U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet FS 2004-3047

September 2003

Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin

Managing Floodplain Forests for Bird Diversity

Floodplain Succession

With their complex and dynamic 

interactions of plants, animals, 

bacteria, fungi, and insects, forest 

ecosystems are constantly changing. 

Succession, a natural and predictable 

process of regrowth and change, 

occurs in an ecosystem over time. In 

floodplains of the Upper Mississippi 

River, the successional sequence 

of trees is a pioneering or young 

cottonwood-willow community 

(Populus deltoides, Salix spp.), 

a transitional cottonwood-silver 

maple (Populus deltoides, Acer 

saccharinum) community, and a 

mature community of silver maple, 

elm (Ulmus spp.), and ash (Fraxinus 

spp.). Once a floodplain forest 

reaches maturity, age, disease or other 

disturbance causes the successional 

sequence to begin again with a young 

forest.

Along the Mississippi River north of 

its confluence with the Ohio River, 

most floodplain forests are dominated 

by aging silver maples, established 

shortly after the locks and dams were 

built in the 1930s. Forest managers 

predict widespread replacement of 

these aging forests by earlier stages 

of succession, including young 

cottonwood and willow, over the 

next decades. In the wettest locations, 

managers worry that forests may be 

replaced by grasslands dominated 

by invasive species such as reed 

canary grass (Phalaris). Currently, 

young floodplain forests dominated 

by cottonwood and willow are 

uncommon along the Mississippi 

River. The study area was located south of St. Louis, Missouri. Both sites were located in the floodplain 

of the Middle Mississippi River. 

Forests for Nesting Birds

Previous research by USGS in 

the Upper Mississippi River and 

Lower Mississippi Alluvial Valley 

demonstrated that mature floodplain 

forests provide important breeding 

habitat for a large group of birds, 

many of which are of concern to 

the U.S. Fish and Wildlife Service 

(FWS), the Federal agency with 

management responsibility for 

migratory birds in the U.S. Bald 

eagles (Haliaeetus leucocephalus), 

red-shouldered hawks (Buteo 

lineatus), and cerulean warblers 

(Dendroica cerulea), all bird species 

of management concern, favor mature 

forests for nesting. 

The USGS Upper Midwest 

Environmental Sciences Center 

recently completed a study that will 

help state and Federal agencies such 

as FWS make decisions about bird 

conservation and management of 

large river floodplains. Because little 

is known about which bird species 

nest in young floodplain forests, we 

studied birds of young cottonwood 

and willow forests at two sites and 

compared them with adjacent shrub 

habitats and mature silver maple 

forests. During the summer of 2001 

we studied Harlow and Wilkinson 

Islands, sites owned by the FWS that 

have large (100–250 ha) stands of 

young floodplain forests. 
The yellow-billed cuckoo was one of the most common species in our study area. 

Young forests comprise primarily willow (Salix spp.) and 

cottonwood (Populus deltoides) trees established on abandoned 

agricultural land after the 1993 flood on the Mississippi River. 

 

Our study showed that the three 

habitat types (young forests, open 

shrub habitats, and mature forests) 

together supported a diversity of bird 

species (69 species). The species we 

most frequently observed were the 

indigo bunting (Passerina cyanea), 

red-winged blackbird (Agelaius 

phoeniceus), and yellow-billed 

cuckoo (Coccyzus americanus). 

Mature silver maple-dominated 

forests supported the largest number 

of bird species (46) compared with 

the young forests and shrub habitats, 

which hosted 34 and 38 species, 

respectively. The open habitat and 

mature forest each had distinct bird 

communities not shared with the 

other habitats, but the young forests 

shared a number of species with the 

other two habitat types. No species 

emerged as an indicator of young 

cottonwood-willow forests, but the 

shrub/scrub and mature forest habitats 

were each associated with a set of 

indicator bird species. We detected 

several bird species of management 

concern, including the orchard oriole 

(Icterus spurious) and the field 

sparrow (Spizella pusilla) in the 

young forests; the dickcissel (Spiza 

americana) in the open habitat; 

and the red-headed woodpecker 

(Melanerpes erythrocephalus), 

northern flicker (Colaptes auratus), 

Kentucky warbler (Oporornis 

formosus), Acadian flycatcher 

(Empidonax virescens), and 

wood thrush (Hylocichla 

mustelina) in mature 

floodplain forests. 

The bird assemblage 

we observed in young 

forests may become more 

prevalent as many aging 

floodplain forests are 

replaced with younger 

stages of forest succession. 

Under this scenario, 

we would predict a 

temporary local decrease 

in bird species richness 

and habitat for species of 

management concern along 

the Mississippi River. Over 

time, however, these young 

forests will mature into 

forests rich in bird species. 

Management should 

focus on restoring mature 

forests with a diversity of 

tree species. Long-term 

management should also 

strive to diversify forest 

age structure across the 

region, creating a shifting 

mosaic of floodplain 

forests of different ages and 

tree species. These actions 

will best restore and sustain 

forest habitats needed 

by many bird species, 

including those most in 

need of management. 

For more information on large floodplain 

forests, see the following publication: 

Urich, R., G. Swenson, and E. Nelson, 

editors. 2002. Upper Mississippi River 

and Illinois River floodplain forests. 

Upper Mississippi River Conservation 

Committee, Rock Island, Illinois, USA: 

http://www.mississippi-river.com/

umrcc/. 

For more information, contact

Melinda Knutson

USGS Upper Midwest Environmental 

Sciences Center

2630 Fanta Reed Road

La Crosse, WI 54603

Phone: 608.781.6339

Fax: 608.783.6066

mknutson@usgs.gov

http://www.umesc.usgs.gov/