Elephant seals show remarkable consistency in 3D foraging behaviour!

In a changing ocean environment, would a deep-diving top predator consistently return to specific areas to find food? Would such a predator show consistent diving behaviour over multiple foraging trips? In the face of rapid environmental change, these were questions we were interested in exploring for southern elephant seals at Marion Island, using tracking and diving data spanning several years. 

A young male southern elephant seal sporting a SMRU tracking device. Photo: Nico de Bruyn

Individual-level specialization in forage strategies may confer advantages to individual animals over longer time periods, even though it may also incur shorter-term costs. In a recently published paper in the journal Animal Behaviour, we illustrate long-term (up to 7-year!) fidelity of individual elephant seals to not only their foraging ranges, but also the depth layers targeted during foraging migrations. We hypothesize that the strong fidelity displayed by individual animals may limit the individual-level adaptability of elephant seals to rapid environmental changes. Furthermore, we recommend more long-term longitudinal studies to quantify the influence of individual specialization on our understanding of the population-level ecology of elephant seals, as well as other key predators.

McIntyre et al. (2017) in Animal Behaviour

Read the full story here: McIntyre et al. (2017) Slow to change? Individual fidelity to three-dimensional foraging habitats in southern elephant seals, Mirounga leonina. Animal Behaviour 127:91-99. 

Killer whale social life at Marion Island

Marion Island killer whale Social Networks. Reisinger et al. 2017 Behavioral Ecology

Killer whales are considered highly social animals, however, social structure has been quantitatively studied in few populations. We have been running a photographic identification programme of killer whales at Marion Island in the Southern Ocean since 2006, and we recently used this dataset to explore how individuals associate with each other and how this correlates with their genetic relatedness. In a new paper published in the journal Behavioral Ecology we show that killer whales at Marion Island have small social modules which are mostly stable over years, but that these can be dynamic over shorter time periods. This may be a response to environmental conditions. The social modules which we identified comprise non-kin as well as kin, in contrast to the highly matrifocal structure in some other killer whale populations.

Kinship and association in a highly social apex predator population, killer whales at Marion Island

Ryan R. Reisinger, Charlene Beukes (née Janse van Rensburg), A. Rus Hoelzel and P.J. Nico de Bruyn

Behavioral Ecology

https://doi.org/10.1093/beheco/arx034

INTRODUCING 2017/2018 OVERWINTERING SEAL & KILLER WHALE FIELD PERSONNEL

The 'new' killer whale and seal field scientists for the 2017/18 13-month long expedition to Marion Island are into their first month alone since the ship departed back to RSA with all the Takeover - and previous expedition team members.

Yinhla Shihlomule is back for a 2nd year as sealer, being joined by Andre van Tonder and Rowan Jordaan for the year.

The 2017 5-week Relief voyage (Takeover) ended a WEEK ago, with the SA Agulhas II bringing home the 2016/2017 killer whale and seal field personnel, Nasreen Khan, Kyle Lloyd and Sydney Tshilingalinga (the latter two will be taking on PhD and MSc degrees respectively, at the University of Pretoria with Principal Investigator, Nico de Bruyn).

 ENJOY THE YEAR YINHLA, ANDRE AND ROWAN!

L-R: Andre van Tonder, Rowan Jordaan and Yinhla Shihlomule are the M74 SEALERS!! (Rowan is also responsible for the killer whale work). Photo: Nico de Bruyn

CAT HUNTER & SEALER LEGACY BOOK PUBLISHED!

Four decades of adventure, tribulations and successes are shared through the memories of the remarkable individuals that hunted feral cats and studied seals on remote Subantarctic Marion and other Southern Ocean islands.

LIMITED STOCK AVAILABLE AND GOING FAST!

"PAIN FORMS THE CHARACTER" delves to the heart and soul of what the life of a 'cat hunter' or 'sealer' on a remote cold, windswept island in the great Southern Ocean for a year or more is like. By interweaving factual background and the remarkable anecdotes from over 100 contributors, editors NICO DE BRUYN and CHRIS OOSTHUIZEN, provide entertaining context to the remarkable science and conservation achievements attained over >40 years on these starkly beautiful fringes of the world. This precious legacy continues to this day!  

To purchase this beautiful fully illustrated, colour, hard-cover coffee table book visit the 'SHOP' page on this website.  

ALL PROCEEDS ARE USED FOR CONTINUED RESEARCH WITHIN THE MIMMP.

MIMMP sealers on National Geographic expedition!

Tristan da Cunha. Photo: Nico de Bruyn

PRISTINE SEAS – National Geographic

EXPEDITION to Tristan da Cunha

The goals of the Pristine Seas project are to find, survey, and help protect the last wild places in the ocean. To this end, National Geographic’s Pristine Seas project, in collaboration with the Royal Society for the Protections of Birds (RSPB) and the Tristan da Cunha Government will conduct a 21-day expedition to Tristan da Cunha, Nightingale, Inaccessible and Gough islands in January-February 2017.  Primary goals of the expedition are to conduct comprehensive quantitative surveys of the health of its largely unknown marine environment, and produce a documentary film to highlight this unique ecosystem and its people.  Prof. Marthán Bester and PhD student Mia Wege (MIMMP sealers) from the Mammal Research Institute, Department of Zoology & Entomology, Pretoria University will join the expedition and continue ongoing seal research (see below Philately commemoration of this seal effort).

The expedition vessel SVS Grenville (http://specialisedvesselservices.com/vessels/svs-grenville/) left Cape Town, South Africa on January 8, 2017 and has just arrived at Tristan.  Scientific exploration and filming of the Tristan da Cunha archipelago for 21 days will ensue, the ship returning to Cape Town on the 12th of February.

Progress during the expedition can be followed on:

http://nationalgeographic.org/projects/pristine-seas/tristan-da-cunha-expedition/

TRISTAN DA CUNHA Biodiversity - Stamp Issue Part 1

The first day cover for this stamp issue, which includes a stamp depicting a Subantarctic fur seal, also carries the logo of UP in recognition of the project entitled 'Subantarctic Fur Seals at the Tristan da Cunha Islands' that the Mammal Research Institute have been carrying out (from 2009) under the direction of Prof. Marthán Bester, involving ‘Sealers’ from the Marion Island Marine Mammal Programme (MIMMP) of Prof. Nico de Bruyn. The project was developed by Prof. Bester at the behest of the Tristan da Cunha Conservation Department, and is executed under permit from the Tristan da Cunha Government. The Biodiversity Stamp Issue can be viewed at: http://www.tristandc.com/po/stamps201611.php

Whiskers tell us what elephant seals eat.. and when!

New paper on whisker replacement phenology and growth rate in southern elephant seals!

Lübcker N, Condit R, Beltran RS, de Bruyn PJN, Bester MN. 2016. Vibrissal growth parameters of southern elephant seals Mirounga leonina: obtaining fine-scale, time-based stable isotope data. Marine Ecology Progress Series 559: 243-255. doi: 10.3354/meps11899

Stable isotope analysis is based on the principle “you are what you eat” – in other words, the biomolecule composition of a consumer’s body tissues can give us an indication of diet over time.

A southern elephant seal's whiskers can tell us what the animal ate, and when it did so! Photo: Nico Lübcker

The nitrogen and carbon stable isotope ratios originating from the diet are chronologically deposited along the length of inert but growing keratinous tissues, such as whiskers (vibrissae), hair, and nails. Analyses of keratinous tissues provide a history of the individual’s diet.  Importantly, the timing of the whisker growth rates or replacement pattern is required to link the ‘stored’ dietary data to the specific time when the actual eating occurred. We sampled whiskers from southern elephant seals (SES) at Subantarctic Marion Island to define the prevalence and timing of their whisker replacement. Secondly, we could determine their whisker regrowth rate thanks to our knowledge of the ages of the sampled animals.

Contrary to the previously described asynchronous whisker-shedding pattern of SES, 71.1% of individuals displayed whisker shedding during the annual pelage moult. Furthermore, the whisker growth ceased once the maximum length was reached, and the whiskers are retained before being replaced. The whisker growth followed a von Bertalanffy growth function as the growth rate decreased near the asymptotic length. The resolution of the isotopic data obtainable per 2 mm whisker section ranged from 3.5 days at the tip to >40 days at the base of the whisker. Using these defined growth rates and shedding patterns, researchers can prudently apply timestamps to stable isotope values captured along the whiskers of SES.

We can now more confidently assess the timing of foraging and what has been eaten while the seals are unobservable out at sea for months on end!

Written by: Nico Lübcker [nlubcker@zoology.up.ac.za], ResearchGate profile . 

Nico checking on a big boy's whiskers!

MIMMP Postdoc, Dr Chris Oosthuizen, at King George Island

 Baby southern elephant seal in a snowstorm, King George Island, South Shetlands. Photo: Chris Oosthuizen

Chris Oosthuizen on expedition. 

The fishery for krill (Euphausia superba) is the largest fishery in the Southern Ocean in terms of biomass removal. CCAMLR (the Commission for the Conservation of Antarctic Living Marine Resources) is responsible for managing the harvest of all Southern Ocean living resources, including krill. CCAMLR aims to ensure that harvesting is sustainable, not only for the harvested species such as krill, but also for dependent predator species such as whales, seals and penguins.

Presently, over 95% of krill fishing is conducted in the West Antarctic Peninsula and South Orkney Islands regions, and it is within this context that Chris Oosthuizen (current Marion Island Marine Mammal Programme postdoctoral researcher) finds himself at the South Shetlands Islands. Chris is working on a collaborative project which includes colleagues from the Norwegian Polar Institute, the Instituto Antártico Argentino and the University of Pretoria. Field work on southern elephant seals, Gentoo and Adélie penguins is now underway at Stranger Point near the Argentine Base Carlini on Isla 25 de Mayo/King George Island, at the tip of the Antarctic Peninsula.

The data on predator foraging behavior collected during this (and past) field season(s) assist CCAMLR in the development of spatially and temporally relevant feedback strategies for long-term management of the krill fishery, including the planning process for Marine Protected Areas (MPA’s). 

Text: WC Oosthuizen

Field assistant positions Marion Island 2017-2018 - NOW CLOSED

Southern elephant seal census, Marion Island. Photo: Nico de Bruyn

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2016 - May 2017. All three positions are embedded within the research programme: "Marion Island Marine Mammals - sensitivity to global drivers of environmental change".

For instructions and more information:
Mammalogist - Seals
Mammalogist - Killer Whales

Read the advertisements carefully and follow the application instructions therein, taking special note of the need for 'hard copy' applications as stipulated by DEA. An official Z83 form can be downloaded here.

An overview documentary of what you might expect in these positions can be viewed here and further insight about our science gained by looking at our publications. Additional information about the positions and a background to the programme can be found on our programme history, 'working with us' and FAQ pages.

Inquiries and cover letters may be sent to Prof Nico de Bruyn (pjndebruyn[at]zoology.up.ac.za), but note that official applications need to be sent to DEA (see above).

DEADLINE: 20 October 2016

Dr Ryan Reisinger awarded a prestigous SCAR fellowship

Ryan Reisinger and a young Weddell seal at King George Island, Antarctica. Photo: Nico de Bruyn

Past MIMMP sealer/killer whaler and current collaborator, Ryan Reisinger, has been awarded a Scientific Committee for Antarctic Research (SCAR) fellowship. Read more here:

http://blogs.sun.ac.za/antarcticlegacy/2016/08/23/a-south-african-researcher-is-awarded-a-scar-fellowship/ 

Mammal Research Institute celebrates 50 years!

The University of Pretoria's Mammal Research Institute (MRI), within which our Marion Island Marine Mammal Programme is seated, is turning 50 years old! The MRI is dedicated to research and teaching on the biology and ecology of African mammals (including marine mammals off it's coasts and into the Southern Ocean). Efforts include the conservation of our indigenous mammal fauna in the context of sustainable human development.

In celebration of this achievement, the MRI will be hosting a symposium in the Kruger National Park, aimed at establishing a "Blueprint for Mammal Research in Africa for the next 20 years". Several illustrious national and international academics and conservationists will be  part of these ambitious efforts. IF YOU ARE INTERESTED IN ATTENDING AND BEING PART OF THE DISCUSSIONS WHERE YOU CAN HAVE YOUR SAY ABOUT THE FUTURE OF MAMMAL RESEARCH AND CONSERVATION, registrations are still open, although abstract submissions have closed. 

The prestigious journal Mammal Review has launched a virtual issue in commemoration of the MRI's 50th and is providing free access to a selection of scientific reviews related to African Mammals. MRI 50th Virtual Issue in Mammal Review

Want to buy an MRI 50th birthday shirt? Mens and Ladies Golf shirts and bush shirts available with MRI 50th branding.

Please contact Mia Wege directly:  mwege@zoology.up.ac.za

Foraging site fidelity in fur seal females

Subantarctic fur seal mother and pup. Photo: Nico de Bruyn

Subantarctic fur seal adult females from Marion Island travel thousands of kilometres across the Southern Ocean when searching for prey. They return to the island to nurse their pups and this provides an excellent ‘research platform’ for assessing conditions and potential environmental changes in distant parts of the Southern Ocean. For several years, we have been attaching satellite tracking devices to lactating fur seal mothers to ascertain their foraging movements. In so doing we tried to unravel the question of fidelity to foraging areas. We were interested in whether these fur seal mothers visited the same foraging grounds over different seasons and/or between different years. Such information provides us with an idea of changes in the environment over time and how these might relate to the population dynamics of the fur seals.

Wege M, Tosh CA, de Bruyn PJN, Bester MN. 2016. Cross-seasonal foraging site fidelity of subantarctic fur seals: implications for marine conservation areas. Marine Ecology Progress Series 554: 225-239

Just like humans often prefer different types of food (and thus restaurants) in summer as opposed to winter, so too did the fur seal females. There was little overlap in where they went to forage over the different seasons in a year. However, in the same seasons across different years they showed a remarkable conformity in travel direction away from Marion Island with substantial overlap in foraging areas considering that they track highly mobile prey!  Read more here (click on text).

Introducing the 2016/2017 overwintering SEAL and KILLER WHALE field personnel

The 2016 5-week Relief voyage (Takeover) ended a couple of days ago, with the SA Agulhas II bringing home the 2015/2016 killer whale and seal field personnel, as well as the Principal Investigator and colleagues. The latter mentioned assisted with debriefing of the returning field personnel and training of the 'newbies'. 

The 'new' killer whale and seal field scientists for the 2016/17 thirteen-month long expedition to Marion Island are into their first month alone since the ship departed with all the Takeover - and previous expedition team members.

The 'newbie' 2016/2017 overwintering sealers/whalers: L-R Sydney Tshilingalinga, Nasreen Khan & Kyle Lloyd; next to the Cat hunter memorial signpost in Santa Rosa Valley, Marion Island. Photo: Nico de Bruyn 

Captive killer whale longevity: important? NATURE

Just how much should the scientific community invest in studying the longevity of captive killer whales as compared to wild ones? Read a short correspondence in the journal Nature, by clicking on the image below:

A wild killer whale at Subantarctic Marion Island. Photo: Chris Oosthuizen

Read the correspondence by clicking on this text.

Trend changes in southern fur seal pup populations at Marion Island

A Subantarctic fur seal mother and her pup (Picture: M. WEGE)

For scientists and conservationists to make judicious decisions about the conservation practices of any population we need to know what the current status of the population is - is the population increasing or decreasing in numbers? Continued monitoring allows us to understand how various external or internal factors influence a population’s growth. Internal factors could include competition between individuals, whereas external factors could be human disturbance, climate change or disease.

Like all fur seals globally, the fur seals of Marion Island (46° 5.25’ S & 37° 51.46’ E; Figure 1) were hunted from the 17th century onwards for their furs. Sealing continued intermittently until 1931 when only a handful of seals remained on Marion Island. These were all Subantarctic fur seals (Arctocephalus tropicalis).

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A 30 day old Antarctic fur seal pup

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Figure 1: The position of Marion Island in relation to South Africa and Antarctica

Today, Marion Island is home to the largest sympatric population (different species co-occur) of Subantarctic and Antarctic fur seals (Arctocephalus gazella) in the world. Both these species recovered spectacularly after the era of sealing had ended and by 2004 ~15 000 Subantarctic and ~700 Antarctic fur seal pups were born on Marion Island. We present our most recent pup population estimates for both species breeding here.

Antarctic fur seals:

Between 2004 and 2013 the Antarctic fur seal population was still increasing, but the rate of change has decreased from 17% in 2004 to 4% in 2013. We suspect this reduced growth in pup production is the result of saturation at the main breeding beach where more than 75% of all pups are born. Over the last 12 years several new breeding beaches have been established around the island. We postulate that with time these new breeding beaches will start to thrive and population growth will increase. We are also currently exploring other counting methods to improve potential error around our estimates.

Subantarctic fur seals:

Surprisingly, the Subantarctic fur seal pup population declined by 46% (95% credible interval 43%–48%) between 2004 (mean = 15,260, credible interval: 14,447– 16,169 pups) and 2013 (mean = 8,312, credible: 7,983–8,697; Figure 2). Your first question might be whether this was perhaps just an anomalous year with exceptionally low pup production. This is where annual counts done on a subsection of the island's coastline come in handy. From 2007 until 2011 we have seen a consistent drop in pup numbers at the beaches counted annually and between 2012 and 2015 it seems pup numbers have stabilised (Figure 3). Furthermore, the biggest decline in pup numbers were at the highest density beaches on the west coast of Marion Island. The first logical explanation is that the number of seals have just grown too numerous that bulls tend to crush pups or females fail to bond with their pups after birth and subsequently abandon them. However, all the dead pups on the beaches are also counted and between 2004 and 2013 there was no mentionable change in pup mortality on the beaches. This suggests other forces are at play.

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Figure 2: Estimated number of Subantarctic fur seal pups on Marion Island in 2004 (right) and 2013 (left)

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Figure 3: Annual decrease of Subantarctic fur seal pups counted along a subsection of Marion Island's coastline

What these forces are, we are currently unsure about. However, it is most likely not just one contributing factor but a combination of several. Population dynamics are never simple. The Marion Island Marine Mammal Programme has an intensive fur seal programme aimed at asking various questions to solve this mystery. This includes tracking fur seal females of both species to see where they are foraging and how hard they are working while foraging (inferred from diving behaviour), what they eat (diet) and how long they are staying away from their pups. Lastly, we then also weigh these females’ pups to see how successful the female has been at obtaining food.

Lastly, it should be stressed that a reduction in numbers does not necessarily mean that animals are dying. Emigration to other colonies could also contribute to population reduction. That means, populations elsewhere in the Southern Ocean could perhaps be growing due to an influx of animals. However, to determine whether this is in fact the case we need to know what is happening to the entire Southern Ocean population of Subantarctic and Antarctic fur seals, not just on Marion Island, before we can make assumptions on the growth of the species.

Written by: Mia Wege [mwege@zoology.up.ac.za]

Reference:

Wege, M., Etienne, M.-P., Oosthuizen, W.C. , Reisinger, R.R., Bester, M.N. & de Bruyn, P.J.N. (2016) Trend changes in sympatric Subantarctic and Antarctic fur seal pup populations at Marion Island, Southern Ocean. Marine Mammal Science, DOI: 10.1111/mms.12306

The full scientific article can be obtained from the Journal of Marine Mammal Science or by contacting the authors directly.

Acknowledgements:

This work would not have been possible without logistical support provided Department of Environmental Affair, funding provided by the National Research Fund's South African National Antarctic Programme. Greg Hofmeyr helped plan the 2013 total island count, gave valuable insight and passed on a wealth of experience. Dawn Cory-Toussaint, Cheryl Tosh, Santjie du Toit, Mashudu Phalanndwa, Paul Visser, Derek van der Merwe, Hugh Purdon, Christiaan Conradie, Shadrack Podile, Thomas Mufanadzo, Johan van der Vyver, Nadia Hansa, Daniël Kotzé and Liezl Pretorius were instrumental in either helping with or doing counts themselves.

Field Assistant Positions on Marion Island: 2016-2017 - NOW CLOSED

Sealer Christiaan Conradie weighing an Antarctic fur seal (Arctocephalus gazella) pup at Marion Island. © Ryan Reisinger.

Three field assistant positions (2 x "Sealers" and 1 x "Whaler") are once again available at Marion Island, April 2015 - May 2016. All three positions are within the research programme "Marion Island Marine Mammals - sensitivity to global drivers of environmental change".

For instructions and more information:
Mammalogist - Seals
Mammalogist - Killer Whales

Read the advertisments carefully and follow the application instructions therein. An overview of the programme can be found here, and by looking at our publications. Further information about the positions and a background to the programme can be found on our programme history, 'working with us' and FAQ pages.

Enquiries and cover letters may be sent to Dr Nico de Bruyn (pjndebruyn at zoology.up.ac.za).

DEADLINE: 5 October 2015
 

New paper on elephant seal weaning mass variation

Our long-term data on elephant seal weaning mass provides a perspective on variation in food availability in a pelagic environment which is poorly known (Click text or photo to link to the article).

An almost weaned southern elephant seal pup at Marion Island

Oosthuizen et al 2015. Ecosphere. 

WATCH SABC's 50/50 programme feature of the MIMMP here!

Visit our programme overview page (click on this text), where the full two-part SABC feature related to the MIMMP's activities are captured. This is the real deal - all footage being captured by the MIMMP sealers/whalers themselves. No camera crews, no staged stuff - real Marion Island expedition work!

MIMMP fellow comment on animal telemetry in SCIENCE

MIMMP research fellow, Trevor McIntyre, has published a letter in Science cautioning researchers to continuously be aware of the potential effects of placing tracking devices on animals. While he does not argue the value of tracking studies, these should be done with due ethical consideration. He includes some examples from our Marion Island efforts in his comment on a review published earlier in Science by Kays et al. ("Terrestrial animal tracking as an eye on life and planet"). 

http://www.sciencemag.org/content/349/6248/596.2.full?utm_campaign=email-sci-toc&utm_src=email 

An elephant seal at Marion Island with a satellite linked tracking device.

STUNNING ORIGINAL KILLER WHALE ART by renowned artist

SUPPORT OUR SCIENCE AND OWN THIS INCREDIBLE ORIGINAL ARTWORK. Well known artist, Vincent Reid, has really produced a special collectors item with this one! Click on this text to securely add your bid.  

MIMMP will feature on SABC 3's "50/50" programme this Sunday 02 August!

Marion Island sealers on SABC's 50/50 this Sunday.