scholarly journals A memory like a female Fur Seal: long-lasting recognition of pup's voice by mothers

2004 ◽  
Vol 76 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Nicolas Mathevon ◽  
Isabelle Charrier ◽  
Thierry Aubin
Keyword(s):  
Field Experiments ◽  
Individual Characteristics ◽  
Lactation Period ◽  
Acoustic Characteristics ◽  
Call Recognition ◽  
Fur Seals ◽  
Fur Seal ◽  
Vocal Recognition ◽  
Modulation Pattern ◽  
Arctocephalus Tropicalis

In colonial mammals like fur seals, mutual vocal recognition between mothers and their pup is of primary importance for breeding success. Females alternate feeding sea-trips with suckling periods on land, and when coming back from the ocean, they have to vocally find their offspring among numerous similar-looking pups. Young fur seals emit a 'mother-attraction call' that presents individual characteristics. In this paper, we review the perceptual process of pup's call recognition by Subantarctic Fur Seal Arctocephalus tropicalis mothers. To identify their progeny, females rely on the frequency modulation pattern and spectral features of this call. As the acoustic characteristics of a pup's call change throughout the lactation period due to the growing process, mothers have thus to refine their memorization of their pup's voice. Field experiments show that female Fur Seals are able to retain all the successive versions of their pup's call.

Long term population changes of fur seals Arctocephalus gazella and Arctocephalus tropicalis on subantarctic (Crozet) and subtropical (St. Paul and Amsterdam) islands and their possible relationship to El Niño Southern Oscillation

1994 ◽  
Vol 6 (4) ◽  
pp. 473-478 ◽  
Author(s):  
C. Guinet ◽  
P. Jouventin ◽  
J-Y. Georges
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Enso Events ◽  
Fur Seals ◽  
Fur Seal ◽  
Arctocephalus Tropicalis

The population trend over the last decade for subantarctic fur seals (Arctocephalus tropicalis) on Amsterdam and St. Paul islands and on Possession Island (Crozet Archipelago) and Antarctic fur seals (A. gazella) on Possession Island are analysed. At Amsterdam Island, based on pup counts, the subantarctic fur seal population appears to have stabilized after a period of rapid growth. At Possession Island subantarctic fur seal and Antarctic fur seal, with respective annual growth rates of 19.2 and 17.4%, are reaching the maximum growth rate for the genus Arctocephalus. Annual pup censuses at Possession Island since 1978 indicate important variations from year to year with pup production for A. gazella significantly lower the year after an El Niño Southern Oscillation (ENSO) event, but with no such relationship for A. tropicalis. Several other long term demographic studies of seabirds and marine mammals at different breeding locations in the Southern Ocean indicate that the breeding success of several of these predators appears to be widely affected in years which appear to be related to the ENSO events. To clarify this, it is necessary to analyse in more detail the demographic data obtained for the different subantarctic and Antarctic locations where long term monitoring programmes are conducted.

The subantarctic fur seal pup switches its begging behaviour during maternal absence

2002 ◽  
Vol 80 (7) ◽  
pp. 1250-1255 ◽  
Author(s):  
Isabelle Charrier ◽  
Nicolas Mathevon ◽  
Mohammed Hassnaoui ◽  
Laurent Carraro ◽  
Pierre Jouventin
Keyword(s):  
Environmental Constraints ◽  
Lactation Period ◽  
Playback Experiments ◽  
Motivational State ◽  
Adult Females ◽  
Begging Behaviour ◽  
Fur Seal ◽  
Shared Characteristic ◽  
Nutritional Balance ◽  
Arctocephalus Tropicalis

Begging signals from the young are used to elicit parental care. Although honest and parent-directed signalling seems to be widely shared characteristic of begging behaviour, offspring might modify their strategy under some ecological or environmental constraints. In the subantarctic fur seal, Arctocephalus tropicalis, mothers forage at sea for 2–3 weeks at a time throughout the lactation period, resulting in regular separations of mothers and pups. Using playback experiments we investigated modifications of pups' begging behaviour during their mother's absence. From the 1st to the 5th day of maternal absence, pups rarely begged in response to other adult females' vocalizations (17.6–46.7% of tested pups), but always responded specifically to their mother's. After its mother had been absent for 5–10 days, the pup's response to playback of strange females' calls was stronger (46–69% of tested pups), but the specificity of the response to the mother remained. However, after the 11th day of maternal absence, pups become highly responsive to calls made by any adult female (up to 37% of tested pups). The variation in responsiveness of fur seal pups during their mother's absence may be explained by changes in their motivational state that were linked to their internal nutritional balance.

The foraging ecology of two sympatric fur seal species, Arctocephalus gazella and Arctocephalus tropicalis, at Macquarie Island during the austral summer

2002 ◽  
Vol 53 (7) ◽  
pp. 1071 ◽  
Author(s):  
S. A. Robinson ◽  
S. G. Goldsworthy ◽  
J. van den Hoff ◽  
M. A. Hindell
Keyword(s):  
Foraging Behaviour ◽  
Foraging Ecology ◽  
Austral Summer ◽  
Sympatric Species ◽  
Arctocephalus Gazella ◽  
Macquarie Island ◽  
Fur Seals ◽  
Fur Seal ◽  
Marine Environmental ◽  
Arctocephalus Tropicalis

Antarctic Arctocephalus gazella and subantarctic Arctocephalus tropicalis fur seals breed sympatrically at Macquarie Island. The two species have different lactation strategies, the former rearing its pup in 4 months and the latter taking 10 months. The diet and at-sea foraging behaviour of these sympatric species was compared during the austral summer period when their pup rearing period overlapped. The prey of the two fur seal species was very similar, with fish dominating the diet. The myctophid, Electrona subaspera, was the main prey item (93.9%) in all months of the study. There were no major differences in the diving behaviour between species. Both species foraged north of the island parallel to the Macquarie Ridge. Foraging activity was concentrated at two sites: (i) within 30�km north of the island; and (ii) at 60 km north. Most locations for overnight foraging trips were within 10 km of the colonies. The different lactation strategies of A. gazella and A. tropicalis allowed for flexibility in foraging behaviour. At Macquarie Island, the local marine environmental conditions have resulted in similar foraging behaviour for both species.

How does a fur seal mother recognize the voice of her pup? An experimental study of Arctocephalus tropicalis

2002 ◽  
Vol 205 (5) ◽  
pp. 603-612 ◽  
Author(s):  
Isabelle Charrier ◽  
Nicolas Mathevon ◽  
Pierre Jouventin
Keyword(s):  
Individual Recognition ◽  
Spectral Energy Distribution ◽  
Individual Variability ◽  
Signal Spectrum ◽  
Spectral Energy ◽  
Fur Seals ◽  
Fur Seal ◽  
Female Attraction ◽  
The Individual ◽  
Arctocephalus Tropicalis

SUMMARY In the subantarctic fur seal Arctocephalus tropicalis, mothers leave their pups during the rearing period to make long and frequent feeding trips to sea. When a female returns from the ocean, she has to find her pup among several hundred others. Taking into account both spectral and temporal domains, we investigated the individual vocal signature occurring in the ‘female attraction call’ used by pups to attract their mother. We calculated the intra- and inter-individual variability for each measured acoustic cue to isolate those likely to contain information about individual identity. We then tested these cues in playback experiments. Our results show that a female pays particular attention to the lower part of the signal spectrum, the fundamental frequency accompanied by its first two harmonics being sufficient to elicit reliable recognition. The spectral energy distribution is also important for the recognition process. Of the temporal features, frequency modulation appears to be a key component for individual recognition, whereas amplitude modulation is not implicated in the identification of the pup’s voice by its mother. We discuss these results with respect to the constraints imposed on fur seals by a colonial way of life.

Sex-specific and latitudinal variance in postnatal growth of the Subantarctic fur seal (Arctocephalus tropicalis)

1994 ◽  
Vol 72 (6) ◽  
pp. 1126-1133 ◽  
Author(s):  
Marthán N. Bester ◽  
Albert S. Van Jaarsveld
Keyword(s):  
Body Size ◽  
Growth Curves ◽  
Postnatal Growth ◽  
Polar Front ◽  
Parameter Estimates ◽  
Antarctic Polar Front ◽  
Fur Seals ◽  
Fur Seal ◽  
Gough Island ◽  
Arctocephalus Tropicalis

Parameter estimates reflecting age-specific growth of Subantarctic fur seals (Arctocephalus tropicalis) on Gough Island were fitted to three sigmoidal (Gompertz, logistic, and von Bertalanffy) growth curves. With a few exceptions, the logistic fit provided the best mathematical approximation of postnatal growth in fur seals from Gough Island, although all fits were significant. Standard length is a better reflection of age-specific changes in size than mass, which displayed considerable variance. Growth was characterized by marked sexual dimorphism. Interisland comparisons of body size from throughout the geographic range of the species suggested a latitudinal graded difference in adult body size, with the largest animals occurring at low-latitude Amsterdam Island and the smallest at Marion Island, which lies just north of the Antarctic Polar Front. These growth and body-size estimates can be used for monitoring the effects of population or ecosystem changes on fur seal productivity, but significant standardization of data collection procedures need to be introduced.

scholarly journals Ontogeny of body size and shape of Antarctic and subantarctic fur seals

2007 ◽  
Vol 85 (12) ◽  
pp. 1275-1285 ◽  
Author(s):  
Sebastián P. Luque ◽  
Edward H. Miller ◽  
John P.Y. Arnould ◽  
Magaly Chambellant ◽  
Christophe Guinet
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Morphological Traits ◽  
Body Shape ◽  
Size And Shape ◽  
Fur Seals ◽  
Fur Seal ◽  
Adult Body ◽  
Weaning Age ◽  
Lactation Duration

Pre- and post-weaning functional demands on body size and shape of mammals are often in conflict, especially in species where weaning involves a change of habitat. Compared with long lactations, brief lactations are expected to be associated with fast rates of development and attainment of adult traits. We describe allometry and growth for several morphological traits in two closely related fur seal species with large differences in lactation duration at a sympatric site. Longitudinal data were collected from Antarctic ( Arctocephalus gazella (Peters, 1875); 120 d lactation) and subantarctic ( Arctocephalus tropicalis (Gray, 1872); 300 d lactation) fur seals. Body mass was similar in neonates of both species, but A. gazella neonates were longer, less voluminous, and had larger foreflippers. The species were similar in rate of preweaning growth in body mass, but growth rates of linear variables were faster for A. gazella pups. Consequently, neonatal differences in body shape increased over lactation, and A. gazella pups approached adult body shape faster than did A. tropicalis pups. Our results indicate that preweaning growth is associated with significant changes in body shape, involving the acquisition of a longer, more slender body with larger foreflippers in A. gazella. These differences suggest that A. gazella pups are physically more mature at approximately 100 d of age (close to weaning age) than A. tropicalis pups of the same age.

scholarly journals Low resolution accelerometers can be used to develop time-energy budgets of wild fur seals from captive surrogates

2018 ◽  
Author(s):  
Monique A Ladds ◽  
Marcus Salton ◽  
David P Hocking ◽  
Rebecca R McIntosh ◽  
Adam P Thompson ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Expenditure ◽  
Energetic Cost ◽  
Energy Budgets ◽  
Gradient Boosting ◽  
Low Resolution ◽  
Fur Seals ◽  
Long Duration ◽  
Fur Seal ◽  
Significant Difference

Background. Accurate time-energy budgets summarise an animal’s energy expenditure in a given environment and are potentially a sensitive indicator of how an animal responds to changing resources. Deriving accurate time-energy budgets requires a precise measure of time spent in different activities, and an estimate of the energetic cost of that activity. Bio-loggers such as accelerometers may provide a solution for monitoring animals such as fur seals that make long-duration foraging trips over multiple days or weeks. Monitoring such behaviour may require low resolution recording due to the memory constraints of bio-loggers. The aim of this study was to evaluate if accelerometers recording at a low resolution could accurately classify and determine the cost of fur seal activity. Methods. Diving and movement data were collected from nine wild juvenile Australian fur seals equipped with tri-axial accelerometers. To validate time-energy budgets for the fur seals, energy consumption during a range of behaviours was determined from twelve captive surrogates. The time wild fur seals spent in four behavioural states - foraging, grooming, travelling and resting - was quantified with low- and high-resolution data from accelerometers using gradient boosting models (GBM). The daily energy expenditure (DEE) from these four activities was estimated using a relatively simple energetics model developed using their location (land, surface or underwater) and estimates of the energetic cost of each behaviour. Models developed from captive seals were applied to accelerometry data collected from wild juvenile Australian fur seals and their time-energy budgets were reconstructed. Results. Low resolution accelerometery was better at classifying fur seal behaviour over long durations than high resolution accelerometry in captive surrogates. The low resolution model was therefore applied to wild data. This revealed that Juvenile fur seals expended more energy than adults of similar species, but there was no significant difference in DEE across sex or season (winter or summer). Juvenile fur seals used behavioural compensatory techniques to conserve energy during activities that were expected to have high energetic outputs (such as diving). Discussion. Behaviours that are displayed over a long duration can be captured accurately by low-resolution accelerometry and these models can be used to develop time-energy budgets of wild animals. In this study we were able to use such models to monitor juvenile fur seals over multiple foraging trips. This revealed that juvenile fur seals appear to be working energetically harder than their adult counterparts, likely due to the relative novelty of diving and foraging, their smaller body size and the additional cost of growth they sustain. Developing time-energy budgets from accelerometers is an efficient method of estimating energy expenditure from individuals over time.

Sign in / Sign up

Export Citation Format

Share Document