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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 123, No. 3, September 2011 
Bridled White-eye (Zosterops conspicillatus ; n 
= 53 specimens. 360 individuals, 389 captures). 
The PF is complete to incomplete and DPB is 
complete. Feather-replacement sequence among 
primaries (at least) appears to be irregular. 
Incomplete PF includes all body feathers, all 
wing coverts, and most flight feathers, with some 
FCF individuals retaining small blocks of juvenal 
secondaries. The DPB occurs primarily post¬ 
breeding. but potentially can occur before or 
during the breeding season. FCF and DCB of both 
males and females are similar in size and plumage 
following the PF, but FCF can often be identified 
by extent of skull pneumatization (timing of 
reliability needs to be examined). Males and 
females are similar in plumage and metrics 
(Table 1; the apparent dimorphism in mass is 
likely an artifact of assigning gender by breeding 
condition only; i.e., heavier females were gravid) 
but CP and BP are reliable for assigning gender 
during breeding seasons. 
Golden White-eye (Cleptomis marcher, n = 16 
specimens, 324 individuals, 410 captures). The PF 
is partial and the DPB is complete; the feather- 
replacement sequence may or may not be irregular 
as in Bridled White-eye. The PF includes body 
feathers and possibly some lesser, median, and 
inner greater covens on some birds. Replaced 
feathers are darker and more yellowish-green than 
retained greenish-brown juvenal feathers, the 
latter becoming increasingly faded and worn as 
the plumage ages. DCB birds have yellow heads, 
orange bills, and yellowish-green wing and hack 
plumage. Juveniles have white mottling and paler 
yellow feathers on the head and face prior to the 
PF, and often have largely unpneumatized skulls. 
Very young juveniles exhibit dusky coloring at 
the base of the bill and, at times, on the tarsi. 
Some FCF birds also have partially unpneuma¬ 
tized skulls, but timing of reliability in relation to 
PF needs to be examined. Length of wing chord, 
exposed culmen, and narcs to tip of bill are useful 
for assigning gender (Table 1). BPs and CPs are 
reliable for assigning gender during breeding, 
although some males can develop partial BPs. 
Micronesian Starling (Aplonis opacir, n = 46 
specimens, 24 individuals, 24 captures). The PF is 
partial and the DPB is complete and proceeds in 
typical sequence. The PF includes body feathers 
and some lesser and median coverts. Juveniles 
(FCJ) and FCF are dark with lighter-streaked 
breast and belly feathers. DCB individuals are 
glossy black with males being glossier than 
females. Wing chord and CP/BP (during breed¬ 
ing) are reliable for assigning gender (Table l). 
DISCUSSION 
We provide previously unknown information on 
molt patterns and age and gender delineation for 
nine species of resident landbirds that commonly 
occur on Saipan. Our data indicate that molt 
strategies of most birds captured on the island are 
like those of resident landbirds in other tropical 
locations (Banks and Layboume 1977; Prys-Joncs 
1982; Avery 1985; Fancy et al. 1993; Jeffery et al. 
1993; Pratt et al. 1994;" Ralph and Fancy 1994; 
Simon et al. 1998; VanderWerf 2001: Pyle et al. 
2004; Ryder and Wolfe 2009; Wolfe et al. 2009a, 
b) and in North American temperate locations 
(Pyle 1997, Howell et al. 2003). Preformative 
molt occurred in all species except Collared 
Kingfisher, while definitive prebasic molt was 
incomplete to complete across all nine species and 
prealternate molt appeared to be absent. 
Separation of birds in juvenal. formative, and 
definitive plumages was possible for all nine 
landbird species captured on Saipan, based upon 
plumage patterns, molt limits, feather shape and 
condition, and extent of skull pneumatization; 
some individuals of the two dove species can be 
identified in third-basic or later plumages. Accu¬ 
rately classifying age of resident birds on Saipan, 
similar to resident species in most other tropical 
locations (e.g.. Wolf et ai. 2009a, b). can be 
challenging because of a lack of distinct season¬ 
ality in breeding and the difference in breeding 
season duration when compared to their temperate 
counterparts. Breeding and molt were observed to 
overlap in at least one species (i.e.. Bridled White* 
eye) and timing of molt and breeding between 
2008 and 2009 was not consistent. Some species 
on Saipan are known to breed more than once in a 
calendar-year or to be capable of breeding year- 
round (e.g., Craig 1996, Mosher and Fancy 20021 
The temperate calendar-based age classification 
system could not properly be used to classify age 
ol birds captured on Saipan. Likewise, the months 
in which age classes could be reliably ascertained 
(i.e., ‘age brackets*; Wolfe et al. 2010) for each 
species cannot yet accurately be estimated. We 
need more data to establish age brackets for each 
species, which will be used in combination 
calendar-based age codes and information on nioJ 
strategies and breeding seasons, to most accural 
ly reflect age of individuals and age structure 
within populations. 
