Greg Hofmeyr

Port Elizabeth Museum · Marine Mammals

Information on resource use and trophic dynamics of marine predators is important for understanding their role in ecosystem functioning and predicting population-level responses to environmental change. Where separate populations experience different local environmental conditions, geographic variability in their foraging ecology is often expected....

Carcasses resulting from natural mortalities are invaluable for use in scientific studies, provided species, sex and age class are known. When such data are unavailable, identifying skeletal remains is necessary if one is to use the information contained within samples. Teeth are amongst the best preserved skeletal remains owing to the durability o...

Detailed examinations of dolphins incidentally caught in bather protection nets along the KwaZulu‐Natal coastline, South Africa, over the past 10 years have yielded a dataset that can assist in the examination of external signs of bycatch. Investigating these external signs of fisheries interactions could aid in determining whether they could be us...

In-air sounds of pinnipeds are important for interactions with conspecifics and threat displays. However, little is known about the in-air acoustic repertoire and associated behaviour of crabeater seals Lobodon carcinophaga. We investigated the in-air acoustic repertoire and associated behaviour of two male and one female wild juvenile crabeater se...

Whilst southern elephant seals Mirounga leonina inhabit the Southern Ocean, hauling out on sub-Antarctic islands, individuals are frequently encountered further north, on southern hemisphere continents. It is unknown whether these animals are merely vagrants or whether they are individuals using the extremes of their range. A single adult male, ide...

Abstract available in English, Spanish and Portuguese. The deep sea has been described as the last major ecological frontier, as much of its biodiversity is yet to be discovered and described. Beaked whales (ziphiids) are among the most visible inhabitants of the deep sea, due to their large size and worldwide distribution, and their taxonomic div...

Abstract available in English, Spanish and Portuguese. The deep sea has been described as the last major ecological frontier, as much of its biodiversity is yet to be discovered and described. Beaked whales (ziphiids) are among the most visible inhabitants of the deep sea, due to their large size and worldwide distribution, and their taxonomic dive...

Beaches are key attractions for tourism and recreation, and considerable effort is made to keep beaches clean, yet many beaches still have substantial litter loads. Lasting solutions to reduce the amounts of marine litter require an understanding of litter sources. We collected bottles and other single-use containers at 32 sites around the South Af...

Taxonomy plays an important role in conservation biology. Despite the variety of methods used to differentiate units, some groups, such as Delphinidae within the Cetacea have proven difficult to untangle. This study aimed to shed light on morphological variation of the genus Tursiops in South African waters using geometric morphometrics and to dist...

We examined external morphometric parameters in incidentally caught long-beaked common dolphins (Delphinus capensis) from the east coast of South Africa for evidence of sexual dimorphism. We evaluated sexual dimorphism and allometric growth in 26 external body measurements from 211 individuals and assessed size and shape dimorphism. Most characteri...

The taxonomy of bottlenose dolphins Tursiops spp. and Delphinus spp. remains unresolved with suggestions that animals from Southern Africa may represent a separate clade. We used a molecular analysis of museum specimens to investigate this. Despite inherent difficulties, analysis of DNA for preserved material (“ancient” DNA) has been extensively ut...

Increasingly, baseline knowledge of habitat preferences and movement patterns of marine species is required to inform anthropogenic developments. The aim of this study was to determine baseline spatio-temporal distribution and habitat preference of cetaceans in the coastal waters of Algoa Bay. Areas of potential conflict with anthropogenic activiti...

Antarctica and the Southern Ocean form a critical natural laboratory where international scientific investigation can infer the fundamental drivers of the entire earth system and of the near-earth space environment. Advancing our understanding is critical to better comprehend the region’s role in global ocean-atmospheric circulation, ecosystem adap...

Many species of seabirds, including the only penguin species breeding on the African continent , are threatened with extinction. The world population of the endangered African penguin Spheniscus demersus has decreased from more than 1.5 million individuals in the early 1900s to c.a. 23 000 pairs in 2013. Determining the trophic interactions of spec...

Measurement errors of carbon and nitrogen stable isotope values determined using three in-house standards that have been calibrated against materials from the International Atomic Energy Agency. Within runs data are presented as the range of SDs (n = number of runs). Overall values among all runs are presented as mean ± SD (n = number of standard d...

Carbon and nitrogen stable isotope values and C:N ratios for the five potential prey species included into the Bayesian mixing model MixSIAR. n: number of samples. (DOCX)

Comparisons in morphometric measurements, body weights, and body condition indices (BCI) of African penguins between sexes and between islands. (DOCX)

Stable isotope mixing model (MixSIAR) results with predicted diet proportions (5th to 95th percentiles and median values in parentheses) of each five potential prey species compared to δ13C and δ15N mixture values of the different groups of African penguins. (DOCX)

Tissue- and species- specific discrimination factors between penguins and their food estimated from captivity studies. (DOCX)

This study assessed the extent of sexual dimorphism in striped dolphin (Stenella coeruleoalba) cranial size and shape off the South African coast. Dorsal and ventral features of 60 striped dolphin crania from both the western and eastern coasts of South Africa were analyzed using landmark-based geometric morphometrics. Although there was no evidenc...

Knowledge regarding interactions between predators and their prey is fundamental for understanding underlying links between climate change and ecosystem responses, including predator demographics, in the Southern Ocean. This study reports data on reproductive performance, total population size and diet composition for macaroni and chinstrap penguin...

Very high frequency (VHF) radiotelemetry data has been used for over 30 yr to monitor the behavior patterns of otariid seals. These data have been used in a wide variety of ways, from characterizing the reproductive and foraging ecology of these species to inferring ecosystem changes based on variation in attendance patterns. Yet the accuracy of VH...

The diet of Cape fur seals Arctocephalus pusillus pusillus in the eastern portion of their distribution has received little attention previously, and was studied using traditional methods only. In 2013 we therefore assessed the diet of seals at the easternmost colony at Black Rocks, Algoa Bay, South Africa (33°50′ S, 26°16′ E) from both scats and t...

At-sea behaviour of central-place foraging fur seals and penguins in the Southern Ocean is understudied during the latter stages of parental care and the subsequent pre-moulting period. This biologically important period is costly to investigate due to the risk (or certainty) of losing tracking instruments when the animals moult. Early in this peri...

Killer whales Orcinus orca occur worldwide in a number of morphotypes that differ in size, pigmentation, acoustic behaviour, food type and genetics – some may indeed warrant subspecific or even specific status. Until recently, all killer whales in South African waters were referred to a single morphotype, Type A, but three individuals (two males an...

The use of biologging instruments has greatly improved our understanding of the behaviour, physiology and ecology of free-ranging marine mammals. However, handling wild animals and attaching instruments to streamlined bodies can cause stress and potentially influence behaviour and swimming/diving energetics. The goals of this study, undertaken on B...

Leopard seals inhabit the pack-ice rim of Antarctica, and they regularly haul out on Antarctic and Sub-antarctic islands. Occasionally, vagrants are sighted further north in South America, Australia, New Zealand, and very rarely in southern Africa and Oceania. Here we report on an observation made on the 15th of July 2010 of a single 3-m-long juven...

Interspecific competition is an important structuring element in marine ecosystems, especially in the Southern Ocean which offers few prey choices to comparatively large predator populations. We present the first simultaneous observations of at-sea behaviour and attendance patterns of 3 synchronously breeding, central place, krill foragers at Bouve...

While studies of dispersal note significant fidelity to natal site and to the site of first reproduction, few consider fidelity to other sites, and none have done so systematically. This study examined fidelity to all terrestrial sites within the study area during the course of its life, by a migratory marine predator, the southern elephant seal, M...

Of the four types of terrestrial haulout periods undertaken by southern elephant seals Mirounga leonina, only the purpose of the winter haulout is unknown. Returning to a haulout site from distant pelagic foraging grounds bears significant costs in terms of increased energy expenditure, reduced foraging time and increased exposure to predation; the...

The small and isolated Cape fur seal Arctocephalus pusillus pusillus rookery at Black Rocks, Algoa Bay, South Africa, is an important component of the marine biota of the Addo Elephant National Park. Although little is known of the demographics of this rookery, it is believed to be declining in abundance. The pupping season for this population coin...

Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great diVerences in morphology, life history and foraging behav-iour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean, to assess intersexual diVerences. This was made possible...

IntraspeciWc diVerences in the diets of many species of pinnipeds are to be expected in view of the great diVerences in morphology, life history and foraging behav-iour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean, to assess intersexual diVerences. This was made possible b...

We describe a long-range migration of a pre-moulting adult chinstrap penguin from Bouvetøya, a small relatively recently established colony, to the South Sandwich Islands, where large, established colonies of this species reside. The trip lasted around three weeks, covered 3600 km, and the time of arrival was consistent with the annual moult. The b...

An immature Subantarctic fur seal was sighted on Unguja Island, Zanzibar, Tanzania, in 2008. This is the most northerly record of a vagrant of this species. The nearest breeding colony is on the Prince Edward Islands, 4500 km distant. While it is likely that this is the natal site of the vagrant due to its proximity and population size, the actual...

An immature Subantarctic fur seal was sighted on Unguja Island, Zanzibar, Tanzania, in 2008. This is the most northerly record of a vagrant of this species. The nearest breeding colony is on the Prince Edward Islands, 4500 km distant. While it is likely that this is the natal site of the vagrant due to its proximity and population size, the actual...

Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great differences in morphology, life history and foraging behaviour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean, to assess intersexual differences. This was made possibl...

During three summer surveys at Prince Edward Island (PEI), southern Indian Ocean (2001, 2004 and 2008), 416 southern elephant seals Mirounga leonina were inspected for identification tags. In all, 42 seals that had been tagged as weaned pups at their natal site were found on Marion Island (MI), 38 of which could be individually identified by resigh...

We present the first data on attendance patterns, at-sea movements and diving behaviour of Antarctic fur seals breeding at Bouvetøya (Bouvet Island), Southern Ocean. While other colonies have been extensively studied, this remote and second largest global population remains relatively unknown. Time depth recorders and satellite relay data loggers w...

Commerson's Dolphins Cephalorhynchus commersonii are distributed in two disjunct populations, one around southern South America and the other around the sub-Antarctic Kerguelen Islands. These populations have been shown to be morphologically and genetically distinct and movement between the two populations is unlikely. We report on the sighting of...

In 1992 and 1993, unknown diseases killed 250-300 King Penguins Aptenodytes patagonicus and an estimated 5-10 thousand Macaroni Penguins Eudyptes chrysolophus at sub-Antarctic Marion Island. At the same island, an outbreak of avian cholera Pasteurella multocida during November 2004 killed approximately 2000 Macaroni Penguins at Kildalkey Bay. Other...

We studied the dispersion of 4-year-old southern elephant seals (Mirounga leonina) along a 75.5km coastal area at the Courbet Peninsula, Iles Kerguelen, relative to their birth site when they were ashore to moult in early 1984. The seals were mostly faithful to their natal sites, but availability of suitable moulting habitat (e.g. wallows, vegetate...

The annual cycle of adult female southern elephant seals (Mirounga leonina) can be divided into 2 pelagic phases, separated by relatively short terrestrial phases: breeding and molting. We used resighting data collected from tagged female southern elephant seals at Marion Island during 1986–1999 to investigate seasonal survival during the 2 pelagic...

The means by which populations are regulated form a central theme in conservation biology, and much debate has revolved around density dependence as a mechanism driving population change. Marion Island (46°54′S, 37°45′E) is host to a relatively small breeding population of southern elephant seals, which like its counterparts in the southern Indian...

Using data from an ongoing mark–resight programme at Marion Island, we tested empirically whether southern elephant seals prefer certain terrestrial sites to others during the breeding, moulting and winter haulouts, and whether the pattern of site use is the same for different age and sex groups. Southern elephant seals preferred some sites, while...

Using data from an ongoing mark–resight programme at Marion Island, we tested empirically whether southern elephant seals prefer certain terrestrial sites to others during the breeding, moulting and winter haulouts, and whether the pattern of site use is the same for different age and sex groups. Southern elephant seals preferred some sites, while...

The means by which populations are regulated form a central theme in conservation biology, and much debate has revolved around density dependence as a mechanism driving population change. Marion Island (46°54‘S, 37°45‘E) is host to a relatively small breeding population of southern elephant seals, which like its counterparts in the southern Indian...

Modelling fur seal populations requires the accurate assessment of demographic parameters such as age-specific mortality. Owing to the highly variable mortality rates that pups are subject to, mortality of this age class is perhaps the most important factor determining the number of surviving individuals within each cohort. Early pup mortality,sex...

An extraordinary light coloured, young southern elephant seal Mirounga leonina was seen at Marion Island during the 2004 austral spring. This is the second record of an extraordinary white colour morph for the species here. It was not unequivocally established that the animal was leucistic.

Opportunistic sightings of some 19 different leopard seals Hydrurga leptonyx at Marion Island (46°54’S, 37°45’E) in the South Indian Ocean were recorded mostly in September to October between 1980 and 2005. Largely immature and both in poor and good condition, they might benefit froma locally abundant food resource. The species appear to be a regul...

Counts on a few of the more recently colonized southeast coast breeding sites at Gough Island during the 2005/06 breeding season indicate a continued overall increase in pup production of Subantarctic fur seals Arctocephalus tropicalis. The mean annual rate of increase of 8.4% for the population inhabiting these beaches for the 17-year period 1988/...

Entanglements of Antarctic fur seals Arctocephalus gazella were recorded during four summers from 1996 to 2002 at the subantarctic island, Bouvetøya. Rates of entanglement varied between 0.024% and 0.059%. These rates are low for a pinniped population and might be because of the geographic isolation of the haulout site. An apparent decrease in the...

Counts at Marion Island during the 2003/04 breeding season indicated a pup production of 16 045 for Subantarctic fur seals, Arctocephalus tropicalis, and 759 for the sympatric population of Antarctic fur seal,A. gazella. While the mean annual rate of increase of 5.2% for the Subantarctic fur seal population at Marion Island for the period 1994/95–2...

Three vagrant Subantarctic fur seals, Arctocephalustropicalis, were seen amongst a colony of Antarctic fur seals, A. gazella, at the isolated subantarctic island, Bouvetøya. Possible sources of the vagrants are populations at either Gough Island or the Prince Edward Islands Archipelago.

Commerson’s Dolphins Cephalorhynchus commersonii are distributed in two disjunct populations, one around southern South America and the other around the sub-Antarctic Kerguelen Islands. These populations have been shown to be morphologically and genetically distinct and movement between the two populations is unlikely. We report on the sighting of...

Three vagrant Subantarctic fur seals, Arctocephalus tropicalis, were seen amongst a colony of Antarctic fur seals, A. gazella, at the isolated subantarctic island, Bouvetøya. Possible sources of the vagrants are populations at either Gough Island or the Prince Edward Islands Archipelago.

One leucistic and one partially leucistic Antarctic fur seal Arctocephalus gazella were seen at Bouvetya during the 1996/97 austral summer. Both likely came from South Georgia, where this colour morph is common. No individuals of this colour morph were sighted during three subsequent expeditions to Bouvetya. The prevalence of this colour morph in t...

Antarctic fur seal Arctocephalus gazella pup production at Nyrysa, Bouvetya was estimated to be approximately 15,000per annum during each of four summers from 1996 to 2002, indicating a total population of about 66,000. While the Bouvetya population is the second largest for this species, pup production at this site still accounts for only 2.4% of...

A rapid decline of at least 66.3% was recorded in the relatively small breeding population of southern elephant seals, Mirounga leonina, at Prince Edward Island between 1977 and 2004. The estimated number of births has declined from at least 386 to 130 and the 2004 population size numbers 410 (excluding pups of the year). A few tagged seals from ne...

Using data from an ongoing mark–resight program at Marion Island, we tested whether there is variation in the timing of the breeding haulout of female southern elephant seals, in relation to breeding experience. Females were classed as primiparous or multiparous according to their age and known life histories. The mean breeding season haulout date...

Using information from a long-term tag-recapture programme, we investigated variation in the timing of the moult haulout phase of the Marion Island southern elephant seal (Mirounga leonina) population in relation to age, sex and breeding experience. Calculated parameters describing the temporal distribution of classes of seals, grouped according to...