Fig 1.
Spectrogram representation of a typical humpback whale song phrase observed during this study.
This phrase is composed of two sub-phrase types (referred to here as A and B). Sub-phrase A is sung at the beginning of the phrase and is composed of a single unit. Sub-phrase B is composed of two different unit types and is repeated throughout the phrase.
Fig 2.
The study area in Skjálfandi bay, NE Iceland.
The black circle represent the location of the EAR recording unit at Fiskisker (66°03’N, 17°40’W). Depth contours are in meters. Source (1) Hydrographic Department of the Icelandic Coast Guard, 2012, (2) National Land Survey of Iceland, 2012 and (3) Esri, DeLorme Publishing Company, Inc. The map was created using ArcGIS_ software (version 10.1) by Esri. Adapted with permission from Magnúsdóttir et al. [37].
Fig 3.
Humpback whale song detection distribution per day of recording, i.e. during January 26th to March 12th 2011.
Table 1.
A summary of the analyzed dataset.
Fig 4.
The observed phrases from 2011.
Spectrographic representations of the observed phrases from the complete recording period. The spectrograms were generated using Fast Fourier Transformation (FFT) (size 2048 Hanning window) with a frequency resolution of 7.8 Hz and a 95% overlap. The vertical, black lines indicate the division between the phrases. Audio is provided in S1 Acoustic File.
Fig 5.
Occurrence of phrases and transitional phrases.
A) An increase in the length of the phrase sequences was observed when including all repeated phrases within the 10 minute recordings. Sequences with fewer than four phrases were not included in this dataset. B) The percentage of transitional phrases within the observed phrase sequences from period-1 to -4.
Table 2.
Consistency of transitions of each phrase type between periods.
Fig 6.
Percentage of phrase occurrence.
Percentage of phrase occurrence within the songs per period. The size of the filled circles represents the prevalence of the phrases during each period, i.e. the larger circles represent greater prevalence of each particular phrase. The values above each period column represents the phrase sample size for each period (n).
Table 3.
Extracted song sequences using Markov matrices and set median analysis.
Fig 7.
A diagram of phrase transitions.
A diagram based on Markov transition matrix of song sequences during each period. Each circle in the The table summarizes the most likely sequences per period according to the diagram represents a phrase type. The colored circles are phrases which were Markov matrices. The set median sequences from each period are shown observed during each particular period while the white phrases were not observed during that particular period, only in other periods. The data points (n) represent the number of analyzed transitions observed during each period. Black lines represent transitions occurring a minimum of 5% of the time while gray lines represent transitions occurring less than 5% of the time. Single transition events are represented with thin light gray lines. The line thickness indicates the prevalence and frequency of the transitions observed, i.e. thicker lines indicate more common transitions.