Table 3. Comparison of spontaneous duet songs (N = 5), predator songs (N = 5), and songs given in response to playback of duet songs (N = 5) by the same five groups (Kruskal–Wallis rank sum test).

Variables**	Spontaneous duet song	Predator song	Response song	df	χ²	P value*
Duration introductory ‘hoo’ series (s)	8.0 ± 3.1	23.4 ± 6.7	4.7 ± 2.7	2	10.5	<0.05
N introductory ‘hoo’ notes	11.0 ± 4.5	48.8 ± 14.4	7.4 ± 2.7	2	10.2	<0.05
Song duration (s)	789.4 ± 294.8	2,396.4 ± 775.8	1,006.8 ± 122.3	2	10.2	<0.05
Latency to 1st great call (s)	101.3 ± 33.5	816.4 ± 368.0	99.0 ± 41.1	2	9.5	<0.05
Latency to 1st ‘sharp wow’ (s) #	78.1 ± 31.1	370.5 ± 183.2	90.8 ± 35.9	2	9.0	<0.05
N ‘sharp wows’	9.2 ± 8.0	362.2 ± 233.9	5.6 ± 6.0	2	9.8	<0.05

Notes:

^#Kruskal–Wallis rank sum test for N = 14 songs (W did not produce any ‘sharp wow’ notes in spontaneous duet; N_duet = 4, N_predator = 5, N_response = 5).

^*P < 0.05 corrected.

^**Means ± SD.