ORNITOLOGIA NEOTROPICAL 19: 417–426, 2008 © The Neotropical Ornithological Society

DIET AND FEEDING PREFERENCE OF THE PLAIN ANTVIREO ( MENTALIS) IN AN AREA OF BRAZILIAN ATLANTIC FOREST

Marco Antônio Manhães1,2 & Manoel Martins Dias1

1Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, São Carlos, São Paulo, Caixa Postal 676, CEP 13565-905, Brasil. E-mail: [email protected]

Resumo. – Dieta e preferência alimentar da Choquinha-lisa (Dysithamnus mentalis) em uma área de floresta atlântica brasileira. – A composição da dieta e a preferência alimentar da Choquinha- lisa (Dysithamnus mentalis) foram estudadas em uma área de Mata Atlântica no sudeste do Brasil, com base em conteúdo fecal e coleta de invertebrados na folhagem. Em 29 amostras foram encontrados 210 itens alimentares dos quais 208 eram invertebrados. Coleoptera, Araneae e Hymenoptera (separados em Formi- cidae e não Formicidae) dominaram a dieta, correspondendo a 56,8% de todos os itens e, em geral, os invertebrados consumidos foram também os mais abundantes na folhagem. Entretanto a representação das presas nas amostras fecais diferiu significativamente das amostras da folhagem, onde os maiores “ranks” de preferência foram para Hymenoptera não Formicidae e Hemiptera Heteroptera, enquanto os menores foram para Araneae e Coleoptera. A Choquinha-lisa mostrou preferência também para presas maiores do que 5 mm. O caráter generalista da espécie em termos de substrato de forrageio possivelmente favorece aumento na taxa de encontro de presas, permitindo selecionar aquelas a serem consumidas, embora sejam necessárias informações mais detalhadas para identificar associações estreitas com o com- portamento. Os resultados também sugerem que a espécie tende a otimizar o forrageio consumindo presas maiores, energeticamente mais rentáveis. Abstract. – We studied the diet composition and feeding preference of the Plain Antvireo (Dysithamnus mentalis, Thamnophilidae) in an area of Atlantic forest in southeastern , based on fecal content and foliage-dwelling invertebrates collected by branch clipping. In 29 samples, 210 food items were found, of which 208 were invertebrates. Diet consisted mostly of Coleoptera, Araneae and Hymenoptera (split into Formicidae and non-Formicidae) which together represented 56.8% of all items. Generally, the types of invertebrates consumed were also the most abundant in foliage samples. However, prey items present in fecal samples differed significantly from foliage samples, resulting in higher ranks of feeding preference for non-Formicidae Hymenoptera and Hemiptera Heteroptera and lower ranks for Araneae and Coleoptera. Plain Antvireo also showed preference for prey larger than 5 mm. The generalist character of its feeding habits in terms of foraging substrate might favor increased encounter rates, allowing for selection of some types of prey. Further studies are necessary to identify associations between diet and behavior. The results also suggest that the tends to forage optimally, consuming larger and more profitable prey. Accepted 29 May 2008. ______2Current address: Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, CEP 36036-900, Brasil.

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Key words: Diet, Plain Antvireo, Dysithamnus mentalis, insectivorous , prey selection, trophic ecology, upper montane rainforest, southeastern Brazil.

INTRODUCTION METHODS

The feeding ecology of is better known Study area. The study was conducted in the for conspicuous species (e.g., Galetti 1997, Ibitipoca State Park, state of Minas Gerais, Manhães 2003) and raptors, where pellets can southeastern Brazil. The park, located at be examined (e.g., Jaksiæ & Yáñez 1979, 21°40’–21°44’S and 43°52’–43°54’W, has Granzinolli & Motta-Júnior 2006). In con- 1488 ha, with an altitude ranging between trast, information regarding small and cryptic 1050 and 1784 m (Dias et al. 2003). The land- forest understory species is rare, and is scape is dominated by rock outcrops, with restricted to diet composition obtained from riparian forests along streams. The climate is studies of species in communities (e.g., Poulin classified as Cwb on the Köppen classifica- et al. 1994, Lopes et al. 2005). tion scheme with dry winters and rainy sum- In Neotropical forests, the resident under- mers. The park receives an annual average story avifauna is dominated by insectivorous precipitation of 1544 mm (Carvalho et al. birds (Develey & Peres 2000) which search 2000) and has an annual average temperature for food on the ground, foliage, or trunks and of 18.9°C (Aragona & Setz 2001). The branches. The Plain Antvireo (Dysithamnus research was restricted to the largest patch of mentalis, Thamnophilidae) is a common insec- upper montane rainforest of approximately tivore that mainly preys upon foliage-dwelling 90 ha, locally known as Mata Grande (Car- (Schulenberg 1983, Remsen & valho et al. 2000). Parker 1984) and is found in many fragments of Atlantic forest in southeastern Brazil. On Mist netting. We captured birds monthly from rare occasions, it follows army ants, capturing January to December of 2004 using 12 × 3 m flushed prey using short flights (Willis 1984). mist nets with 38-mm mesh. Five sites ran- Although it is not a threatened species and domly selected along pre-existing trails were occurs throughout southeastern Brazil (e.g., sampled one per day with nine nets arranged Willis & Oniki 1981, Ribon et al. 2003), Aleixo in a line at each site. The sites were sampled & Vielliard (1995) observed that Plain once every month. Mist nets remained open Antvireos disappeared from a 251-ha isolated approximately 7 h starting at 06:30 h. Birds forest fragment within an inhospitable were banded with numbered, metallic rings, landscape matrix. Though a common and held in cloth bags for 20–30 min, and released widespread species in , the close to the capture site. The feces deposited biology of the Plain Antvireo is poorly known in the bags were scraped and conditioned in and its diet has just been recently described by paper bags on which band information was Lopes et al. (2005) and Durães & Marini recorded. Fecal samples supplied informa- (2005) in studies of several understory bird tion similar to regurgitated samples, with suf- species. ficient sample size, without the need for In this paper, we described the diet of harmful emetic substances (Carlisle & Hol- the Plain Antvireo in an area of Brazilian berton 2006). Atlantic rainforest and measured the feeding preferences for taxonomic groups and prey Sorting and identification of fecal samples. The feces size. were transferred to 30-ml test tubes with 10

418 FEEDING HABITS OF THE PLAIN ANTVIREO ml of water, and boiled for approximately 10 biased for sessile invertebrates (Cooper & min to remove uric acid and clean fragments. Whitmore 1990), but sampling directly in the Next, the samples were filtered with filter vegetation should at least approximate paper, dried in a stove, and sorted under ste- resource availability for a foliage-gleaning reoscopic microscope (10–40x). Prey items bird. were classified usually to order, but Formi- cidae were easy to identify and separated of Statistical analyses. We analyzed feeding prefer- other Hymenoptera, adding one more feeding ence for the following size classes of inverte- item. Fragments of invertebrates were identi- brates: > 0–2.5, > 2.5–5.0, > 5.0–7.5, > 7.5 fied based on published guides (Ralph et al. mm. We defined “preference” as the con- 1985, Moreby 1987, Burger et al. 1999, Gomes sumption greater or less than the expected et al. 2001) and comparisons with structures given availability determined by field samples. removed from dissected specimens. Frag- Size of specimens collected from vegetation ments that could not be identified as belong- and feces were visually estimated on millime- ing to individuals different from those already ter-scaled graph paper. The total length of a identified or to new taxa in the sample were prey item was then approximated using linear discarded (Burger et al. 1999). Larvae of regression. These equations were calculated holometabolous were treated as relating the body length of a specimen to the “ larvae”, but nymphs were lumped width or length of a structure (e.g., jaw, head, with adults. The number of invertebrates in a etc.), but only one equation was obtained for fecal sample was determined according to the taxa with many small or damaged individuals. isolated (e.g., head) or paired (e.g., jaws, wings) Measurements also were taken with a caliper occurrence of the structure in the consumed rule with 0.05 mm precision. To investigate prey. Size and color were also used to differ- inaccuracies in visual estimates compared to entiate prey with similar structures (e.g., caliper measurements, we correlated esti- Coleoptera elytra). mated body lengths for some specimens mea- sured in both ways. The strong correlation

Invertebrate sampling. After a bird capture ses- obtained (rs = 0.99, N = 34, P < 0.001) sug- sion, we used a branch-clipping method gests the visual estimates were accurate. In (Cooper & Whitmore 1990) to collect inverte- cases of two equations for a same prey type brates from foliage. At a maximum distance we applied that of larger coefficient of deter- of 5 m to the side of each net, branches at mination. least 2-m high were clipped and placed in The feeding preferences for size classes one plastic bag for each of the nine nets. In and for the most prevalent invertebrate order to minimize escape of more mobile groups were analyzed with the software Prefer invertebrates, we quickly bagged and closed 5.1 (Pankratz 1994), based on the rank analy- the mouth of the bag tightly around the sis method proposed by Johnson (1980). For branch before clipping. Sampling was feeding preference analyses of invertebrate alternated between sides of the net each groups, we only considered fecal samples with month. Before discarding the clippings, they at least four identified items whereas, for size- were shaken vigorously into the bag to dis- class samples, we only considered those with lodge the invertebrates. The residual vegeta- at least three measured items. This criterion, tion was spread on a screen and inspected for although arbitrary, was employed in order to further invertebrates, which were collected generate more consistent ranks. Accumulation and dried in freezer. Branch clipping can be curves of food items were obtained by Mao

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TABLE 1. Diet composition of the Plain Antvireo and samples of foliage invertebrates collected in Mata Grande, Ibitipoca State Park, Brazil.

Food items Diet Foliage invertebrates1

FreqT2 %FreqA%FreqT% Mean ±%3 (N = 29) (N = 21) SE Orthoptera 4 1.9 Mantodea 1 0.5 Psocoptera 2 1.0 Hemiptera Heteroptera 16 7.6 14 9.5 73 4.7 4.3 ± 2.1 5.4 Non-Hemiptera Heteroptera 13 6.2 13 8.8 103 6.7 6.1 ± 1.5 7.7 Coleoptera 48 22.9 41 27.7 219 14.2 12.9 ± 1.0 16.3 Lepidoptera 1 0.5 Diptera 2 1.0 Hymenoptera Formicidae 22 10.5 21 14.2 101 6.6 5.9 ± 4.0 7.5 Non- Formicidae Hymenoptera 23 11.0 21 14.2 44 2.9 2.6 ± 1.5 3.3 Insect larvae 18 8.6 18 12.2 74 4.8 4.4 ± 1.1 5.5 Insect egg 21 10.0 Araneae 26 12.4 20 13.5 728 47.3 42.8 ± 3.5 54.2 Acari 1 0.5 Pseudoscorpiones 2 1.0 Diplopoda 2 1.0 Non-identified invertebrates 6 2.9 Others4 196 12.7 13.0 ± 2.3 Non-identified fruit (pulp) 1 0.5 Non-identified plant matter 1 0.5 Total 210 148 1538 90.5 ± 7.9

1Invertebrates collected on the same days of the fecal samples included in feeding preference analysis (N = 17 days). 2FreqT: Frequency of diet items in all fecal samples; FreqA: Frequency of more common items, consider- ing only samples included in feeding preference analysis; N: Number of fecal samples in each case; SE: Standard error;. 3Percentage of most common invertebrates included in feeding preference analysis. 4Least frequent invertebrates: Mollusca (14 individuals), Collembola (1), Orthoptera (41), Blattariae (8), Plecoptera (1), Psocoptera (41), Thysanoptera (1), Lepidoptera (5), Diptera (28), Isopoda (3), Opiliones (16), Acari (22), Diplopoda (14), cocoon (1).

Tau’s method, using the software EstimateS brates groups were Coleoptera, Araneae, non- 7.5 (Colwell 2006). Formicidae Hymenoptera, Formicidae, insect larvae, Heteroptera, and non-Heteroptera RESULTS Hemiptera. These taxa represented 79.8% of all invertebrates consumed (Table 1). These We collected 29 samples from 59 captures of prey types also were the most abundant 37 individuals. Among the 210 food items groups found in field samples. However, identified, the seven most frequent inverte- Araneae constituted almost half of all inverte-

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FIG. 1. Accumulative curves of food items consumed by Plain Antvireos, obtained by the Mao Taus method. Dotted lines indicate 95% confidence intervals on the mean. brates collected from vegetation and more of size classes, the curve stabilized after a few than the half of the items from the seven samples. groups included in the preference analysis. The coefficients of determination from Frequencies of seven most common prey linear regression for 15 invertebrate groups, items in total fecal samples differed from whose specimens varied from 2.18 mm to those obtained from invertebrate sampling in 16.3 mm, ranged from 0.41 for insect larvae the field (G6 = 109.94, P < 0.0001) (Table 1). to 0.96 for Curculionids (Table 2). We deter- Eggs of insects constituted important mined the size of 94 invertebrates in the fecal food items, but they were excluded from the samples, but only 83 were considered in the analyses because they were not counted in the analyses, because the remaining 11 were vegetation samples. Eggs of insects are recorded in samples with less than three mea- numerous, very small, and strongly adhered to sured prey items (see above). Plain Antvireos the foliage, and can easily pass unobserved consumed invertebrates between 1.6 mm for during sorting. In the same way, six unidenti- non-Formicidae Hymenopterans and 20.6 fied invertebrates were excluded. The accu- mm for insect larvae (Fig. 2). Intermediate mulation curve for feeding items revealed sizes (> 2.5–5.0 and > 5.0–7.5 mm) occurred 92% of items after an average of 22 samples, most frequently in the diet. For invertebrates but did not reach an asymptote (Fig. 1). How- collected in the field, the most frequent ever, the feeding preference analyses should classes were > 0–2.5 and > 2.5–5.0 mm not have been affected because it included (Table 3). Hymenoptera Formicidae and only the most numerous items. For analyses Hemiptera Heteroptera were most preferred

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TABLE 2. Linear regression equations for invertebrates collected in Mata Grande, Ibitipoca State Park.

Invertebrates Regression equations1 r2 N Invertebrates range sizes (mm) Orthoptera BL = 1.373 + 9.400ML 0.77 19 2.3–14.3 Hemiptera Heteroptera BL = 3.507 + 1.380SL 0.75 13 2.8–13.9 BL = 0.240 + 4.815HW 0.90 17 2.2–13.9 Non-Hemiptera Heteroptera BL = 1.137 + 2.970HW 0.70 25 3.0–11.6 Coleoptera BL = 0.009 + 5.052HW 0.89 29 2.2–16.3 BL = 0.077 + 1.346EW 0.91 27 2.7–16.3 BL = 0.072 + 5.257EW 0.56 27 2.7–16.3 Curculionidae BL = -0.015 + 5.471HW 0.96 19 2.9–12.6 Hymenoptera Formicidae BL = 0.139 + 2.971HW 0.63 36 2.5–7.9 Non-Formicidae Hymenoptera BL = 0.086 + 3.797HW 0.73 28 2.2–11.8 BL = 0.039 + 1.091WL 0.93 28 2.2–11.8 Insect larvae BL = 3.321 + 4.247HW 0.41 27 3.4–14.7 BL = 2.320 + 18.236 ML 0.69 21 3.4–14.7 Araneae BL = 1.085 + 4.074CL 0.79 46 3.3–15.0 BL = 1.018 + 7.978FL 0.78 46 3.3–15.0

1BL: body length; ML: mandible lenght; SL: scutellum lenght; HW: head width; EW: elytra width; EL: elytra lenght; WL: wing lenght; CL: chelicera lenght; FL: fang lenght. prey types, whereas the least preferred were common foliage-dwelling taxon. Data from Araneae and Coleoptera (Table 4), despite Lopes et al. (2005) are based only on five being the most frequent prey in the diet. items, of which three Coleoptera and one Ranks also indicateda preference for the larg- Araneae. These surveys were not detailed est invertebrates in the available size classes. analyses about the species, precluding com- This pattern was detected for all but one parisons. However, in spite of the apparent taxon: Formicidae, which were slightly smaller generalist character of its diet, the Plain than individuals collected in foliage (Fig. 2). Antvireo showed preference for certain prey types in Mata Grande. Paradoxically, non-For- DISCUSSION micidae Hymenopterans, which are primarily flying insects (Poulin & Lefebvre 1996, The Plain Antvireo consumed mostly inverte- Burger et al. 1999), were the most captured brates consistently characterized as the most prey items in relation to availability in the abundant in the environment and regularly environment. The low relative abundance of found on foliage (Poulin & Lefebvre 1997, those arthropods in the samples might be due Johnson 2000), as expected for a species that to bias caused by the sampling method, which forages mainly on such substrates and moving was designed for sampling sessile inverte- quickly among branches (Schulenberg 1983). brates (Cooper & Whitmore 1990). On the There was a fair similarity with the results other hand, the behavior of moving through obtained by Durães and Marini (2005) for diet the vegetation can shake the foliage and can of Plain Antvireo in Minas Gerais, mainly for cause mobile insects to flee, resulting in a sim- Coleoptera and Hymenoptera Formicidae, ilar effect. Other invertebrate sampling meth- but in 195 items they did not find Araneae, a ods resulted in intermediate abundances of

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atricapillus), a non-Thamnophilidae dead-leaf specialist. According to Schulenberg (1983), Remsen & Parker (1984) and Lopes et al. (2006), the Plain Antvireo occurs in environ- ments with varying vegetation structure and is, therefore, a substrate generalist forager, consuming invertebrates found on live leaves, branches and dead leaves. Thus, it may achieve higher encounter rates than substrate specialist species, allowing selection among available prey. Although we have not com- pared species, the feeding preferences exhib- ited by the Plain Antvireo resembled that found by Rosenberg (1993). Feeding preference analysis indicated how FIG. 2. Mean size ± SD of foliage invertebrates much a certain food item was consumed in found in the diet of Plain Antvireos. Hy: non-For- proportion to its availability, but the nutri- micidae Hymenoptera (N = 13 in the diet and N = tional value of items such as Araneae and 33 in the vegetation); He: Hemiptera Heteroptera Coleoptera in the diet of the Plain Antvireo (5/35); Fo: Formicidae (9/89); Co: Coleoptera cannot be evaluated based only on abundance (25/133); La: insect larvae (16/50); Ar: Ara- ranks. Very abundant items can be consumed neae (15/414). Non-Hemiptera Heteroptera was less than expected because the consumer excluded because the size was calculated for only needs less nutrients than are available to sat- one individual. isfy its nutritional requirements (Johnson 1980). Although differential digestibility of non-Formicidae Hymenopterans in the inver- soft-bodied invertebrates compared to hard- tebrate community (Poulin & Lefebvre 1997, bodied ones can occur (Major 1990), prey Johnson 2000). A plausible hypothesis for the such as insect larvae and Araneae have hard preference for non-Formicidae Hymenop- body structures that persist in feces (Carlisle teran is that flight movements exhibited by & Holberton 2006), like the mandibles and the Plain Antvireo while foraging on some fangs that were regularly found in the samples occasions (Schulenberg 1983) are adapted for in this study. These two types of structures prey that attempts rapid escapes, as in the case constituted large portion of the total diet, so of non-Formicidae Hymenopterans. The low this issue probably did not cause the low rank- proportion of Diptera in the diet is question- ing of Araneae. Invertebrate prey items not able, because flies do not have hard body found in the diet, such as Lepidoptera, were parts and can be digested more easily. also very rare in the invertebrate samples A study of Myrmotherula sp. (Thamnophil- and consumption of such items was likely idae) in Peru revealed that substrate general- incidental. Nevertheless, as with Diptera, the ists selected the types of prey to be consumed, absence of hard body parts should have whereas dead-leaf specialists took prey in pro- facilitated digestion. Limitations in the portion to their availability (Rosenberg 1993) amount of some types of prey in the diet although, in southeastern Brazil, Mallet- also can be related to anti-predatory defenses. Rodrigues (2001) recorded some prey selec- For instance, we observed that a lot of tion in Black-capped Foliage-gleaner (Philydor collected Araneae had brown or green cryptic

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TABLE 3. Prey size consumed by Plain Antvireos and samples of foliage invertebrates collected in Mata Grande, Ibitipoca State Park.

Prey size Diet Foliage invertebrates1 FreqT2 %FreqA %FreqT% Mean ± Se (N = 23) (N = 15) > 0-2.5 10 10.6 8 9.6 277 36.7 25.2 ± 6.1 > 2.5-5.0 34 36.2 32 38.6 364 48.3 33.1 ± 4.5 > 5.0-7.5 29 30.9 26 31.3 78 10.3 7.1 ± 0.8 > 7.5 21 22.3 17 20.5 35 4.6 3.2 ± 0.5 Total 94 83 754 68.5 ± 6.9

1Invertebrates collected on the same days of the fecal samples included in feeding preference analysis (N = 11 days). 2FreqT: Frequency of diet items in all fecal samples; FreqA: Frequency of more common items, consider- ing only samples included in feeding preference analysis; N: Number of fecal samples in each case; SE: Standard error.

TABLE 4. Ranking of feeding preference for invertebrate groups and sizes consumed by Plain Antvireos, arranged from most (negative values) to least (positive values) preferred, relating to those found in the environment.

Rank mean difference Order Invertebrate Non-FormicidaeHymenoptera -1.286 1 Hemiptera Heteroptera -1.024 2 Hymenoptera Formicidae -0.762 3 Insect larvae -0.238 4 Non-Heteroptera Hemiptera 0.167 5 Coleoptera 0.524 6 Araneae 2.619 7 Prey size (mm) > 7.5 -1.133 1 > 5.0-7.5 -0.600 2 > 2.5-5.0 0.533 3 > 0-2.5 1.200 4

Invertebrates: F6-15 = 9.693, P < 0.001

Size: F3-12 = 8.923, P < 0.01 coloration matching their substrate, whereas However, the relatively lower abundance of several Coleoptera presented aposematic col- larger prey types could have decreased the oration or camouflaged forms. probability of encounter with foraging birds, Feeding preferences for larger prey sizes resulting in their lower frequencies in the diet. also were recorded for five of the six most The high preference rank for items > 7.5 mm frequent invertebrate groups in the diet. size was due mostly to consumption of insect

424 FEEDING HABITS OF THE PLAIN ANTVIREO larvae, which measured 12.5 mm on an aver- ments in English usage made by Jeff Lusk age, with the largest measuring 20.6 mm. through the Association of Field Ornitholo- Insect larvae larger than this size and adult gists. insects > 7 mm on average (Hemiptera Het- eropterans) maybe require a long time to be REFERENCES subdued and consumed, with low compensa- tion for the effort. In contrast, prey items Aleixo A., & J. M. E. Vielliard. 1995. Composição e belonging to the smallest size classes and rep- dinâmica da avifauna da mata de Santa Gene- resenting a small portion of the diet possibly bra, Campinas, São Paulo, Brasil. Rev. Bras. have low energy content per individual. These Zool. 12: 493–511. results were similar to those of Raley & Aragona, M., & E. Z. F. Setz. 2001. Diets of maned Anderson (1990) for Wilson’s Warbler (Wilso- wolf Chrysocyon brachyurus (Mammalia: Canidae), nia pusilla), a Nearctic foliage gleaning bird during wet and dry seasons at Ibitipoca State similar in size to the Plain Antvireo. Raley & Park, Brazil. J. Zool. 254: 131–136. Anderson (1990) noted that, in comparison to Burger, J. C., M. A. Patten, J. T. Rotenberry, & R. A. Redak. 1999. Foraging ecology of California arthropods sampled in the environment, Wil- gnatcatcher deduced from fecal samples. Oeco- sons Warblers consumed few small prey items logia 120: 304–310. (< 3 mm) and many big ones (57 mm), and Carlisle, J. D., & R. L. Holberton. 2006. Relative exhibited an upper size limit of approximately efficiency of fecal versus regurgitated samples 7 mm of plecopteran prey, although larger for assessing diet and deleterious effects of a individuals were the most abundant. For this tartar emetic on migratory birds. J. Field Orni- size limit, they proposed a handling time dis- thol. 77: 126–135. proportionate to the food value. Additionally, Carvalho, L. M. T., M. A. L. Fontes, & A. T. Lepidoptera larvae constituted an exception Oliveira-Filho. 2000. Tree species distribution in relation to prey size and were the largest in canopy gaps and mature forest in an area of prey captured, apparently due to the sessile cloud forest of the Ibitipoca Range, south-east- ern Brazil. Plant Ecol. 149: 9–22. nature of the soft-bodied arthropod (Raley & Colwell, R. K. 2006. EstimateS: Statistical estima- Anderson 1990). The results of our study sug- tion of species richness and shared species gest that, like Wilson’s Warbler, the Plain from samples. Version 7.5. Available at http:// Antvireo uses foraging strategies that maxi- viceroy.eeb.uconn.edu/EstimateS. mize energy intake, given the preferential con- Cooper, R. J., & R. C. Whitmore 1990. Arthropod sumption of larger and probably more sampling methods in ornithology. Stud. Avian profitable prey items. Biol. 13: 29–37 Develey, P. F., & C. A. Peres. 2000. Resource sea- ACKNOWLEDGMENTS sonality and the structure of mixed species bird flocks in a coastal Atlantic forest of southeast- We are grateful to the Instituto Estadual de ern Brazil. J. Trop. Ecol. 16: 33–53. Florestas (IEF) of the state of Minas Gerais Dias, H. C. T., C. E. G. R. Schaefer, E. I. Fernandes for authorizing the research in the Ibitipoca Filho, A. P. Oliveira, R. F. M. Michel, & J. B. Lemos Jr. 2003. Caracterização de solos alti- State Park. We also thank Ana Luísa de Car- montanos em dois transectos no Parque Estad- valho Lima and Ricardo Oliveira Garcia for ual do Ibitipoca (MG). Rev. Bras. Ciênc. Solo field support. The Centro Nacional de Pes- 27: 469–481. quisa para a Conservação das Aves Silvestres Durães, R., & M. A. Marini. 2005. A quantitative (CEMAVE/IBAMA) supplied the bands and assessment of bird diets in the Brazilian Atlan- banding license. We appreciate the improve- tic Forest, with recommendations for future

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