Table 2. Comparison between laboratory- and wild-recorded 2SVs.

		wild			laboratory
		(n = 8c)			(n = 23)
Acoustic Variable	Median	Q25	Q75	Median	Q25	Q75	U(b)	P
Syllable 1
Duration (ms)	157.58	116.00	206.00	258.00	193.00	290.00	42.0	0.0240
Start Freq (kHz)	22.36	18.23	32.65	18.50	17.00	19.50
End Freq (kHz)	22.55	19.29	31.00	16.10	14.10	18.00
Max Freq (kHz)	25.64	20.60	33.65	18.50	18.00	20.00
Min Freq (kHz)	21.44	17.88	31.00	15.60	14.10	17.00
Freq Max Amp (kHz)	24.06	19.35	32.40	16.60	15.10	18.50
Bandwidth (kHz)	2.78	2.45	3.18	2.40	1.50	3.90	17.0	0.7675
Internal Modulation	47348.27	21236.17	84237.6	24271.84	15537.85	42647.1	54.0	0. 0863
Overall Modulation	9935.08	7663.42	12917.15	7584.95	2429.26	12600.81	65.0	0. 2229
PC1 (a)	−0.67	−2.47	0.16	0.57	0.20	0.86	17.0	0.0007*
Syllable 2
Duration (ms)	130.83	112.50	161.39	176.00	117.00	220.00	63.0	0.1905
Start Freq (kHz)	25.10	21.58	31.45	19.00	18.00	19.50
End Freq (kHz)	24.18	20.00	29.95	18.50	18.00	19.50
Max Freq (kHz)	28.05	23.40	33.40	19.50	19.00	20.50
Min Freq (kHz)	23.82	18.86	29.70	17.50	17.00	18.50
Freq Max Amp (kHz)	26.56	21.24	33.15	19.00	17.50	20.00
Bandwidth (kHz)	3.81	2.69	4.90	2.40	1.50	2.50	31.0	0.0059*
Internal Modulation	60814.94	45261.21	111174.8	30208.33	18248.18	71428.6	44.0	0. 0302
Overall Modulation	11839.43	3936.88	23091.41	3685.14	0.00	7421.88	47.0	0. 0422
PC1	−1.12	−2.33	−0.24	0.22	0.03	0.38	15.0	0.0005*

^(a)PC1 = First principal component of Frequency Variables.

^(b)Mann-Whitney U test statistics for test between captive and wild recorded vocalizations from P. californicus on 5 spectral variables. Mann-Whitney U tests significant (*) at p<0.01. Median values (with 25% and 75% quartiles) and samples size from Mann-Whitney U tests are shown.

^(c)Data are from 8 individuals and 19 vocalizations.