Nests, Eggs, and Nestlings of the Restinga Antwren Formicivora Littoralis (aves: Thamnophilidae)

We describe the nest, eggs, and nestlings of the Restinga Antwren (Formicivora littoralis), an endangered bird of Restinga ecosystem (sandy coastal plain vegetation) that is endemic to Rio de Janeiro state. Twelve nests were found at the edges of trails or natural gaps at Massambaba Restinga region, in different supporting plants and heights from the ground (X ± SD 1.27 ± 0.97 m, range 0.27 to 3.45 m). Nests were cup-shaped and were in horizontal forks attached to branches at three to fi ve points with whitish, soft, and thin cotton-like vegetable fi ber. The nests' cup shape and measurements were similar to congeneric species, but nest material was different. Eggs were white with brown spots concentrated on the large end or around the middle, giving the appearance of a rough brown ring. Their mean (± SD) minimum diameter was 13.1 ± 0.34 mm, with maximum diameter of 18.0 ± 0.38 mm, and mass of 1.7 ± 0.18 g (n = 8). We found two nestlings completely naked on their fi rst day after hatching.


F. melanogaster
Formicivora littoralis is considered the only bird endemic to the Restinga habitat (sandy coastal plain vegetation) (Gonzaga and Pacheco 1990).This species has a small range, only inhabiting the area in the state of Rio de Janeiro between the municipalities of Saquarema and Armação dos Búzios (Mattos et al. 2009).The little scientifi c information about this species in the literature mostly addresses its ecology, conservation, and distribution (Gonzaga and Pacheco 1990, Tobias and Williams 1996, Vecchi and Alves 2008).Mattos et al. (2009) have recently presented 547-552 FLÁVIA G. CHAVES, MAURÍCIO B. VECCHI, THIAGO F.S. LAURINDO and MARIA ALICE S. ALVES more detailed information on the distri bution and abundance estimates of this species.Our objective is to present a description of the nests, eggs, and nestlings of the Restinga Antwren.

STUDY AREA
Our fi eld work was conducted at Massambaba Restinga (22° 56' 21.9" S, 42° 17' 58.0" W), District of Praia Seca in the municipality of Araruama, state of Rio de Janeiro, Brazil.Massambaba Restinga is pristine area of restinga habitat mostly included in Parque Estadual da Costa do Sol, a recently created state reserve.This area is composed of scrub and arboreal vegetation (~ 1-7 m height), which is rich in bromeliads and cacti.
We searched monthly for nests throughout 2008, 2010 and 2011 (January to June), using 17 hand-made trails due to the diffi culty in penetrating the scrub and dense vegetation.Nest measurements, taken just after the nestlings fl edged, were: external and internal diameters, height, depth and weight.Branches of the plants used to support the nests were collected for identifi cation.Egg measurements included weight and minimum and maximum diameter.Nestling measurements only included body mass.
Nest, egg, and nestling measurements were made with calipers (precision 0.1 mm) and a scale (Pesola ® with 0.1 g precision); height of nests above ground were scored using a tape measure (precision 1 cm).

NEST DESCRIPTION
We found 12 nests at edges of trails or natural gaps (usually less than 5 m from the trail), in various supporting plants and heights (Table I).Nests 1 to 12 were found on, respectively: May 20, August 23, November 20 (2008), June 17, September 5, September 12, October 23 and 24 (two nests) (2010), May 26 and June 15 (two nests) (2011).All nests were active when found (egg or nestling stages), except one nest found during the nest building stage (Table I).As we could not ensure if this nest was completely built we did not measure its diameters and depth.The nests were cupshaped and were attached in horizontal forks from three to fi ve points (Fig. 1).Nests were attached to the branches with a soft, whitish, thin cottonlike vegetable fi ber.This same material was used in different proportions to attach the nest.All nests were under branches of shrubs or trees, that provided partial protection from the sun and rain.They were externally constructed with light brown branches and fi ne fi bers, many of which were of the cactus Pilosocereus arrabidae (Cactacea).Internally, the nests were darker, composed of fi ne dark brown and black tangled vines.Some nests had pieces of dry leaves, bark (some with lichens), cobwebs, and insect pupas.The nests measured (x ± SD): 1.27 ± 0.97 m in height (in relation to the ground), 73.7 ± 8.79 mm external diameter, 61.4 ± 5.43 mm internal diameter, 57.0 ± 19.33 mm internal depth, and had a mass of 4.25 ± 1.0 g.

EGG DESCRIPTION
The number of eggs (all oval shaped, n = 8) in the nests varied from one (n = 2) to two (n = 3).The eggs were white with brown spots concentrated on the large end or close to the middle, giving the appearance of a rough brown ring (Fig. 2).Their mean ± SD minimum diameter was 13.1 ± 0.38 mm with a maximum diameter of 18.0 ± 0.34 mm, and mass of 1.7 ± 0.18 g (n = 8).

NESTLING DESCRIPTION
We found nestlings in different stages, including two on the day of hatching.These two nestlings were born completely naked with closed eyes (Fig. 2) and yellow bills.Both nestlings were in the same nest and weighed 5 and 6 g, respectively.NESTS, EGGS, AND NESTLINGS OF THE RESTINGA ANTWREN

DISCUSSION
Nests of the Restinga Antwren were similar to the form (cup) of other species of the family.We followed Simon and Pacheco (2005), and categorized the cup form as low cup/fork, because the external height was less than the external diameter.
The nests varied from 0.27 to 3.45 m in height above ground level with the majority (n = 9) above 0.5 m.M. Soneghet (unpublished data) provided a minimal amount of information on nest height of this species (1.7 to 2.1 m, n = 3).Besides that, C.H.P. Oliveira (unpublished data) and also A.Q. Navegantes (unpublished data) found only one nest each close to the soil level (~ 0.5 m or less) (Table II).Nests of Formicivora vary in terms of height.Data for F. grisea (Silva 1988; n = 1), F. rufa (Willis and Oniki 1988; n = 1), F. melanogaster (Zimmer and   F. erythronotos, despite the comparatively high sampled number, were less than 1 m above ground. Our data are similar to those for congeneric species (Table II).There was no apparent relation between nest building and supporting plants.Despite all nests were found near trails and natural gaps, it is not clear if there was microhabitat selection for nesting sites because dense and imbricated vegetation makes searching for nests in inner patches very diffi cult.We found some differences between F. littoralis and congeneric species F. erythronotos and F. grisea, in terms of nest composition.For the latter, E.C. Mendonça (unpublished data) and Silva (1988) reported the presence of bryophytes in the external area of the nests.This material was absent in the 12 nests we found in the present study.The dried and dead leaves, lichens, and the cottonlike material we found in F. littoralis nests were not recorded for F. erythronotos or F. grisea.The eggs in our study were similar in coloration, patch distribution, and measurements of congeneric species.The maximum diameter of F. littoralis eggs was slightly larger than that of F. erythronotos (Table III).
Two nestlings were found on the fi rst day after hatching.They were completely naked, contradicting M. Soneghet (unpublished data), who reported that nearly hatched nestlings were covered by a dark brown plumage, similar to the female plumage.It is possible that Soneghet had found nestlings a few days after hatching.There is no information available about this issue for other species of Formicivora.
This article provides valuable information on nests, eggs and nestlings of a Critically Endangered species, Formicivora littoralis.The original information we presented in this paper is important to understand life history strategies and demography of the species.It certainly will contribute for increase the knowledge on the ecology of F. littoralis and help to support future actions in terms of its conservation.

TABLE III Mean egg measurements in Formicivora.
* n not reported.