Annual Patterns of Molt and Reproductive Activity of Passerines

Annual Patterns of Molt and Reproductive Activity of Passerines in South-Central Brazil Author(s) :Miguel Â Marini and Renata Durães Source: The Condor, 103(4):767-775. 2001. Published By: Cooper Ornithological Society DOI: URL: http://www.bioone.org/doi/full/10.1650/0010-5422%282001%29103%5B0767%3AAPOMAR %5D2.0.CO%3B2

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BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. The Condor 103:767±775 ᭧ The Cooper Ornithological Society 2001

ANNUAL PATTERNS OF MOLT AND REPRODUCTIVE ACTIVITY OF PASSERINES IN SOUTH-CENTRAL BRAZIL

MIGUEL AÃ .MARINI1 AND RENATA DURAÄ ES Departamento de Biologia Geral, ICB-Instituto de CieÃncias BioloÂgicas, Universidade Federal de Minas Gerais, C.P. 486, 30161-970, Belo Horizonte, MG, Brazil

Abstract. We analyzed the occurrence of molt and brood patches in resident passerines from four localities in south-central Brazil. The annual patterns of molt and reproductive activity were very similar among the sites. Brood patches ®rst appeared in August, but were most common between October and January, with a peak in November, early in the rainy season. Molt started in October but was most widespread from the middle to the end of the rainy season, between December and April with a peak in February. Timing of the appear- ance of brood patches was not related to trophic guild (insectivores, frugivores, omnivores). Molt of ¯ight feathers started at the end of the reproductive period, which varied slightly among trophic guilds. Molt and brood patch overlap occurred in little more than 4% of individual birds, or in less than 2% considering just those molting ¯ight feathers. This overlap occurred mostly between November and February. Regional environmental factors, instead of local factors, seem to be responsible for the annual breeding and molt patterns of the considered species. Key words: Atlantic forest, Brazil, cerrado region, molt, passerine birds, reproduction.

PadroÄes Anuais de Muda e Atividade Reprodutiva de Passeriformes na RegiaÄo Centro-Sul do Brasil Resumo. Este estudo analisa a ocorreÃncia de muda de penas e reproducËaÄo em Passeri- formes residentes em quatro localidades na regiaÄo centro-sul do Brasil. A atividade reprodutiva foi inferida a partir da presencËa de placas de incubacËaÄo ativas. Os padroÄes anuais de muda e reproducËaÄo apresentaram-se bastante similares entre as regioÄes estudadas. Placas de incubacËaÄo comecËaram a ser detectadas em agosto, sendo mais comuns entre outubro e janeiro, com um pico em novembro, no inõÂcio da estacËaÄo chuvosa. O principal perõÂodo de mudas comecËou em outubro, sendo mais intensas nos dois tercËos ®nais da estacËaÄo chuvosa, entre dezembro e abril, com um pico em fevereiro. Os padroÄes de ocorreÃncia de reproducËaÄo e mudas apresentaram pequenas diferencËas entre diferentes guildas alimentares, e, de modo geral, o inõÂcio do perõÂodo de mudas esteve relacionado ao ®m do perõÂodo reprodutivo. SobreposicËaÄo entre mudas e placas de incubacËaÄo foi detectada em pouco mais de 4% do total de indivõÂduos analisados, ou em menos de 2%, quando apenas indivõÂduos mudando penas de voÃo foram considerados. Esta sobreposicËaÄo ocorreu principalmente entre novembro e fevereiro. Os padroÄes ambientais regionais, mais que os locais, parecem in¯uenciar os ciclos anuais das espeÂcies analisadas.

INTRODUCTION nual cycle of birds is obtained by a mutual ad- The biology of molt and reproduction are inti- justment, in which breeding affects molt as molt mately related in the annual cycles of birds affects breeding (Langston and Rohwer 1996). (Snow 1976, Poulin et al. 1992). The extra en- Our understanding, however, of how this ®ne ergy demanded by these activities exerts an evo- and complex adjustment takes place is far from lutionary pressure for their occurrence during complete, since different patterns have evolved the most favorable time of the year and for the among species and regions (Payne 1972). minimization of overlap between them (Foster Long-term studies about molt of Neotropical 1975). The timing of both events during the an- birds are rare, and most of them emphasize observations about molt sequence (Wagner 1955), occasional molt records (Oniki 1981, Dyrcz Manuscript received 17 June 2000; accepted 14 June 1987), or records for single species (Miller 2001. 1961, Davis 1971, Mallet-Rodrigues et al. 1995, 1 Present address: Departamento de Zoologia, IB, Universidade de BrasõÂlia (UnB), 70.910-900, BrasõÂlia, Valente 2000). Reproduction of Neotropical DF, Brazil. E-mail: [email protected] birds also has received relatively little attention

[767] 768 MIGUEL AÃ . MARINI AND RENATA DURAÄ ES

(Skutch 1968, Oniki and Willis 1982, Cruz and Andrews 1989). In addition, molt and reproduction rarely have been studied together in the annual cycles of bird communities (Snow 1976, Poulin et al. 1992, Piratelli et al. 2000). Studies of the occurrence of molt and reproduction at the community level may indicate general patterns on the annual cycle of birds at a local level, and may help us to understand how these activities relate to each other and to local environmental characteristics. Here, we describe the annual patterns of molt and breeding activity, indicated by the occurrence of brood patches, in passerines residing mostly in forests within the cerrado region of south-central Brazil. Trophic guilds are compared to evaluate whether these patterns are affected by diet. Finally, by comparing four sites, we evaluate whether molt and breeding patterns are determined at a local or regional level.

METHODS STUDY AREA We conducted this study in gallery, semi-decid- uous, and mesic forests of Minas Gerais State and the Federal District of Brazil. In Minas Ge- rais, three regions were sampled: (1) Belo Ho- rizonte: forest fragments within the Water Man- agement Areas of Barreiro, Mutuca, and Ta- booÄes owned by the Companhia de Saneamento de Minas Gerais (21Њ00ЈS, 44Њ00ЈW, 800±900 m elevation); (2) UberlaÃndia: forest fragments within private cattle farms (18Њ57ЈS, 48Њ12ЈW, 800 m); and (3) Canastra: two study sites 65 km apart, including a gallery forest owned by the FIGURE 1. Location of the study sites in Minas Ge- Companhia EleÂtrica de Minas Gerais (20Њ40ЈS, rais State and Federal District. GO ϭ GoiaÂs State; MG 46Њ19ЈW, 900 m), and natural forest patches ϭ Minas Gerais State; DF ϭ Federal District; UB ϭ UberlaÃndia; CA ϭ Canastra (2 sites); BH ϭ Belo Ho- within the Parque Nacional da Serra da Canastra rizonte. (22Њ00ЈS, 46Њ45ЈW, 1033±1493 m). Three gallery forests were sampled in the fourth region, BrasõÂlia, including two at the Fazenda AÂ gua Limpa, owned by the Universidade de BrasõÂlia Horizonte sites, which lie at the transition be- (15Њ58ЈS, 47Њ56ЈW, 1100 m), and one at the Re- tween the cerrado and the Atlantic Forest biome serva BioloÂgica do Instituto Brasileiro de Geo- (Veloso 1966, Ab'Saber 1977). gra®a e EstatõÂstica (IBGE; 15Њ56ЈS, 47Њ54ЈW, Climate of the cerrado region is seasonal, with 1100 m; Fig. 1). a rainy warm season between October and The cerrado biome is a savanna-like ecosys- March and a dry cool season between April and tem of open vegetation formations, from grass- September. The rainiest months are December lands to dense scrub, as well as gallery forests and January and the driest are June, July, and in wetter areas and dry forests in rich-soil areas August. Temperature ranges from 18±24ЊC, with (Eiten 1978, Ferri 1981). All localities sampled a mean of 21ЊC. Monthly precipitation ranges lie within the cerrado biome, except for the Belo from 9 to 320 mm, with mean annual total of ANNUAL PATTERNS OF MOLT AND REPRODUCTION IN BRAZIL 769

1500 mm at all localities sampled (Departamen- red to Nacional de Meteorologia 1992).

DATA COLLECTION 470 (368) 360 (335) 377 (358)

Data were collected between March 1986 and 1311 (1254) 2518 (2315) February 2000, with different efforts in each site, varying from nine months over four years up to 0 6 0

34 months over six years (Table 1). Birds were 126 132 captured with 36-mm, 12 ϫ 2.5 m mist nets, opened usually between 06:00 and 13:00 along 12 36 39 transects in the interior and at the edge of the 156 243 forests. Each bird caught received a metal band

provided by the of®cial Brazilian banding agency 0 57 10

(CEMAVE/IBAMA). Birds were checked for the 195 262 presence of molt and brood patch. Molt was di-

vided into three types: (1) contour feathers: molt 0 of any type of feather, except the ¯ight feathers 129 106 112 347 of the wings and the tail, with a minimum of 10 feathers growing in one or more body regions; 0 34 23 (2) wing ¯ight feathers or remiges, and (3) tail 157 214 ¯ight feathers or rectrices. Wing and tail feathers were considered in molt only when the replace- 51 59 93 ment was symmetrical. Immature birds and mi- 110 313 gratory species were excluded. Species sampled Months 0

were mostly forest dwelling, but open-area spe- 42 14 69 cies were considered as well. Birds recaptured in 125 different months were considered as independent

records, but only the ®rst record of an individual 34 72 31 80 during each month was considered. 217 Brood patch was scored as present or absent.

A brood patch was considered present when 48 74 39 119 280 well characterized with evident vascularization and wrinkled, opaque-rose skin. The presence of a brood patch was taken as an indication that the 19 19 20 41 99 bird was reproductively active. In order to min-

imize error in our estimation of the proportion 0 12 22 92 of birds with brood patches, we adopted the fol- 126 lowing method for species with different incubation strategies: (1) We included in the analyses 32 25 32 71 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total all captured individuals for species in which 160 both sexes incubate the eggs (families Rhi- nocryptidae, Formicariidae, Conopophagidae, Vireonidae, Dendrocolaptidae, and Furnariidae); (2) for sexually dimorphic species in which only the females incubate the eggs, only the females were considered (families Tyrannidae, Emberi- zidae, and Cotingidae). For manakins (Pipridae) whose immature males resemble females, all

``green'' (female-plumaged) individuals were in- Study sites cluded; and (3) for monomorphic species in (Sampling period)

which only the females incubate the eggs (fam- Ãndia (1994±1996) ilies Tyrannidae, some Pipridae, Muscicapidae Âlia (1986±1990) Canastra (1994±1995, 1997±1998) Belo Horizonte (1995±2000) Total [Turdinae], Emberizidae, and Troglodytidae), the TABLE 1.independent samples Number (number of of birds individuals in analyzed parentheses). by month and study site in forests ofBrasõ south-central Brazil.Uberla Individuals recaptured in different months were conside 770 MIGUEL AÃ . MARINI AND RENATA DURAÄ ES

TABLE 2. Number of species (individuals) of analyzed passerines by study site. Taxonomy follows Sick (1997).

Belo Family UberlaÃndia BrasõÂla Canastra Horizonte Total Rhinocryptidae 0 0 1 (1) 0 1 (1) Formicariidae 6 (29) 1 (9) 2 (26) 4 (124) 8 (188) Conopophagidae 1 (3) 1 (7) 1 (13) 1 (64) 1 (87) Furnariidae 6 (18) 4 (33) 4 (25) 8 (64) 14 (140) Dendrocolaptidae 2 (5) 2 (34) 3 (11) 3 (67) 5 (117) Tyrannidae 9 (71) 7 (62) 14 (98) 14 (331) 22 (562) Pipridae 3 (72) 2 (77) 2 (27) 4 (135) 6 (311) Cotingidae 0 0 0 1 (1) 1 (1) Troglodytidae 1 (7) 1 (16) 0 0 1 (23) Muscicapidae (Turdinae) 2 (19) 3 (27) 2 (20) 3 (94) 3 (160) Vireonidae 1 (2) 1 (2) 0 2 (14) 2 (18) Emberizidae 7 (134) 17 (203) 22 (156) 23 (417) 37 (910) Total 38 (360) 39 (470) 51 (377) 63 (1311) 101 (2518) total number of captured individuals was divided the family both sexes incubate the eggs. Species by two. These percentages were calculated nomenclature, classi®cations, and diet character- monthly, for each year and study area. This ization follow Sick (1997). method may have produced small errors by including a few non-incubating males or excluding STATISTICAL ANALYSES a small number of incubating females, but a sep- We compared brood patch frequency by month arate analysis using only evidently incubating between pairs of regions using Spearman rank individuals produced similar results, indicating correlation (Sokal and Rohlf 1981). We com- that this error did not alter overall conclusions. pared molt frequency by month between pairs of The classi®cation of the reproductive behav- regions using Pearson correlation coef®cients. ior of males and females was based on Willis Non-normal data were normalized using arcsine (1995) and Sick (1997). For Vireonidae, we fol- transformation (Sokal and Rohlf 1981). Only lowed Sick, who reports that for all species of months with at least 10 individuals for each site were included. Results were considered statisti- cally signi®cant at P Յ 0.05.

RESULTS Our analyses are based on 2518 records from 2315 individuals belonging to 101 species in 12 families of Passeriformes. The numbers of individuals and species sampled were similar for three regions, and larger for the Belo Horizonte region (Table 2). The number of bird families was similar among the four regions sampled (Ta- ble 2). Brood patches were recorded in 349 (21%) of 1649 individuals considered for this analysis. Reproductive activity, as indicated by the presence of brood patches, began in August, and was more frequent in November in all four regions (Fig. 2a). All regions showed high correlation (r values ϭ 0.58±0.87) between monthly molt FIGURE 2. Monthly frequencies of (a) brood patch s and (b) total molts (contour or ¯ight feathers) of pas- frequency, even though two of the six compar- serines in forests of south-central Brazil. Only months isons were not signi®cant (P Ͼ 0.2), probably with a minimum sample of ten individuals are graphed. due to the small number of months included in ANNUAL PATTERNS OF MOLT AND REPRODUCTION IN BRAZIL 771

FIGURE 3. General patterns of occurrence of brood patch (solid line), molts (contour or ¯ight feathers, dot- FIGURE 4. Monthly molt frequencies for contour ted line) and molt-breeding overlap (contour or ¯ight feathers, remiges, and rectrices of passerines in forests feathers, shaded bars; ¯ight feathers only, unshaded of south-central Brazil. bars) of passerines in forests of south-central Brazil. Comparison of molt and brood-patch timing these analyses. We therefore pooled data from among trophic guilds revealed small differences the four regions to evaluate the regional repro- related to diet within the general pattern (Fig. ductive-period pattern for south-central Brazil. 5). Insectivores and frugivores started to breed As above, brood patches began to appear in Au- in August. Although omnivores also showed gust, at the end of the dry season, and reached some breeding activity in August, it increased the highest frequencies between October and substantially in September. For all three guilds, December with a peak in November, early in the however, the reproductive period was most pro- rainy season (Fig. 3). nounced (Ͼ40% of individuals with brood Molt was recorded in 774 (31%) of 2518 patch) from October to December or January. birds, most of them replacing contour feathers Insectivores had high frequencies of brood separately (n ϭ 437) or together with ¯ight feathers (n ϭ 274), while 63 individuals were molting just ¯ight feathers. Molt of remiges was recorded in 254 (10%) of the assessed individuals and molt of rectrices was recorded in 208 (8%) of these individuals. Molt was concentrated between January and March in all regions sampled, diminishing or stopping completely in the other months (Fig. 2b). This period corresponds to the second half of the rainy season in the region. Molt frequency was highly correlated between regions (all r Ͼ 0.65) and the comparisons were signi®cant in all cases but two (P ϭ 0.07 and 0.16), so we pooled data to evaluate the existence of a general molt pattern for south-central Brazil. The pooled data for the four regions revealed higher molt frequency between December and April, with a molt peak in February±March, late in the rainy season (Fig. 3). Molt of all types of feathers (wing, tail, and contour) occurred mostly in this period, but Ͼ15% of birds replaced contour feathers even during dry-season months, reveal- ing a year-round replacement of body feathers not necessarily related to post-nuptial molt (Fig. 4). The peak of rectrix molt occurred in March, FIGURE 5. Monthly frequencies of brood patch (cir- a month after the peak of remige and body molt cles) and ¯ight feather molt (squares) in passerines of (Fig. 4). forests in south-central Brazil, by trophic guilds. 772 MIGUEL AÃ . MARINI AND RENATA DURAÄ ES

TABLE 3. Species with overlap between brood patch and molt. Any ϭ number of individuals molting any type of feather; Flight ϭ only those molting ¯ight feathers; n ϭ number of analyzed individuals.

Molt Species Any Flight n Plain Antvireo Dysithamnus mentalis 2 2 70 Black-capped Antwren Herpsilochmus atricapillus 1 0 5 Variable Antshrike Thamnophilus caerulescens 10 7 77 Rufous Gnateater Conopohaga lineata 6 3 82 Buff-fronted Foliage-gleaner Philydor rufus 1 0 6 Rufous-breasted Leaftosser Sclerurus scansor 2 4 7 Euler's Flycatcher Lathrotriccus euleri 1 0 81 Sepia-capped Flycatcher Leptopogon amaurocephalus 1 1 40 White-throated Spadebill Platyrinchus mystaceus 1 1 79 Short-crested Flycatcher Myiarchus ferox 2 0 12 Gray-hooded Flycatcher Mionectes ru®ventris 1 0 20 Yellow-olive Flycatcher Tolmomyias sulphurescens 13 4 48 Helmeted Manakin Antilophia galeata 2 0 77 Blue Manakin Chiroxiphia caudata 1 0 23 Pin-tailed Manakin Ilicura militaris 2 2 56 Pale-bellied Tyrant-Manakin Neopelma palescens 2 2 8 White-necked Thrush Turdus albicollis 1 0 17 Pale-breasted Thrush Turdus leucomelas 3 0 48 Rufous-bellied Thrush Turdus ru®ventris 1 0 35 White-bellied Warbler Basileuterus hypoleucus 1 1 126 Blue Dacnis Dacnis cayana 1 0 3 Ruby-crowned Tanager Tachyphonus coronatus 1 0 5 Palm Tanager Thraupis palmarum 1 1 2 Saffron-billed Sparrow Arremon ¯avirostris 2 2 31 Buff-throated Saltator Saltator maximus 1 0 1 Green-winged Saltator Saltator similis 1 1 42 Total 66 29 1620

patches between October and December, with a tween breeding and molt of ¯ight feathers was peak in November, and their molt was most fre- shorter, occurring mostly between December quent between December and March. Frugivores and February (Fig. 3). also had a high frequency of brood patches between October and December, but without a DISCUSSION very pronounced peak. Molt frequency began to Reproduction and molt are two activities that de- increase in January, but peaked in February± mand a high amount of energy, are generally March. Omnivores had a high frequency of concentrated in a period of high food productiv- brood patches from October to January, with a ity, and overlap minimally (Cruz and Andrews peak in December±January, later than the other 1989, Poulin et al. 1992, Piratelli et al. 2000). guilds. Their molt was more frequent between In seasonal tropical regions, the time of the year January and March, with a peak in February. with the greatest food availability is the end of Overlap between molt and breeding was re- the dry season and the rainy season (Davis 1945, corded in 4.1% (n ϭ 66) of the 1620 individuals Diamond 1974, Poulin et al. 1992). Matching assessed for both molt and brood patch. These this pattern, brood patches began to appear at 66 individuals represent 26 species from six late dry season±early rainy season in all four families. Overlap occurred from August until sampled regions, while molt was more pro- May, but was most frequent from November to nounced from the middle to the end of the rainy February. When we considered only those in- season. dividuals molting ¯ight feathers, whether or not The observed cycle of breeding activity is in conjunction with body feather molt, the rate very similar to that reported by Davis (1945) for of overlap dropped to 1.8% (n ϭ 29), in 13 spe- forest birds in SaÄo Paulo state, south of our cies and ®ve families (Table 3). The overlap be- study sites. Through analyses of gonadal devel- ANNUAL PATTERNS OF MOLT AND REPRODUCTION IN BRAZIL 773 opment, Davis determined a well-de®ned repro- of forest passerines. The latitudinal difference of ductive period starting in August±September 5Њ between BrasõÂlia and the other regions was not with a peak in October. He also registered two enough to cause major changes in reproduction peaks in the production of forest fruits, one in and molt periods. Altitude, also, did not strongly July±September (late dry season±early rainy interfere in the determination of reproduction and season) and another small peak in December± molt periods over the 300±600 m difference be- January, and found that insect abundance was tween Canastra and the other three regions. high between November and March, dropping Molt of ¯ight feathers indicate better the period after April. Thus, the peak in reproduction co- of postnuptial molt than the molt of contour incided with the peak of fruit production, and feathers, since at least 15% of individuals were the peak in insect production occurred by the replacing contour feathers year round. The peak time most birds were rearing nestlings, a phase of molt of remiges preceded the peak of molt of of extreme energetic demand for the bird. rectrices by about one month. However, there was Both in tropical and in temperate regions, the high overlap, suggesting that birds have little time start of the molt is almost always associated with to molt before the onset of the dry season. the end of reproduction (Snow 1976, Poulin et Foster (1974) stated that the proportion of al. 1992, Ralph and Fancy 1994). The general overlap between molt and reproduction is higher molt pattern observed in this study showed that in tropical than in temperate habitats, due to a the molt frequency began to increase about one prolonged breeding period in the tropics. The month after the peak of reproduction, when most low proportion of individuals overlapping molt individuals had already ®nished the incubating and breeding that we observed is similar to or phase, and extended until the end of the rainy smaller than the frequencies recorded in other season. By the early dry season the number of tropical regions. Piratelli et al. (2000) registered individuals in molt was small. This molt pattern a 3.2% overlap between birds presenting brood agrees with studies conducted in two other Bra- patches and any type of molt in southern Brazil. zilian states, SaÄo Paulo (molt period from De- Payne (1969) reported a 3.8% overlap between cember to February, Oniki 1981) and Mato gonads in reproductive stage and feather re- Grosso do Sul (molt period from November to placement in a collection of African birds, but April, Piratelli et al. 2000). this rate dropped to 1.5% when only individuals Differences in timing of reproduction and molting ¯ight feathers were considered. In Costa molt between trophic guilds were slight. Con- Rica, Foster (1975) observed overlap between trary to other studies (Skutch 1950, Snow and high gonadal development or active brood patch Snow 1964), but in agreement with Poulin et al. and molt in approximately 9% of individuals. (1992), frugivores did not start reproduction be- Ralph and Fancy (1994) registered overlap of fore insectivores; both guilds started to breed in 3.2% between brood patch or well-developed August. Noticeable reproductive activity for om- cloacal protuberance and molt of ¯ight feathers nivores began later, in September, and had a in six Hawaiian ®nch species. The comparison very sharp decrease in January. Insectivores also between these studies, however, must be made concluded the reproductive period in January, carefully. Many tropical species show incom- while frugivores extended reproduction until plete regression of gonads (Payne 1972), which February. The start of the molting period varied probably explains the higher proportion of over- with the end of the incubation period for each lap observed in studies based on gonadal stage guild, but the end of molt coincided with the end in relation to studies based on occurrence of of the rainy season. Omnivores, for example, brood patches. In addition, while our study con- which had a longer period with high frequencies siders only incubating species and sexes, both of brood patches, presented a shorter period of Foster and Payne included in their analyses birds molt than frugivores and insectivores. On the with different life histories. For example, brood other hand, insectivores had the frequency of parasites (Icterinae) certainly have smaller costs brood patches largely reduced by January and of reproduction and could overlap breeding and started to molt earlier, in December. molt to a larger extent. Regional climatic patterns in south-central Bra- Molt demands energy not only for the produc- zil, instead of local variations, are more likely to tion of new feathers, but also to compensate for determine the periods of reproduction and molt the loss of insulation and ¯ight ef®ciency (Ginn 774 MIGUEL AÃ . MARINI AND RENATA DURAÄ ES and Melville 1995, Swaddle and Witter 1997). DAVIS, J. 1971. Breeding and molt schedules of the Payne (1972) pointed out that even a small in- Rufous-collared Sparrow in coastal Peru. Condor 73:127±146. crease in metabolic rate associated with an in- DEPARTAMENTO NACIONAL DE METEOROLOGIA. 1992. crease in protein demand and reduced ¯ight ef®- Normais climatoloÂgicas (1961/1990). Secretaria ciency may be ecologically restrictive when a bird Nacional de IrrigacËaÄo, MinisteÂrio da Agricultura, is reproducing. Birds overlapping breeding and BrasõÂlia, DF, Brazil. molt can incur reduced clutch size, nest success, DIAMOND, A. W. 1974. Annual cycles in Jamaican forest birds. Journal of Zoology, London 173:277± and survivorship of nestlings and adults (Nilsson 301. and Svensson 1996, Svensson and Nilsson 1997). DYRCZ, A. 1987. Fat deposits and molt of birds mist- Even considering that the frequency of over- netted in southeastern Peru. Journal of Field Or- lap may be higher in tropical than temperate re- nithology 58:306±310. gions, the proportion of overlap observed in this EITEN, G. 1978. Delimitation of the cerrado concept. Vegetatio 36:169±178. and the other mentioned studies is still low. This FERRI, M. G. 1981. Os cerrados, um grupo de formas low overlap and the concentration of the molting de vegetacËaÄo semelhantes aÁs savanas. Revista de and reproductive cycles in a period of high food ServicËo PuÂblico 1:57±61. availability suggest that, even in the tropics, FOSTER, M. S. 1974. A model to explain molt-breeding these activities may represent an energetic con- overlap and clutch size in some tropical birds. straint and that there may be selection against Evolution 28:182±190. FOSTER, M. S. 1975. The overlap of molting and breed- the simultaneous occurrence of both. ing in some tropical birds. Condor 77:304±314. Our results support previous studies from GINN, H. B., AND D. S. MELVILLE. 1995. Moult in birds. tropical regions showing that reproduction and British Trust for Ornithology, Guide 19, Crowes molt cycles of forest resident passerines are in- of Norwich, UK. timately associated with the rainy season, but LANGSTON,N.E.,AND S. ROHWER. 1996. Molt-breeding tradeoffs in albatrosses: life history implica- have little overlap with each other. Small ad- tions for big birds. Oikos 76:498±510. justments of the periods of reproduction and MALLET-RODRIGUES, F., G. D. A. CASTIGLIONI, AND L. molt occur in different trophic guilds, and the P. G ONZAGA. 1995. Muda e sequeÃncia de pluma- regional climate in¯uences the annual molt and gens em Ramphocelus bresilius na restinga de Ba- breeding patterns more than the local climate. rra de MaricaÂ, Estado do Rio de Janeiro (Passe- riformes: Emberizidae). Ararajuba 3:88±93. ACKNOWLEDGMENTS MILLER, A. H. 1961. Molt cycles in equatorial Andean sparrows. Condor 63:143±161. During the period of this study MAM and RD held NILSSON,J.A.,AND E. SVENSSON. 1996. The cost of scholarships or research fellowships from CNPq, reproduction: a new link between current repro- CAPES, and FAPEMIG. Companhia de Saneamento ductive effort and future reproductive success. de Minas Gerais (COPASA), Companhia HidreleÂtrica Proceedings of the Royal Society of London Se- de Furnas, Universidade de BrasõÂlia, Instituto Brasilei- ries B 263:711±714. ro de Geogra®a e EstatõÂstica (IBGE) and several land- ONIKI, Y. 1981. Weights, cloacal temperatures, plum- owners allowed our entrance in their areas. CEMAVE age and molt condition of birds in the State of SaÄo (IBAMA) provided metal bands and band permits dur- Paulo. Revista Brasileira de Biologia 41:451±460. ing the study. R. A. Dornellas and M. AnciaÄes allowed ONIKI,Y.,AND E. O. WILLIS. 1982. Breeding records us to use some of their data. Dozens of collaborators of birds from Manaus, Brazil: Formicariidae to Pi- helped with mist netting. F. Mallet-Rodrigues shared pridae. 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