Black-throated greens thus hopped 59 times in 400 seconds for a mean number of seconds per
hop of 6.78. Tennessees hopped 50 times in 576 seconds for a mean number of seconds per hop of 11.52. By an extended sign test (Dixon and Massey 1951) this difference is well within the 5.5% level of significance. Hence, it is clear that black-throated greens hop across branches more often than Tennessees, partially confirming the subjective impression described above.