Abstract

It has been postulated that both digestive capacity and intestinal biochemical features are correlated to dietary habits in birds. Therefore, it would be expected to find biochemical constraint to hydrolyze sugars in those species, which predate exclusively on marine invertebrates. In vitro intestinal activities of these enzymes were studied in Cinclodes nigrofumosus (d' Orbigny) and Cinclodes patagonicus (Gmelling). Due to differences in dietary habits between species I predicted the lack of sucrase activity in C, nigrofumosus but not in C. patagonicus. Also, low activities of maltase would be expected in both species. On the other hand due to the considerable amount of proteins and trehalose present in preys, high activities of both trehalase and aminopeptidase-N were also expected. Contrary to previous reports in birds, significant activity of trehalase was found. Also lack of sucrase and small amounts of maltase were observed as well as a significant aminopeptidase-N activity in both species. Although the digestive enzyme activities of C. nigrofumosus and C. patagonicus appear to be correlated with their natural diet, the similarities between species in all enzymes activities suggest an strong effect of phylogenetic inertia.