The Role of the Leopard Seal in the Tropho-Dynamics of the Antarctic Marine Ecosystem

Siniff, Donald B.; Stone, Sheridan

doi:10.1007/978-3-642-82275-9_75

Cited by 48 publications

(37 citation statements)

References 8 publications

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“…In addition to capturing images for estimating abundance of animals, aerial photographs allow post-processing of morphometrics in target species which can be used to track changes in animal size, body shape, and nutritive condition (Perryman and Lynn 2002;Miller et al 2012). Thus, we wanted to test the feasibility of using a VTOL to estimate size and condition of leopard seals, an apex predator that affects Antarctic populations of penguins and seals (Siniff and Stone 1985;Boveng et al 1998;Ainley et al 2005;Schwarz et al 2013). Similarly, aerial methods to collect data on size and identification of individual marine mammals, including pinnipeds and cetaceans, may help reduce disturbance associated with capture and traditional measurement.…”

Section: Introductionmentioning

confidence: 99%

A small unmanned aerial system for estimating abundance and size of Antarctic predators

et al. 2015

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Quantifying the distribution and abundance of predators is integral to many ecological studies, but can be difficult in remote settings such as Antarctica. Recent advances in the development of unmanned aerial systems (UAS), particularly vertical takeoff and landing (VTOL) aircraft, have provided a new tool for studying the distribution and abundance of predator populations. We detail our experience and testing in selecting a VTOL platform for use in remote, windy, perennially overcast settings, where acquiring cloud-free high-resolution satellite images is often impractical. We present results from the first use of VTOLs for estimating abundance, colony area, and density of krilldependent predators in Antarctica, based upon 65 missions flown in 2010/2011 (n = 28) and 2012/2013 (n = 37). We address concerns over UAS sound affecting wildlife by comparing VTOL-generated noise to ambient and penguingenerated sound. We also report on the utility of VTOLs for missions other than abundance and distribution, namely to estimate size of individual leopard seals. Several characteristics of small, battery-powered VTOLs make them particularly useful in wildlife applications: (1) portability, (2) stability in flight, (3) limited launch area requirements, (4) safety, and (5) limited sound when compared to fixed-wing and internal combustion engine aircraft. We conclude that of the numerous UAS available, electric VTOLs are among the most promising for ecological applications.

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Section: Introductionmentioning

confidence: 99%

A small unmanned aerial system for estimating abundance and size of Antarctic predators

et al. 2015

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“…Scat and stomach contents analysis suggests that Adelie penguins Pygoscelis adeliae are eaten throughout the year, but are also the main prey item in the Prydz Bay region during the austral summer (Rogers & Bryden 1995, Hall-Aspland & Rogers 2004. Crabeater seals Lobodon carcinophagus become important in the diet between November and February when newly weaned pups are available as easy prey targets (Siniff & Bengtson 1977, Siniff et al 1979, Bengtson 1982, Siniff & Stone 1985. Krill and fish are preyed on throughout the summer from September to March whereas Antarctic silverfish Pleuragramma antarcticum predominated during winter (Green & Williams 1986).…”

Section: Introductionmentioning

confidence: 99%

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Hall-Aspland¹,

Rogers²,

Canfield³

2005

Mar. Ecol. Prog. Ser.

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In order to assess seasonal and spatial changes in diet, the δ 15 N and δ 13 C signatures of vibrissae from leopard seals Hydrurga leptonyx obtained from Prydz Bay, Eastern Antarctica, were compared with those of a captive seal on a known diet. Using the isotopic signatures of known prey, and those revealed by the assimilation rates of vibrissae, we constructed trophic models to estimate diet composition. Assuming that current diet was reflected only in the actively growing portion of the vibrissae, the latter were sectioned. Each section was then analysed independently. Two methods of analysis of the vibrissae isotopic data were compared in order to ascertain the best analytical approach to these data. A simple linear model and a von Bertalanffy growth model were used to estimate section age and vibrissae growth rates. The age predictions of the von Bertalanffy growth model allowed the existence of repeated seasonal oscillations in both δ 15 N and δ 13 C values. Temporal variations in stable isotope ratios consistent with changes in source of feeding (inshore vs. offshore) and prey types were identified in the Antarctic leopard seals, but not in the captive seal. This preliminary study has possible implications for the use of vibrissae to track dietary changes over time and may serve as a tool for investigating foraging preferences of highly mobile or migratory pinniped species.KEY WORDS: Leopard seal · Stable isotope · Vibrissae · von Bertalanffy · Antarctic · Prey switching Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 305: [249][250][251][252][253][254][255][256][257][258][259] 2005 al. 2004). Changes along the length of whale baleen have provided an isotopic record of seasonal variation in the location of feeding (Best & Schell 1996, Hobson & Schell 1998, Lee et al. 2005) and diet (Schell et al. 1989, Hobson & Schell 1998. Vibrissae may be a useful tissue for isotopic analysis and the study of longterm and seasonal dietary changes. Vibrissae lengths may be transformed into measurements of time, which can then be related to isotopic ratios.Growth rates have been determined for a number of pinniped species using dated vibrissae. Harbour seal vibrissae growth rates were irregular (Hirons et al. 2001) or variable (Zhao & Schell 2004), while growth rates in the case of grey seals Halichoerus grypus varied according to the length and age of the vibrissae and involved asynchronous shedding and discontinuous replacement (Greaves et al. 2004). Conversely, Steller sea lions Eumetobias jubatus displayed more consistent growth and annual retention of their vibrissae (Hirons et al. 2001). Greaves et al. (2004) suggested that vibrissae growth follows a von Bertalanffy growth curve.This study aims to transform vibrissae lengths into time lines using both a simple linear and von Bertalanffy growth model. With information gained through stable carbon and nitrogen isotope analysis of sequentially segmented vibrissae, their potential as indicators of seasonal cha...

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“…The prey taken varies with the age of a seal; juvenile seals feed mainly on krill, while older seals feed on penguins, seals and other prey (Hofman et al, 1977). Krill, ®sh and cephalopods are eaten from September to March (éritsland, 1977;Bengtson, 1982;Siniff & Stone, 1985;Green & Williams, 1986;Lowry et al, 1988). Penguins are eaten throughout the year, but form an especially large proportion of the leopard seal diet in January to March, when the penguins are breeding ashore and are readily available to leopard seals (Penney & Lowry, 1967;Hunt, 1973;Mu È ller-Schwarze & Mu È ller-Schwarze, 1975;Bengtson, 1982;Siniff & Stone, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Krill, ®sh and cephalopods are eaten from September to March (éritsland, 1977;Bengtson, 1982;Siniff & Stone, 1985;Green & Williams, 1986;Lowry et al, 1988). Penguins are eaten throughout the year, but form an especially large proportion of the leopard seal diet in January to March, when the penguins are breeding ashore and are readily available to leopard seals (Penney & Lowry, 1967;Hunt, 1973;Mu È ller-Schwarze & Mu È ller-Schwarze, 1975;Bengtson, 1982;Siniff & Stone, 1985). Crabeater seals Lobodon carcinophagus seem to be an important part of the leopard seal diet in November to February in the pack ice near the Antarctic Peninsula, when newly weaned crabeater seal pups become available as prey (Siniff & Bengtson, 1977;Siniff et al, 1979;Bengtson, 1982;Siniff & Stone, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Penney & Lowry, 1967;Mu È ller-Schwarze & Mu È ller-Schwarze, 1975;Borsa, 1990;Kooyman et al, 1990;Rogers & Bryden, 1995;Court, 1996). Leopard seals are known to feed on other Antarctic seals (Siniff et al, 1979;Siniff & Stone, 1985;Borsa, 1990;Erb, 1993;Shaughnessy, Erb & Green, 1998;Walker et al, 1998), but there are few descriptions of leopard seals hunting pinniped prey due to the logistical dif®culty of observing animals in the pack ice (Siniff et al, 1979) and the rareness of opportunities to observe a predation event (e.g. Gentry & Johnson, 1981;Lopez & Lopez, 1985).…”

Section: Introductionmentioning

confidence: 99%

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Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica

1999

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The hunting behaviour of leopard seals Hydrurga leptonyx was monitored opportunistically at Seal Island, South Shetland Islands, during the austral summers from 1986 / 87 to 1994 / 95. Leopard seals used several methods to catch Antarctic fur seal pups Arctocephalus gazella and chinstrap penguins Pygoscelis antarctica, and individuals showed different hunting styles and hunting success. One to two leopard seals per year were responsible for an average of 60% of observed captures of fur seal pups. Leopard seals preyed on penguins throughout the summer, but preyed on fur seal pups only between late December and mid-February. Hunting behaviour differed signi®cantly between different locations on the island; fur seals were hunted only at one colony, and penguins were hunted in several areas. The relative abundance of prey types, size of prey in relation to predator, and specialization of individual leopard seals to hunt fur seal prey probably in¯uence individual prey preferences among leopard seals. On ®ve occasions, two leopard seals were seen together on Seal Island. Possible interpretations of the relationship between the interacting leopard seals included a mother±offspring relationship, a consorting male±female pair, and an adult leopard seal followed by an unrelated juvenile. In two incidents at Seal Island, two leopard seals were observed interacting while hunting: one seal captured fur seal pups and appeared to release them to the other seal. Observations of leopard seals interacting during hunting sessions were dif®cult to con®rm as co-operative hunting, but they strongly implied that the two seals were not agonistic toward one another. The hunting success of individual leopard seals pursuing penguins or fur seals is probably high enough for co-operative hunting not to become a common hunting strategy; however, it may occur infrequently when it increases the hunting productivity of the seals.

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The Role of the Leopard Seal in the Tropho-Dynamics of the Antarctic Marine Ecosystem

Cited by 48 publications

References 8 publications

A small unmanned aerial system for estimating abundance and size of Antarctic predators

A small unmanned aerial system for estimating abundance and size of Antarctic predators

Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals

Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica

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