flowed under the bridge. Our activitiesinduced five full-sizednestling Barn Swallowsto leave their nest prematurely.Four of them fell into the canal and floated 100 feet downstreambefore disappearingaround a bend. The birds in the water archedand rotated their wingsslightly forward and spreadtheir flight feathers,holding their heads above water as they floated. At no time were they observedattempting to swim. On the morningof the followingday we found that all five young had returnedto their originalnest; thus their swimmingefforts were successful. At dusk on 4 July 1970 we banded in a Cliff Swallow colony located in a concretehighway culvert in Hope Valley, Alpine Co., California.Nine adult birds accidentallyfell into the four-inch-deep rapidly-flowingbrook and were carrieddownstream. The birdshit the water with outstretchedwings, and with wingsand tail spreadwere carriedthrough ripples and smallfalls to a sharpturn. There the birds climbed out onto a sandy bank and onto grassand immediately began preening.Never did they exhibit any detectablewing move- ments of the "butterfly" type nor loose their buoyant upright positionin the water. In order to study the swimmingof passetinesmore closely,we undertooksome simple tests with full grownHouse Sparrows. When 66 SWIMMING PASSERINES thrown into water, dry birds immediately swam as describedabove and were able to fly from the surfacealmost immediately. However, wetted individualswere unable to do so and swam actively about, restingintermittently on extendedwings and tail. A bird that was previouslycompletely soakedwas unable to swim nearly as well as the drier birds. In resting, the wings of the soakedbird were only partially extendedand hung beneaththe surfaceof the water. With more than half of its trunk below the surface,the bird was unstable, tending to roll from sideto side. Immediatelyafter removalfrom the water, wetted birds were able to fly, but not with normal efficiency. The well-soakedindividual could not fly when taken from the water, and it spent more than a half hour preeningand drying before it flew. Downed birds are occasionallytaken by aquaticpredators. During the summer of 1967 while we were banding Cliff Swallowsin a colony near Clarksville,E1 Dorado Co., California, an adult bird fell into the pool at the colony entrance. The bird immediately swam toward shorebut was capturedby a Bullfrog(Rana catesbeiana}and killed. The Tree Swallow seenswimming by Deuel was alsotaken by a Bullfrog. Since passefinebirds landingon the surfaceof the water normally already have their wings open, the observedspread posture of downed birds is expected.The above observationssuggest that the spreadingof remigesand rectricesis not merely part of the swimming movementand that there is sufficientbuoyancy in the feathersof a bird to keep it afloat without spreading.However, spreading reduces the extent of wetting of a downed individual,thus enablinga more rapid escapefrom the water with concomitantlyincreased chances of avoidingpredation and difficultiesin thermoregulation.

ACKNOWLEDGEMENTS

We wish to thank GeorgeA. Clark, Jr. and Miklos D. F. Udvardy for aid in preparationof this note.

LITERATURE CITED

Broun, M. 1943. Swimmingability of young Robin. Auk 60: 445-446. Creutz, G. 1953. SchwimmendeHaussperlinge. Vogelwelt 73: 141. Hickling, R. A. O. 1950. Swimming of small birds. British Birds 43: 292. Jackson,D. 1970. Swimming ability of the Barn Swallow. Auk 87: 577. Petrides,G. A. 1942. Swimmingability of youngCatbird. Auk 59: 584. 67 SWIMMING PASSERINES

Schemer, E. R. 1969. Swimmingability of Willow Warbler. Auk 86: 350. Stoner, D. 1928. Observationsand banding notes on the Bank Swallow - IV. Auk 45: 310-320. Stoner, D. 1936. Studies on the Bank Swallow, Riparia riparia riparia (Lin- naeus), in the Oneida Lake region. Roosevelt Wild Life Ann. 4: 127-233.

Department of BiologicalSciences, University of Arizona, Tucson, Arizona 85721, and Rehabilitation Center, University of Arizona, Tucson, Arizona 85721.