SHORT COMMUNICATIONS 381

The Condor 88:381-382 0 The Cooper Ornithological Society 1986

ATTEMPTED NEST PARASITISM OF THE MARSH WREN BY A BROWN-HEADED COWBIRD ’

JAROSLAVPICMAN Department of Biology, Universityof Ottawa, 30 SomersetE., Ottawa, ON KIN 6N5, Canada

Key words: Brown-headedCowbird; Molothrus ater; nestsare domed with a small entrance that prevents cow- Marsh Wren; Cistothoruspalustris; nestparasitism. birds from entering them and, perhapseven more impor- tantly, this domed shape concealsthe nest contents (suc- The Brown-headed Cowbird, Molothrus ater, is a brood cessfulparasitism requires that a female cowbird lay an parasite known to have laid in nests of 220 host species egg in the host nest at an appropriate time; Clark and (Friedmann et al. 1977. Friedmann and Kiff 1985). The Robertson 1981, Burgham 1985). This proposition is sup- Brown-headed Cowbird is a generalistthat tends to par- ported by generally rare reports of cowbird parasitism of asitize passerinesbuilding open nests, although relatively small hole-nesting passerinessuch as the Tree Swallow rare casesof parasitism of hole-nestingspecies such as the Tachycinetabicolor, Black-capped Chickadee Parus atri- House Wren, Troglodytesaedon, have been reported capi&, Carolina ChickadeeP&us carolinensis,and Brown (Friedmann et al. 1977). The purpose of this note is to Creever Certhia familiaris (seeFriedmann and Kiff 1985). describethe first caseof cowbird parasitism of the Marsh Second, Marsh *Wrensmay benefit from the presence of Wren, Cistothoruspalustris, and hence add this passerine Red-winged Blackbirds,Agelaius phoeniceus, which also to the list of the cowbird hosts. inhabit marshesand whosecolonial nestingand high level The Marsh Wren is a small (about 12 g) passerinebreed- of aggressionmay provide effective defense against cow- ing in marshes across temperate North America. Male bird parasitism (seeClark and Robertson 1979). This idea wrens build many domed nests,each with a small entrance is supportedby the fact that althoughcowbirds were com- (about 3 cm in diameter) near the top, concentratedin the mon near my study area, only 3 of approximately 1,400 courtship sites (e.g., Vemer 1965). The female usually redwing nests that I found from 1976 through 1982 con- choosesone of these “courtship” nests for breeding, lines tained a cowbird egg.Third, the presenceof a largenumber it, and then lays a clutch that she alone incubates(Vemer of redwings, which build open nests and are presumably 1965). a more suitable host, might reduce chances of cowbird From 1977 through 1982 I collecteddata on the breed- parasitismof Marsh Wrens. However, this hypothesisdoes ing ecologyof Marsh Wrens in a brackish water marsh on not provide a plausible explanation for the above case of Westham Island, Delta, B.C.. Canada. and obtained in- attempted parasitism of Marsh Wrens, becausethis case formation on over 1,200 breeding nests.On 26 June 1981 occurred late in the seasonwhen most redwings had al- I found a Marsh Wren nest that contained two broken ready departedfrom the marsh, and becausecowbird par- wren eggsand one cold, undamagedcowbird egg.The nest asitism of redwingsin this marsh is very rare. And finally, was not damaged; i.e., the entrance near the top of this the generalizedegg-pecking behavior exhibited by Marsh domed structurewas not enlarged. Becausethe entrances Wrens (Picman 1977) could be consideredas a preadap- into Marsh Wren nestsare presumably too small to allow tation making rejection of cowbird eggsthrough ejection entry by cowbirds, the female cowbird had to lay an egg likely to evolve. However, this hypothesis requires that by perching on the nest top, placing her cloaca near the we examine the Marsh Wren responsesto cowbird eggs entrance, and depositing an egg. by experimentally introducing them into wren nests. My data on Marsh Wrens suggestthat cowbird parasit- To conclude,the Marsh Wren appearsto be an unsuit- ism of this host is extremely rare. The probability that able host presumably because of its domed nests with some parasitized nests escapeddetection is very low, be- small entrance holes and possibly also becauseof its as- cause contents of all nests were checked twice a week sociationwith co-occurringRed-winged Blackbirds,which throughout each seasonby inserting a forefinger through provide effective protection from cowbird parasitism. the entranceand touchingthe eggsor young. Becausecow- I would like to thank the Canadian Wildlife Service and bird eggsare larger (2 1.5 x 16.5 mm) than those of Marsh Mrs. V. Robertson for permission to work on their prop- Wrens (16 x 12 mm), it is unlikely that observerswould erties. It is a measureto thank D. Goodwin, A. K. Picman, have failed to detect them. In addition, none of the Marsh M. Taitt, and P. Thompson for assistancewith field work: Wren nestsever contained a cowbird chick, although this M. Burgham,H. W. Kale, M. Leonard, and an anonymous could have been the result of the rejection of cowbird eggs reviewer provided constructive comments on this manu- by this host. Unfortunately, it is not known whether Marsh script. This work was supported by NSERC Operating Wrens are acceptersor rejecters(see Rothstein 1975). The grants to C. L. Gass and J. Picman. lack of any reports on cowbird parasitism of Marsh Wrens that were the subject of four additional extensive studies LITERATURE CITED (Kale 1965; Verner 1965; Vemer and Engelsen 1970; M. Leonard, pers. comm.) further suggeststhat cowbird par- BURGHAM,M. 1985. The impact of brood parasitism by asitism of this speciesis very unusual. the Brown-headed Cowbird on the reproductive tat- The low rate of parasitism of Marsh Wren nests by tics of the Yellow Warbler. M.Sc.thesis. Universitv cowbirds indicates that Marsh Wrens are an unsuitable of Ottawa, Ottawa, ON, Canada. host. At least four featuresof Marsh Wren ecologyshould CLARK,K. L., AND R. J. ROBERTSON.1979. Spatial and make them unattractive for cowbirds. First, Marsh Wren temporal multi-species nesting aggregationsin birds as anti-parasite and anti-predator strategies.Behav. Ecol. Sociobiol. 5:359-37 1. CLARK, K. L., AND R. J. ROBERTSON.1981. Cowbird ’ Received 9 September 1985. Final acceptance3 Jan- parasitism and evolution of anti-parasite strategiesin uary 1986. the Yellow Warbler. Wilson Bull. 93:249-258. 382 SHORT COMMUNICATIONS

FRIEDMANN,H., L. F. KIFF, AND S. I. ROTHSTEIN.1977. PICMAN,J. 1977. Destruction of eggsby the Long-billed A further contribution to knowledge of the host re- Marsh Wren (Telmatodytespalustris palustris). Can. lations of the parasitic cowbirds. Smithson. Contrib. J. Zool. 55:1914-1920. Zool. 235:1-75. ROTHSTEIN,S. I. 1975. An experimental and teleonomic FRIEDMANN,H., AND L. F. KIFF. 1985. The parasitic investigation of avian brood parasitism. Condor 77: cowbirdsand their hosts.Proc. West. Found. Vertebr. 250-271. Zool. 2~227-303. VERNER,J. 1965. Breeding biology of the Long-billed KALE, H. W. 1965. Ecology and bioenergetics of the Marsh Wren. Condor 67:6-30. Long-billed Marsh Wren, Telmatodytespalustrisgris- VERNER,J., AND G. H. ENGELSEN.1970. Territories, mul- eus (Brewster), in Georgia salt marshes. Nuttall Or- tiple nest building, and polygyny in the Long-billed nithological Club Publ. No. 5. Marsh Wren. Wilson Bull. 47:3-34.

The Condor X8:382-384 0 The Cooper Ornithological Soclety 1986

THE DAILY ACTIVITY PERIOD OF NESTING WHITE-CROWNED SPARROWS IN CONTINUOUS DAYLIGHT AT 65”N COMPARED WITH ACTIVITY PERIOD AT LOWER LATITUDES ’

JAMESR. KING Department of Zoologv WashingtonState University,Pullman, WA 99164

Key words: Daily activitycycles; White-crowned Spar- seasonsof 1962 through 1965, 1967 to 1968, and 1972. rows;Zonotrichia leucophrys;time budgets. Daylight (civil daylengthplus civil twilights) is continuous from 16 May to 28 July at this latitude. Male White- crowned Sparrows usually arrive in the second week of Time-and-activity budgets attempt to express how ani- May, females about one week later. Nesting is very well mals allocate time to vital activities such as foraging, synchronized in the population. Except for unusual re- courtship, and territorial defense. The baseline of an ac- nestingsfollowing loss of a nest, young have left the nest tivity budget is the duration of an animal’s voluntary ac- by 1 July, when postnuptial molt begins in all but failed tivity period per 24-hr cycle. An accurateestimate of this nesters.Southward migration begins soon after mid-Au- period is thereforean indispensableelement of the budget, gust (King et al. 1965, 1966; Wingfield and Famer 1979). as Hussell (1985) recently emphasized in an analysis of A few comparative data were available also from Z. I. the correlation between clutch size and daylength or ac- oriantha at Tioga Pass, California, Niwot Ridge, Colo- tivity period. Daan and Aschoff (1975) found that the daily rado, and Hart Mountain, Oregon. See King and Hubbard activity span of captive finches is a shallow sigmoidal (1981) for details about these localities. All lie between function of civil daylength, so that the activity span is j8”N and 42”N, and hence have similar daylengths. nearly the same as daylength at middle values (ca. 8 to 16 Measures of activity used herein include (1) incidence hr) but is longer than daylength when days are very short of singing,(2) recordsof periods in which White-crowned and shorterwhen daysare very long. For instance,captives Sparrowscould not be heard or found in the study area, are active for 17 to 18 hr per day in continuous daylight. and (3) observation of the schedulesof parents feeding In the handful of casesin which comparisonsare possible, nestlings.Except for the latter (1972 only), the resultsare free-living birds reflect fairly closelythe daily activity span presentedas a compositeof data from the six earlier years, in relation to daylength found in captives (cf. Armstrong all from the samesample site. My assistantsand I routinely 1954, Aschoff 1969, Daan and Aschoff 1975). Analysis of countedthe number of White-crownedSparrow songs heard my own field records and of published reports yielded a in a IO-min sample of every hour that we were afield. reasonablydetailed picture of the daily activity cycle in a During the twilight hours we recorded the times in which subarcticbreeding population of White-crowned Sparrows we could neither see nor hear White-crowned Sparrowsin (Zonotrichia leucophrys)and estimates of their daily ac- the study area, and in 1972 we systematicallysearched for tivity span in localities at lower latitudes where midsum- males during the quiescent period (when females were mer cycles of daylight and darkness are clear-cut. These incubating or brooding and therefore known to be inac- data help in designingrealistic experiments with captives tive). and in analyzing the time budgetsof free-living birds. MATERIALS AND METHODS RESULTS AND DISCUSSION The majority of the original data reported herein were ACTIVITY PERIOD AT FAIRBANKS obtained from Zonotrichia leucophrysgambelii near Fair- White-crowned Sparrows can be heard singing at nearly banks, Alaska (64’5 l’N, 147”52’W), during the breeding any time of the day during the nestingseason at Fairbanks, althoughthere is a consistentlull lasting about 3.5 to 4 hr before midnight and a shorter lull centered at about 1530 (Fig. 1). This pattern is repeated from year to year and is I Received 9 September 1985. Final acceptance3 Jan- not an artifact of merged data. The daily cycle of song uary 1986. intensity reflects the number of singers rather than the