Young, J.R., Braun, C.E., Oyler-McCance, S.J., Quinn, T.W., Hupp, J.W. (2000). A new species of Sage Grouse (Phasianidae: Centrocercus) from southwestern Colorado, USA. Wilson Bulletin 112: In Press.
Pitman, R.L., Jehl, J.R. (1998). Geographic variation and reassessment of species limits in the "Masked" boobies of the eastern Pacific Ocean. Wilson Bulletin 110:155-170.
Roberson, D. (1998). Sulids unmasked: Which large booby reaches California? Field Notes 52:276-297.
Question marks after a number indicate that the species name has changed due to a
split or lump after the reference was published and the measurements do not necessarily
pertain to the new species. A dash indicates a range of measurements for the species
indicating some variation among subspecies.
A discussion of some of the problems with group summaries is in: