Kristen Hawkes, Kim Hill, and others have conducted careful and detailed
analyses of the caloric intake patterns of the Ache, a tribe of lowland
foragers in Paraguay.  Richard Lee and others have claimed that meat intake
will only be high in groups dwelling at high lattitudes, but their very
careful study of the Ache confounds that prediction.  Despite abundant
edible plant resources, the Ache derive about four times as much of their
caloric intake from animal sources as plant sources.

A very careful analysis of the total calories invested in garnering foods
clearly shows why: medium and larger-sized game animals produce more
calories per hour invested in foraging than almost any other resource.
Only  honey and oranges were able to compete with meats in terms of the
amount of calories they delivered vs. the amount of hours needed to put in
to utilize those foods--and even then, many forms of game animals (e.g.
peccary, armadillo, coati, paca) still far out-produced both these
resources.

Insects such as palm larvae did not produce as much caloric intake per hour
of investment in obtaining them as did almost any medium- or larger-sized
game animal.

Furthermore, very small game, such as birds and snakes, produced far -less-
food value than anything else the Ache ate.  Very small game such as these
were highly undependable and required almost more effort to garner than
they were worth.

See:

Hawkes K et. al. Why Hunters Gather: Optimal Foraging and the Ache of
eastern Paraguay.  American Ethnologist, pp 379-398, Vol 9, 1982

Hill K et. al. Seasonal Variance in the Diet of Ache Hunter-Gathererrs in
Eastern Paraguay. Human Ecology, Vol. 12, No. 2, 1984