Green Castle Recreation Area

Education at Green Castle Recreation Area

Bison
American Bison were once the most abundant mammal in North America but by the late 1800’s less than 1000 bison survived. This massive six foot tall, 2,000 pound animal once roamed most of North America with only one natural predator -  the wolf.  Even the wolf couldn’t take down a mature, healthy animal, instead they preyed on the young, sick, and older animals.  People, however, did have an impact.   Population decline was due to unregulated hunting as settlers and railroads moved west. The last reported bison in Iowa was in 1869 in the northwest corner of the state. The small bison herd at Green Castle is one of the few places that bison can be found in Iowa. Once on the verge of extinction, the bison population is now on the rise throughout the United States. 

Bison roamed the tall grass prairie eating grasses and sedges, slowly grazing through an area mostly  during the morning and late afternoon. Bison also wallow in the mud or dirt to get relief from insects.  At Green Castle, watch for a wallowing hole on the east side of the enclosure or on the west side where they dust themselves. Notice their thick long coats which they slowly shed as summer approaches. 

Bison mating occurs in the fall and the gestation period is around nine months, with the calves being born in April or May. The calves are light brown in color and are able to walk a few hours after being born.  There are a couple new residents at Green Castle this spring with two bison calves being born in late April. Both calves were born the same weekend and both are healthy and doing great. 

Imagine seeing thousands of these magnificent animals roaming the prairies. What a sight that would have been!  Watching the bison at Green Castle can give you a small glimpse of bison behavior and of what Iowa used to be like.  When you visit the bison remember that even though they are captive, they are a wild animal with young to protect. 

Trumpeter swan
Also, located next the bison corral is the Trumpeter Swan exhibit.  Located on the pond is  a pair of breeding swan and in the Spring it is not uncommon to see cygnets.  Trumpeter Swans vanished from most of the United Sates over 100 years ago due to over hunting and lead poisoning.