Table 3 Generalized additive mixed model results. Models are compared within the same measure of time (calling period or recording length) for each population. Those with ΔAICc scores less than two are shown. If an explanatory variable is included in the model, the parameter estimate (for linear terms) or estimated degrees of freedom (for smooth terms) is shown in the first line; standard error (for linear terms) in the second line; and p-value in the third line. Asterisks indicate statistical significance at α = 0.05. Adjusted R2 (variability explained by fixed effects), conditional R2 (variability explained by fixed and random effects), the standard deviation (SD) of the random intercept for acoustic encounter (recordings from the same day and location), SD of the residuals, and ΔAICc relative to the best model are shown. Dashes indicate that the variable was not included in the modeling approach.

From: Killer whale call detection rates vary among subspecies and populations in the North Pacific

Population

Measure of time

Pod

Location

Presence of other pods

Day of year

Time of day

(night)

Signal-to-noise ratio

R2 (adjusted, conditional)

SD (random intercept, residual)

ΔAICc

Southern Alaska resident

Calling period

     

2.2180

0.0191*

0.0184, 0.1229

0.1893, 0.6000

0

   

1.2340

0.0866

 

2.2460

0.0167*

0.0265, 0.1253

0.1893, 0.6000

0.98

Recording length

  

0.1373

0.0760

0.0716

  

3.0170

0.0001*

0.0430, 0.2471

0.2524, 0.7524

0

  

0.1206

0.0776

0.1210

 

0.0803

0.0783

0.3040

3.0170

7.9 × 10− 5*

0.0435, 0.2457

0.2504, 0.7521

0.99

     

3.0780

6.2 × 10− 5*

0.0379, 0.2577

0.2584, 0.7534

1.20

Gulf of Alaska transient

Calling period

-

0.2607

0.0961

0.0072*

-

 

0.1697

0.0860

0.0497*

1.0000

0.0092*

0.0718, 0.0992

0.0650, 0.5625

0

-

0.2752

0.0989

0.0058*

-

 

-

1.0000

0.0037*

0.0605, 0.0931

0.0896, 0.5640

1.75

-

0.2887

0.0979

0.0035*

-

0.9526

0.1317

0.2001

0.0893

0.0260*

1.0000

0.0103*

0.0799, 0.1143

0.0644, 0.5603

1.87

Recording length

-

0.3123

0.1768

0.0785

-

 

0.2250

0.1386

0.1057

2.7390

0.0005*

0.1080, 0.3555

0.3712, 0.6830

0

-

0.3384

0.1849

0.0685*

-

  

2.6680

0.0005*

0.0939, 0.3710

0.4112, 0.6763

0.35

-

 

-

  

2.7200

0.0006*

0.0545, 0.3991

0.4586, 0.6697

0.45

AT1 transient

Calling period

-

0.5411

0.2408

0.0281*

-

2.2490

0.0152*

  

0.1850, 0.3268

2.5 × 10− 5, 0.4384

0

-

 

-

2.0360

0.0150*

  

0.1200, 0.2452

0.1191, 0.4479

1.48

Recording length

-

 

-

1.3980

0.0963

  

0.0984, 0.5498

0.3904, 0.3818

0

-

 

-

1.4650

0.0826*

0.1268

0.1243

0.3110

 

0.1010, 0.5676

0.3904, 0.3818

1.28

-

 

-

    

0.4284, 0.3809

1.73

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