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Our refuge provides food and shelter for a wide variety of plant and animal species. The animal population includes over 230 species of birds, 46 species of mammals, 25 species of amphibians and 18 species of reptiles.


Of our 46 species of mammals, many are quite abundant. White-tailed deer are common throughout the refuge and our population of bobcats' have been increasing over the years. River otters were introduced on the refuge in 1996, and populations have increased since! Be on the lookout in winter, its the best time to see them! 

Additionally, coyotes, wood chucks, red foxes, gray foxes, minks, and striped skunks appear on the refuge! Beaver impoundments are found in several places on the refuge. Our ecosystem engineers provide habitat for countless other species. Other species include Virginia opossums, raccoons, gray squirrels and fox squirrels. Hunting is allowed for squirrels and deer! There are roughly 11 species of bats including the federally-endangered Indiana Bat.

In 2016-2017 a black bear from Kentucky wintered on the refuge. In May 2017 sightings reported indicated that the bear left the refuge and returned to Kentucky.

black and white image of a coyote standing up tall

Reptiles and Amphibians

An assortment of amphibians and reptiles inhabit the refuge. The streamside salamander is an exciting sight. Other salamanders include the spotted salamander, marbled salamander, cave salamander, and 9 other present species. The Crawfish Frog is a very important species that is state-endangered here on the refuge. Many actions are taken by refuge staff and volunteers to help preserve habitat and monitor this species. 11 other species of tree frogs and true frogs exists on the refuge. 

There are not many venomous snakes that occur on the refuge besides the Northern Copperhead. The southern black racer is a common sight, look out for them on the refuge roads! There are many other interesting snakes including Milk snakes, Eastern hognose snakes and the state-endangered Copperbelly water snake. Eastern box turtles are another species to look out for on the refuge roads! Please, drive slowly and help our turtles cross the roads.

turtle with red stripes under shell and on legs and yellow stripes on head
lake with dead trees and shore line of large green trees in far distance


Old Timbers lake is home to a variety of panfish including Crappie, Blue Gill, and Sunfish. Largemouth Bass occur in addition to many other species of fish!


Big Oaks National Wildlife Refuge has been designated a "Globally Important Bird Area". Species of particular interest include the Henslow's Sparrows. These birds breed in the grasslands of the refuge. Kirtland's Warblers occur here and are federally-endangered. Bachman's Sparrow are also present and are state-endangered. 

Many waterbirds occur on the refuge. Great Blue Herons are known to nest, as well as Green Herons, Wood Ducks, Blue-winged Teal, and Mallards. Old Timbers lake hosts a variety of waterfowl species during migration. 

One can also find a variety of raptors, including a pair of breeding federally-threatened Bald Eagles at Old Timbers lake. Northern Harriers, Red-shouldered Hawks, American Kestrels are common on the refuge. Golden Eagles will utilize the grassland habitat during the winter. Many species of owls are also present. 

Woodpeckers can be found throughout the property along with Blue Jays, Carolina Chickadees, White-breasted Nuthatches , Northern Mockingbirds and Cedar Waxwings. The refuge is also home to many migrants- Cerulean Warblers, Worm-eating warblers, Northern Parula, Louisiana Warblers and more will occur!

Many game species, like wild turkey and bobwhite quail occur on the refuge!

little black and brown bird sitting on a branch
a yellow and gray bird pirched on a dogwood tree branch
tan snake with pattern curled up
small light tan bird perched on a plant with its mouth open

Endangered Species

Big Oaks Conservation Society works in concert with, and under the direction of, Fish and Wildlife Refuge staff to enhance and assist with protection of these endangered species, and development and preservation of the habitat necessary for their continued survival.

State-endangered Species include:

  • Mammals- Evening Bat, Indiana Myotis (FE)

  • Birds- American Bittern, Osprey, Northern Harrier, Black Rail, King Rail, Yellow-crowned night Heron, Barn Owl, Short-eared Owl, Loggerhead Shrike, Sedge Wren, Golden-winged Warbler, Cerulean Warbler, Henslow's Sparrow

  • Amphibians- Crawfish Frog

  • Reptiles- Kirtland's Snake

  • Plants-  Broom Panic-grass, Clasping St. Johns wort, Climbing Fern, Elliptical Rushfoil, Mayland Meadow-beauty, Narrow-leaved Sunflower, Northern bog Clubmoss, Thread-like Naiad, Weakstalk Bulrush

A very important state-endangered species is the Crawfish frog (Rana areolata). This is a unique amphibian species that utilizes crawfish burrows and breeds in the many ponds across the refuge. Historically, this species would breed in buffalo wallows in Indiana. In place of these wallows, impact areas where ordinances have exploded allowed for the creation of ponds that are now used by these frogs. 

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