Jim Brandenburg / Thickspike Gayfeather (Liatris pycnostachya) flowers in grass, Touch the Sky Northern Tallgrass Prairie National Wildlife Refuge, Minnesota

Jim Brandenburg / Tree in tallgrass prairie, Blue Mounds State Park, Minnesota

Jim Brandenburg / Storm over Touch the Sky Northern Tallgrass Prairie National Wildlife Refuge, Minnesota

LYNN M. STONE / Bottle Gentian (Gentiana andrewsii) flowering in tallgrass prairie remnant, Downers Grove, Illinois, USA

LYNN M. STONE / Monarch Butterfly (Danaus plexippus), showing some wear and tear on wing, feeding on nectar of Rough Blazing-Star (Liatris aspera) growing in tallgrass prairie remnant, Downers Grove, Illinois, USA

LYNN M. STONE / Eastern Tiger Swallowtail butterfly (Papilio glaucus), dark phase female, on Pink Thistle in tallgrass prairie remnant, Illinois, USA (an intermediate phase between the typical yellow and the entirely...

Jim Brandenburg / Sioux Quartzite in tallgrass prairie with oncoming storm, Blue Mounds State Park, Minnesota

Jim Brandenburg / Great Plains Toad (Bufo cognatus) male calling and competing for access to female in amplexus with another male, Touch the Sky Northern Tallgrass Prairie National Wildlife Refuge, southwest Minnesota

Thomas Lazar / Eastern bluebird (Sialia sialis) male in breeding plumage perched, Tallgrass Prairie WR, Wisconsin, USA, June

Thomas Lazar / Eastern bluebird (Sialia sialis) male in breeding plumage perched on nestbox sumac tree, Tallgrass Prairie WR, Wisconsin, USA, May

Thomas Lazar / Eastern bluebird (Sialia sialis) male in breeding plumage perched on nestbox, Tallgrass Prairie WR, Wisconsin, USA, June.

Thomas Lazar / Eastern bluebird (Sialia sialis) female in breeding plumage perched on nestbox with insect prey for chicks, Tallgrass Prairie WR, Wisconsin, USA, June