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THE WILSON JOURNAL OF ORNITHOLOGY • Vol 123. No. 4. December 2011 
vegetation (Skutch 1954, Schulenberg and Gill 
1987). 
Nest characteristics are a part of the extended 
phenotype that have been useful in reconstruction 
of avian relationships (Winkler and Sheldon 1993. 
Zyskowski and Prum 1999). Most of the species 
in the genus Ammon (Snethlage 1935. Skutch 
1954, Haverschniidt 1968, Tye and Tye 1992, 
Auer et al. 2007) build dome nests on the ground. 
However, based on the latest phytogeny of the 
group (Cadena et al. 2007, Florez-Rodiguez et al. 
2011). two additional species are now included in 
Ammon (A. torqiuxtus and A. brimneirtucha ; 
previouly placed in the genus Buarremon). These 
species are not basal and build cup nests above 
ground (Skutch 1954. Skutch and Stiles 1989) 
suggesting the cup nest shape derived from the 
dome nest in the genus Arremon. 
Egg coloration of A. tacitumus varied greatly 
between nests, ranging from immaculate pinkish 
glossy white to glossy white lightly or heavily 
spotted with brown speckles. Similarly. A 
castaneiceps eggs were first reported to be while 
wdh heavy red spotting at the larger end (Sclaler 
and Salvin 1879), and later described to be 
immaculate white (Schulenberg and Gill 1987) 
I his difference was suspected to be due a 
mistaken label or species identification by Sclater 
and Savin (Schulenberg and Gill 1987) The 
differ? in ^ « could account for 
Is bth r s rePO,led in A castane ' ce ps eggs, 
as both colorations were found in A. taettumm 
thTgenS ” VanMl0n raay be rommon across 
Incubation. The incubation period of 4 , aci . 
btrnus appears to be similar to other Arret ' 
members, based on the longest observed ineuha 
n penod whteh incubate between 15 an d 
17 days (Skutch 1954. Martin 2002) N c "t 
attentiveness tn Arremon is also remarkabh! 
ne™ atter™ 8 A ^ 57% 
nest attentiveness, A. flmirostris 62% an d 4 
torqmtus 55% (Auer et al, 2007); all are below 
the average ior neotropical passerines ( 69 % ■ 
Mantn e, ai. 2007k Average egg temperatum ft 
tJt 32 ,1 C al an average ambien 
temperature of 24.4 C, The average egg 
3 ture to^other neotropicai passerines species is 
20° C iM ,• avera S e ambient temperature of 
warmth VVT 1 ' D “ P ‘ ,e bdn * to a 
temperature AmbiemT™'" ^ had 11 lower 
and does o„ tem P Cra,ure could have. 
on many occas.ons, an effect on egg 
heat loss but the role the nest has on heal 
regulation is not well understood (Ar and Sidis 
2002). Thus, inter- and intra-specific variation m 
egg heat loss cannot always be attributed it 
ambient temperature. Lower temperature of .4 
tacitumus eggs may be caused by lone foragin. 
trips by the female (on average 46.4 nun 
resulting in a 10.8 C difference betweec 
average egg temperature during off boui- 
(24.0 C) and on bouts (34.8 C). Birds m? 
decrease the number of trips to the nest m 
reduce nest predation risk (Ghalamhor and 
Maitin 2002); the high predation risk in our 
study site may contribute to the low egg 
temperature and low nest attentiveness observed 
Average body mass of A. tacitumus of 26.7g 
(Dick et al. 1984). in relation to egg (3.5 gland 
clutch mass (7.2 g), was similar to the proportion 
observed in several neotropical passerines subject 
to high predation rates (Martin et al. 2006 1 . This 
pattern may suggest reproductive investment is 
reduced by reducing clutch mass rather than egg 
mass with clutch mass being lower in species with 
high predation rates (Martin et aJ. 2006). 
Nestling Growth, Provisioning and Brooding - 
The male supplied most of the food to the young 
once the eggs hatched. Most (76%) of the 
provisioning visits were by the male and only 
24% by the female, based on 21 feeding visits 
where gender of the parent was known. A similar 
proportion was reported for A. aurantiirostris 
(male 75% and female 25%; Skutch 1954). 
The breeding strategies of A. tacitumus 
small clutch sizes with large eggs, female only 
incubation, low nest attentiveness, and the male as 
the main food provider; these are common 
include 
strategies among neotropical passerines and art 
shared by all members of Arremon ( Skutch 1954, 
Auer et al. 2007). The only aspect with nesting 
inconsistency among members of the genus 
nest shape, placement, and material between the 
dome- and the cup-nesting species. These nesting 
differences are insufficient to support splitting •>( 
the genus. Analysis of behavioral differences 
among the traditional genera Arremon, Bum' 1 ' 
own, and Lysurus paired with research on the 
genetics of the expanded Arremon genus may help 
resolve the phylogenetic relationships ot the 
genus. 
ACKNOWLEDGMENTS 
We thank S. D. Rivera, Giovany Valencia. M A. 
S. C. Perez, and J. A. Hazlehurst'for help in the field - SSc 
