Exercise 1 solution

(a) 3000 / 5 = 600 times (maximum thrasher repertoire against maximum swamp sparrow repertoire). Against the sparrow's minimum of 3 it would be 1000 times.
(b) 125 - 116 = 9 dB.
(c) 1889 - 8 = 1881 (assuming the age and year are both right; not checked elsewhere).