Assessment of Nongame Bird 

 Habitat Using Forest Survey Data 



Renee A. O'Brien 



INTRODUCTION 



Recent environmental concern has generated 

 much pubhc pressure to protect and conserve the 

 Nation's renewable natural resources. Necessary 

 for regionwide decisions is information on current 

 resource conditions. Wildlife habitat is one resource 

 of current interest that is an important element in 

 forest planning and management decisions. Infor- 

 mation on existing habitat conditions and predictive 

 capabilities about future conditions on a regionwide 

 scale is needed to allow evaluation of resource 

 tradeoffs involved in management decisions. Forest 

 inventory data may offer opportunity as an efficient 

 way to streamline the task of wildlife resource 

 monitoring. 



To meet the requirements for National assess- 

 ments mandated by the Forest and Rangeland Re- 

 newable Resources Planning Act of 1974 and other 

 legislation, forest resource inventories are con- 

 ducted on public and private lands by Forest Sur- 

 vey, Forest Service, U.S. Department of Agriculture. 

 Forest Survey projects are located throughout the 

 continental United States and Alaska and are some 

 of the most comprehensive, permanent plot invento- 

 ries in the country. They provide permanent base- 

 line data for most forested land, including most pri- 

 vate. State, Bureau of Land Management of the 

 U.S. Department of the Interior, and Indian lands; 

 and excluding some National Forest lands in the 

 West. The inventory procedures for the various 

 Survey projects produce standardized timber statis- 

 tics, with some regional differences in the scope and 

 details of the inventories. 



The Forest Survey data base has the potential to 

 provide information on forest conditions relevant to 

 wildlife populations and on change in these condi- 

 tions over time (O'Brien and Van Hooser 1983). At 

 the regional level at which Forest Survey operates, 

 some efforts have been made in the area of wildlife 

 habitat assessment by Brooks (1986) in the North- 

 east, Flather and others (1989) in the South, 

 Ohmann (1983) in the Pacific Northwest, Rudis 

 (1988) in the South, and Sheffield (1981) in the 

 Southeast. This paper focuses on the ponderosa 

 pine forests of Arizona. 



Forest Survey variables that could be useful for 

 assessment of potential wildlife habitat are: 



Forest type 



Asf)ect 



Evidence of use 



Basal area 



Slope 



Distance to roads 



No. trees per acre 



Habitat type 



Fire history 



Site index 



Percent crown cover 



Logging history 



Quadratic mean 



Sf)ecies composition 



Understory cover 



diameter 



Size of condition 



and height 



Stand-size class 



Vegetation 



Insect and disease 



Tree height 



concealment 



evidence 



Elevation 







THE PROBLEM 



Evaluating wildlife habitat is complex. Wildlife 

 managers have made use of general timber stand 

 variables such as forest type, stand-size class, age, 

 canopy cover, and other stand features to predict 

 potential wildlife use of a site for feeding, breeding, 

 or resting. Specific habitat suitability models are 

 being developed for predicting occurrence and quan- 

 tifying value of potential habitat for some wildlife 

 species. Most models are designed to provide site- 

 specific comparisons and are not applicable to exten- 

 sive forest inventory data. Forest Surveys operate 

 at a much broader level than most research model- 

 ing being done for wildlife habitat evaluation. 

 This paper evaluates Forest Survey plot data for 

 potential nongame bird habitat. Greneral habitat 

 criteria on food and shelter from the literature were 

 used for habitat assessment. These habitat assess- 

 ments were then evaluated using bird numbers col- 

 lected on the same plots. 



The birds chosen for this study were secondary 

 cavity-nesting foliage-gleaners and bark-gleaners 

 (subsequently referred to as cavity-nesting glean- 

 ers). These birds are important for several reasons. 

 They are sensitive to timber management practices 

 because they use old and dying trees for nesting 

 (Balda 1969, 1975; Cunningham and others 1980; 

 Diem and Zeveloff 1980; Medin 1985; Owens 1983; 

 Sturman 1968; Szaro and Balda 1979) and because 

 they forage in tree canopies. They are conspicuous, 

 in many places common, and their diets consist of 

 75 to 90 percent insects (Bent 1946, 1948; Scott and 

 Patton 1975), making them important for insect 



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