Badge Size and Extra-Pair Fertilizations in the House Sparrow1

The Condor 102:342-348 0 The Cooper Ornithological Socmy 2000

BADGE SIZE AND EXTRA-PAIR FERTILIZATIONS IN THE HOUSE SPARROW1

R. R. WHITEKILLER~ Department of Zoology, University of Oklahoma, Norman, OK 73019

DAVID E WESTNEAT Center for Ecology, Evolution, and Behavior, T. H. Morgan School of Biological Sciences, 101 Morgan Building, University of Kentucky, Lexington, KY 40506

l? L. SCHWAGMEYER AND DOUGLAS W. MOCK Department of Zoology, University of Oklahoma, Norman, OK 73019

Abstract. For House Sparrows, Passer domesticus, it has been proposedthat the size of a male’s throat badge correlateswith his successin avoiding cuckoldry as well as obtaining extra-pair copulations(EPCs), and that females gain indirect (genetic) benefits from EPCs with large-badged males. Alternatively, female House Sparrows may engage in EPCs as a guard against their social mate’s infertility. We used multi-locus DNA fingerprinting to examine paternity and found that among 41 broods and 136 offspring, 20% of the offspring were attributableto extra-pair fertilizations (EPFs). Forty-one percent of the 34 males were cuckolded; however, large-badged males were as likely to be cuckolded as small-badged males. Moreover, we found no evidence that large-badged males were inherently superior to small-badgedmales in terms of survivorship.We comparedthe prevalence of unhatched eggs in broods with and without extra-pair offspring to determine whether EPFs are associated with hatching failure. Although we detected no associationbetween hatch failure and EPFs, enhanced fertility remains a plausible EPC benefit to females, but experimental ap- proachesmay be required to evaluate its significance. Key words: cuckoldry, extra-pair copulation, extra-pair fertilization, fertility insurance, House Sparrow, Passerdomesticus, sexual selection.

INTRODUCTION (1988) showed that males with large throat Conspicuous ornaments could be favored under badges were more likely to acquire mates than sexual selection if they provide some advantage small-badged males; large-badged males, in in male-male competition for mates and/or are turn, tended to occupy areas with better nesting attractive to females. In the latter case, two types sites. In an Oklahoma population, Voltura of benefits to females have been proposed. Fe- (1998) found that large-badged males do a great- males might gain direct (nongenetic) benefits er share of nestling feeding than small-badged (Trivers 1972, Kirkpatrick and Ryan 1991) if or- males. namented males provide more parental care, Male ornamentation additionally has been possessbetter territories, or better guard the fe- suggestedto play a role in the extra-pair mating male from predators or the harassment of con- system of House Sparrows. Although the species specifics. Alternatively, conspicuoustraits might is considered mainly monogamous, females so- indicate indirect (genetic) benefits (Fisher 1930, licit extra-pair copulations (EPCs) and are tar- Hamilton and Zuk 1982, Kirkpatrick and Ryan gets for forced extra-pair copulations (Moller 1991), thereby conferring greater fitness on the 1987). Moller (1990) reported that large-badged female’s offspring. males performed more EPCs than small-badged Research on House Sparrows (Passer domes- males, and he suggestedthat females may gain ticus) indicates that females of this speciesmay indirect benefits by choosing large-badged males gain direct benefits from pairing with highly or- as EPC Partners. namented males. In a Danish population, Moller Moller’s perspective (1990) emphasizes the potential role of badge size as a true indicator of male genetic quality; he proposed that the ’ ’ Received22 July 1999.Accepted 25 January2000. 2 Current address:Department of Biology and trait is under strong directional sexual selection Chemistry,University of Montevallo,Montevallo, AL by virtue of its importance in female mate 35115. choice and in the context of sperm competition.

13421 BADGE SIZE AND EXTRA-PAIR FERTILIZATIONS 343

In addition to finding that male badge size is nest boxes (Summers-Smith 1963); both parents related to EPC participation, Moller (1990) also participate in nest building, incubation, and found that large-badged males copulate more of- feeding of the nestlings. Incubation lasts approx- ten with their own mates than small-badged imately 11 days and most young fledge about 14 males, and that they appear to guard their mates days after hatching. more intensely than do small-badged males (Moller 1987). These behavioral observations, METHODS along with the larger testes size of large-badged STUDY SITE AND GENERAL FIELD METHODS males (Moller and Erritzoe 1988), led Mprller (1990) to predict that such males have greater We erected 100 nest boxes at two sites (North success at siring extra-pair offspring while si- Base and South Base, University of Oklahoma, multaneously avoiding cuckoldry. Norman, Oklahoma) in 1993 and 1994. One Using DNA fingerprinting techniques, Wetton hundred and nineteen additional nest boxes were and Parkin (1991a) found that 13.6% of the off- erected at four additional sites near North and spring in a British population were sired by ex- South Bases in 1995 and 1996. We censused tra-pair males. However, subsequentresearch on nest boxes at least twice weekly during the both that population as well as a Spanish pop- 1994-1997 breeding seasons to determine the ulation showed no support for Moller’s predic- date the first egg was laid, clutch size, number tion that large-badged males would be cuckold- of eggs that hatched, number of young that ed less often than small-badged males (Corder0 fledged, and inter-brood interval. When the date et al. 1999). Instead, Wetton and Parkin’s the first egg was laid was not observed, it was (1991b) results have led to an alternative hy- calculated assuming that a female lays one egg pothesisfor why female House Sparrows engage per day. in EPCs. They found a striking association be- Adults were captured in ground traps, mist tween the number of unhatched eggs in a clutch nets, or in wire corridors attachedto the nest box and the presence of extra-pair offspring in the (Mock et al. 1999). We weighed individuals on brood: the extra-pair fertilization (EPF) rate in an electronic balance (t 0.1 g) and then banded broods with at least some hatching failure was each with U.S. Fish and Wildlife aluminum roughly twice as high as in broods where all bands plus a unique combination of plastic color eggs hatched successfully. This result prompted bands for field identification. A scaled close-up them to suggest that females may use EPCs photograph of each male’s badge was taken at more as a guard against a mate’s potential in- the time of his capture using a 0.5 X 0.5-cm grid fertility, than as a means to upgrade the genetic in the background. All badge area estimates quality of their offspring. were from males captured during the breeding We examined the frequency of extra-pair off- season, which minimizes the effects of feather spring in House Sparrows using multi-locus tip abrasion on visible badge size (Griffith et al. DNA fingerprinting. We also used video image 1999b). The badge area was quantified using analysis to measure digitized photographs of video image analysis. In a separate sample, we male badges, and we used those measurements found that area estimates obtained from photo- to investigate whether variation in male badge graphs were highly correlated with estimates for size is related to loss of paternity to extra-pair the same individuals based on video-taped im- matings, as Moller (1990) predicted, or to male ages of their badge sizes (Whitekiller, unpubl. survival. By comparing the prevalence of un- data). Badge sizes were scoredindependently by hatched eggs among broods with and without R. R. Whitekiller and K. Voltura. Badge size for extra-pair offspring, we also testedthe generality each male was scored “blind” as to his identity. of Wetton and Parkin’s (1991b) finding that fe- The areas obtained by the two scorers were male production of offspring sired by EPFs is highly correlated (1. = 0.99, IZ = 65, P < 0.001). associatedwith hatching failure. Corder0 et al. (1999) reported a similar tech- House Sparrows are semi-colonial passerines nique for measuring badge size and found that that begin breeding in central Oklahoma in it produced similar measures as that of Moller March and continue through early August, pro- (1990). Mean values for the two sets of scores ducing two to three clutches of approximately are used in all analyses. four to five eggs each. This speciesreadily uses To examine the relationship between badge 344 R. R. WHITEKILLER ET AL size and adult male survival, we compared the FINGERPRINT SCORING AND PARENTAGE badge size of males banded as adults in 1994 or ANALYSES 1995 that were resighted within the next two Scoring followed the methods outlined in West- years with the badge size of males that failed to neat (1990, 1993). Bands on the autoradiographs return. Individuals were considered to have sur- were marked on acetate sheet overlays with per- vived if they were resighted at any nest boxes, manent markers. We compared banding patterns during ground trapping, or at any other location. between two individuals (putative parent and offspring) using the statistic D = 2N,,/(N, + BLOOD COLLECTION AND MULTI-LOCUS DNA Na) where N, and N, are the number of frag- FINGERPRINTING ments in individual A (putative parent) and in- A 70-100 pl blood sample was collected (from dividual B (offspring), and N,, is the number of putative parents and offspring) from the brachial bands shared by both (Wetton et al. 1987). Pu- vein into heparinized capillary tubes, placed on tative parents were run in lanes directly adjacent ice in the field, and transported back to the lab- to offspring for scoring accuracy. For each off- oratory. We expelled the sample into microcen- spring, we also determined the number of novel trifuge tubes filled with 500 p,l of lysis buffer bands present. (Applied Biosystems Inc., Foster City, Califor- The number (2 SD) of storable bands for nia) and stored it at 4°C until processed.Adults probe Ml3 averaged 14.7 ? 5.6 (n = 135), were bled at the time of capture and most chicks whereas the number of storable bands for 19.6 were bled on day 11 when they were banded; averaged 24.7 ? 4.5 (n = 132). The proportion this routine reduced the amount of handling. of bands sharedbetween adults in the local pop- We analyzed parentage of 136 nestlings (14 ulation averaged 0.31 + 0.10 for Ml3 and 0.42 broods, 42 offspring in 1994; 19 broods, 63 off- + 0.10 for 19.6. Average (+ SD) band sharing spring in 1995; and 8 broods, 31 offspring in between random adults for both probes was 0.37 1996, collectively representing the offspring of Ifr 0.07 (n = 22). All fragments that were found 34 different males) using multi-locus DNA fin- in 81 nestling fingerprints were present in at gerprinting. DNA was extracted from blood least one of the putative parents’ fingerprints. samples using the procedure described by West- The remaining offspring (n = 55) contained at neat (1990, 1993). least one fragment not found in the fingerprint Approximately 15 trg of DNA was digested of either putative parent. with the restriction enzyme Hue111 following Novel bands can result from mutation, extra- standard procedures (e.g., Westneat 1990). The pair fertilizations, intraspecific brood parasitism, concentration of each sample was determined or scoring errors. Scoring errors were unlikely with a spectrophotometerand adjusted to 6 pg given that scoring was performed independently DNA per lane in 20 pl TE. Each sample was by two individuals and only those bands that electrophoresedin a 0.8% agarose gel for 48 hr were clearly distinguishable were marked. If at 1.5 V cm-‘. Each gel was then stained with novel bands arose from mutation, then the num- ethidium bromide, photographed under UV il- ber observed should fit that expected from a low lumination, and washed following proceduresin rate of random events. The expected number of Westneat et al. (1988). The DNA was transferred novel bands arising from mutation is dependent to a nylon membrane (Zetabind) using a vacuum on the number (? SD) of bands scored for both blotter. The membrane was rinsed briefly with probes, which averaged 38.6 2 9.5. To deter- 2XSSC and baked for 2 hr at 80°C. The mem- mine mutation rates, we assumed that nestlings branes were placed in pre-hybridization mixture with one or two novel bands were not likely to (Westneat et al. 1988) for 24 hr. have misassigned parents. We found a mutation The membranes were hybridized with a 32P- frequency of 0.31 per individual, with a muta- labeled PCR-amplified fragment of wild-type tion rate per fragment = 0.008 (0.31/39). There- Ml3 (Vassert et al. 1987) at 60°C for 24 hr. fore, the expected probability of observing three Washes followed the protocols in Westneat et al. novel bands from mutation alone was 0.31’ = (1988) and Westneat (1990). After exposure to 0.03, four novel bands was 0.314 = 0.009, and film, the membranes were stripped and rehybri- five novel bands was 0.315 = 0.003. Given that dized with a second multi-locus probe, 19.6 we analyzed 136 nestlings, we expected 4, 1, (equivalent to 33.6; Jeffreys et al. 1985). and < 1 nestlings to have three, four, and five BADGE SIZE AND EXTRA-PAIR FERTILIZATIONS 345 novel bands, respectively. The observed values for three and four novel bands were close to or below that expected, whereas the observed number with five was much greater than expected. We concluded that offspring with fewer than four novel bands were likely to be descendent from both putative parents; those with five or more novel bands were unlikely to be descendent from at least one of the putative parents. For nestlings with four novel bands, we used band-sharing values to help determine parentage. For all excluded offspring, we also used band-sharing to determine whether exclusions were the result of extra-pair fertilizations or intraspecific brood parasitism. Nestlings with zero or one novel band shared 0.62 ? 0.09 of their bands with each parent. The lower, one-tailed, 95% confidence limit of this distribution was 0.47 [0.62 - (0.09 X 1.65)], which indicates that the probability is less than 0.05 that offspring would have a band-sharing coefficient less than 0 2 4 6 8 10 12 14 16 0.47 with a genetic parent. Individuals having a NOVEL BANDS higher band-sharing than this level might not be FIGURE 1. Relationship between the proportion of relatives. We used the band-sharing of random bands sharedwith the attendingparent and the number adults as an estimate of the expected band-shar- of novel bands for each nestling House Sparrow. Band sharing with (a) the attending male and (b) the attending between the male and offspring if the off- ing female. The dotted line representsthe lower, one- spring was from an EPE The upper, one-tailed, tailed, 95% confidence limit for band sharingbetween 95% confidence limit on the distribution of attending parents and offspring. Some of the data band-sharing values between random adults is points are hidden from view. [0.37 + (0.07 X 1.65)] or 0.49. Thus the two distributions overlap sufficiently that we expected some nestlings to fall within this uncertain siderably lower than the probability of having a intermediate zone. band-sharing of between 0.5 and 0.6 without be- We found that 22 of the offspring were ex- ing a descendant), and the band-sharing with the cluded as descendents of the male under both female in each case was higher than for the criteria (4+ novel fragments and band-sharing male, we excluded these offspring as descendant < 0.47; Fig. la, b). All but 20 of the remaining from the male. We ran statistical analyses with offspring had fewer than four novel bands as these five nestlings considered as within-pair well as band-sharing coefficients > 0.47 with fertilizations and found only slight differences in both putative parents. Ten nestlings had a band- the outcomes. sharing coefficient with the male slightly lower STATISTICAL ANALYSES than 0.47 and fewer than two novel bands (Fig. la). Four other nestlings had a coefficient with Parametric analyses were used when variables the female of just under 0.47 and zero novel were normally distributed; otherwise nonpara- bands (Fig. lb). We assigned these nestlings as metric tests were used. Means and standard de- descendant from both putative parents. One viations are reported unless otherwise indicated. nestling had a band-sharing coefficient of 0.49 Alpha levels of 0.05 were considered significant. with the male and four novel bands. To be con- RESULTS servative, we assigned this nestling to the male. Five nestlings had band-sharing coefficients EXTRA-PAIR PATERNITY AND GENERAL above 0.47 and five to eight novel bands. Be- TRENDS cause the probability of getting so many novel Overall, we concluded that 27 of the 136 off- bands from mutation alone was very low (con- spring (20%) in 15 of 41 broods (36.5%) came 346 R. R. WHITEKILLER ET AI

= 339 + 87 mm2, it = 14) did not differ from . . the badge size of non-cuckolded males (378 2 . 116 mm2, n = 19, independent sample t,, = 1.1, : . P = 0.30). The results of a logistic regression analysis also indicated that badge size was not a good predictor of whether a male was cuckolded (Likelihood ratio x2 = 1.2, n = 33, P = 0.28).

BADGE SIZE AND SURVIVAL We found no difference in the badge sizes of 100 200 300 400 500 600 700 males that survived at least one season post-cap- BADGE SIZE (mm)’ ture (.? = 369 ? 158 mm2, n = 15) and the badge FIGURE 2. Relationship between male House Spar- sizes of males that failed to return (357 + 101 row badge size and percent extra-pair fertilizations in mm*, n = 20; Mann-Whitney U-test, z = 0.1, P his brood. Some of the data points are hidden from view. = 0.96). An additional analysis, using logistic regression, also indicated that male badge size was not a good predictor of adult male survivorship from matings between the female and an extra- (Likelihood ratio x2 = 0.1, n = 35, P = 0.78). pair male and none came from intraspecific brood parasitism. Of 42 offspring in 1994, 8 CUCKOLDRY AND HATCHING SUCCESS were extra-pair (19%). Out of 63 offspring in The 41 broods used in the fingerprinting analysis 1995, 23.8% were extra-pair; and of 31 in 1996, developed from a total of 191 eggs. Eleven per- 12.9% were extra-pair. Heterogeneity among cent (21/191) of eggs laid failed to hatch; only years in percent extra-pair offspring was not sig- 1% (2/191) contained embryos that clearly died nificant (G, = 2, P = 0.44). In 1994, 1995, and during the hatching process. We found no rela- 1996, 29, 47, and 25% of the broods, respec- tionship between time in breeding season and tively, contained extra-pair offspring. proportion of unhatched eggs (Y, = -0.09, n = 41, P = 0.59). Eleven of 26 (42%) legitimate BADGE SIZE AND EXTRA-PAIR PATERNITY broods (those with no extra-pair offspring) con- Overall, 14/34 (41%) of the males were cuck- tained at least one unhatched egg, whereas 7 of olded. In 1994, 33% (3/9) of the males were 15 (47%) broods with at least one extra-pair off- cuckolded. In 1995 and 1996, 53% (9/17) and spring contained at least one unhatched egg. 25% (2/8) of the males were cuckolded, respec- Thus, presence of extra-pair young in a brood tively. Badge size ranged from 174 to 609 mm2 was not associatedwith hatch failure (x2 = 0.1, and averaged 361 ? 105 mm2; male badge size P > 0.50). Reanalyzing those data with the as- was not related to male body mass (r = 0.02, n sumption that the five questionable offspring = 33, P = 0.90). might be within-pair did not change the results We found no relationship between a male’s of this analysis. badge size and the percentage of extra-pair offspring in his own brood (rs = -0.18, n = 33, P DISCUSSION = 0.33; Fig. 2). Assigning the five questionable We found that 41% of the socially monogamous offspring as within-pair, does not change the re- female House Sparrows copulated with an extra- lationship (I, = -0.10, II = 33, P = 0.58). We pair male and produced at least one extra-pair also found no relationship when comparing the offspring. The overall frequency of extra-pair fer- proportion of extra-pair offspring in the nests of tilizations we observed (20%) is comparable to males with smaller (2 = 0.3 ? 0.4, II = 13) that found by Wetton and Parkin (1991a) in a versus larger than average badges (0.2 2 0.3, n British population (13.6%) and Corder0 et al. = 20; Mann-Whitney U-test, z = 0.7, P = 0.57). (1999) in a Spanish population (10.4%). How- Categorizing males as large vs. small-badged ever, the size of the conspicuously sexually di- based on the median, rather than the mean, did morphic throat patch of males was not associated not change the outcome of this latter analysis. with paternity. Our results agree with those of Similarly, the badge size of cuckolded males (.? Corder0 et al. (1999) in finding no support for BADGE SIZE AND EXTRA-PAIR FERTILIZATIONS 347

Moller’s (1990) prediction that EPCs would be a overall infertility risk is roughly 1.5% per egg. source of sexual selection on male badge size. Although this may seem trivially low, it could Corder0 et al. (1999) also found no relation- be sufficient to promote female multiple mating ship between badge size and extra-pair paternity if EPCs are not especially costly to females. Un- in both Spanish and British populations. All less EPCs are highly costly to females, the ob- three studies show weak trends toward males served infertility rate is likely to underestimate with larger badges being cuckolded somewhat the rate that would occur if females did not en- less, but combining the P-values for these three gage in EPCs. Rather than simply using mea- independent testsdoes not approachsignificance sures of the associations between hatch failure (Fisher’s combined probabilities test: x*6 = 5.9, and EPFs, a fertility insurance advantage may P > 0.3; Sokal and Rohlf 1981). Overall, these be most readily detected via experimental ma- results suggestthat if badge size influences ex- nipulation of the number of female mating part- tra-pair sexual activity, that effect is weak. ners and/or female mating frequency. Only re- Moller had based his prediction about EPCs cently have such experimental approachesbeen on three findings: large-badged males copulate used for non-domesticated bird species (Sax et more frequently with their mates than small- al. 1998), and they may be feasible for House badged males (Moller 1990) they guard them sparrows. more intensely than small-badged males (Moller Despite no evidence that male badge size af- 1987), and they have larger testes (thus presum- fects paternity losses,large-badged males in this ably produce more sperm) than small-badged population may be favored by sexual selection, males (Moller and Erritzoe 1988). The absence on several counts. First, they may have an ad- of a relationship between paternity and male vantage in male-male competition for breeding badge size in these subsequent studies suggests resources (e.g., nesting sites) as suggested by that one or more of Moller’s findings do not ap- both Moller (1988) and Veiga (1993, 1996). We ply to these populations or that, if they do, they made no attempt to assessthis, but note that are mitigated by other factors that affect cuck- such competition might be expected to be rela- oldry independently of a male’s badge size. tively relaxed in our study population given the A candidate for such mitigation would be fe- abundance of both natural and artificial nest male multiple mating that is driven primarily by sites. Second, there is evidence that in this pop- fertility insurance, and we explored this possi- ulation, a male’s badge size is positively corre- bility. Wetton and Parkin (199 lb) had found a lated with both the relative share of nestling greater proportion of unhatched eggs in House feeding he performs and with the proportion of Sparrow nests with EPFs, lending support for hatched young that fledge (Voltura 1998). Fe- the fertilization insurance hypothesis. We ex- males therefore would have ample incentives for amined this possibility in the Oklahoma popu- basing their choice of pair-mates on male oma- lation and found no association between extra- mentation, because of the direct benefits in do- pair offspring in a brood and hatch failure. How- ing so. Whether there also exist genetic benefits ever, without examining each egg, it is difficult from pairing with or engaging in EPCs with a to determine whether unhatched eggs have been large-badged male is less certain. Although fertilized, and hatch failure may be more likely Moller (1989) found relatively high heritability to represent embryo mortality, rather than infer- of badge size (0.60) in a Danish population, a tility (Lifjeld 1994). recent cross-fostering study has revealed that a A technique for distinguishing between early male’s badge size resembles that of his foster embryo mortality and infertility was implement- father much more than it resembles his genetic ed recently to addressthis problem. Birkhead et father’s badge size (Griffith et al. 1999a). Ad- al. (1995) used microscopic examination of the ditionally, we found no effect of male badge size perivitelline layers of House Sparrow eggs to on adult survivorship and, if badge size is an discriminate between early embryo mortality indicator of male genetic quality, we would have and infertility; from their results, they estimated predicted that large-badged males would have that 15% of hatch failures in a Spanish colony higher survivorship. For example, in Belgian were attributable to infertility. Thus, if hatch Blue Tits (Pm-us caeruleus), “attractive” males, failure occurs at about a 10% rate, as in both those that are preferred as EPC partners (mates) the Spanish and Oklahoma populations, the and are able to avoid lost paternity at their own 348 R. R. WHITEKILLER ET AL. nests, had greater over-winter survivorship 1999. A trap design for capturing individual birds at the nest. J. Field Omithol. 70:276282. (Kempenaers et al. 1992). Finally, large-badged MQ)LLER,A. P 1987. House Sparrow, Passer domesticus, males may well sire more offspring through communaldisplays. Anim. Behav. 35:203-210. EPFs than small-badged males, as M@ller (1990) MILLER, A. l? 1988. Badge size in the House Sparrow predicted. We were unable to assign paternity of Pnsser domesticus. Effects of intra- and intersex- ual selection. Behav. Ecol. Sociobiol. 22:373-378. offspring produced through EPFs in this study, MILLER, A. P 1989. Natural and sexual selection on a so we cannot evaluate this directly. plumage signal of status and on morphology in House Sparrows, Passer domesticus. J. Evol. Biol. ACKNOWLEDGMENTS 2:125-140. MILLER, A. l? 1990. Sexual behavior is related to We thank 0. M. Fincke, V. H. Hutchison, L. E. To- badge size in the House Sparrow Passer domes- othaker, J. Quinn, W. D. Koenig, and an anonymous ticus. Behav. Ecol. Sociobiol. 27123-29. reviewer for their constructive comments on earlier MILLER, A. P, AND J. ERRITZOE. 1988. Badge, body drafts of the manuscript. Karen Voltura, Amy Skypala, and testes size in House Sparrows Passer domes- Carie Weddle, Misty Hankinson, and Gin Wang pro- ticus. Omis Stand. 19:72-73. vided valuable assistance in the field. Tammy Roush, SAX, A., H. HOI, AND I‘ R. BIRKHEAD. 1998. Copula- Richard Hanshu, and Herman Mays provided assis- tion rate and sperm use by female Bearded Tits, tance in the lab. The research was supported by a Panurus biurmicus. Anim. Behav. 56: 1199-1204. GAANN (GraduateAssistantships in A&as of Nation- SOKAL, R. R., AND E J. ROHLF. 1981. Biometry. 2nd al Need) Fellowshiu. George Miksch Sutton Scholar- ed. W. H. Freeman, New York. & ship in Ornithology, the Umversity of Oklahoma’s De- SUMMERS-SMITH,J. D. 1963. The House Sparrow. Col- partment of Zoology, and in part by NSF IBN- lins Clear-Type Press, London. 9408148 to P.L.S. and D.W.M. We also thank the Uni- TRIVERS, R. L. 1972. Parental investment and sexual versity of Kentucky, the Kentucky NSF-EPSCoR selection, p. 136-179. In B. G. 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