title: Temporal and spatial variation in harbor seal (Phoca vitulina L.) roar calls from southern Scandinavia.
abstract: Male harbor seals gather around breeding sites for competitive mating displays. Here, they produce underwater vocalizations possibly to attract females and/or scare off other males. These calls offer prospects for passive acoustic monitoring. Acoustic monitoring requires a good understanding of natural variation in calling behavior both temporally and among geographically separate sites. Such variation in call structure and calling patterns were studied in harbor seal vocalizations recorded at three locations in Danish and Swedish waters. There was a strong seasonality in the calls from end of June to early August. Vocalizations at two locations followed a diel pattern, with an activity peak at night. Recordings from one location also showed a peak in call rate at high tide. Large geographic variations were obvious in the total duration of the so-called roar call, the duration of the most prominent part of the call (the roar burst), and of percentage of energy in roar burst. A similarly large variation was also found when comparing the recordings from two consecutive years at the same site. Thus, great care must be taken to separate variation attributable to recording conditions from genuine biological differences when comparing harbor seal roars among recording sites and between years.
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Puk Faxe
authors.initials: PF
authors.lastname: Sabinsky
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Ole Næsbye
authors.initials: ON
authors.lastname: Larsen
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Magnus
authors.initials: M
authors.lastname: Wahlberg
authors.affiliation: Department for Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Tougaard
mesh_terms: D000162:Acoustics; D000818:Animals; D006801:Humans; D008297:Male; D046049:Phoca / Q000145:classification / Q000502:physiology*; D012537:Scandinavian and Nordic Countries; D012621:Seasons; D012726:Sexual Behavior, Animal / Q000145:classification; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013997:Time Factors; D014828:Vocalization, Animal / Q000145:classification