Development of an animal-borne “sonar tag” for quantifying prey availability: test deployments on northern elephant seals

Table 3 Comparison of dive characteristics during periods when the sonar tag was not pinging (NP) vs. pinging (P)

Dive metric	Seal #1	Seal #2	Seal #3	Seal #4
Maximum depth	NS 0.200	NP > P** 0.182	NP > P*** 0.353	NS 0.080
Dive duration	NS 0.242	NP > P*** 0.231	NP > P*** ° 0.338	NS 0.083
Bottom time	P > NP* 0.317	NP > P*** ° 0.334	NP > P*** 0.317	NS 0.056
Descent rate	P > NP* 0.325	NP > P** 0.182	NS 0.129	NP > P** ° 0.123
Ascent rate	NS 0.175	NS 0.123	NP > P*** 0.297	NS 0.047
Post-dive interval	NS 0.133	NS 0.143	NP > P*** 0.228	NS 0.040
# Inflections descent phase	NS 0.033	NS 0.021	NS 0.021	NS 0.010
# Inflections bottom phase	NP > P*** 0.467	NP > P*** 0.299	NS 0.124	NS 0.059
# Inflections ascent phase	NS 0.050	NS 0.042	NS 0.028	NS 0.024

Kolmogorov-Smirnov tests were used to compare the distribution of these metrics comparing all dives made by each seal with the system pinging relative to when it was not. Table entries provide the Kolmogorov-Smirnov test statistics and for comparisons where dive metrics differed significantly indicate whether the metric was greater with the system pinging (P > NP) or not pinging (NP > P) and indicate the significance level. Kolmogorov-Smirnov tests were also conducted on the average of metrics for all dives conducted during a pinging or non-pinging interval. The small number of such intervals limits the power of these tests, which mostly found non-significant differences, other than three tests (denoted via °) where differences were significant at the p < 0.05 level
NS non-significant
*p < 0.05; **p < 0.01; ***p < 0.001