Secure Shopping
Birds as Indicators of Riparian Vegetation Condition in the Western U.S.

Wetlands and riparian areas comprise <1% of the land area in the western U.S., yet they support a tremendous diversity and abundance of wildlife. For example, in Arizona and New Mexico, at least 80% of all animals use riparian areas at some stage of their lives. In the Interior Columbia River Basin, 64% of neotropical migratory landbirds depend on riparian vegetation during the breeding season. This habitat may harbor from 2-10 times as many individual birds as does adjacent, non-riparian, vegetation.

Monitoring the health of riparian ecosystems involves the measurement of several different variables. For example, channel characteristics and vegetation age-class distribution are currently evaluated under the Proper Functioning Condition process (TR 1737-9, BLM, 1993). Additional monitoring to assess the occurrence of riparian obligate or dependent bird species will provide a fuller picture of ecosystem health. Experience on the San Pedro River in Arizona shows that the Common Yellowthroat and Song Sparrow, among other species, are excellent indicators of ecosystem recovery following the cessation of livestock grazing (see graph).


Populations of five riparian obligate species increased dramatically on the San Pedro River in Arizona following the complete removal of livestock.

Those monitoring riparian systems can readily learn the distinctive songs of species that should be present and thereby help assess the health of riparian vegetation. Some good indicators, such as the Song Sparrow, are widespread and still reasonably common. Others, such as the Willow Flycatcher, require conservation action now to prevent further losses of habitat and population numbers (see table).

Although a large number of bird species use riparian vegetation at some time during the year, it is possible to define two sub-groups of landbird species that are especially reliant on riparian habitats during the breeding season.


Riparian Obligate Species
These are species that place >90% of their nests in riparian vegetation or for which >90% of their abundance occurs in riparian vegetation during the breeding season. They may forage outside riparian vegetation. Without riparian vegetation in good ecological condition, these species will not occur in a given area. Some species may be classified as obligates in one geographic area but not another.

Obligate Species1 Conservation Action Required in Geographic Region3 Vegetation Layer(s) Used4
Coastal Northern Rockies Great Basin Arid S. West Co. Plat./S. Rockies Prairies Understory Midstory Canopy
Abert's Towhee       •     •    
American Dipper             •    
American Redstart             • • •
Bald Eagle             •   •
Bell's Vireo •   • •     • •  
Belted Kingfisher             • •  
Black Swift         •       •
Broad-billed Hummingbird       •     • •  
Brown-crested Flycatcher               •  
Common Blackhawk       • •     • •
Common Yellowthroat •       •   •    
Elegant Trogon       •       • •
Gila Woodpecker       •       • •
Gray Hawk               • •
Green Kingfisher             • •  
Lincoln's Sparrow             •    
Lucy's Warbler     • •     • •  
Northern Beardless-tyrannulet               • •
Orange-crowned Warbler     •       • •  
Orchard Oriole               • •
Painted Bunting       •   • • •  
Rose-throated Becard               • •
Song Sparrow •           •    
Streak-backed Oriole               • •
Sulphur-bellied Flycatcher               • •
Summer Tanager       • •     • •
Thick-billed Kingbird       •       • •
Tropical Kingbird               • •
Varied Bunting             • •  
Veery   • •       • •  
Vermillion Flycatcher             • •  
Violet-crowned Hummingbird       •     • •  
Willow Flycatcher • • • • • • • •  
Wilson's Warbler • • •       • • •
Yellow Warbler •   •         • •
Yellow-billed Cuckoo •   • • • •   • •
Yellow-breasted Chat •   • • •   • •  
1Species is considered to be Obligate (see definitions) in at least one geographic region (see map).
3The Western Working Group of Partners in Flight determined that conservation action is needed now for the species in the geographic region(s) indicated.
4The vegetation layer(s) used most by the species. The species is most useful as an indicator of the ecological condition of the layer(s) used.


Riparian Dependent Species
These are species that place 60%-90% of their nests in riparian vegetation or for which 60%-90% of their abundance occurs in riparian vegetation during the breeding season. Riparian dependents might still occur in an area if riparian vegetation were seriously degraded but their populations would be greatly reduced and they might not persist in the long-term. Some species may be classified as dependents in one geographic area but not another.
Dependent Species2 Conservation Action Required in Geographic Region3 Vegetation Layer(s) Used4
Coastal Northern Rockies Great Basin Arid S. West Co. Plat./S. Rockies Prairies Understory Midstory Canopy
American Goldfinch             • • •
Bank Swallow •             • •
Bewick's Wren     • • •   •    
Black-billed Cuckoo                 •
Black-capped Chickadee               •  
Black-chinned Hummingbird             • •  
Black-headed Grosbeak •             • •
Blue Grosbeak •           • •  
Blue-throated Hummingbird               • •
Bronzed Cowbird             • • •
Bullock's Oriole               • •
Calliope Hummingbird             • •  
Cooper's Hawk               • •
Cordilleran Flycatcher   •         • •  
Eastern Kingbird               • •
Elf Owl       •     • •  
Ferruginous Pygmy-owl       •     • •  
Fox Sparrow             •    
Gray Catbird             • •  
Harris' Hawk       •     • •  
Hooded Oriole               • •
House Wren             •    
Indigo Bunting             • •  
Lazuli Bunting •           • •  
Lesser Goldfinch             • • •
Lewis' Woodpecker     •         • •
MacGillivray's Warbler             • •  
Mississippi Kite                 •
Northern Goshawk     •         • •
Painted Redstart             • •  
Phainopepla       •       •  
Red-eyed Vireo               • •
Red-faced Warbler       •     • •  
Red-headed Woodpecker         • • • • •
Red-naped Sapsucker               • •
Swainson's Hawk •   •           •
Swainson's Thrush •           •    
Tree Swallow               • •
Warbling Vireo •               •
Western Wood-pewee               • •
White-eared Hummingbird       •     • •  
Zone-tailed Hawk                 •
2Species is considered to be Dependent (see definitions) in at least one geographic region (see map).
3The Western Working Group of Partners in Flight determined that conservation action is needed now for the species in the geographic region(s) indicated.
4The vegetation layer(s) used most by the species. The species is most useful as an indicator of the ecological condition of the layer(s) used.

Evaluate Your Riparian Habitat
If you have a riparian area and do not have obligate and dependent birds, particularly understory species that should occur in your geographic area during the breeding season, then your riparian vegetation may not be in as good a condition as it could be.

The Western Working Group of Partners in Flight has defined six general geographic regions with inherent commonalities in the occurrence of riparian bird species. These correspond with groups of physiographic areas defined for the Breeding Bird Survey



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