The behavioural response of lactating Weddell seals (Leptonychotes weddellii) to over-snow vehicles: a case study

2007 ◽  
Vol 85 (4) ◽  
pp. 488-496 ◽  
Author(s):  
T.D. van Polanen Petel ◽  
M.A. Giese ◽  
S. Wotherspoon ◽  
M.A. Hindell
Keyword(s):  
Adult Female ◽  
Scientific Research ◽  
Weddell Seal ◽  
Behavioural Response ◽  
Leptonychotes Weddellii ◽  
Weddell Seals ◽  
Fast Ice ◽  
Vehicle Activity

Over-snow vehicles are used extensively at Antarctic scientific research stations. Adult female Weddell seals ( Leptonychotes weddellii (Lesson, 1826)) also utilise the fast-ice and are therefore often exposed to vehicular activity, with the potential of affecting their behaviour. Guidelines for vehicular travel have been developed to minimise disturbance to Antarctic wildlife; however, these guidelines have not yet been scientifically tested. To examine the efficiency and sensitivity of existing guidelines used within the Australian Antarctic Territory (AAT), we conducted drive-by experiments of two types of over-snow vehicles. The results of these experiments showed that the probability of a lactating Weddell seal looking at the vehicles and the duration of the seals’ looking at the vehicles were dependent on the distance between vehicles and seals, the position of the pups in relation to its mother, and the distance the adult female was from the water. Although the seals apparently perceived the vehicles to be a threat, no seals fled in response to vehicle activity. We propose that the existing guidelines used in the AAT could be amended to increase separation distances between vehicles and breeding Weddell seals if the goal of management is to ensure that Weddell seal behaviour is unaffected by vehicle travel.

Age-specific survival, abundance, and immigration rates of a Weddell seal (Leptonychotes weddellii) population in McMurdo Sound, Antarctica

2004 ◽  
Vol 82 (4) ◽  
pp. 601-615 ◽  
Author(s):  
Michael F Cameron ◽  
Donald B Siniff
Keyword(s):  
Information Criterion ◽  
Weddell Seal ◽  
Adult Survival ◽  
Sea Ice Extent ◽  
Leptonychotes Weddellii ◽  
Mcmurdo Sound ◽  
Weddell Seals ◽  
Abundance Estimates ◽  
Fast Ice ◽  
The 1960S

Since the 1960s, Weddell seals (Leptonychotes weddellii (Lesson, 1826)) have been tagged and surveyed annually in McMurdo Sound, Antarctica. Mark–recapture analyses and model selection trials using Akaike's Information Criterion indicate that sex, cohort, and year affect juvenile (ages 1 and 2) survival. In contrast, year and perhaps sex and cohort are less important factors for adult survival. Average annual survival is higher among adults (0.93) than juveniles (0.55–0.59) and there is little evidence for senescence to at least age 17. The oldest known-aged female and male in the study were 27 and 24 years old, respectively. Data suggest that the abundance of a resident population of Weddell seals remains relatively stable over time despite annual fluctuations in Jolly–Seber abundance estimates for the entire population. We argue that this annual variability is likely the result of temporary immigration of animals born outside the study area; mean rates are estimated from a simulation model and tagging data to be between 16.8% and 39.7% for females and between –13.1% and 31.6% for males. Sea ice extent appears to affect immigration where, during times of reduced fast-ice, immigrants are forced, or allowed easier access, into the ice-covered areas of Erebus Bay from surrounding locations. Our findings contradict previous studies reporting lower survival and higher immigration. Model choice is shown to be the most likely cause of these discrepancies and we provide evidence that our models are more appropriate than those used elsewhere.

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.

Preweaning mortality of Weddell seal pups

1996 ◽  
Vol 74 (9) ◽  
pp. 1775-1778 ◽  
Author(s):  
Jason F. Schreer ◽  
Kelly K. Hastings ◽  
J. Ward Testa
Keyword(s):  
Mortality Rates ◽  
Weddell Seal ◽  
Leptonychotes Weddellii ◽  
Mark Recapture ◽  
Mcmurdo Sound ◽  
Weddell Seals ◽  
Ice Surface ◽  
Open Populations ◽  
Significant Mortality

We examined mortality prior to weaning of Weddell seal pups (Leptonychotes weddellii), using resighting data collected from 1984 to 1993 on the annual ice of McMurdo Sound, Antarctica. Mortality rates were estimated using counts of dead pups found on the surface and mark–recapture techniques. The standard Jolly–Seber model for open populations fit the recapture data best and corresponded well to the known biology of these animals. Yearly mortality rates estimated by mark–recapture techniques ranged from 6 to 22%, with a mean across years of 13%. These values are twice as high as those previously reported for Weddell seals and those calculated from counts of dead pups in this study. This suggests that there is significant unseen mortality due either to undiscovered fatalities on the ice surface or to significant mortality occurring in the water.

Apparent twin pups of the Weddell seal Leptonychotes weddellii (Carnivora: Phocidae) near Mawson, Antarctica.

2003 ◽  
Vol 25 (2) ◽  
pp. 197
Author(s):  
P Shaughnessy ◽  
E Erb
Keyword(s):  
Adult Female ◽  
Weddell Seal ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Field Observations ◽  
Mirounga Leonina ◽  
Leptonychotes Weddellii ◽  
Pinniped Species ◽  
Phocid Seals ◽  
Made In

PHOCID seals give birth annually, generally to a single pup. Twins have been reported occasionally, either from observations made in utero or from observations of live pups in the field. Examples of the former are reports of two embryos in a Weddell seal, Leptonychotes weddellii (Bertram 1940) and of twin foetuses of a southern elephant seal, Mirounga leonina (Bryden 1966). Observations of two pups suckling one adult female have been reported for L. weddellii (e.g., Gelatt et al. 2001). For M. leonina, Carrick et al. (1962) reported an adult female that expelled two placentae and gave birth to a pup while another newborn pup was nuzzling the female. The occurrence of twin pups in several pinniped species is reviewed by Spotte (1982). Here we use the expression 'apparent twins' to refer to reports of twin L. weddellii pups that are based solely on field observations of two pups with the same adult female on several occasions.

scholarly journals An assessment of the audibility of sound from human transport by breeding Weddell seals (Leptonychotes weddellii)

2006 ◽  
Vol 33 (4) ◽  
pp. 275 ◽  
Author(s):  
Tamara D. van Polanen Petel ◽  
John M. Terhune ◽  
Mark A. Hindell ◽  
Melissa A. Giese
Keyword(s):  
Detection Threshold ◽  
Weddell Seal ◽  
Anthropogenic Noise ◽  
Noise Levels ◽  
Leptonychotes Weddellii ◽  
Vehicle Noise ◽  
Weddell Seals ◽  
Vocal Behaviour ◽  
Pedestrian Travel ◽  
Low Amplitude

Anthropogenic noise generated through travel in the Antarctic has the potential to affect the region’s wildlife. Weddell seals (Leptonychotes weddellii) in particular can be exposed to anthropogenic noise because they live under, and breed on, the fast ice on which humans travel. To investigate the potential effects of anthropogenic noise on Weddell seals we developed sound profiles for pedestrian travel, over-snow vehicles, aircraft and watercraft operating at various distances and altitudes from breeding seals. The received 1/3-octave noise levels were then related to an assumed detection threshold for the Weddell seal. We found that most noise levels generated by the pedestrian, quad (4-wheeled, all-terrain vehicle) and Hagglunds (tracked, all-terrain vehicle) were commonly categorised in the inaudible and barely audible range of detection (both in-air and underwater), while noise levels generated by the helicopter, Twin Otter aircraft and Zodiac boat were categorised more commonly in the barely audible and clearly audible range. Experimental underwater recordings of vocal behaviour of Weddell seals exposed to continuous low-amplitude over-snow vehicle noise (i.e. Hagglund operation) were also made. Weddell seals underwater did not alter individual call types in response to low-level Hagglunds noise, but they did decrease their calling rate.

Over-winter movements and diving behavior of female Weddell seals (Leptonychotes weddellii) in the southwestern Ross Sea, Antarctica

1994 ◽  
Vol 72 (10) ◽  
pp. 1700-1710 ◽  
Author(s):  
J. Ward Testa
Keyword(s):  
Ross Sea ◽  
Diving Behavior ◽  
Winter Period ◽  
Pleuragramma Antarcticum ◽  
Long Distance ◽  
Leptonychotes Weddellii ◽  
Mcmurdo Sound ◽  
Weddell Seals ◽  
Pack Ice ◽  
Fast Ice

The movements and diving behavior of 18 adult female Weddell seals (Leptonychotes weddellii) were determined by satellite telemetry during the over-winter period in 1990 and 1991. Nine seals provided diving and movement data for 8 – 9 months. Seals that normally bred in the eastern part of McMurdo Sound spent most of the winter in the middle and northern parts of McMurdo Sound before the annual shore-fast ice had formed in those areas, or in the pack ice 0–50 km north of the sound and Ross Island. This is a greater use of pack ice, as opposed to shore-fast ice, in winter than was previously believed. Some long-distance movements (one over 1500 km in total) to the middle and northwestern parts of the Ross Sea also occurred. Although highly variable within and between individuals, dives indicative of foraging were primarily to mid-water regions (100 – 350 m) in both years, and were similar to those that have been observed in spring and summer, when Pleuragramma antarcticum is the primary prey of Weddell seals in McMurdo Sound.

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.

Possible food caching and defence in the Weddell seal: observations from McMurdo Sound, Antarctica

2005 ◽  
Vol 17 (1) ◽  
pp. 71-72 ◽  
Author(s):  
S.L. KIM ◽  
K. CONLAN ◽  
D.P. MALONE ◽  
C.V. LEWIS
Keyword(s):  
Shallow Water ◽  
Benthic Communities ◽  
Weddell Seal ◽  
Leptonychotes Weddellii ◽  
Mcmurdo Sound ◽  
Weddell Seals ◽  
Food Caching ◽  
The Common ◽  
Made In

On the basis of observations of Weddell seals (Leptonychotes weddellii Lesson) made in the course of studying shallow-water benthic communities in McMurdo Sound, Antarctica, we suggest that caching and/or defence of uneaten food may be a strategy practiced by this animal. Such a phenomenon is uncommon but taxonomically widespread among vertebrates. Depending on circumstances, it is termed hoarding, caching, or storage and may be short- or long-term, include defence of the resource, or have other variable expressions, with the common threads being deferred consumption and deterrence of consumption by others (Vanderwall 1990). Many vertebrate taxa exhibit hoarding behaviour, including rodents (e.g. Sciuridae), carnivores (e.g. Canidae, Felinidae) and birds (e.g. Corvidae, Picidae). No form of food caching, to our knowledge, has ever been reported in a wild pinniped.

scholarly journals Weddell seal observations on female and pup behavior and breeding status for four overwintering periods (2015 to 2018) at Barton Peninsula, King George Island, Antarctica

2020 ◽  
Vol 10 (1) ◽  
pp. 1-6
Author(s):  
Yejin Kim ◽  
In-Young Ahn ◽  
Ji Kang Park ◽  
Won Young Lee
Keyword(s):  
Weddell Seal ◽  
Breeding Cycle ◽  
King George Island ◽  
Weddell Seals ◽  
Barton Peninsula ◽  
Fast Ice ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Breeding Status

In animal ecology studies, it is a fundamental monitoring work to observe annual breeding cycle. In this study, we report the detailed observations on seven mother and pup pairs of Weddell seal (Leptonychotes weddellii) at Barton peninsula, King George Island, Antarctica. Two or three pairs had been observed along the coast on the fast ice in 2015, 2017, and 2018 and no breeding was recorded in 2016. Although it varied among individuals, pups were recorded to be born on 19−25 Sept., began swimming at day 18−19 after birth, and molted at day 21−25. Our observations may provide fundamental breeding information of Weddell seals in our study site and contribute to the future long-term monitoring research of seals.

Difficulties in assessing population status of ice seals

1995 ◽  
Vol 22 (2) ◽  
pp. 193 ◽  
Author(s):  
RA McFarlane ◽  
AA Flaherty ◽  
BC Pahl ◽  
SA Haigh
Keyword(s):  
Prey Species ◽  
Weddell Seal ◽  
Population Status ◽  
Reproductive Condition ◽  
Elephant Seals ◽  
Weddell Seals ◽  
Southern Elephant Seals ◽  
Fast Ice ◽  
Crabeater Seals

The best method of monitoring ice seal populations in shifting packice is by aerial censuses. However, there are a number of problems with this method that are difficult to address in the packice and are best addressed on more accessible ice seals such as the Weddell seal. Counts made during the moult are affected by the fact that Weddell seals can leave the fast ice to forage. Seal numbers on the fast ice will therefore differ depending upon the proximity and availability of prey species, with lower numbers being recorded on the fast ice the further the seal has to travel from the ice to find food. In any census the subgroup of the population that is being counted must be known. Southern elephant seals and Weddell seals haul out to moult in sequences on the basis of age, sex and reproductive condition. This leads to periods of high and low counts through the moult. Examination of data on crabeater seals indicates that a putative 60% decline in numbers may have been due to counts being made at different times of the moult and therefore with different subgroups of the population being counted.

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