• Kristensen, D.L., Erikstad, K.E., Reiertsen, T.K. & Moum, T. (2014) "Differential breeding investment in bridled and non-bridled common guillemots (Uria aalge): morph of the partner matters" Behavioral Ecology and Sociobiology 68(11):1851-1858


  • Wikipedia - Polymorphism in biology and zoology is the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species. In order to be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating).