Proportional Weekly Use of Underwater Call Types by Weddell Seals, Leptonychotes Weddellii (Pinnipedia: Phocidae), During the Breeding Season at the Vestfold Hills

1996 ◽  
Vol 44 (1) ◽  
pp. 75 ◽  
Author(s):  
BC Pahl ◽  
JM Terhune ◽  
HR Burton
Keyword(s):  
Breeding Season ◽  
Leptonychotes Weddellii ◽  
Weddell Seals ◽  
Behavioural Patterns ◽  
Vestfold Hills

Underwater vocalisations by Weddell seals, Leptonychotes weddellii, were recorded during the 1992 breeding season, at the Vestfold Hills, Antarctica. Only 3 of the 12 major call types recorded at all sites had statistically significant variations in utilisation throughout the season. No consistent trends were evident. The underwater calls of Weddell seals increased;in number during the breeding season, hut the proportional weekly usage of each of the major call types did not change. The absence of vocalisation changes suggests that the breeding behaviours of Weddell seals are not synchronous and that the underwater behavioural patterns either do not change during the breeding season or could not be detected because of the asynchrony.

Proportional underwater call type usage by Weddell seals (Leptonychotes weddellii) in breeding and nonbreeding situations

2012 ◽  
Vol 90 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Elyse E. Doiron ◽  
Philippe A. Rouget ◽  
John M. Terhune
Keyword(s):  
Sea Ice ◽  
Breeding Season ◽  
Ice Formation ◽  
Leptonychotes Weddellii ◽  
Mating Period ◽  
Call Type ◽  
Weddell Seals ◽  
Breeding Behaviour ◽  
Dark Conditions

Proportional underwater call type usage by Weddell seals ( Leptonychotes weddellii (Lesson, 1826)) near Mawson, Antarctica, investigated the hypothesis that certain call types function specifically in breeding behaviour. Recordings were collected at various sites in 2000 and 2002 from June to December. Twenty-four hour recordings were collected in 2002 at two sites. One hundred consecutive calls from each of 248 recordings were classified into one of ten common call types. Time to 100 calls provided the calling rate. The study period was divided into four periods representing initial sea-ice formation, pre-pupping, pupping, and mating. Calling rate and light–dark differences were also examined. No presence–absence differences were observed for any of the call types with season. The largest difference between nonbreeding and breeding situations was an increase from 32.2% to 38.1% for descending whistles (F[3,244] = 4.483, p = 0.004). Trills gradually increased from 1.8% to 7.3% toward the mating period (F[3,244] = 30.932, p < 0.001). The proportion of trills, chugs, descending whistles, and other call types also varied with calling rate and light–dark conditions. Some pre-reproductive behaviours may occur in winter, but no call types of Weddell seals function solely in the breeding season.

Repertoire and Geographic Variation in Underwater Vocalisations of Weddell Seals (Leptonychotes weddellii, Pinnipedia : Phocidae) at the Vestfold Hills, Antarctica

1997 ◽  
Vol 45 (2) ◽  
pp. 171 ◽  
Author(s):  
B. C. Pahl ◽  
J. M. Terhune ◽  
H. R. Burton
Keyword(s):  
Weddell Seal ◽  
Recording Site ◽  
Leptonychotes Weddellii ◽  
Breeding Sites ◽  
Analysis Techniques ◽  
Weddell Seals ◽  
Larsemann Hills ◽  
Vestfold Hills ◽  
Study Sites ◽  
Hills Area

The underwater vocalisations of Weddell seals (Leptonychotes weddellii) near Davis, Antarctica, were many and varied. A total of 11029 vocalisations recorded throughout and immediately after the breeding season were analysed. Vocalisations were classified by cluster analysis techniques, based on differences in frequency, duration, call shape, waveform and number of elements. Thirteen broad call categories (many with subdivisions) were identified. Twelve call types (belonging to nine categories) made up 91· 9% of the vocalisations and were present at all seven study sites within the Vestfold Hills, and a single site at the Larsemann Hills approximately 150 km away. A further eight call types (five categories) made up another 6·7% of the vocalisations. These were not detected at every recording site. An additional 29 call types (11 categories) were infrequent and probably reflect the diversity of individual seals. This study strengthens the case for macrogeographic variation in underwater Weddell seal vocalisations around Antarctica. Microgeographic differences, between sites within 150 km, were weak and not consistent between sites or years. Some adult females move to different breeding sites within the Vestfold Hills area between years. This would probably preclude the establishment of site-specific (microgeographic) repertoire differences.

Calling depth and time and frequency attributes of harp (Pagophilus groenlandicus) and Weddell (Leptonychotes weddellii) seal underwater vocalizations

2005 ◽  
Vol 83 (11) ◽  
pp. 1438-1452 ◽  
Author(s):  
Hilary B Moors ◽  
John M Terhune
Keyword(s):  
Light Condition ◽  
Weddell Seal ◽  
Harp Seal ◽  
Vertical Array ◽  
Vocal Cords ◽  
Leptonychotes Weddellii ◽  
Call Duration ◽  
Weddell Seals ◽  
Pagophilus Groenlandicus ◽  
Breeding Seasons

Harp seal (Pagophilus groenlandicus (Erxleben, 1777)) daytime calling depth during the breeding season and Weddell seal (Leptonychotes weddellii (Lesson, 1826)) daytime and nighttime calling depth during the winter and breeding seasons were investigated using a small vertical array with hydrophones placed at depths of 10 and 60 m. Rough calling depth estimates (<35 m, ~35 m, >35 m) and more accurate point depth estimates (±5–10 m in most cases) were obtained. Significantly more calls were produced at depths ≤35 m for both species. The point depth estimates indicated that the calls occurred most frequently at depths >10 m; 60% of harp seal calls and 71% of Weddell seal calls occurred at depths between 10 and 35 m. The seals called predominately within areas of the water column where light would likely penetrate, but still avoided sea-ice interference to some extent. The vocalizations did not change over depth with respect to call type, the number of elements within a call, or total call duration, or with respect to season and light condition for Weddell seals. Frequency (kHz) of calls also did not change with depth, suggesting that harp and Weddell seals control the pitch of their vocalizations with the vocal cords of the larynx.

The Weddell seals of Larsen Harbour, South Georgia: a unique but apparently declining colony

Polar Record ◽  
2015 ◽  
Vol 51 (6) ◽  
pp. 667-671 ◽  
Author(s):  
Robert Burton
Keyword(s):  
Sea Ice ◽  
Breeding Season ◽  
Small Population ◽  
Single Observation ◽  
South Georgia ◽  
Weddell Seals ◽  
Cruise Ships

ABSTRACTThe small population of Weddell seals at Larsen Harbour, South Georgia, is isolated from the rest of the species and is unique because nearly all pups are born on land rather than on sea-ice. Observations of seals in Larsen Harbour during the breeding season are summarised. These have been infrequent until cruise ships started to visit. With often only a single observation in a year, accurate estimates of pup production are impossible but it appears that the population has decreased over the last three decades.

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