Research Articles (Mammal Research Institute)

Permanent URI for this collectionhttp://hdl.handle.net/2263/5233

A collection containing some of the full text peer-reviewed/ refereed articles published by researchers from the Mammal Research Institute

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Do mixed-species groups travel as one? An investigation on large African herbivores monitored using animal-borne video collars
(University of Chicago Press, 2025-04) Dejeante, Romain; Valeix, Marion; Chamaillé-Jammes, Simon
Although prey foraging in mixed-species groups benefit from a reduced risk of predation, whether heterospecific groupmates move together in the landscape, and more generally to what extent mixed-species groups remain cohesive over time and space, remains unknown. Here, we used GPS collars with video cameras to investigate the movements of plains zebras (Equus quagga) in mixed-species groups. Blue wildebeest (Connochaetes taurinus), impalas (Aepyceros melampus), and giraffes (Giraffa camelopardalis) commonly form mixed-species groups with zebras in savanna ecosystems. We found that zebras adjust their movement decisions solely on the basis of the presence of giraffes, being more likely to move in zebra-giraffe herds, and this was correlated with a higher cohesion of such groups. Additionally, zebras moving with giraffes spent more time grazing, suggesting that zebras benefit from foraging in the proximity of giraffes. Our results provide new insights into animal movements in mixed-species groups, contributing to a better consideration of mutualism in movement ecology.
The ontogeny of foraging in meerkats, a cooperatively breeding mongoose
(Elsevier, 2025-09) Duncan, Chris; Turner, Zoe; Gaynor, David; Thorley, Jack Benjamin; Vink, Tim J.F.; Clutton-Brock, Tim H.
Delayed reproductive life histories characterize many singular cooperative breeders, where the onset of first breeding is often delayed beyond adulthood. These delays are commonly attributed to factors including inbreeding avoidance and reproductive suppression, but an additional possibility is that the slow development of foraging skills constrains successful reproduction because of its energetic demands. While this explanation for delayed breeding has found limited support, there is evidence in some cooperative breeders of relatively long foraging ontogenies that could influence reproduction. To investigate whether delays in foraging skill acquisition might contribute to delays in a cooperatively breeding mammal's reproductive life-history, we analysed age-related changes in the foraging behaviour of meerkats, Suricata suricatta, in the Kalahari Desert. Kalahari meerkats are primarily insectivorous, although they also predate some small vertebrates and forage most of their prey by digging them up from below ground. We found that age-related increases in the rate of prey capture and in the size of the prey consumed level off at 9 months old, although improvements in foraging efficiency continue until individuals are around 1 year of age. Sex and dominance status had little effect on foraging performance. Our results indicate that meerkats' foraging skills mature around the onset of adulthood, well before dominance is usually acquired, the point at which successful breeding commonly begins. As a result, the acquisition of foraging skills is unlikely to delay the onset of successful breeding in meerkats. Instead, the maturation of foraging performance is more closely aligned with the age at which individuals' growth begins to asymptote, suggesting their foraging ontogeny may be constrained by physical traits. HIGHLIGHTS • We investigated if foraging skills constrain the onset of breeding in meerkats. • Meerkat foraging skills matured around adulthood at 1 year of age. • In contrast, the onset of breeding generally occurred much later. • Sex and dominance status did not influence foraging performance.
Spatial position relative to group members affects weight gain in meerkats, Suricata suricatta
(Elsevier, 2025-07) Mosia, Rasekuwane; Demartsev, Vlad; Le Roux, Aliza; Manser, Marta B.; Strandburg-Peshkin, Ariana; Johnson-Ulrich, Lily
Social animals often face a trade-off between the costs of foraging competition among group members and the benefits of protection from predators offered by group living. The spatial position of an individual in relation to the other group members during foraging can mediate the effects of this trade-off as individuals at the front or edge may have better access to food resources, but also higher predation risk than individuals near the centre of the group. Using meerkats, Suricata suricatta, as a model species, we investigated the effect of individual spatial position within a group on foraging success. We determined the spatial position of individuals in a meerkat group by fitting the animals with high-resolution GPS loggers. As a proxy of foraging success, we used meerkats' individual body weight differences between the start and the end of daily data collection over foraging periods (3 h). We found significant individual differences in meerkats’ spatial positions within the group. In addition, age-dependent differences in spatial position became obvious, with older meerkats spending less time in the centre of the group and more time in side positions, subordinate females spending less time in the front, and subordinate males spending more time in the back. Younger meerkats who spent more time in the front of the group relative to older meerkats had decreased daily weight gain, indicating less successful foraging. We also found that the dominant females tended to spend more time towards the front of the group, but gained less weight in this position, contrary to the predicted association between front edge of the group and better access to food resources. Our results suggest that the relationship between weight gain and spatial position is highly nuanced and likely to be dependent on more than just trade-offs between foraging success and predation risk. HIGHLIGHTS • Meerkats occupied consistent spatial positions within the group during foraging. • Dominant females spent more time in the front but gained less weight there. • Older meerkats spent less time in the centre and more time on the side of the group. • Meerkats may trade-off more than just foraging success and predation risk.
Acoustic parameters of bat echolocation calls in Zambia : a collaborative effort to develop a call library for non-invasive research and monitoring
(Museum and Institute of Zoology, Polish Academy of Sciences, 2025-08) Taylor-Boyd, Helen; Fuentes-Montemayor, Elisa; Monadjem, Ara; Cooper-Bohannon, Rachael; Montaubans, Cecilia; Mata, Vanessa A.; Rebelo, Hugo; Kangwa, Bernard; Mateke, Clare; Park, Kirsty
Passive acoustic monitoring (PAM) of bats enables non-invasive research that improves monitoring efficiency, and can be used for species identification, documenting occurrence and measuring activity levels. However, equipment costs and a dearth of experienced personnel, as well as a lack of local open access reference datasets (call libraries), have limited the study of African bat communities using PAM. This study compiles the first publicly available call library of this scale from Zambia. Echolocation calls were recorded upon release of captured bats during various projects from 2015 to 2023, using full spectrum ultrasound detectors. Acoustic calls from 238 individuals of 22 species were collated. We aimed to determine whether Zambian bat species could be accurately distinguished using acoustic measures. We predicted that some species (or species groups) would be easily identifiable, while other species would have substantial similarities in their calls, which would hinder identification. After considering multicollinearity, we selected five acoustic parameters to analyse the recordings: ‘Frequency of Maximum Power’, ‘Preceding Interval’, ‘Start Slope’, ‘End Slope’ and ‘Ledge Duration’. Principal Component Analysis was conducted to identify parameters that were best able to separate the calls of different functional groups (identified by sonotype) or species. Discriminant Function Analysis was then used to determine the accuracy with which the parameters may be used to acoustically distinguish species or sonotypes. The parameters ‘Start Slope’ and ‘Frequency of Maximum Power’ were the most useful for separating the species considered. It was possible to separate some sonotypes and species with relatively high accuracy. Many species, however, could not be identified with certainty, underscoring the importance of other identification techniques, such as morphological measures or genetic sampling.
Determining sound exposure levels for marine fauna during a past seismic survey to inform effective mitigation measures in South African waters
(Elsevier, 2025-11) Purdon, Jean; Shabangu, Fannie Welcome; Pienaar, Marc; Findlay, Kenneth Pierce; Somers, Michael J.; Vermeulen, Els; Scheun, Juan; Doh, Yann
Please read abstract in the article.
Estimated baseline density of a spotted hyaena population in a post-war landscape
(Cambridge University Press, 2025) Briers-Louw, Willem D.; Kendon, Tamar A.; Rogan, Matthew S.; Leslie, Alison J.; Bantlin, Drew; Evers, Emma; Gaynor, David; Lindsey, Peter; Almeida, Joao; Naude, Vincent N.
The spotted hyaena Crocuta crocuta is relatively understudied across its range despite evidence of widespread declines. It is therefore essential that robust baseline population density assessments are conducted to inform current management and future conservation policy. In Mozambique this is urgent as decades of armed conflict followed by unchecked poaching have resulted in large-scale wildlife declines and extirpations. We conducted the first robust population density estimate for a spotted hyaena population in Mozambique using spatially explicit capture–recapture methodologies. We recorded a relatively low population density of 0.8–2.1 hyaenas/100 km2 in the wildlife management area Coutada 11 in the Zambezi Delta of central Mozambique in 2021. These densities are well below the estimated carrying capacity for the landscape and are comparable to published densities in high human-impact, miombo woodland-dominated and arid environments. The combination of historical armed conflict, marginal trophy hunting and bushmeat poaching using wire snares and gin traps (with physical injuries evident in 9% of identified individuals) presents persistent anthropogenic pressure, limiting the post-war recovery of this resident hyaena population. We provide insights into the dynamics of hyaena population status and recovery in such post-war landscapes, adding to mounting evidence that the species is less resilient to severe anthropogenic disturbances than previously believed. We recommend long-term monitoring of this and other carnivore populations in post-war landscapes to ascertain demographic trends and implement effective conservation interventions for population recovery.
Camera trap-based estimates reveal spatial variability in African clawless otter population densities and behaviour
(Cambridge University Press, 2025) Lewis, Candice B.; Majelantle, Tshepiso Lesedi; Haussmann, Natalie S.; Mcintyre, Trevor
Estimating the population size of shy and elusive species is challenging but necessary to inform appropriate conservation actions for threatened or declining species. Using camera-trap surveys conducted during 2017–2021, we estimated and compared African clawless otter Aonyx capensis population densities and activity times in six conserved areas in southern Africa. We used two different models to estimate densities: random encounter models and camera-trap distance sampling. Our results highlight a general pattern of higher estimated densities and narrower confidence intervals using random encounter models compared to camera-trap distance sampling. We found substantial variation in densities between study areas, with random encounter model estimates ranging between 0.9 and 4.2 otters/km2. Our camera-trap distance sampling estimates supported the relative density estimates obtained from random encounter models but were generally lower and more variable, ranging from 0.8 to 4.0 otters/km2. We found significant differences in otter activity patterns, with populations either being nocturnal, mostly nocturnal or cathemeral. As all study areas experience little human disturbance, our results suggest that there are large natural variations in otter densities and activity patterns between regions. When densities are converted to metrics that are comparable to previous studies, our estimates suggest that African clawless otter population numbers are generally lower than previously reported. This highlights a need for broader spatial coverage of otter population assessments and future studies to assess potential environmental drivers of spatial, and potentially temporal, variation in population numbers and activity patterns.
Incidents of high tick load in injured cheetahs after reintroduction into a tropical ecosystem
(AOSIS, 2025-04) Kendon, Tamar A.; Pereira, Carlos L.; Pereira, Hugo; Brown, Kelsey; Gaynor, David; Briers-Louw, Willem D.
Ectoparasites can severely impact wildlife species, both through their feeding behaviour and by facilitating secondary infestations or bacterial infections. Here, we report on two cases of periorbital damage caused by ixodid tick infestations in cheetahs (Acinonyx jubatus), including a rare record of traumatic myiasis in wildlife. Both cheetahs were recently reintroduced to the Marromeu-Coutada Complex in Central Mozambique and had sustained relatively severe injuries. This ostensibly yielded them immunocompromised and thus more vulnerable to tick infestations, particularly when exposed to novel species. These incidents occurred during the peak hot-wet season in which adult tick abundance is likely highest. These cases provide novel insights into the risks of tick infestations for reintroduced cheetahs and the importance of intensive post-release monitoring to allow for timeous veterinary intervention. CONTRIBUTION : This study falls within the scope of the journal. Ixodid ticks are of veterinary importance for wildlife and domestic animals across Africa because of the associated direct damage and potential spread of tick-borne pathogens. This study investigates two cases of tick infestations in cheetahs recently reintroduced into a tropical environment. The identified risk factors appear to be exposure to novel ectoparasites, injuries, and the hot-wet season. This highlights the need to consider ectoparasite risk when planning wildlife translocations.
Paramyxo- and coronavirus diversity and host associations in non-volant small mammals : evidence of viral sharing
(Oxford University Press, 2025-05) Mortlock, Marinda; Geldenhuys, Marike; Keith, Mark; Rademan, Rochelle; Swanepoel, Lourens H.; Von Maltitz, Emil F.; Kearney, Teresa; Markotter, Wanda; wanda.markotter@up.ac.za
Rodents and other non-volant small mammals (like shrews) maintain major ecological and epidemiological roles as reservoirs of zoonotic pathogens. Their presence within human-modified landscapes and interfaces with people, wildlife, and livestock create frequent opportunities for viral spillover. Despite this, the pathogen diversity and true risk of viral transmission are poorly understood by these hosts in Africa. Here, we explored the diversity and host association of paramyxoviruses and coronaviruses in non-volant small mammals from South Africa through longitudinal and opportunistic sample collection and molecular detection of viral RNA and host genetic barcoding. A high diversity of viruses was identified, with prevalences of 11.9% and 1.79% for paramyxoviruses and coronaviruses, respectively. Five instances of coinfections involving multiple paramyxoviruses and a coronavirus were detected, as well as nine Bayesian-supported paramyxovirus host genus, subfamily, and family switching, signifying frequent unrestrained viral sharing. Though the zoonotic potential of these identified viruses is unknown, the frequency of host switching suggests that these viruses may be more prone to adaptation to new host species or utilize highly conserved entry mechanisms. This highlights the risks for potential cross-species transmission events to livestock, domestic animals, and people, warranting continued surveillance.
Lactate as a key energy source facilitating cooperative behaviour in helper Damaraland mole-rats
(Royal Society, 2025-07) Cumming, Gisele S.; Bennett, Nigel Charles; Scantlebury, David Michael; Hart, Daniel William; Jacobs, Paul Juan; nigel.bennett@up.ac.za
This study explores the metabolic factors that may aid in the division of labour in cooperatively breeding Damaraland mole-rat (Fukomys damarensis) colonies, particularly during digging activities. In these group-living mammals, both breeders and non-breeders participate in digging, among other cooperative tasks; however, non-breeding males and females (NBFs), often referred to as ‘helpers’, undertake this task at a higher frequency and engage in other energetically demanding activities more often than their breeding counterparts. We investigated how variation in glucose and lactate levels, two key energy substrates, relates to different levels of digging activity between breeders and non-breeders and how these metabolic patterns might underpin reproductive differences in activity and energy budgets. While both breeding females (BFs) and NBFs exhibited similar decreases in glucose levels after digging, lactate dynamics revealed a key distinction, NBFs experienced a significant drop in plasma lactate, suggesting lactate utilization. In contrast, BFs showed an increase in lactate, indicating its accumulation rather than utilization, potentially contributing to their reduced involvement in digging activity. These findings suggest that lactate recycling and metabolism may play a crucial role in sustaining prolonged physical exertion in NBFs, providing a potential physiological explanation for the division of labour in mole-rat colonies.
Guidelines for evaluating the success of large carnivore reintroductions
(Elsevier, 2025-10) Briers-Louw, Willem D.; Lindsey, Peter Andrew; Gaylard, Angela; Cristescu, Bogdan; Verschueren, Stijn; Du Plessis, Cole; Drouilly, Marine; Bantlin, Drew; Kendon, Tamar A.; Evers, Emma E.M.; Curry, Caitlin J.; Almeidaj, Joao; Gaynor, David; Leslie, Alison J.; Naude, Vincent N.
Anthropogenic impacts have led to widespread species decline and extirpation, compelling a global movement to regenerate biodiversity through holistic ecosystem restoration including reintroductions. Despite increasing conservation-driven reintroduction efforts over the past century, peer-reviewed literature and policy providing criteria to evaluate reintroduction efficacy remain limited. Without comprehensive and quantifiable metrics of reintroduction success, such drastic conservation intervention strategies cannot be objectively evaluated nor compared, hindering the advancement of the restoration discipline. Herein, we reviewed 227 large carnivore reintroductions of 14 terrestrial mammal species across 23 countries since 1930 to contextualize global efforts to date, and from these, developed a standardized framework to evaluate reintroduction success. We retrospectively determined the extent to which existing studies met these criteria towards identifying current knowledge gaps and guide future reintroduction efforts. Most large carnivore records were of Felidae (70 %) reintroduced into ‘closed’ systems (69 %) across southern Africa (70 %). Our proposed framework provides a full suite of stages, indicators, and targets for reintroduction evaluation, which, when retrospectively applied to reviewed studies, indicated that at least one-third lacked sufficient information to effectively evaluate reintroduction outcomes. This comprehensive and prioritized framework provides novel transparency and scalability to large carnivore reintroduction programs, which is increasingly required to secure sustained support of impacted communities and stakeholder networks. Moreover, incorporating this framework into future practice and policy as an applied tool may directly benefit the recovery of at least 30 large carnivore species, while its principles may be applied more broadly across taxonomic groups for faunal rewilding and global ecosystem restoration. HIGHLIGHTS • Large carnivore reintroductions are increasing, but reported success rates are not. • Most reintroductions were of Felids into fenced systems in southern Africa. • With 21 % of past studies reporting no metrics, knowledge transfer remains limited. • We developed a framework to evaluate and compare large carnivore reintroductions. • Our guidelines promote best-practice in faunal restoration and improve transparency.
Taxonomic revision of African pipistrelle-like bats with a new species from the West Congolean rainforest
(Oxford University Press, 2025-06) Torrent, Laura; Juste, Javier; Garin, Inazio; Aihartza, Joxerra; Dalton, Desire L.; Mamba, Mnqobi; Tanshi, Iroro; Powell, Luke L.; Padidar, Sara; Mudarra, Juan Luis Garcia; Richards, Leigh; Monadjem, Ara
The taxonomic conundrum of pipistrelle-like or pipistrelloid bats remains one of the unsolved challenges posed by African Chiroptera. Historically, their cryptic morphology has led to a frequently confused classification and cast doubt on taxonomic arrangements at both genus and species levels. While molecular analyses and extensive reviews of specimens housed in collections worldwide have clarified many systematic relationships among pipistrelloid bats, some species still require validation, leaving gaps in our overall understanding of the systematics of the group. The Congo rainforest, one of Africa's least explored regions, remains underrepresented in systematic studies of pipistrelloid bats. In this study, we combine the use of two mitochondrial genes and cranial morphometric analyses to provide an updated perspective on African pipistrelloid bats, focusing on new material from Equatorial Guinea sampled over multiple years. We confirm the placement of Af. musciculus and Af. crassulus within the genus Afropipistrellus. The former was previously included in Hypsugo, while the latter lacked generic confirmation. Additionally, we describe a new species of Pipistrellus from Bioko Island, Central Africa, uncovered during systematic bat surveys in the region. Further surveys in the Congo rainforest are needed to unveil African bat diversity and its phylogenetic relationships fully.
Water economics of African savanna herbivores : how much does plant moisture matter?
(Wiley, 2025-04) Van Driessche, Jeremy A.; Chamaillé-Jammes, Simon; Nutter, Ciara M.; Potter, Arjun B.; Pringle, Robert M.; Long, Ryan A.
Water is an essential and often limiting resource that pervades all aspects of animal ecology. Yet, water economics are grossly understudied relative to foraging and predation, leaving ecologists ill-equipped to predict how the intensifying disruption of hydrological regimes worldwide will impact communities. For savanna herbivores, reliance on surface water can increase exposure to predators and competitors, and thus strategies that reduce the need to drink are advantageous. Yet, the extent to which increasing dietary water intake while decreasing water loss enables animals to forego drinking remains unknown. We studied water budgets of sympatric African savanna antelopes that differ in size, bushbuck (Tragelaphus sylvaticus, ~35 kg) and kudu (T. strepsiceros, ~140 kg). We hypothesized that both species compensate for seasonally declining water availability by increasing consumption of moisture-rich plants and reducing faecal water loss, and that these adjustments are sufficient for small-bodied—but not large-bodied—herbivores to avoid spending more time near permanent water sources as the dry season advances. We tested our predictions using temporally explicit data on antelope movements, diets, plant traits and drinking behaviour in Gorongosa National Park, Mozambique. Water content declined between the early and late dry seasons in roughly half of plant taxa consumed by antelope. Although both species reduced faecal water loss and shifted their diets towards relatively moisture-rich plants as the dry season progressed, dietary water intake still declined. Contrary to expectation, kudu reduced selection for surface water in the late dry season without adjusting total time spent drinking, whereas bushbuck increased selection for surface water. We developed a generalizable approach for parsing the importance of dietary and surface water for large herbivores. Our results underscore that variation in surface-water dependence is a key organizing force in herbivore communities, that simple allometric predictions about the behavioural and ecological consequences of this variation are unreliable. Understanding wildlife water economics is a research frontier that will be essential for predicting changes in species distribution and community composition as temperatures rise and droughts intensify.
Separating historical catches among pygmy blue whale populations using recent song detections
(Wiley, 2025-07) Branch, Trevor A.; Monnahan, Cole C.; Leroy, Emmanuelle C.; Shabangu, Fannie Welcome; Sirovic, Ana; Cerchio, Salvatore; Al Harthi, Suaad; Allison, Cherry; Cabrera, Naysa Balcazar; Barlow, Dawn R.; Calderan, Susannah V.; Double, Michael C.; Dreo, Richard; Gavrilov, Alexander N.; Gedamke, Jason; Hodge, Kristin B.; Jenner, K. Curt S; Jenner, Micheline N. -M.; Kiszka, Jeremy J.; Letsheleha, Ishmail S.; Mccauley, Robert D.; Miksis-Olds, Jennifer L.; Miller, Brian S.; Panicker, Divya; Pierpoint, Chris; Rand, Zoe R.; Reeve, Kym; Rogers, Tracey; Royer, Jean-Yves; Samaran, Flore; Stafford, Kathleen M.; Thomisch, Karolin; Torres, Leigh G.; Torterotot, Maelle; Tripovich, Joy S.; Warren, Victoria E.; Willson, Andrew; Willson, Maia S.
In the Southern Hemisphere and northern Indian Ocean, there are at least five populations of pygmy blue whales, Balaenoptera musculus brevicauda, residing in the Northwest Indian Ocean (NWIO, Oman), central Indian Ocean (CIO, Sri Lanka), Southwest Indian Ocean (SWIO, Madagascar to Subantarctic), Southeast Indian Ocean (SEIO, Australia to Indonesia), and Southwest Pacific Ocean (SWPO, New Zealand). Each population produces a distinctive repeated song, but none have population assessments or reliable measures of historical whaling pressure. Here we created pygmy blue whale catch time series by removing Antarctic blue whale catches using length data and then fitting generalized additive models (based on latitude, longitude, and month) to contemporary song data (largely from 1995 to 2023) to allocate historical catches to the five populations. Most pygmy blue whale catches (97% of 12,207) were taken by Japanese and Soviet operations during 1959/1960 to 1971/1972, with the highest totals taken from the SWIO (6514), SEIO (2593), and CIO (2023), and lower catches from the NWIO (549) and SWPO (528). The resulting predicted annual catch assignments provide the first indication of the magnitude of whaling pressure on each population and are a key step toward assessing the status of these five pygmy blue whale populations.
Short communication : impact of rest intervals and habituation on electro-ejaculated semen quality in merino-type rams
(South African Society for Animal Science, 2024-12) O’Neill, H.A.; Scholtz, J.; Kruger, L.P.; Maqhashu, A.; Ganswindt, Andre
This study evaluated the effects of habituation and electro-ejaculation techniques on semen quality in merino-type rams in South Africa, aiming to refine the electro-ejaculation method to improve semen quality. Parameters assessed included semen volume, sperm motility, sperm viability, sperm concentration, sperm viscosity, sperm consistency, and sperm abnormalities. Forty mature (six- to eighttooth) merino-type rams, approximately two and a half to four years old, were randomly assigned to four groups: habituated with a 3-second rest (H3) (n = 10), non-habituated with a 3-second rest (N3) (n = 10), habituated with a 10-second rest (H10) (n = 10), and non-habituated with a 10-second rest (N10) (n = 10). Each group underwent a two-week habituation period to human presence before electroejaculation using a commercial device. Analysed semen samples showed no significant differences in semen volume (0.93–1.28 mL), sperm motility (75.2%–83.1%), sperm viability (73.1%–85.5%), sperm concentration score (3.45–3.83), sperm viscosity score (3.5–4.00), or sperm consistency score (3.5– 4.0). However, the H3 group had a higher percentage of sperm abnormalities (12.3%) compared to the N3 (6.11%) and H10 (6.7%) groups, indicating that a shorter rest interval may negatively impact semen quality. The study concludes that extending the rest interval to ten seconds can enhance semen parameters.
Population changes in a Southern Ocean krill predator point towards regional Antarctic sea ice declines
(Nature Research, 2024-10-28) Germishuizen, Matthew; Vichi, Marcello; Vermeulen, Els; u15029507@tuks.co.za
While foraging, marine predators integrate information about the environment often across wide-ranging oceanic foraging grounds and reflect these in population parameters. One such species, the southern right whale (Eubalaena australis; SRW) has shown alterations to foraging behaviour, declines in body condition, and reduced reproductive rates after 2009 in the South African population. As capital breeders, these changes suggest decreased availability of their main prey at high-latitudes, Antarctic krill (Euphausia superba). This study analysed environmental factors affecting prey availability for this population over the past 40 years, finding a notable southward contraction in sea ice, a 15–30% decline in sea ice concentration, and a more than two-fold increase in primary production metrics after 2008. These environmental conditions are less supportive of Antarctic krill recruitment in known SRW foraging grounds. Additionally, marginal ice zone, sea ice concentration and two primary production metrics were determined to be either regionally significant or marginally significant predictors of calving interval length when analysed using a linear model. Findings highlight the vulnerability of recovering baleen whale populations to climate change and show how capital breeders serve as sentinels of ecosystem changes in regions that are difficult or costly to study.
The road to a long lifespan in the Persian squirrel, a natural model for extended longevity : resisting free radical stress and healthy phospholipids
(Springer, 2025) Salehi, Fahimeh; Kavoosi, Gholamreza; Jacobs, Paul Juan; Bennett, Nigel Charles; Ahmadian, Shahin; Bastani, Babak; Gholami, Mahdi
Longevity is influenced by various factors, including fatty acid composition and free radical stress, which relate to the membrane pacemaker and rate of living hypotheses. While these aspects are well-documented in some long-lived species, they remain largely unexplored in tree squirrels. This study aimed to compare oxidative stress, antioxidant activity, nitrosative stress, and lipid composition between the long-lived Persian squirrel (Sciurus anomalus) and the short-lived Wistar rat across age cohorts (younger and older). Tissue homogenates from skin, liver, skeletal muscle, spleen, lung, and kidney were analysed for lipid composition (monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), arachidonic to linoleic acid ratio, peroxidation index, and unsaturation index. Oxidative, nitrosative, and antioxidant markers were assessed, including NADPH oxidase, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase (GST), nitric oxide synthase, superoxide, hydrogen peroxide, nitric oxide, malondialdehyde, 4-hydroxynonenal, and total antioxidant capacity (TAC). Squirrels demonstrated higher GST activity, lower free radical stress, lower PUFA, and higher MUFA compared to rats. Antioxidant activities, except for TAC were negatively correlated with longevity. Older squirrels exhibited similar oxidative, nitrosative, and antioxidant profiles to younger squirrels, whereas younger rats displayed highly susceptible fatty acids, similar to older rats. The Persian squirrel’s longevity appears closely linked to fatty acid composition and free radical resistance, likely due to increased GST activity. We propose GST’s multifunctional role in reducing inflammation, enhancing immune response, providing disease resistance, and antioxidant activity contributes significantly to the longevity of the Persian squirrel.
A review of Southern Hemisphere humpback whaling by period and catch location
(International Whaling Commission, 2024-11) Seyboth, Elisa; Paarman, S.; Allison, C.; Meynecke, J.-O.; De Bie, J.; Findlay, Kenneth Pierce; elisa.seyboth@up.ac.za
Comprehensive Assessments of the seven Southern Hemisphere humpback whale (Megapteranovaeangliae) breeding stocks require an understanding of their respective catch histories. A lack of information on humpback whale catches from American, British and French open‐boat (or pre‐modern) pelagic and land‐based whaling from 1760 to the late 1920s from some fleets precludes detailed estimations of catch histories from this era. We therefore provide a review of the whaling of the species across the Southern Hemisphere by modern whaling period, during which some 215,928 humpback whales are estimated to have been taken between 1903 and 1973, comprising land‐based, moored floating factory, and both regulated and unregulated illegal pelagic whaling. Between 1904 and 1914, humpback whales were the main catch at South Georgia and the South Shetland Islands, while, at further Southern Ocean land stations, catch efforts were carried out from the South Orkney, the South Sandwich and Kerguelen Archipelagos, with more limited success. Off the coasts of South America, humpback whales were taken off the west coast and from the Brazilian coast between 1905 and 1963. Southern African catch records show extensive humpback catches from whaling stations across the coast from Madagascar to Gabon from 1908 to 1963, as do catch records from Australia and New Zealand across the same period. A rapid growth in pelagic whaling across the Southern Ocean from 1923 onwards resulted in extensive humpback catches until 1963, despite significant temporal and spatial restrictions. Although humpback whales were totally protected across the Southern Hemisphere by the International Whaling Commission from October1963, the Soviet Union fleets violated catch and reporting regulations from 1947 to 1973, resulting in significant illegal catches. Additional unregulated catches were made by the Olympic Challenger fleet between 1950 and 1955 in the Antarctic and off the west coast of South America. The information compiled in this review is critical to the evaluation of the whaling impact on each breeding stock, and for future status assessments of the species, and can provide evidence of the historical distributions of the species in breeding and feeding grounds.
Extreme herding behavior in adult male sub-Antarctic fur seals
(Springer, 2025-05) Bester, Marthan Nieuwoudt; Rossouw, G.J.; mnbester@zoology.up.ac.za
We re-analyzed unpublished data on herding behavior in adult male sub-Antarctic fur seals Arctocephalus tropicalis recorded at Gough Island during the 1975/76 austral summer breeding season. The results extend the study of competition and injury in adult males from the same population. Herding behavior is defined and shows that adult males in this population exhibit the most extreme herding behavior of the fur seal genus Arctocephalus. Extreme herding responses result from both human disturbance and in natural settings without human disturbance. Such information is needed for comparative studies about aggression and territorial behavior in otariids.
Sodium retention in large herbivores : physiological insights and zoogeochemical consequences
(Wiley, 2025-07) Abraham, Andrew J.; Duvall, Ethan S.; Doughty, Christopher E.; Riond, Barbara; Ortmann, Sylvia; Terranova, Melissa; Le Roux, Elizabeth; Clauss, Marcus
The assimilation, retention, and release of nutrients by animals fundamentally shapes their physiology and contributions to ecological processes (e.g., zoogeochemistry). Yet, information on the transit of nutrients through the bodies of large mammals remains scarce. Here, we examined how sodium (Na), a key element for animal health and ecosystem functioning, travels differently through fecal and urinary systems of cows (Bos taurus) and horses (Equus ferus caballus). We provided a large dose of Na and compared its timing of release in feces and urine to that of nonabsorbable markers. Na excretion by urine occurred approximately twice as fast as excretion by feces, yet both were shorter than indigestible particle markers. These differences correspond to rapid absorption of Na in the upper gastrointestinal tract and transport by blood to the kidneys (urine Na excretion) or resecretion of Na into the lower intestinal tract (fecal Na excretion). Interestingly, for cows, we found a second peak of Na excretion in urine and feces > 96 h after dosage. This result may indicate that surplus Na can be rapidly absorbed and stored in specific body cells (e.g., skin), from which it is later released. Using a propagule dispersal model, we found that the distance of cattle- and horse-driven nutrient dispersal by urine was 31% and 36% less than the fecal pathway and 60% and 41% less than the particle marker pathway, which is commonly used to estimate nutrient dispersal. Future physiological and zoogeochemical studies should resolve different pathways of nutrient retention and release from large mammals.

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