Click image to enlarge

---

Click image to enlarge

Figure 2.  The vegetative characteristics of bird sampling points in Petrified Forest National Park, by habitat type.  Distances among points indicate their relative differences in terms of ground cover types and tree densities.   

---

Click image to enlarge

Figure 3.  The number of bird species detected in the park increases with subsequent sets of surveys within a year.  Data presented are from strip-transect surveys, all transects combined.

---

Click image to enlarge

Figure 4.  The total number of species detected by strip-transect surveys during the breeding

season, for 1998, 1999, and the two years combined. 

---

Click image to enlarge

Figure 5.  Numbers of birds and species detected per hour of survey effort, which includes

travel time among points for point count surveys.  Averages are from all transects surveyed

during breeding season (n=60 for strip transects; n=40 for point counts).

---

 

Bare ground

Grass

Shrubs and trees

                                      

Click image to enlarge

 

Figure 6.  Bird communities according to habitat type at Petrified Forest National Park, Arizona.  Points are the results of ordinating the abundances of thirty two species of birds detected during point-counts in 1995 and 1996 throughout Petrified Forest National Park.  Superimposed on the plot are habitat variables that explain significant variation in the bird communities, illustrated as lines radiating from the center of the plot; the habitat measure increases in the direction of the arrow.