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Section 779.20 (c) Continued. <br />• transect method proposed by several authorities (Balph, Stoddard, <br />and Balph (1977); Emlen (1977); Franzeb (1977); and Dickson <br />(1978)). Locations of transects are provided on Twentymile Park <br />Avian Observations (Flap 23). Field procedures for the quantitative <br />transects were as follows: A single 800 meter transect was located <br />in a homogenous section of each habitat type. On three mornings <br />between Play 31st and June 5th, 1979, an experienced ornithologist <br />slowly walked each transect and recorded all birds seen or heard <br />according to their perpendicular distance from the centerline <br />(i. e., 0-10 ft; 10-25 ft.; 25-50 ft.; 50-100 ft.; 100-200 ft.; 200- <br />400 ft.). Flyovers and birds farther than 400 feet from the center- <br />line were recorded as qualitative observations only. All transects <br />were surveyed during periods of peak bird activity (within 3.5 <br />hours after sunrise) and during. favorable weather conditions. <br />Density indices were calculated based on the effective detection <br />distance (EDD) for each species in each habitat type. The EDD is <br />• defined as the distance in which all individuals of a species are <br />assumed to hrve been detected by the observer and is used to define <br />the effective census area for each species. Particular EDD's were <br />picked according to: (1) the distribution of individual observa- <br />tions; or (2) where sample size was small, the professional judge- <br />ment of the observer. The density index was calculated as: <br />Birds/100 acres = <br />X observed (3 reps.) 43560 sq.ft./acre <br />2 EDD x Transect length x 100 <br />(both sides of transect) (2625 ft.) <br />Relative abundance was calculated as: <br />%RA = density of a given species x 100 <br />density of all species <br />• <br />779-142 <br />