-4- 



trapline, resulting in 500 trap-nights of effort per line except when 

 conditions resulted in missing traps. Results of trapping effort on 

 ten plots is presented in Table 1. 



Avian Studies 



Burrowing Owl Investigations 



Status of the Burrowing Owl (Speotyto aunicularia) in Montana 



Preliminary observations of burrowing owls in Montana indicate investi- 

 gation is necessary to reveal the status of the species. Zarn (197A) 

 indicated that burrowing owls are generally declining throughout most 

 of their range. This phenomenon is more apparent in the northern part 

 of its range (central Colorado to Canada) than in the southern portion. 



Historical reports typically refer to burrowing owls as a normal component 

 of all prairie dog towns. Scheffer (1937:392), in Kansas, stated "In the 

 usual association with prairie dog villages, about twenty burrowing owls 

 (Speotyto ounicularia) claimed this townsite as their abiding place." 

 He apparently counted both adult and young birds. Koford (1958:34), 

 also referring to burrowing ovrl-prairie dog associations, stated "In 

 Wichita Mountains Refuge and many other localities, burrowing owls once 

 were common, but they have disappeared." 



In 1976, 23 prairie dog towns were inspected in south Phillips County, 

 Montana for the presence of burrowing owls. Twenty-one of these contained 

 no owls or any evidence of owl occurrence. A single owl was present on 

 one town temporarily, while another town (1000 A.) contained 5 adults 

 (2 of which were nonbreeders) and 10 young (broods of 4 and 6). 



Efforts to locate burrowing owls were expanded in 1977. Eleven occupied 

 sites were visited in Sheridan, Phillips, Fergus and Wheatland Counties. 

 Seven sites contained only a single nonbreeding adult, one contained a 

 pair but no young, and three contained pairs with young. 



Previous 2-year studies suggest expansion of burrowing owl investigations. 

 Objectives of these efforts should be to determine population status, 

 fledging success, breeding: nonbreeding ratios, and site fidelity. 



The following procedures are recommended: 



1. Inventory at least 100 occupied sites through cooperation with 

 Audubon Society members, department employees and U. S. Bureau 

 of Land Management (BLM) personnel. 



2. Visit each site during July of two successive years and determine 

 a) number of adults, b) number of broods, c) number of young, and 

 d) type of burrow. 



