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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 2. June 2012 
(A) 
Year 1 Year 2 Year 3 
JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND 
Northern Fulmar PJ 
PBI 
PB2 
Red-tailed Hawk PJ 
PBI 
PB2 
Merlin (European) PJ | PB1 
PB2 
PB3 
Merlin (New World) PJ 
PBI 1 PB2 
Glaucous-winged Gull PJ | PBI 
PB2 PA2 PB3 
Glaucous-winged Gull PJ 
PBI PA] | PB2 
(B) 
Year 1 Year 2 Year 3 
JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND 
Northern Fulmar 
PBI 
PB2 PB3 
Red-tailed Hawk 
PBI 
PB2 PB3 
Merlin (European) 
PBI PFI 
PB2 PB3 
Merlin (New World) 
PBI 
PB2 PB3 
Glaucous-winged Gull 
PBI PA 1 
PB2 PA2 PB3 
Glaucous-winged Gull 
PBI 
PB2 PA2 PB3 
(C) 
Yearl Year 2 Year 3 
- JFMAMJJASOND JFMAMJJASOND IFMAMIfASOND 
Northern Fulmar 
PJ 
PB2 PB3 
Red-tailed Hawk 
PJ 
PB2 PB3 
Merlin (European) 
PJ PBI 
PB2 PB3 
Merlin (New World) 
PJ 
PB2 PB3 
Glaucous-winged Gull 
PB2 PA2 PB3 
Glaucous-w'inged Gull 
PJ 
PB2 PA2 PB3 
FIG. 1. Diagrammatic comparison of molt cycles of Northern Fulmar ( Fulmarus glacicilis). Red-tailed Hawk (Buteo 
jama,cams). European and New World populations of Merlin (Falco columbarius), and two strategies of Glaucous-winged 
Gull (Lurus glaucescens). (A) Conventional molt terminology under the H-P system based on Howell etal. (2003: figure L 
(B) Proposed modifications to the H-P system of Howell et al. (2003: figure 1). (C) The proposed solution to the ‘first basic 
problem The shaded zone represents the first molt cycle. No position is taken in (C) with respect to the identity of the 
partial molt in the first molt cycle of populations of the Glaucous-winged Gull that have such a molt. 
My proposal to start the first molt cycle with 
commencement of the initial acquisition of 
contour feathers makes the H-P system more 
facile with respect to species that have a 
presupplemental molt that precedes the conven¬ 
tional first prebasic molt (Thompson 2004) and 
species that have a uniformly-complele conven¬ 
tional first prebasic molt (Table 2). Presupple¬ 
mental molts were known only for adults at (he 
time Humphrey and Parkcs (1959) wrote their 
article (Rohwcr et al. 1992). but a first-cycle 
presupplemental moll has since been reported for 
at least 16 North American passerines (Pyle 1997) 
and likely is present in many more passerines 
(Rohwer et al. 1992. Thompson and Leu 19941. 
The end of the first molt cycle for all birds is 
commencement of the second prebasic molt under 
the definition of the first molt cycle in Howell et 
al. (2003). This is true for the vast majority ot 
birds, but some species (Table 2) have a uniform- 
ly-complete conventional first prebasic molt that 
is equivalent in timing with subsequent prebasic 
molts, and commence the definitive molt cycle 
with this molt. (The definitive molt cycle may or 
may not commence the definitive basic plumage 
cycle, which commences w'hen a bird first 
