Wildlife and habitat have suffered since the 1860s when the mining boom hit, but in some ways things are better off now. Residents have adopted new attitudes, especially sportspeople, who initiated the wildlife protection ethic that is becoming more prevalent today.
Birds
Ducks, mallards and common mergansers are often seen on the river, as well as Canadian geese. A flash of yellow could be a western tanager, yellow-rumped warbler, yellow warbler or American goldfinch. Stellar jays, with their dark blue plumage and dark crests, are often around campsites. Water ouzels, also called American dippers, are dark gray birds that bob while standing and can be seen along the river shores. A membrane covering their nostrils enables them to feed up to 45 seconds underwater.
Great horned owls are identifiable by horn-like feather tufts, and they nest in dense trees well out of sight. To some Native American tribes, they were the carriers sent to fly the souls of the dead to the spirit world. Peregrine falcons nest on the Chalk Cliffs on the face of Mt. Princeton, and hunt periodically in Browns Canyon to the east. They have long slate-blue wings with horizontal bars on their underbelly. Golden and bald eagles fly throughout the river valley and corridor, hunting fish and rodents. Golden eagles are one of the largest birds in the west and have been known to attack deer mired in deep snow. Other raptors include Swainson's, red-tailed and ferruginous hawks. In addition, turkey vultures may also be seen in the area.
Kingfishers perch on limbs over the river throughout the corridor, then dive in and out of the water in search of small fish for dinner. Below Florence to Lake Pueblo, great blue herons roost in the cottonwoods that line the shore.
Fish
Yellowfin and greenback cutthroat trout were once native to the Arkansas, but a number of harmful, man-made circumstances led to the extinction of yellowfin by the early 1900s. Greenbacks were thought to be extinct, but small populations were discovered, and in 1978 their status was changed from endangered to threatened, thanks to recovery efforts. Brown trout, imported from Europe in the late 1800s, are now the most common fish in the river due to their ability to adapt. Rainbow trout were imported from California, but have a difficult time reproducing naturally in the Arkansas River.
Heavy metal concentrations from mining leached into the Arkansas River and drastically cut the life span of fish. Reclamation and clean-up efforts begun in the 1980s have restored the fishery and increased tremendously the fish population that live to a normal age.
Mammals
Elk, once the most common hoofed animals in North America, were killed to the point of decimation in the 1800s for their two oversized canine teeth, or "ivories". Through wise management, the local elk population is now one of the largest on the continent. Elk stay in the cool mountains until snow drives them into lower elevations.
The Colorado mule deer population is the largest in America, and it is very common to see these animals throughout the river valley.
Mountain goats live near timberline and were imported from South Dakota and Montana as game animals in the 1940s. Goats are difficult to spot on the rocky cliffs, but herds are common in both Chalk Creek and Cottonwood Creek canyons west of Buena Vista. Rocky Mountain bighorn sheep were hunted to the point of disappearance, but were reintroduced in the 1920s. There are several hundred sheep living between Browns Canyon and the Royal Gorge, and they can be observed as they come down to the Arkansas River to drink.
