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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 2. June 2012 
timing and extent (Stangel 1985). Similarly, 
despite the position of Howell and Corben 
(2000) to the contrary, it is reasonable to presume 
the variably partial or partial to complete 
conventional first prebasic molts of closely- 
related species such as Calidris sandpipers are 
homologous with definitive prebasic molts not¬ 
withstanding the varying forces acting on the 
extent of these molts. 
The wide variability in timing and extent of 
conventional first prebasic molts is consistent 
with the H-P system. Humphrey and Parkes 
(1959:7) stated, as to timing, “the temporal 
location of a homologous molt in the cycles of 
plumage succession may vary among different 
groups of birds or among individuals of a 
species”. Humphrey and Parkes (1959:2) also 
believed the conventional first prebasic moll was 
present in some form in most birds and part of “a 
fundamental pattern of plumage succession which 
can be traced almost throughout the class of 
Aves”. Nothing contained in Howell et al. (2003) 
contradicts this position. This does not mean the 
conventional first prebasic molt is present in every 
bird, however. The conventional first prebasic 
moll molt may not be present, for example, in any 
particular individual, population, or species be¬ 
cause it is developmentally suppressed in re¬ 
sponse to environmental conditions or lost as a 
result of the effects of selection (Howell et al. 
2004, Thompson 2004). 
Some birds exhibit atypical molt patterns that 
make identification of first-cycle molts under the 
H-P system extremely difficult, hut this is no less 
true under the system of Howell et al. (2003). 
Atypical molts include delayed, interrupted, 
protracted, and continuous molts that initially 
produce basic feathers and later alternate feathers, 
or so-called ‘merged' molts. No one can say for 
sure, but I suspect that most atypical molt patterns 
are not ancestral and instead represent the effects 
of selection on typical prebasic and prealternate 
molt patterns. This is suggested by bird species 
with individuals or populations that exhibit typical 
or atypical first-cycle molt patterns (Erskinc 1971, 
Howell et al. 2003, Pyle 2008), and a phyloge¬ 
netic analysis of the evolution of moll patterns in 
Western Palearctic warblers (Svensson and He- 
denstrom 1999). 
First Prealternate Molls and Alternate Plumages 
Howell et al. (2003) generally deemed first 
piealternate molts to be homologous with defin¬ 
itive prealternate molts and not nonrecurring 
auxiliary preformative molts. This position raises 
the question how Howell et al. (2003) could 
routinely conclude that some first-cycle molts art- 
homologous with definitive prealtemate molts 
while other first-cycle molts that are indistin¬ 
guishable from definitive prebasic molts in 
timing, extent, and resulting plumage are not 
homologous with definitive prebasic molts 
(Thompson 2004). This position also appears to 
be inconsistent with that of Howell et al. (2003) 
with respect to conventional first prebasic molts 
because the first prealtemate molt also varies 
significantly in timing and extent, both across and 
within species (Pyle 1997. 2008). Gulls, for 
example, have first prealternate molts that vary 
in extent from 0 to 100%. and certain large, white- 
headed gull species have a partial first prealtemate 
molt in some populations but not others (Howell 
et al. 2003. Pyle 2008. Howell 2010). Howell ct 
al. (2003), as well as Pyle (2008) and Howell 
(2010), considered these molts to be alternate and 
not preformative in nature despite this variability. 
Plumage Color and Pattern 
Perhaps the most contentious position of 
Howell et al. (2003) is that plumage color and 
pattern should not be used in evaluating homol¬ 
ogies among molts and plumages because the 
physiological processes that govern plumage color 
and pattern are independent of those that govern 
molt. The extent of separation between these 
processes is difficult to evaluate because, despite 
decades of study, there is much that is not known 
about the environmental, physiological, and 
behavioral control of molts and plumage colora¬ 
tion (Thompson 2004. Dawson 2006, Kimball 
2006). However, it is one thing to maintain that 
different physiological processes and selective 
forces may affect plumage color and pattern and 
the underlying molts, which appears reasonable 
and has been suggested elsewhere (Voitkevich 
1966, Oring 1968, Jenni and Winkler 2004. 
Willoughby 2004). and another thing to maintain 
these processes are independent to an extent that 
plumage color and pattern are irrelevant to molt 
homology analyses. How'ell et al. (2004) appeared 
to soften this position, but both Pyle (2005) and 
Howell (2009) strongly maintained that plumage 
color and pattern should be divorced from molt 
homology analyses. 
Howell et al. (2003) maintained the similar- 
appearing conventional first basic and definitive 
