The odds of yellow-billed cuckoo occurrence decreased rapidly as the amount of tamarisk cover increased or when cottonwood-willow vegetation was limited.
Aerial-photo and satellite models identified several key features associated with yellow-billed cuckoo breeding locations: (1) a 4.5 ha core area of dense cottonwood-willow vegetation, (2) a large native, heterogeneously dense forest (72 ha) around the core area, and (3) moderately rough topography.
Palynological evidence indicates the presence of mesic shrub tundra (including sedge, birch, willow and heath vegetation), and microfossil indicators point to wetter eutrophic conditions during this period.
The right bank of the bay, where the observing stations were located, is low-laying, overgrown with single willow bushes and riverside vegetation.
Next to willow thickets, higher aquatic vegetation is represented mainly by thickets of narrow-leaved cat's-tail (Typha angustifolia L). and common reed [Phragmites australis (Cav). Trin. Ex Steud.].
As the use of short-rotation coppice willow crops increases, this vegetation type will comprise a greater extent of the landscape, yet its attendant effects on biodiversity remain poorly understood.
Overall, we observed 33 bird species and five small mammal species in five focal sites (i.e., areas consisting of willow crops and adjacent vegetation) and 20 bird species and four small mammal species in two reference sites (i.e., areas of the settling basins without willow crops).
Plant life consists mainly of tundra vegetation, with willows and some conifers and other trees found along rivers and streams.
"The beetles, at least from what we've seen, have beaten back tamarisk, and native vegetation, especially willows, have come back strongly," said Dan Bean, the director of the Palisade Insectary, the biological pest control program for the Colorado Department of Agriculture.
Nonforest cover types of sagebrush, grasslands, willows, sedges, and other wetland vegetation were mapped in the Lamar Valley of Yellowstone.
The maps dated 1966 to 1987 also contained vegetation consisting of mainly willow (Salix sp).
