Mercival R. Francisco

BREEDING BIOLOGY OF THE DOUBLE-COLLARED SEEDEATER (SPOROPHILA CAERULESCENS)

Abstract The Double-collared Seedeater (Sporophila caerulescens) is the most common seedeater in southern South America. Because information on its breeding biology is mostly limited to descriptions of nests and eggs, I studied the reproductive biology of the Double-collared Seedeater in southeastern Brazil. I found 41 active nests during seven breeding seasons (1997–2003). Nesting occurred from December to May. All nests found during incubation contained two eggs, eggs were laid on consecutive days, and incubation started the morning the female laid the last egg. Incubation and nestling periods were 12 and 12–15 days, respectively. Only females incubated the eggs. Mean time spent incubating/hr was 52.3 min, and incubation recesses averaged 6.6 min. Nestlings were fed 7.6 times/hr, and although both males and females fed the young, the participation of females was significantly greater than that of males. Predation was the major cause of nest failure. Daily survival rates during the incubation (0.990) and nestling (0.935) stages differed. Overall nesting success was 36%. Although studies conducted in disturbed areas can reveal greater rates of nest predation than those found in undisturbed areas, some Sporophila species seem to benefit from habitat disturbance. The conversion of native habitats to agricultural lands in Brazil, as well as the spread of exotic grasses, has resulted in the expansion of the Double-collared Seedeater to previously forested areas.

Patterns of Individual Relatedness at Blue Manakin (Chiroxiphia Caudata) Leks

Abstract.— Patterns of relatedness among males attending leks can provide insights into how this reproductive behavior has evolved. Past research on birds has found that lekking males show either elevated levels of relatedness, supporting a mechanism based on kin selection, or a lack of relatedness, supporting a direct-benefits mechanism. We show that males attending Blue Manakin (Chiroxiphia caudata) leks exhibit a third pattern, with leks consisting of mixtures of related and unrelated individuals. Kinship analyses of males sampled from 13 leks in three local populations showed that close male relatives (r = 0.5) were present, but only at half the leks sampled. Analysis of male relatedness among leks in each local population showed that overall levels of relatedness were not significantly different between males from the same lek and those at different leks and that no isolation-by-distance relationships were present. We argue that these patterns are most parsimoniously explained as a byproduct of limited dispersal rather than as direct selection operating via reproductive behavior to produce specific patterns of relatedness among lek attendees.

First Description of Nests and Eggs of the White-bellied Seedeater (Sporophila leucoptera)

Abstract I describe nests and eggs of the White-bellied Seedeater (Sporophila leucoptera) in Brazil. Nests (n  =  5) were cup-shaped and built of thin grass roots and spider web silk with thin walls allowing eggs and young to be seen through them. Nests were in trees (2.5–4.5 m above ground) and close to water. Eggs (n  =  3) were white with black and brown spots concentrated at the large end and measured 19.2 × 13.0 (1.7 g), 18.7 × 13.3 (1.8 g), and 18.8 × 13.9 mm (1.8 g). Both parents fed nestlings, but only females incubated. The White-bellied Seedeater is not presently endangered, but many local populations have been extirpated because of intense commercial trapping and habitat loss. Additional knowledge on the ecology and breeding biology of seedeaters is urgently needed for development of effective conservation plans.

Reproductive Life History Traits of the Yellowish Pipit (Anthus lutescens)

Abstract We describe reproductive traits of the Yellowish Pipit (Anthus lutescens) in the State of São Paulo, Brazil. We found 32 active nests during three breeding seasons (2008–2010). Domed nests were built exclusively on the ground where the grass was sufficiently tall to conceal them. Clutch initiation across years occurred from July to October and average ± SD clutch size was 3.05 ± 0.4 eggs or young. Yellowish Pipits were predominantly single-brooded. Eggs were pale white with brown spots and blotches that could be more concentrated at the larger end or homogeneously distributed over the entire surface. Eggs were 18.2 ± 0.8 mm in length, 13.7 ± 0.3 mm in width, and weighed 1.7 ± 0.12 g. Incubation and nestling periods lasted 13.03 ± 0.2 and 14.5 ± 1.0 days, respectively. Mean time incubating/hr was 38 ± 7.1 min, and incubation recesses averaged 9.4 ± 4 min. Young were provisioned on average 13.3 ± 7.9 times/hr, by both males and females. Estimated overall nesting success using a null model of constant nest survival rates was 87% (95% CI, 56–97%). Model selection analyses indicated survival was negatively correlated to nest age and time within the breeding season. Comparisons of Yellowish Pipit life history traits with northern temperate congeners provided support for the premises that clutch sizes are smaller and young development is slower in the tropics. The hypothesis that annual fecundity can be similar across latitudes due to a negative correlation between clutch size and number of renesting attempts was not supported. Our data contradicted the commonly claimed, but poorly tested hypothesis, that smaller clutch sizes in the tropics can be explained by a longer breeding season that permit more opportunities to renest within the same breeding season.

Description of the nest and eggs of the Great-billed Seed-Finch (Sporophila maximiliani)

ABSTRACT Seed-finches are Neotropical passerines highly specialized in the consumption of grass seeds. Most species are endangered because of the conversion of native grasslands into agricultural fields, and they are among the main victims of trapping for the illegal cage-bird trade in South America. The Great-billed Seed-Finch (Sporophila maximiliani) is very rare, with few records in the wild in the last 50 years. Here, we present the first descriptions for nest, eggs, and nesting habitat of the Great-billed Seed-Finch from Mato Grosso state, Brazil. We found the nests (two) on 18 December 2014 and on 8 January 2015. They were located in a seasonally flooded lowland area composed predominantly of herbaceous vegetation and sparse shrubs, mainly Curatella sp. Nests were built in 5 days, and only females participated in nest construction and incubation. Nests were cup-shaped made mainly of stems and tendrils of vines, and their measurements were: outside diameter (85.0, 93.0 mm); inside diameter (55.0, 60....

Nest, Eggs, and Nestlings of the Atlantic Forest Endemic Star-throated Antwren (Rhopias gularis)

ABSTRACT Here, we describe nests, eggs, and nestlings of the monotypic Star-throated Antwren, Rhopias gularis (formerly Myrmotherula gularis), found at Carlos Botelho State Park, in Atlantic Forest in the state of São Paulo, Brazil. Nests were pensile cups of dark rootlets and black fungal hyphae, found near forest streams, 34–70 cm high, over ground or water. A leaf appeared to form a roof over two nests. Clutch size was always two eggs, white with reddish and dark brown spots and blotches. Hatchlings were naked with pinkish skin. Nest architecture, eggs, and nestlings were similar to other Myrmotherula and Epinecrophylla, suggesting that nesting characteristics may not be informative to reconstruct recent DNA-based phylogenies that resolved the monotypic genus of this Brazilian Atlantic Forest endemic species.

Nest and Fledglings of the Red-ruffed Fruitcrow (Pyroderus scutatus)

Abstract Information on the breeding behavior of the Red-ruffed Fruitcrow (Pyroderus scutatus) is scarce and restricted to the subspecies P. s. granadensis and P. s. orenocensis. We found the first nest of the nominate subspecies (P. s. scutatus) in an Atlantic Forest area in southeastern Brazil on 28 November 2004. The nest contained two nestlings and was built on a horizontal fork, 16.7 m above ground. It was cup-shaped with a substantial base composed of twigs: outside diameter 38 cm, cup diameter 16.5 cm, outside height 11.3 cm, and inside height 5 cm. The nestlings were thickly covered with brownish down. Only one unknown gender adult visited the nest. Although locally endangered, the breeding cycle of this species remains poorly known.

Intraspecific Brood Parasitism of the Pale-breasted Thrush (Turdus leucomelas)

Abstract We report the first evidence for intraspecific brood parasitism (IBP) of the open-cup nesting Pale-breasted Thrush (Turdus leucomelas) in southeast Brazil. Four of 15 nests followed from building stage onwards had evidence of IBP (27%), as detected from laying of two eggs in the same day in a nest (n  =  2), laying of an additional egg after onset of incubation (n  =  1), and egg laying before the end of nest construction (n  =  1). Only a few cases of IBP have been reported for neotropical songbirds but it is likely more will be reported as they become better studied. We believe limited territory availability or nest loss during laying were potential causes of IBP in our study population.

First description of nests, eggs, and nestlings of the Pearly-bellied Seedeater (Sporophila pileata)

ABSTRACT The “capuchinos” form a monophyletic group within the Neotropical seedeaters of the genus Sporophila and are typically smaller than the other congeners. Many of the 12 species of this group are endangered, but reproductive information is scarce for most of them. Here we present the descriptions of nests, eggs, nestlings, and nesting habitats for the Pearly-bellied Seedeater (Sporophila pileata). From 2012 to 2017 we found 83 nests constructed in herbaceous plants present in open marshlands, 15–73 cm above water or humid ground. Nests were deep cups built of grass stems, inflorescences, and rootlets, attached with spider web. Nests measured 59.3 ± 4.7 mm outside diameter, 50.7 ± 6.5 mm outside height, 41.6 ± 3.2 mm internal diameter, and 35.7 ± 3.3 mm internal depth. Eggs were oval with white, grayish, or greenish background color with black and brown spots mainly in the obtuse pole. They weighed 1.2 ± 0.1 g and measured 16.3 ± 0.8 per 12.2 ± 0.3 mm. Clutches consisted of 1–3 eggs. Our study sites represent the northernmost reproductive areas ever documented for a migratory capuchino.

Breeding behavior of the Atlantic forest endemic Blue Manakin (Chiroxiphia caudata)

ABSTRACT.— Manakins are small frugivorous birds found in the understory of humid Neotropical forests. Although aspects of their complex sexual displays have been addressed in various studies, their nesting biology is poorly documented. The Blue Manakin (Chiroxiphia caudata) is characterized by a cooperative courtship display but knowledge about its reproduction is limited to descriptions of the nest and eggs. We investigated 36 active nests during two breeding seasons in a well-preserved stretch of Atlantic Forest in southeastern Brazil. Nests were shallow cups attached at their rim to horizontal forks in bushes or saplings with slender branches and were usually built over or close to forest streams. Reproductive activities were recorded from October to February and clutches were invariably consisted of two eggs. The incubation period was 18 days; nestling periods varied from 15 to 16 days, and estimated overall nesting success was 34%. Comparisons of nest architecture, egg color, and nestling characteristics revealed important variations among the Pipridae, suggesting that these traits may not be diagnostic of genera and may not be informative in the phylogenetic reconstruction of the group. The duration of the breeding season is shorter than in manakin populations distributed near the equator and provides one of a few pieces of evidence of this tendency in the Neotropics. Our data support the findings that only females provide parental care in the Pipridae, which is hypothesized to be the result of a frugivorous diet.