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(burrow mounds and open areas between) and all nearby structures that may provide perches <br /> (e.g., fences, utility poles, etc.) <br /> For prairie dog towns that can not be entirely viewed from a single location because of terrain or <br /> size, enough survey points should be established to provide unobstructed views of the entire <br /> prairie dog town and nearby structures that may provide perches. Survey locations should be <br /> separated by approximately 800 meters (1/2 mile), or as necessary to provide adequate visual <br /> coverage of the entire prairie dog town. <br /> Number of surveys to conduct <br /> Detection of burrowing owls can be highly variable and multiple visits to each site should be <br /> conducted to maximize the likelihood of detecting owls if they are present. At least three surveys <br /> should be conducted at each survey point. Surveys should be separated by approximately one <br /> week. <br /> Conducting the survey <br /> • Weather Considerations Because poor weather conditions may impact the ability to detect <br /> burrowing owls, surveys should only be conducted on days with little or no wind and no <br /> precipitation. <br /> • Passive surveys Most burrowing owls are detected visually. At each survey location, the <br /> observer should visually scan the area to detect any owls that are present. Some <br /> burrowing owls may be detected by their call, so observers should also listen for burrowing <br /> owls while conducting the survey. <br /> Burrowing owls are frequently detected soon after initiating a survey (Conway and <br /> Simon 2003). However, some burrowing owls may not be detected immediately <br /> because they are inconspicuous, are inside of burrows, or are not present on the site <br /> when the survey is initiated. We recommend that surveys be conducted for 10 minutes <br /> at each survey location. <br /> • Call-broadcast surveys To increase the likelihood of detecting burrowing owls, if present, <br /> we recommend incorporating call-broadcast methods into burrowing owl surveys. Conway <br /> and Simon (2003) detected 22% more burrowing owls at point-count locations by <br /> broadcasting the primary male (coo-coo) and alarm (quick-quick-quick) calls during <br /> surveys. Although call-broadcast may increase the probability of detecting burrowing owls, <br /> most owls will still be detected visually. <br /> • We recommend the following 10-minute timeline for incorporating call-broadcast methods <br /> (Conway and Simon 2003, C. Conway pers. commun.). The observer should scan the area <br /> for burrowing owls during the entire survey period. <br /> o 3 minutes of silence <br /> o 30 seconds call-broadcast of primary call (coo-coo) <br /> o 30 seconds silence <br /> o 30 seconds call-broadcast of primary call (coo-coo) <br /> o 30 seconds silence <br /> o 30 seconds call-broadcast of alarm call (quick-quick-quick) <br /> o 30 seconds silence <br /> o 4 minutes of silence <br /> 2 <br />