Reinert el al. • NEST AND EGGS OF THE MARSH ANTWREN 
287 
some species names were adapted from Forzza 
ei al. 12010 ). 
Nests were collected at the end of the breeding 
season. Some nests were deposited at the Museu 
«je Zoologia da Universidade de Sao Paulo 
(MZUSP #s 2276. 2277, 2278. and 2279). Sao 
Paulo, and some nests will be deposited at the 
Museu de Historia Natural Capao da Imbuia, 
iMHNCI), Curitiba. Brazil. Tw'eniy-one nests 
were disassembled to analyze materials used and 
nest building techniques following the categories 
proposed by Hansell (2000). Well-preserved nests 
were weighed after being dried using a dyna¬ 
mometer to the nearest 0.1 g. Materials used for 
nest building were separated, classified, and 
weighed separately. Nest material categories were 
libers (plant materials <2 mm in thickness), straw 
(plant material >2 mm in thickness), silk (spider 
webs, oothecas. and diverse kinds of cocoons), 
and root or leaf fragments (independent of plant 
species). Nest descriptions followed the nest type 
(H.) categories of Hansell (2000) and (S&P) 
Simon and Pacheco (2005) with the different sets 
of categories presented in the results referring to 
these two publications, respectively. 
Flooded and abandoned eggs were collected, 
measured (with a digital caliper to the nearest 
0-1 cm), and weighed (with a dynamometer to the 
nearest 0.1 g) if not damaged. Egg colors were 
evaluated in comparison with ((Uppers' (1996) 
color alias with acronyms referring to specific 
color shades. Eggs in active nests were measured 
dn <l weighed only for the rare cases when access 
10 'he incubation chamber was possible with 
minor chance of damaging the nest. Four 
collected eggs were deposited at MZUSP (#s 
-272. 2273, 2274, and 2275), and others will be 
deposited at MHNC1. Values presented are mean 
- SD. 
RESULTS 
We conducted -1.560 hrs of nest searching and 
found 178 nests from more than 40 breeding pairs. 
"11 constructed between August and February. All 
nests were made with dry fiber, dry straw, and silk 
w >th leaf fragments in about one half ot the nests 
'Table I). All other materials occurred in fre¬ 
quencies <25%. Birds were observed collecting 
fiber and straw from Panicum cf. mertensii (/? = 
12), Schoerwplectus califomicus (n = 7). Fuirena 
fobusta (n = 4). and Acrostichum danaefolium (n 
= 4); leaf fragments were from S. califomicus. F. 
robusta, and Eleocharis geniculata , while dry 
TABLE I. Materials used to build nests (n = 21) of the 
Marsh Antwren {Stymphalomis acutirostris) in Guaratuba 
Bay. Parana, southern Brazil. 
Total mass 
Material 
n 
(g) 
Plant 
Fiber (diverse kinds of plant material 
<2 mm width) 
21 
59.2 
Straw (diverse kinds of plant material 
>2 mm width) 
21 
24.6 
Leaf fragments 
11 
0.1 
Base of the pinae of Acrostichum 
danaefolium 
5 
0.3 
Tillandsia usneoides 
4 
0.1 
Fragments of Acrostichum danaefolium 
petiole 
2 
U.l 
Poaceae inflorescence 
2 
<0.05 
StigmaphvUon ciliaium and/or Vigna 
luieola stems 
2 
<O.U5 
Rootlets 
2 
<0.05 
Cyperaceae inflorescence 
1 
<0.05 
Rhynchospora cf. corymbosa 
inflorescence 
1 
U.l 
Crinum americanum fiber 
1 
0.3 
Fibers with mud 
1 
0.3 
Acrostichum danaefolium roots 
1 
0.2 
Animal 
Silk (spider silk, oothecas, and 
different kinds of cocoons) 
21 
1.3 
Feather 
2 
<0.05 
Other 
Foam 
1 
<0.05 
leaves and bracts of Cladium jamaicense, dry 
leaves, petioles, and inflorescence of Echinodorus 
grandiflorus, dry leaves and stems ot P. cf. 
mertensii , roots of A. danaefolium and Crinum 
americanum. and silk from spider webs (n = 20), 
oothecas (n = 8). and cocoons (n = 6) were also 
used. The same birds were repeatedly seen 
collecting nest material from the same patches 
of dry plants. Fibers < 2 cm in length dominated 
in the incubation chamber, whereas fibers could 
reach up to 44 cm in length in other parts of the 
nest. Nests were constructed using the technique 
of interlocking (entangle and velcro). Only two 
nests had decorations on their outer walls, one 
with live mosses and another with lichens. 
The nest of the Marsh Antwren is cup-shaped 
(H) (Fig. 1) and in grass/rceds (/; = 144) or tree/ 
bush (// = 21) sites. The remaining 13 nests were 
in sites with trees/bushes and grasses/reeds. Nests 
were attached to the vegetation using the 
