Summer foraging by lactating female New Zealand fur seals (Arctocephalus forsteri) off Otago Peninsula, New Zealand

1995 ◽  
Vol 73 (4) ◽  
pp. 678-690 ◽  
Author(s):  
Robert G. Harcourt ◽  
Andrew M. Schulman ◽  
Lloyd S. Davis ◽  
Fritz Trillmich
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Time Of Day ◽  
Daily Observation ◽  
Attendance Patterns ◽  
Fur Seals ◽  
Depth Contour ◽  
The Hours ◽  
Satellite Transmitters

The behaviour of female New Zealand fur seals (Arctocephalus forsteri) at sea and on land at the rookery of Fuchsia Gully, Otago Peninsula, New Zealand (45 °52′S, 170 °44′E), was examined during the early stages of lactation in the 1993 – 1994 breeding season. The attendance patterns of 19 females were investigated using daily observation at the rookery. Trips to sea to forage ranged from 3.4 h up to 8 days (mean 3.26 ± 1.1 days), and attendance periods at the rookery ranged from 1 to 13 days (mean 3.09 ± 1.63 days). At sea, the behaviour of four females was examined by deploying time–depth recorders. Females showed a nocturnal pattern of diving, 88.8–97.3% of dives being made during the hours of darkness. For all females and each night of foraging, the deepest dives were completed around dawn and dusk. The deepest dive recorded was 163 m and all females dove over 100 m deep on at least one dive. The overall median dive depth was considerably less than this, as around 24:00–03:00, females undertook many shallow dives, and during this time the median dive depth ranged from 5 to 10 m for the four females. Dives occurred in bouts, but bout duration varied significantly with time of day. Bouts were short during the day and longer at night, 55% of night bouts lasting throughout the night. Maximum dive durations ranged from 3.17 to 6.17 min and mean dive durations from 0.67 to 1.18 min for individual females. Dive depth was significantly related to dive duration for all four females. Two of the females also carried satellite transmitters, and at sea location was determined on three separate nights of foraging. Females were found to be foraging up to 78 km from the rookery, but always over the continental shelf (in water shallower than the 200 m depth contour).

Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri)

1998 ◽  
Vol 76 (2) ◽  
pp. 350-360 ◽  
Author(s):  
R H Mattlin ◽  
N J Gales ◽  
D P Costa
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Early Summer ◽  
Late Winter ◽  
Individual Values ◽  
Dive Behaviour ◽  
Fur Seals ◽  
Fur Seal ◽  
Bay Islands

The dive behaviour of 18 female New Zealand fur seals (Arctocephalus forsteri) from Taumaka, Open Bay Islands, New Zealand (43°52'S, 168°53'E), was recorded during early (summer; December-February), mid (autumn; March-May), and late (winter; June-August) lactation. Mean dive depth, dive duration, and bottom time for dives >=6 m in depth increased from summer through winter. Variation in individual seal dive behaviour within a season accounted for approximately 11, 9, and 11% of the observed difference between seasons in dive depth, dive duration, and bottom time, respectively. Seasonal dive data (mean ± 1 SD) were as follows: summer: dive depth 30 ± 37 m, dive duration 1.4 ± 1.1 min, and bottom time 0.5 ± 0.6 min; autumn: dive depth 54 ± 47 m, dive duration 2.4 ± 1.3 min, and bottom time 1.0 ± 0.8 min; winter: dive depth 74 ± 64 m, dive duration 2.9 ± 1.5 min, and bottom time 1.2 ± 1.1 min. Maximum recorded dive depth was 274 m for a 5.67-min dive in autumn. Maximum duration was 11.17 min for a dive to 237+ m in winter. New Zealand fur seals are the deepest diving fur seal species reported thus far. The estimated theoretical aerobic dive limit was exceeded on 18.4% of dives (range of individual values 0.2-57.8%). Females (n = 12) were ashore about 1.8 days at a time during February through November, and this increased to about 4.3 days during December and January. Average time spent away from the rookery ranged from 3 to 15 days.

In the shallow end: diving behaviour of recolonising female New Zealand sea lions (Phocarctos hookeri) around the Otago Peninsula

2011 ◽  
Vol 89 (12) ◽  
pp. 1195-1205 ◽  
Author(s):  
Amélie A. Augé ◽  
B. Louise Chilvers ◽  
Lloyd S. Davis ◽  
Antoni B. Moore
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behaviour ◽  
Marine Habitat ◽  
Sea Lions ◽  
The Core ◽  
The Mean ◽  
Historical Range ◽  
Phocarctos Hookeri

Female New Zealand sea lions ( Phocarctos hookeri (Gray, 1844)) at the Auckland Islands (remnant populations) are the deepest and longest diving otariids. These remnant populations are found at the margin of the historical range of the species. We hypothesized that diving behaviours of animals in the core of their historical range is less extreme owing to a better marine habitat. All female New Zealand sea lions (n = 13, aged 2–14 years) born on the Otago Peninsula (initial recolonising population) were equipped with time–depth recorders during April and May 2008, 2009, and 2010. The mean dive depth was 20.2 ± 24.5 m and mean dive duration was 1.8 ± 1.1 min, some of the lowest values reported for otariids. Otago female New Zealand sea lions did not exhibit two distinct diving specialisations as reported at the Auckland Islands. Otago adult females exceeded calculated aerobic dive limits in 7.1% of dives compared with 68.7% at the Auckland Islands. The contrasting differences in diving behaviour between Otago and the Auckland Islands suggest that Otago represents a better marine habitat for New Zealand sea lions, with food easily accessible to animals of all ages.

Diurnal and seasonal variations in the duration and depth of the longest dives in southern elephant seals (Mirounga leonina): possible physiological and behavioural constraints

2001 ◽  
Vol 204 (4) ◽  
pp. 649-662 ◽  
Author(s):  
K.A. Bennett ◽  
B.J. McConnell ◽  
M.A. Fedak
Keyword(s):  
Dive Depth ◽  
Dive Duration ◽  
Time Of Day ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
Dive Behaviour ◽  
Physiological Capacity ◽  
Data Loggers ◽  
Southern Elephant Seals ◽  
Seasonal Basis

This study seeks to understand how the physiological constraints of diving may change on a daily and seasonal basis. Dive data were obtained from southern elephant seals (Mirounga leonina) from South Georgia using satellite relay data loggers. We analysed the longest (95th percentile) dive durations as proxies for physiological dive limits. A strong, significant relationship existed between the duration of these dives and the time of day and week of year in which they were performed. The depth of the deepest dives also showed a significant, but far less consistent, relationship with local time of day and season. Changes in the duration of the longest dives occurred irrespective of their depth. Dives were longest in the morning (04:00-12:00 h) and shortest in the evening (16:00-00:00 h). The size of the fluctuation varied among animals from 4.0 to 20.0 min. The daily pattern in dive depth was phase-shifted in relation to the diurnal rhythm in dive duration. Dives were deeper at midday and shallower around midnight. Greater daily changes in duration occurred in seals feeding in the open ocean than in those foraging on the continental shelf. The seasonal peak in the duration of the longest dives coincided with austral midwinter. The size of the increase in dive duration from autumn/spring to winter ranged from 11.5 to 30.0 min. Changes in depth of the longest dives were not consistently associated with particular times of year. The substantial diurnal and seasonal fluctuations in maximum dive duration may be a result of changes in the physiological capacity to remain submerged, in addition to temporal changes in the ecological constraints on dive behaviour. We speculate about the role of melatonin as a hormonal mediator of diving capability.

Effect of seasonal changes in upwelling activity on the foraging locations of a wide-ranging central-place forager, the New Zealand fur seal

2008 ◽  
Vol 86 (8) ◽  
pp. 774-789 ◽  
Author(s):  
A. M.M. Baylis ◽  
B. Page ◽  
S. D. Goldsworthy
Keyword(s):  
New Zealand ◽  
Continental Shelf ◽  
Seasonal Changes ◽  
South Australia ◽  
Central Place ◽  
Fur Seals ◽  
Ocean Productivity ◽  
Satellite Transmitters ◽  
Seasonal Decline ◽  
New Zealand Fur Seal

Lactating New Zealand fur seals ( Arctocephalus forsteri (Lesson, 1828)) that breed at Cape Gantheaume, South Australia, experience broad-scale seasonal changes in ocean productivity. To assess how seasonal changes in ocean productivity influenced foraging behaviour, 18 lactating New Zealand fur seals were fitted with satellite transmitters and time–depth recorders (TDRs). Using temperature and depth data from TDRs, we used the presence of thermoclines as a surrogate measure of upwelling activity in continental-shelf waters. During the austral autumn 80% of lactating fur seals foraged on the continental shelf (114 ± 44 km from the colony), in a region associated with the Bonney upwelling. In contrast, during winter months seals predominantly foraged in oceanic waters (62%), in a region associated with the Subtropical Front (460 ± 138 km from the colony). Our results indicate that lactating New Zealand fur seals shift their foraging location from continental-shelf to oceanic waters in response to a seasonal decline in productivity over the continental shelf, attributed to the cessation of the Bonney upwelling. This study identified two regions used by lactating New Zealand fur seals: (1) a nearby and seasonally productive upwelling system and (2) a distant and permanent oceanic front.

The ontogeny of diving behaviour in New Zealand fur seal pups (Arctocephalus forsteri)

2005 ◽  
Vol 83 (9) ◽  
pp. 1149-1161 ◽  
Author(s):  
A M.M Baylis ◽  
B Page ◽  
K Peters ◽  
R McIntosh ◽  
J Mckenzie ◽  
...  
Keyword(s):  
New Zealand ◽  
Dive Depth ◽  
Dive Duration ◽  
Diving Behaviour ◽  
South American ◽  
Fur Seal ◽  
Time Periods ◽  
Prey Remains ◽  
New Zealand Fur Seal ◽  
Prey Items

This study investigated the development of diving in 21 New Zealand fur seal pups, Arctocephalus forsteri (Lesson, 1828), prior to weaning at Cape Gantheaume, Kangaroo Island. Diving behaviour was examined using time–depth recorders, which were deployed during two time periods, 5 months prior to weaning (n = 6) and 2 months prior to weaning (n = 15). Scats were also examined to assess whether fur seal pups foraged prior to weaning. The maximum dive depth attained was 44 m, while the maximum dive duration was 3.3 min. Immediately prior to weaning, fur seal pups spent a greater proportion of their time diving at night, and concomitantly several measures of diving performance also increased. In general, pups dived successively deeper (6–44 m between June and September), and the average number of dives per day, dive frequency, and vertical distance travelled increased. Prey remains were present in approximately 30% of scats and indicated that some pups were foraging as early as June (5–6 months of age, approximately 4–5 months prior to weaning). Of the scats that contained prey remains, fish (South American pilchard, Sardinops sagax (Jenyns, 1842); Australian anchovy, Engraulis australis (White, 1790); and redbait, Emmelichthys nitidus Richardson, 1845) accounted for 43% of the prey items found, crustaceans accounted for 36%, and cephalopods (Gould's squid, Nototodarus gouldi (McCoy, 1888)) accounted for 20%.

scholarly journals Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Monique Ladds ◽  
David Rosen ◽  
Carling Gerlinsky ◽  
David Slip ◽  
Robert Harcourt
Keyword(s):  
Foraging Strategy ◽  
Central Place ◽  
Dive Duration ◽  
Foraging Strategies ◽  
Body Morphology ◽  
Sea Lions ◽  
Fur Seals ◽  
Adequate Food ◽  
Physiological Capacity ◽  
Total Body Oxygen

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

scholarly journals Behavioral responses of Australian fur seals to boat approaches at a breeding colony

2018 ◽  
Vol 31 ◽  
pp. 35-52 ◽  
Author(s):  
Julia J. Back ◽  
Andrew J. Hoskins ◽  
Roger Kirkwood ◽  
John P.Y. Arnould
Keyword(s):  
Time Of Day ◽  
Species Variation ◽  
Strong Response ◽  
Approach Distance ◽  
Fur Seals ◽  
Increase Energy Expenditure ◽  
Fur Seal ◽  
Steep Decline ◽  
Breeding Seasons ◽  
Resting Behavior

In Australia, a multi-million-dollar industry is based on viewing the Australian fur seal (Arctocephaluspusillusdoriferus), predominantly through boat visits to breeding colonies. Regulation of boat approaches varies by site and no systematic investigations have been performed to inform management guidelines. To investigate possible effects of disturbance, experimental boat approaches were made to a colony at Kanowna Island in northern Bass Strait and seal responses were monitored using instantaneous scan sampling. Colony attendance (individuals remaining ashore) was found to be influenced by approach distance and time of day, but was not affected by environmental variables or season, whereas onshore resting behavior was influenced by approach distance, time of day, ambient temperature and wind direction. Onshore resting behavior decreased following experimental boat approaches to 75 m, but changes in abundance of individuals ashore were not observed at this distance. In contrast, approaches to 25 m elicited a strong response, with a steep decline in the number of individuals ashore. This response was strongest when approaches occurred in the morning, with a decline of approximately 47% of individuals, compared to a decline of 21% during afternoon approaches. With regard to onshore resting behavior, afternoon approaches to 75 m led to minimal response. The remaining three combinations of approach distance and time of day had a similar pattern of reductions in the proportion of individuals engaging in onshore resting behavior. The strongest response was again seen during approaches to 25 m conducted in the morning. These behavior changes suggest that unrestricted boat-based ecotourism at Australian fur seal colonies has the potential to increase energy expenditure and reduce the number of seals ashore. Increasing minimum approach distances to ≥75 m and/or restricting visits to afternoons may minimize these impacts at Kanowna Island during the post-molt and non-breeding seasons. As several studies have demonstrated considerable intra-species variation in seal responses to boat approaches, research at other colonies is needed before these findings can be generalized to the remainder of the Australian fur seal population.

Foraging energetics and diving behavior of lactating New Zealand sea lions, Phocarctos hookeri

2000 ◽  
Vol 203 (23) ◽  
pp. 3655-3665 ◽  
Author(s):  
D.P. Costa ◽  
N.J. Gales
Keyword(s):  
New Zealand ◽  
Metabolic Rate ◽  
Dive Depth ◽  
Diving Behavior ◽  
Metabolic Rates ◽  
Sea Lion ◽  
Water Turnover ◽  
Sea Lions ◽  
The Mean ◽  
Phocarctos Hookeri

The New Zealand sea lion, Phocarctos hookeri, is the deepest- and longest-diving sea lion. We were interested in whether the diving ability of this animal was related to changes in its at-sea and diving metabolic rates. We measured the metabolic rate, water turnover and diving behavior of 12 lactating New Zealand sea lions at Sandy Bay, Enderby Island, Auckland Islands Group, New Zealand (50 degrees 30′S, 166 degrees 17′E), during January and February 1997 when their pups were between 1 and 2 months old. Metabolic rate (rate of CO(2) production) and water turnover were measured using the (18)O doubly-labeled water technique, and diving behavior was measured with time/depth recorders (TDRs). Mean total body water was 66.0+/−1.1 % (mean +/− s.d.) and mean rate of CO(2) production was 0. 835+/−0.114 ml g(−)(1)h(−)(1), which provides an estimated mass-specific field metabolic rate (FMR) of 5.47+/−0.75 W kg(−)(1). After correction for time on shore, the at-sea FMR was estimated to be 6.65+/−1.09 W kg(−)(1), a value 5.8 times the predicted standard metabolic rate of a terrestrial animal of equal size. The mean maximum dive depth was 353+/−164 m, with a mean diving depth of 124+/−36 m. The mean maximum dive duration was 8.3+/−1.7 min, with an average duration of 3.4+/−0.6 min. The deepest, 550 m, and longest, 11.5 min, dives were made by the largest animal (155 kg). Our results indicate that the deep and long-duration diving ability of New Zealand sea lions is not due to a decreased diving metabolic rate. Individual sea lions that performed deeper dives had lower FMRs, which may result from the use of energetically efficient burst-and-glide locomotion. There are differences in the foraging patterns of deep and shallow divers that may reflect differences in surface swimming, time spent on the surface and/or diet. Our data indicate that, although New Zealand sea lions have increased their O(2) storage capacity, they do not, or cannot, significantly reduce their at-sea metabolic rates and are therefore likely to be operating near their physiological maximum.

Urban cat (Felis catus) movement and predation activity associated with a wetland reserve in New Zealand

2009 ◽  
Vol 36 (7) ◽  
pp. 574 ◽  
Author(s):  
S. A. Morgan ◽  
C. M. Hansen ◽  
J. G. Ross ◽  
G. J. Hickling ◽  
S. C. Ogilvie ◽  
...  
Keyword(s):  
New Zealand ◽  
Home Range ◽  
Home Range Size ◽  
Time Of Day ◽  
Ecological Impacts ◽  
Pest Species ◽  
Domestic Cats ◽  
Hunting Activity ◽  
The Impact ◽  
Prey Items

Context. House cats are increasingly suggested as having major ecological impacts in semiurban environments. Information on the activity of house cats is relatively scarce, especially in habitats such as wetlands. Aims. This study examines the movement and foraging behaviour of house cats living on the periphery of a wetland reserve in Christchurch city, New Zealand. Methods. Twenty-one domestic cats living in a suburban residential area were studied using radiotelemetry to determine home-range size, mean and maximum distances travelled into the adjacent wetland, and the proportion of time spent in the wetland over a 12-month period. Surveys of prey retrieval for 88 cats were also carried out by cat owners over the same 12-month period. Key results. Cat age and the distance of the cat’s home from the periphery of the wetland were highly correlated with cat movement and hunting activity. These movements were not markedly influenced by season or time of day. Younger cats (<6 years of age) living on the periphery of the wetland had larger home-range sizes, moved significantly further into the wetland and spent a significantly greater proportion of time in the wetland. Cats living close to the wetland also brought a greater diversity and a greater total number of prey items to their home-site. Rates of predation were not significantly influenced by sex or whether the cat was wearing a bell. The most common prey items were introduced rodents and birds; however, 172 of 981 prey items were identified as a native common skink. Conclusions.Consequently, cats living in households on the wetland periphery currently pose a predation risk for the wetland species, and the impact of cats on the native skink population warrants further investigation. Implications. This study suggests that domestic cats will exploit wild habitats but that their potential impact will have both positive (predation of introduced pest species) and negative (occasional direct predation) effects on native wildlife.

Records of vagrant fur seals (family Otariidae) in South Australia

2014 ◽  
Vol 36 (2) ◽  
pp. 154 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Catherine M. Kemper ◽  
David Stemmer ◽  
Jane McKenzie
Keyword(s):  
New Zealand ◽  
South Australia ◽  
The South ◽  
South Indian Ocean ◽  
Fur Seals ◽  
South Indian ◽  
Fur Seal ◽  
New Zealand Fur Seal ◽  
The Antarctic ◽  
Subantarctic Fur Seals

Two fur seal species breed on the southern coast of Australia: the Australian fur seal (Arctocephalus pusillus doriferus) and the New Zealand fur seal (A. forsteri). Two other species are vagrants: the subantarctic fur seal (A. tropicalis) and the Antarctic fur seal (A. gazella). We document records of vagrant fur seals in South Australia from 1982 to 2012 based primarily on records from the South Australian Museum. There were 86 subantarctic fur seals: 49 specimens and 37 sightings. Most (77%) were recorded from July to October and 83% of all records were juveniles. All but two specimens were collected between July and November. Sightings were prevalent during the same period, but there were also nine sightings during summer (December–February), several of healthy-looking adults. Notable concentrations were near Victor Harbor, on Kangaroo Island and Eyre Peninsula. Likely sources of subantarctic fur seals seen in South Australia are Macquarie and Amsterdam Islands in the South Indian Ocean, ~2700 km south-east and 5200 km west of SA, respectively. There were two sightings of Antarctic fur seals, both of adults, on Kangaroo Island at New Zealand fur seal breeding colonies. Records of this species for continental Australia and nearby islands are infrequent.

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