Passer Domesticus)

INTRASEASONAL REPRODUCTIVE COSTS FOR THE HOUSE SPARROW (PASSER DOMESTICUS)

W. BRUCE McGILLIVRAY • Museumof NaturalHistory, University of Kansas,Lawrence, Kansas 66045 USA

ABSTP,•CT.--HouseSparrows (Passer domesticus) near Calgary, Alberta begin breeding in earlyspring and continuethrough to late summer.High productivityfrom previousbroods is negativelycorrelated with fledglingproduction from secondand third broods.Although fat reservesmay limit the ability of femalesto raiseyoung, there is no concomitantdrop in clutchsize or in the probabilityof renesting.Pairs that fledgemany young in a yearspace fledglingproduction evenly over the breeding seasonbut are most productivein mid- season.The interval between fledging and the initiation of the next clutchincreases with the numberfledged. This delay,an indicationof the physiologicalstrain involved in rearing young,is greaterfor laterbroods and for femalesnesting in trees.Measures of reproductive effort(dutch size, numberfledged, length of the nestlingperiod) vary seasonallybut give no indicationof peakingfor last broods.Thus, reproductiveeffort is not adjustedto parallel changesin the probability of surviving to the next breeding attempt. Received3 November 1981, accepted24 April 1982.

A COMMONassumption underlying theoret- ship of double-broodedfemale House Martins ical discussionsof life-history phenomena is (Delichonurbica), and male Pied Flycatchers that trade-offsin life-history characteristicsoc- (Ficedulahypoleuca) feeding many young were cur (Williams 1966, Chamov and Krebs 1974, lesslikely to return to the study area than those Steams 1976, Snell and King 1977). For exam- feeding fewer young (Askenmo 1979). Lack ple, Pianka and Parker (1975)partition the re- (1966) and Kluyver (1970) present evidence productive value of an individual of age X in suggesting an inverse relationship between a stablenongrowing population into fecundity brood size and parental survivorship. De Ste- at age X and expected fecundity conditioned ven (1980), however, did not find a reduction by survival to ages X + 1, X + 2.... , X + in the survivorship of female Tree Swallows N. Clearly if survivorshipis lowered by current (Iridoprocnebicolor) as a result of brood en- reproduction,future fecundity is reduced. largement. Smith (1981), after demonstratinga Many researchersof life-historyphenomena positive associationbetween reproductive ef- in birds have investigated whether or not the fort and survivorship, concludedthat a trade- modal clutch size is the most productive, as off between fecundity and survivorshipshould predicted by Lack (1947, 1966). If productivity not be assumedfor passerinebirds. is measured as the number of young fledged The longevity and mobility of birds usually from a brood, then clutch sizes larger than prevents a precise determination of mortality modal appear to be optimal (Klomp 1970, von rates for individuals with a known reproduc- Haartman 1971,Jones and Ward 1976, Murphy tive history. If dispersers are a nonrandom 1978). If parental survivorship is reduced by sampleof the population (Lowther 1979),then the effort of raising a large brood, however, estimatesof survivorshipbased on individuals then the optimal clutch size might be lower staying at or returning to the study area will than the most productive (Fisher 1930, Char- be biased. As a consequence,the effect of re- nov and Krebs 1974). Studies testing the rela- production on survivorship is often estimated tionship between brood size and parental sur- from physiologicalevidence. Weight lossesfor vivorshipshow equivocal results. Bryant (1979) femalesthrough the breeding seasonsuggest a found a reduction in the overwinter survivor- physiologicalstrain that may reduce survivorship (Newton 1966,Hussell 1972, Bryant 1979). For femaleHouse Sparrows(Passer domesticus), Pinowska (1979) has shown that levels of fat • Present address: Water ResourcesBranch, On- influence clutchsize, while lean dry weight (an tario Ministry of the Environment 135 St. Clair Av- indicator of protein level) may determine the enue W., Toronto, Ontario M4V 1P5, Canada. number of broods raised in a season.Norberg 25 The Auk 100: 25-32. January 1983 26 w. BRUCEMcGxLLXVRA¾ [Auk, Vol. 100

(1981) presented the hypothesis that adult countedand numbered. Nestlings 5•5 days old were weight lossesduring breedingmay be adap- banded with a U.S. Fish and Wildlife Service alu- tive. This would be true if the reduced cost of minum leg band and color marked with leg bands collecting food for the nestlings increases after reachinga 20-g weight. Data analysis.--Becausethe nestswere not checked fledgling numbersmore than it reducessur- every day, exact clutch-initiation data and nestling vivorship and future fecundity. ages were not known for all nests. For these cases, Birds that raise more than one brood in a estimateswere used. Nestling age when first found seasonmay be expectedto show differential was estimatedby comparingthe weight of the largest reproductiveeffort and productivitythrough nestling in a brood to averagevalues obtained from the breedingseason. There is a higher proba- broods of known age. Clutch-initiation date was es- bility of survivingfrom one broodto the next timated by assuming an average incubation period ct-uringthe breedingseason than from the last of 11 days and a laying rate of one egg per day brood of one seasonto the following spring. (McGillivray 1978). This estimate was needed only An increasein the level of reproductiveeffort for clutchesbegun before my arrivalat the studyarea. would be expectedas the probability of sur- In this study I investigatedthe productivity from multiple broodsof a pair; hence,I made the general viving to the next breeding attempt decreases. assumptionthat broodsraised at a singlenest through There is someevidence that high levelsof re- the breeding seasonwere raised by the same pair. productiveeffort lower the ability of females House Sparrowsusually remain at the same site un- to invest in a subsequentbrood. For Great Tits less one of the pair dies (Summers-Smith 1963). To (Parusmajor), Kluyver (1963) found a lesser reducethe importanceof this potentialsource of error, probabilityof a secondbrood if the first was I imposed some residency conditions. If a tree nest large. Pinkowski(1977) noted a drop in the was extensively modified following a nesting at- clutch size of second broods for Eastern Blue- tempt, ! assumedthat a new pair was nesting. The birds(Sialia sialis) that raised a largefirst brood, average interval between successiveclutch initia- and Smith and Roff (1980) found that an in- tions for first through third clutchesfor each brood crease in the interbrood interval was associate0 size was determined. Ninety five percent prediction intervals were calculated for each clutch-interval, with a largefirst brood for SongSparrows (Me- brood-size combination. Nests where the interclutch lospizamelodia ). interval fell outside these limits were excluded from In this study I look at the productivityof further analyses. multibrooded House Sparrows through the The interval between the departureof the last nest- breeding seasonand address two questions. ling and the initiation of the next clutchis called the First, is there variation in the productivity of interbrood interval. The date of fledgling departure successivebroods within the breeding season was considered to be the midpoint of the interval associatedwith brood size in earlier broods (is between the last observationof the nestlingsand the there a demonstrable within-season cost as- first nest checkafter departure. Fledging is a gradual process,so a departure date is only an approximate sociatedwith reproduction)?Second, do adults measure. Paired comparison t-tests were used to modify their reproductiveeffort in accordance compare the mean interbrood interval of successive with seasonalchanges in the probabilityof re- broods and different nest types. nesting and surviving? For the investigationof the effectsof one brood on the next breeding attempt, data for the two years were pooled.Pooling requires trends to be consistent METHOVS ANt) MATERIALS over the two years in order for the trends to be de- Studysite.--In 1977,the studyareas were six farms tected, and productivity for both years was similar near Conrich, Alberta, 5 km eastof Calgary. For 1978, except for the first broods. The strength of trends all data were collected at one of these farms, 8 km associatedwith brood size was measured by Pear- east of Calgary. At each of the farms, about 20 nest son's product-momentcorrelation coefficient, r. Al- boxeswere erectedin fall 1974 (seeMurphy 1978 for though significancelevels were determined for r, details). As well as nesting in boxes, the sparrows paired variableswere not testedfor bivariate normal- used buildings, machinery, and trees. At the farm ity. Nonetheless, r is a useful indicator of trend. studied both years, nests built in trees were moni- This analysis assumesthat fledglings of equal tored in addition to those in nest boxes. weight contribute equally to parental fitness. This Data collection.--Nestswere inspectedat 3-5 day assumptionmay not be valid for a specieswith a intervalsfrom 2 May to 15 August 1977and from 20 long breeding season.Dyer et al. (1977) published April to 13 August 1978. If weather conditionsper- the following survivorship equation for juvenile mitted, a 3-day interval was maintained. Eggswere House Sparrows (from Summers-Smith 1963); Y = January1983] HouseSparrow Reproductive Costs 27

TABLE2. Interbroodinterval (days).

Number of 1977-box 1977-tree fledglings 1978 nestsa nests•

First to second 0 11.4 6.0** 8.1' i 6.4 6.3 8.0 2 7.4 7.3 8.3 3 10.8 8.0 9.4 4 9.5 9.1 11.0 5 11.0 8.3 --

Second to third 0 10.7 6.9** 7.2 1 10.0 7.4 9.2 2 10.9 7.9 9.4 3 11.7 8.7 10.0 4 10.2 8.1 9.2 5 12.0 10.6 9.5

• * - correlationwith numberof fledglingsis significantat P < 0.05. ß* = correlationwith numberof fledglingsis significantat P < 0.01. Paired comparisont-test for differencesbetween first to second and secondto third intervals: d = 0.694, t - 1.92, 16 df, 0.05 < P < 0.10. Paired comparisont-test for differencesbetween tree and box nests for 1977: d = 1.18, t - 4.32, 10 df, P < 0.01.

102.9X0.•;s,, where Y = percentageof juvenilessur- viving and X = month after fledging. If this equation accuratelydescribes juvenile survivorship, then late-fledgingyoung are more likely to be recruited into the population, and reproductive effort should be concentratedtoward thff end of the breedingseason. In a seasonal environment such as that at Cal- gary, however, late-fledgingyoung experiencecold temperatures, snowcover, and food shortagesat a younger age than do early-fledging young. Thus, a late-fledgingcohort might suffer greateroverwinter mortality(McGillivray 1981a). Predation on eggs and nestlingswas rare at this site. Few entire clutchesor broodsdisappeared, and mostnesting mortality canbe attributed to starvation.

RESULTS

For speciesthat raise a single brood each season,the breedingseason would be that period of the year during which parentshave the highest probability of successfullyfledging young. The same is true for a multibrooded species,but conditionsare unlikely to be con- stant through the season.The averageHouse Sparrow productivity for clutch initiations 1 through4 is displayedin Table 1. If one con- siders only the averagenumber fledged, the secondbrood is the most productive,the third slightly less, the fourth relatively unproduc- tive, and the first quite differentbetween years. 28 w. BRUCEMcGILLIVRAy [Auk, Vol. 100

TABLE3. Relationship between fledgling production and measuresof reproductive effort (and standard error) for each brood.

Number Nestling period Breeding attempt fledged Clutch sizea Fledglingweight length(days) • length(days) a'b Brood 1 0 4.68** (0.06) -- 2.82* (0.25) 26.32** (0.60) 1 4.81 (0.17) 24.52 (0.48) 13.03 (0.50) 33.32 (0.55) 2 4.50 (0.13) 25.47 (0.35) 13.56 (0.41) 35.73 (0.31) 3 4.87 (0.10) 25.21 (0.36) 13.58 (0.28) 36.65 (0.52) 4 5.29 (0.11) 24.30 (0.39) 13.77 (0.36) 37.23 (0.55) 5 5.58 (0.15) 23.74 (0.45) 13.91 (0.72) 37.80 (1.08) 6 6.00 (0.00) 27.84 (0.00) 15.00 (0.00) 39.00 (0.00) Brood 2 0 4.95** (0.08) -- 2.28* (0.27) 24.00** (0.88) 1 4.96 (0.19) 25.78 (0.64) 12.41 (0.55) 33.94 (0.84) 2 5.13 (0.11) 26.57 (0.36) 12.31 (0.30) 35.72 (0.66) 3 5.20 (0.09) 26.17 (0.35) 12.90 (0.26) 37.46 (0.56) 4 5.37 (0.10) 25.07 (0.38) 12.76 (0.52) 36.03 (0.51) 5 5.45 (0.11) 24.96 (0.63) 13.23 (0.50) 39.03 (0.98) 6 6.00 (0.00) 25.75 (3.50) 14.50 (2.50) 43.00 (0.00) Brood 3 0 4.59* (0.10) -- 2.06 (0.27) 23.44 (1.03) 1 5.00 (0.25) 26.20 (0.83) 12.08 (0.57) 37.00 (3.50) 2 4.50 (0.19) 26.64 (0.52) 11.74 (0.51) --• 3 4.89 (0.14) 26.80 (0.42) 11.97 (0.32) 37.25 (1.70) 4 5.19 (0.09) 26.77 (0.41) 12.67 (0.32) 35.80 (1.96) 5 5.25 (0.11) 26.05 (0.58) 12.57 (0.80) 33.60 (0.68) 6 6.00 (0.00) 25.42 (0.00) 13.00 (0.00) __c Brood 4 0 4.22 (0.17) -- 1.87 (0.50) __c 1 4.67 (0.42) 26.65 (0.83) 10.67 (1.10) -- 2 4.20 (0.26) 24.76 (1.74) 10.50 (0.87) -- 3 4.80 (0.37) 27.60 (0.72) 11.80 (0.58) -- 4 5.00 (0.00) 24.31 (1.31) 13.50 (1.50) --

• * - correlationwith the number of fledglings significant at P < 0.05. ß* - correlationwith the number of fledglings significant at P < 0.01. • Interval between successive clutch initiations. "No subsequentclutch initiated.

High fledgling output from first broodsis un- an increase over the second to third interval is usualfor House Sparrowsin this area(Murphy observed.The longer interbrood interval for 1977), because cold weather, rain and snow are pairs nesting in trees suggeststhat daily en- commonthroughout May (McGillivray 1981b). ergy requirementsare lower for box-nesting That the interval between the fledging of a females. brood and the initiation of the next clutch (in- Why the physiologicalcost of nestingmight terbrood interval) increases as the number increasewith the numberof youngfledged from fledging increasesis shown in Table 2. The a brood is shown in Table 3. On the average, longer interval between second and third femalesmust expendenergy laying additional broods comparedto the interval between first eggs,and the pair must spenda longer time and secondbroods implies that the physiolog- feeding the young in large broods.As brood ical costsof breeding are cumulative. Sample size increases, adult House Sparrows increase sizes for the third to fourth brood interval are the rate of feedingtrips to the nestlings(Sum- too small to consider(<5), exceptfor box nests mers-Smith1963, Seel 1969,Sappington 1975, in 1977that fledgedno youngin the third brood McGillivray 1981a), and, at least for these two (interbroodinterval = 7.6 days,n = 17), where years,average fledging weight doesnot change January1983] HouseSparrow Reproductive Costs 29

TABLE4. Relationship between the number of TABLE5. Modal number fledgedin each brood for fledglingsproduced and productivityin the sub- pairs groupedby seasonaltotal fledgling produc- sequentbreeding attempt. tion.

Proba- Seasonaltotalfledglingproduction bility of starting Brood 1-2 3•4 •6 7-8 %10 >10 Number Clutch Number next I 2.0 3.0 3.0 3.5 3.0 3.0 fledged n size fledged clutch 2 2.0 3.0 3.0 4.0 5.0 4.5 Brood 1 Brood 2 3 0.0 0.0 0.0 0.0 4.5 4.0 4 0.0 0.0 0.0 0.0 1.5 1.5 0 234 5.10 1.69 0.70 1 38 5.48 2.36 0.82 2 61 5.21 2.23 0.77 3 81 5.06 2.07 0.84 4 56 5.10 1.88 0.73 broods, I compared third and fourth brood 5 14 5.40 1.60 0.71 productivitywith summedfledgling totals from 6 1 4.00 0.00 1.00 all previous broods. For pairs fiedging at least Brood 1 and Brood 2 Brood 3 one young, the summed fledgling production 0 41 4.63 1.22 0.60 from broods i and 2 is negatively correlated 1 13 5.08 1.69 0.81 2-3 75 4.84 1.83 0.75 with the number fiedging in brood 3 (Table 4, 4-5 65 4.83 1.54 0.69 r = -0.81, 4 df, 0.05 < P < 0.10). Again, the 6-7 37 4.51 1.46 0.51 probability of renesting and the average clutch 8-9 12 5.00 0.50 0.75 size are not related to productivity earlier in >9 1 5.00 0.00 1.00 the season. Broods 1, 2, and 3 Brood 4 There is a nonsignificant, negative relation- 0 7 4.00 1.14 0.22 ship between total productivity in broods 1, 2, 1-3 18 4.78 0.50 0.41 4-6 20 4.20 1.00 0.22 and 3 and the averagenumber fiedging in brood 7-9 8 4.25 0.62 0.15 4 (Table4). The probability of initiating a sub- 10-12 2 4.00 0.50 0.15 sequent brood has dropped from the previous two comparisonsand is lowest for pairs with the highest fledgling numbers from the previous three broods. with brood size. Although thermoregulatory When the fledgling data from the three com- costs should be lower for nestlings in larger parisons (broods I vs. 2; i and 2 vs. 3; and 1, broods, these are unlikely to offset the extra 2, and 3 vs. 4) are combined and standardized feeding demands on parents created by more by transformation to Z-scores, previous pro- nestlings. ductivity is shown to be negativelycorrelated For the combined breeding seasons1977 and with future productivity(r = -0.63, 14 df, P < 1978, pairs that showed higher productivity 0.05). from the first clutch tended to have lower out- The strongnegative relationship between first put from the secondclutch (Table 4). For pairs and secondbrood productivity is reflected in that fledged at least one young from the first the distribution of fledgling production over brood, there is a negative correlationbetween the breeding season.Table 5 demonstratesthat the number fledged in brood 1 and the number the highest fledgling totals were achieved by fledged in brood 2 (r = -0.85, 4 df, P < 0.05). pairs with high post-first-broodproductivity. The classcontaining pairs fiedging no young A prediction from life-history theory is that, was excludedfrom analysesbecause of its het- unlessthe raising of last broods lowers adult erogeneity. It includes a range from pairs rais- survivorship, reproductive effort should be ing young to near fiedging to others losing higher for that brood than for broodsearlier in clutches before hatching. The probability of the season. Last broods, as defined here, in- startinga secondclutch and the size of second clude fourth broods and third broods after clutches are uncorrelated with the number of which no fourth clutch was initiated. Because fledglings from brood one. no physiologicalmeasures were made, only in- Becausethe interbrood interval data sug- direct estimates of effort can be used. Table 6 gestedthat physiologicalstrain is additive over demonstratesthat, for four possible indicators 30 w. BRUCEMcGILLIVRAY [Auk, Vol. 100

TABLE6. Measuresof reproductiveeffort (and standarderror) by pairs for broodsafter which fourth clutches were initiated, third broods that were last broods and fourth broods.

Third broods

Variable Not last Last Fourth broods

Clutch size 4.83 (0.10) 4.74 (0.07) 4.36 (0.13) Number fledged 2.93 (0.18) 2.78 (0.13) 2.11 (0.23) Fledglingweight (g) 26.54 (0.40) 26.48 (0.25) 26.01 (0.65) Nestling period (days) 12.36 (0.37) 11.70 (0.25) 11.22 (0.48)

of reproductiveeffort, averagevalues for third secondbroods indicatesa cumulativephysio- broods that are also last broods are not signif- logicaleffect of the first two broods.This effect icantly different from those of third broods af- is suggestedby Pinowska's observations(1979) ter which a fourth clutch was laid. There is also of protein levels and by the reduced survivor- no evidence of enhanced effort for fourth ship of double-brooded House Martins found broods. by Bryant (1979).

DISCUSSION The longer interbrood interval for pairs us- ing tree nests supports other observations These data suggestthat the trade-offs and (Murphy 1978,McGillivray 1981b)showing that the theoryrequired to accountfor them are dif- box nestsare superior nest sites. A warmer mi- ferent for single and multibrooded species.An croclimate (Mertens 1977) would reduce nest- inverse relationship between present and fu- ling thermoregulatorycosts, and a reduction in ture fecundity is suggestedbut not as a func- the need for nest maintenance would facilitate tion of reduced survivorship. Rather, high pro- renesting in boxes. ductivity delaysthe initiation of the following While the tree-versus box-nest comparisons clutch and is negatively correlatedwith pro- provide appealing evidence for physiological ductivity from future clutches. correlatesof reproductive costs,they point out Two studies (Schifferli 1976, Pinowska 1979) a problem in the evaluation of reproductive ef- have monitored the physiologicalcondition of fort. If nest-site selection can modify the cost adult House Sparrows through the breeding of raising young, then other factors such as season.For females, fat level drops during egg weather, distance to food sources, time of clutch laying, is partially replacedduring incubation, initiation, and parental age and size are also drops again during the nestling period, and likely to modify the reproductiveeffort asso- presumably is restored in the interbrood in- ciated with raising a brood of fixed size. The terval. Protein level drops gradually through importanceof factorsother than productivity the breeding season. Pinowska (1979) found may provide a partial explanationfor the con- that clutch size was correlated with fat level tradictoryresults obtained in previous studies and the number of clutches initiated in a sea- of the trade-offbetween reproductiveeffort and son was limited by protein level. For males,fat survivorship in passerines (Bryant 1979, As- level drops during the nestling period and is kenmo 1979, De Steven 1980, Smith 1981). replenished in the interbrood interval. There is no simple physiologicalhypothesis These two studies suggestthat, after com- to accountfor reduced productivity from pairs pleting a brood, both sexesof a pair fiedging fledging many young. Becauseclutch size and many young would have lower fat levelsthan the probability of renesting are generally un- those of a pair fiedging few young. The lower related to previous productivity, the cost of re- fat level should result in either a smaller clutch production is felt by parents during the incu- size or a longer delay in the initiation of the bation and nestling period. While the nestling subsequentclutch. My observationsshow that period is consideredhighly demanding(Rick- clutch size is not affectedby previousproduc- lefs 1973), much of the evidence (particularly tivity but subsequentclutch initiations are de- weight lossesfor adults) is now questionable layed. The longerinterval betweensecond and (Norberg 1981). third broodscompared to that betweenfirst and There is no evidence from the data that re- January1983] HouseSparrow Reproductive Costs 31 productive effort increasesas the probability BRYANT,D. 1979. Reproductivecosts in the House of surviving to the next breeding attempt de- Martin (Delichon urbica). J. Anim. Ecol. 48: 655- creases.As mentioned earlier, however, only 675. partial estimatesof reproductiveeffort are pos- CHARNOV, E. L., & J. R. KREBS. 1974. On clutch sible. Pinowska (1979) felt that breeding in size and fitness. Ibis 116: 217-219. House Sparrowsfollowed a cyclicalpattern in DE STEVEN,D. 1980. Clutch size, breeding success and parental survival in the Tree Swallow (Iri- which a poolof resourcesis alternativelytapped doprocnebicolor). Evolution 34: 278-291. and partially replenisheduntil depletedbelow DYER, M. I., J. PINOWSKI, & B. PINOWSKA. 1977. a critical point and breeding ceases.Hence, Populationdynamics. Pp 55-103 in Granivorous second, third, and fourth broods are initiated birds in ecosystems(J. Pinowski and S. C. Ken- only by females that possess sufficient re- deigh, Eds.). Cambridge, England, Cambridge sources. Last broods, which should show en- Univ. Press. hanced reproductiveeffort accordingto life- FISHER,R. A. 1930. The geneticaltheory of natural history theory, might, in fact, show evidence selection. Oxford, Clarendon. of physiologicalstrain. Seasonaldifferences VON HAARTMAN,L. 1971. Populationdynamics. Pp. make comparisonsamong broods difficult to 392-459 in Avian biology (D. S. Famer and J. R. King, Eds.). New York, AcademicPress. interpret, but the comparisonbetween third HUSSELL,D. J.T. 1972. Factorsaffecting clutch size broods that were last broods and third broods in arctic passerines. Ecol. Monogr. 42: 317-364. after which a fourth clutch was initiated is re- JONES,P. J., & P. WARD. 1976. The level of reserve vealing. Table 6 indicatesthat, while none of protein as the proximate factor controlling the the chosen measures of effort is different be- timing of breeding and clutch size in the Red- tween groups, the direction of difference al- billed Quelea, Queleaquelea. Ibis 118: 547-573. ways suggestslower resourcelevels for pairs KLOMP, H. 1970. The determination of clutch size raising last broods. in birds, a review. Ardea 58: 1-124. A reviewer pointed out that life-history KLUYVER,H. N. 1963. The determination of reproductive rates in Paridae. Proc. 13th Intern. Or- theorists consider ultimate causes, but field nithol. Congr.: 706-716. workers are forced to explain proximate rea- 1970. Regulation of numbers in popula- sonsfor phenomena such as clutch size, num- tions of Great Tits, Parusm. major. Pp. 507-523 ber of breedingattempts per season,and sur- in Dynamics of numbers in populations (P. J. vivorship. The lack of concordance between den Boer and G. R. Gradwell, Eds.). Wagenigen, theory and field observations(Smith 1981, this The Netherlands. Proc. Adv. Study Inst. Oos- study), while perhapsan indictmentof the the- terbeck, The Netherlands, PUDOC. ory, is equally likely to be the result of failure LACK,D. 1947. The significanceof clutchsize. Ibis to controland accountfor proximatevariation. 89: 302-352. 1966. Population studiesof birds. Oxford, ACKNOWLEDGMENTS Clarendon Press. LOWTHER,P. E. 1979. Growth and dispersal of I firstwould like to thankEdward C. Murphy and nestlingHouse Sparrows: sexual differences. In- Peter E. Lowther, whose ideas generatedmy study land Bird Banding 5: 23-29. and focusedmy attention. RichardF. Johnstonpro- McGirriVR•Y, W.B. 1978. The effectsof nest po- vided constantencouragement and financialsupport sition on reproductiveperformance of the House and gave freely of his extensiveknowledge of Passer Sparrow. Unpublished M.A. thesis, Lawrence, biology. S.C. McGillivray, R. C. Fleischer,G. Pitt- Kansas, Univ. Kansas. man, and J. T. Paul, Jr. aided with the fieldwork. I 1981a. Breeding ecology of House Spar- appreciatethe time given by H. L. Levenson,P. E. rows. Unpublished Ph.D. dissertation, Law- Lowther, R. C. Fleischer,M. T. Murphy, and G. E. rence, Kansas, Univ. Kansas. Gurri-Glass in considerationof my ideas. R. F. John- 1981b. Climatic influences on productivity ston, M. S. Gaines, N. A. Slade, D. C. Seel, and an in the House Sparrow. Wilson Bull. 93: 196-206. anonymousreviewer all read and improveddrafts of MERTENS,J. A. L. 1977. Thermal conditions for this manuscriptwith their comments.Financial sup- successfulbreeding in Great Tits (Parusmajor port was supplied by National ScienceFoundation L.). II. Thermal propertiesof nestsand nestbox- grants DEB-02374and DBS-7912412to R. F. Johnston. es and their implications for the range of tem- peraturetolerance of Great Tit broods.Oecologia LITERATURE CITED 28: 31-56. ASKENMO,C. 1979. Reproductive effort and return MORVHY,E. C. 1977. Breeding ecologyof House rate of male Pied Flycatchers.Amer. Natur. 114: Sparrows. Unpublished Ph.D. dissertation, 748-752. Lawrence, Kansas, Univ. Kansas. 32 w. BRUCEMcGILLIVRAy [Auk, Vol. 100

1978. Seasonal variation in reproductive SCHIFFERLI,L. 1976. Weight conditions in the output of House Sparrows:the determinationof HouseSparrow particularly when breeding.Un- clutchsize. Ecology59: 1189-1199. published Ph.D. dissertation, Oxford, Oxford NEWTON,I. 1966. Fluctuationsin the weight of Univ. bullfinches. Brit. Birds 19: 89-100. SEEr, D.C. 1969. Food, feeding rates and body NORBERG,R. •. 1981. Temporaryweight decrease temperature in the nestling House Sparrow in breeding birds may result in more fledged (Passerdomesticus) at Oxford. Ibis 111: 36-47. young. Amer. Natur. 118: 838450. SMITH,J. N.M. 1981. Does high fecundityreduce PIANKA,E. R., & W. S. PARKER.1975. Age specific survival in Song Sparrows?Evolution 35: 1142- reproductivetactics. Amer. Natur. 109: 453-464. 1148. PINKOWSK•,B.C. 1977. Breeding adaptationsin , & D. A. RUFF. 1980. Temporal spacingof the Eastern Bluebird. Condor 79: 289-302. broods, brood size and parental care in song PINOWSKA,J. 1979. The effect of energy and build- sparrows (Melospiza melodia). Can J. Zool. 58: ing resourcesof females on the production of 1007-1015. House Sparrows Passerdomesticus L. popula- SNELL,T. W., & C. E. KINe. 1977. Lifespan and tions. Ecol. Polska 27: 363-396. fecunditypatterns in rotifers:the costof repro- R•CKLEES,R. E. 1974. Energeticsof reproduction duction. Ecology31: 882490. in birds. Pp. 152-292 in Avian energetics(R. A. STEARNS,S.C. 1976. Life-history tactics:a review Paynter, Jr., Ed.). Publ. Nuttall Ornithol. Club of the ideas. Quart. Rev. Biol. 51: 3-47. No. 15. SUMMERS-SMITH,D. 1963. The House Sparrow. SAPPINGTON,J. N. 1975. Cooperative breeding in London, Collins. the House Sparrow (Passerdomesticus). Unpub- WILL•AMS, G.C. 1966. Natural selection, the costs lished Ph.D. dissertation, Mississippi State, of reproductionand a refinementof Lack'sprin- Mississippi, Mississippi State Univ. ciple. Amer. Natur. 100: 687-690.

Now AVAILABLE

WorldInventory of Avian Skeletal Specimens. 1982. D. ScottWood, RichardL. Zusi, and Marion Anne Jenkinson. WorldInventory of Avian SpiritSpecimens. 1982. D. ScottWood, Richard L. Zusi, and Marion Anne Jenkinson. Published by The American Ornithologists'Union and The Oklahoma BiologicalSurvey, the cost of each inventory is $25.00, including surface mail postage.For air mail, add $5.00 (U.S.), $5.50 (Canada, Alaska, Hawaii), $9.00 (Mexico, Central America), $15.50 (Europe, South America), or $22.00 (Asia, Australia, New Zealand, Africa). Make checkor money order, in American dollars, payable to University of Oklahoma. Order from Dr. Gary D. Schnell, Oklahoma BiologicalSurvey, Sutton Hall, University of Oklahoma, Norman, Oklahoma 73019, U.S.A.

The First Conferenceon Birds Wintering in the MediterraneanRegion will be held on 23-25 February1984 at Aulla, Italy. Emphasiswill be on the ecology,ethology, distribution, and migration of birds wintering in this region. For further information and preregistrationmaterials contact Dr. Almo Farina, Museum of Natural History of Lunigiana, Fortezzadella Brunella, 54011Aulla, Italy.

The Raptor ManagementInformation System(RMIS) is a collectionof published and unpublishedpapers, reports, and other works on raptor management and human impacts on raptors and their habitats. It currentlyconsists of nearly 2,500 original papers, 160 keyworded notecarddecks comprised of 15,000key paragraphsfrom the original papers,and a computerprogram to retrieve partially annotatedbibliographies by species,by keyword, or by any combinationof keywordsand/or species. A geographicalindex is under development, and new papers are added as they are received. Originally designed to facilitate land-use planning and decisionmakingby governmentagencies and industry, the RMIS has since grown into a powerful researchand environmentalassessment tool for scholars,students, consultants, as well as land managersand their staff biologists. For more information write Dr. Richard R. Olendorff, U.S. Bureau of Land Management,2800 Cottage Way, Sacramento,California 95825 U.S.A., or phonecommercial (916) 484-4701or throughthe FederalTelephone System 468-4701.