The Costa Rican varieties are smaller
The white-tailed deer (vanado; Odocoileus virginianus) is well known to North Americans. The Costa Rican variety is smaller. They are grey to red with a straight back, white belly and white markings on the throat, eyes, ears, and muzzle. When running the tail is lifted, revealing the conspicuous white underside. The males have branched antlers, except for the yearlings, which have single prongs.
The smaller, shyer, and less common red brocket deer (cabro de monte; Mazama americana) is reddish (including the belly), with a slightly humped back and no facial markings. The tail is white below and is also raised in alarm. The male antlers are single prongs at all ages. These deer are more likely to be seen in rainforests, while white-tailed deer are fairly common in drier areas such as Guanacaste.