Is the social hierarchy always linear in tits

habitat use of North Island Kokako in Puketi state forest, Northland. N. Z. J. Ecol. 10: 117-128. Ramos, J. A. in press. The diet of the Azores bullfinch and floristic variation within its range. Biol. Conserv. Rhoades, D. E and Cates, R. G. 1976. Towards a general theory of plant antiherbivore chemistry. Rec. Adv. Phytochem. 10: 168-213. Rosenberger, G. and Heeschen, W. 1960. Adlerfarn (Pteris aquilina) die Ursache des sog. Stallroter der Rinder (Haematuria vesicalis bovis chronica). Dt. Tierarz. Wschr. 67: 201-207. Seigler, D. S. 1991. Cyanide and cyanogenic glycosides. In: Rosenthal, G. A. and Berenbaum, M. R. (ed.). Herbivores: their interactions with secondary plant metabolites. The chemical participants. Academic Press, London, pp. 35-77.