Wild Asian elephants distinguish aggressive tiger and leopard growls according to perceived danger

Prey species exhibit antipredator behaviours such as alertness, aggression and flight, among others, in response to predators. The nature of this response is variable, with animals reacting more strongly in situations of increased vulnerability. Our research described here is the first formal study to investigate night-time antipredator behaviour in any species of elephants, Asian or African. We examined the provocative effects of elephant-triggered tiger and leopard growls while elephants attempted to crop-raid. Tigers opportunistically prey on elephant calves, whereas leopards pose no threat; therefore, we predicted that the elephant response would be reflective of this difference. Elephants reacted similarly cautiously to the simulated presence of felids of both species by eventually moving away, but differed markedly in their more immediate behavioural responses. Elephants retreated silently to tiger-growl playbacks, whereas they responded with aggressive vocalizations, such as trumpets and grunts, to leopard-growl playbacks. Elephants also lingered in the area and displayed alert or investigative behaviours in response to leopard growls when compared with tiger growls. We anticipate that the methods outlined here will promote further study of elephant antipredator behaviour in a naturalistic context, with applications for conservation efforts as well.     

Effect of a birth on the behavior of a family group of Asian elephants (Elephas maximus) at Dublin Zoo

Elephants in the wild live in herds of related females from several generations. Zoos, therefore, tend to house elephants in female groups, consisting where possible of related individuals. This type of group structure is very beneficial as it allows group members to experience events such as births in the group, and means that natural social interactions can take place between the group members. The behavior of four related female Asian elephants (Elephas maximus) at Dublin Zoo was recorded before and after the birth of a calf, to examine what effects it would have on the behavior and associations in the elephant group. The mother of the calf significantly decreased the amount of time she spent walking after the birth and the aunt of the calf showed significant decreases in both walking and standing. The mother spent the majority of her time closest to her calf after the birth, but the proportion of time she spent with each of the other individuals in the group did not change. The associations of the aunt also did not change after the birth. The older sister of the newborn calf increased the proportion of time she spent nearest to her mother after the calf was born, and reduced the time she spent close to another young elephant in the group. The new calf seems to have been successfully assimilated into the elephant group.     

Employing participatory surveys to monitor the illegal killing of elephants across diverse land uses in Laikipia–Samburu,Kenya

Levels and trends of illegal killing of elephants are measured by the Convention on International Trade in Endangered Species (CITES) Monitoring the Illegal Killing of Elephants (MIKE) programme in sites across Africa and Asia. In the mostly unprotected Laikipia–Samburu MIKE site in northern Kenya, elephant mortality data were collected using both standard law enforcement monitoring procedures, relying on patrolling, and participatory methods involving local communities. Qualitatively, traditional patrolling techniques were more successful in protected areas whereas participatory approaches provided more information outside protected areas, where elephant were most at risk from ivory poachers. A minimum of 35% of the 389 verified carcasses during 2001–2003 were illegally killed. In this baseline study, land uses ranked from highest to lowest by the proportion of illegally killed elephants (PIKE) were community conservation areas, government trust lands, forest reserves, private ranches, settlement areas and national reserves. PIKE trends derived from traditional and participatory data sources were similar across years and indicate elephants were at greater risk in regions outside government or privately patrolled areas. We suggest that PIKE is a useful index for comparing levels and trends in illegal killing of elephants, and that carcass ratios and presence/absence of tusks are useful proxy indicators of mortality and its causes.     

Landscape‐scale effects of herbivores on treefall in African savannas

Herbivores cause treefalls in African savannas, but rates are unknown at large scales required to forecast changes in biodiversity and ecosystem processes. We combined landscape‐scale herbivore exclosures with repeat airborne Light Detection and Ranging of 58 429 trees in Kruger National Park, South Africa, to assess sources of savanna treefall across nested gradients of climate, topography, and soil fertility. Elephants were revealed as the primary agent of treefall across widely varying savanna conditions, and a large‐scale ‘elephant trap’ predominantly removes maturing savanna trees in the 5–9 m height range. Treefall rates averaged 6 times higher in areas accessible to elephants, but proportionally more treefall occurred on high‐nutrient basalts and in lowland catena areas. These patterns were superimposed on a climate‐mediated regime of increasing treefall with precipitation in the absence of herbivores. These landscape‐scale patterns reveal environmental controls underpinning herbivore‐mediated tree turnover, highlighting the need for context‐dependent science and management.     

Elephant survival,rainfall and the confounding effects of water provision and fences

Elephant are increasing across some areas of Africa leading to concerns that they may reduce woodlands through their feeding. Droughts may help limit elephant numbers, but they are generally both episodic and local. To explore more general impacts of rainfall, we examine how its annual variation influences elephant survival across ten sites. These sites span an almost coast-to-coast transect of southern Africa that holds the majority of the ~500,000 remaining savanna elephants. Elephants born in high rainfall years survive better than elephants born in low rainfall years. The relationship is generally weak, except at the two fenced sites, where rainfall greatly influenced juvenile survival. In these two sites, there are also extensive networks of artificial water. Rainfall likely affects elephant survival through its influence on food. The provision of artificial water opens new areas for elephants in the dry season, while fencing restricts their movements in the wet season. We conclude that the combination of these factors makes elephant survival more susceptible to reductions in rainfall. As a result, elephants living in enclosed reserves may be the first populations to feel the impacts of global warming which will decrease average rainfall and increase the frequency of droughts. A way to prevent these elephants from damaging the vegetation within these enclosed parks is for managers to reduce artificial water sources or, whenever practical, to remove fences.     

Forest elephant group composition, frugivory and coastal use in the Réserve de Faune du Petit Loango, Gabon

Results of a 16‐month study of forest elephant (Loxodonta africana cyclotis Matschie) group size and composition, coastal use and frugivory are presented from the Réserve de Faune du Petit Loango, Gabon (now the Parc National de Loango). Mean forest elephant group size was 2.2 (n = 140) including solitary animals, and 3.1 excluding solitaries. Elephants consumed fruits of at least 49 species, and of the 220 elephant dungpiles examined, 185 (84.1%) contained seeds and 203 (92.3%) contained the remains of fruits (seeds and/or pulp). The mean number of seed species per dungpile (±SD) was 2.01 ± 1.49, and the mean number of fruit species was 2.28 ± 1.43. Elephants used the coastal habitat more during warmer months, and during the afternoon than the morning. It is hypothesized that coastal habitat use is related to sodium intake through consumption of salt‐coated vegetation.     

Geographic variation in sperm production by Trinidadian guppies

Population comparisons yield important insights into adaptive differentiation. However, despite the current interest in sperm competition and spermatogenesis, geographic variation in these traits has received little attention. We tested the hypothesis that sperm production covaries with risk by comparing five natural populations of Trinidadian guppies (Poecilia reticulata): two that inhabited dangerous Crenicichla localities, two from low-risk Rivulus sites and a ''transplant'' population comprised of the descendants of guppies moved from one of the high-risk sites to a low-predation environment. As predicted, males from the three low-risk sites performed significantly more courtship displays and had larger sperm reserves than their high-risk counterparts. This result implies higher rates of sperm competition in the low-risk sites.     

Agonistic Interactions in Juvenile Sticklebacks (Gasterosteus aculeatus) in Relation to Local Predation Risk

Size-matched groups of three-spined stickleback (Gasterosteus aculeatus) fry were established using fish from two sites, one with abundant piscivorous predators (the high-risk site) and the other with very few heterospecific predators (the low-risk site). Over a period of two months, social interactions within groups were monitored regularly and mean lengths and coefficients of variance in length were tracked. Agonistic behaviour was observed in 45% of observation periods, but was more common in the groups of fry from the low-risk site, where it was more likely to take the form of direct attack rather than displacement without contact. In both categories of fish, the great majority of agonistic acts were directed to fish of a similar size or smaller. Mean size increased rapidly in all groups. At the same time, the coefficient of variation also increased, approaching 15% after two months in both categories of fish, reflecting differing growth rates among individuals. After three months, the two largest and the two smallest fish from each group were observed individually during an encounter with a model predatory fish. Large and small fish from both sites behaved identically in this test, suggesting that in sticklebacks (unlike guppies, for example) early experience of aggressive attacks from conspecific companions may not influence the development of anti-predator responses. As has been reported previously, sticklebacks from the high-risk site responded much more strongly than low-risk fish.     

The presence of black vultures at the calving sites and its effects on cows’ and calves’ behaviour immediately following parturition

Black vultures (Coragyps atratus) are often present near calving sites, and under this situation they may play a positive role by removing animal carcasses and afterbirth or a negative role by attacking neonate calves or disturbing cow–calf behaviours following parturition. Cow–calf behaviour was recorded over a 4-year study period from a total of 300 births involving 200 Nellore, 54 Guzerat, 20 Gyr and 26 Caracu cows. The calving site in relation to the location of the herd, considering cow–calf pairs within, close or distant to the herd, the presence of vultures and the behaviour of cows and calves were recorded instantaneously, at 5-min interval. On average, vultures were present at 80% of the calving sites. The frequency of vultures present at calving sites was dependent on the years for the Nellore herd, increasing from 1998 to 2003. When vultures were present, the time that the cow was in contact with its calf decreased, and the percentage of time that the cow was standing still increased. Vultures were observed pecking cows and their neonates during 34.1% of all recordings. However, in only two cases pecking injuries were actually observed on calves that were noted to be very weak. The preliminary results suggest that although black vultures cannot be characterized as a predator of neonate calves, they sometimes attack neonate calves and their presence near the calving sites alter the behaviours of cows and calves.     

Elephant herbivory in Majete Wildlife Reserve,Malawi

Elephants have a major influence on vegetation structure, composition and ecosystem processes, and are primary agents of habitat change in Africa. At moderate‐to‐high population densities, elephants can damage vegetation, especially when enclosed in protected areas. This study examines the effects of elephant browsing on woody trees in Majete Wildlife Reserve (WR), south‐western Malawi. Regression analysis is used to assess the associations of six factors known to drive elephant browsing in other areas and determine which ones have the most influence on browsing at Majete WR. Twenty‐four per cent of tagged trees had been subject to elephant browsing. The model with vegetation type, stem diameter and distance from permanent water correctly predicted browsing for 80% of the observations. Elephants mostly favoured riparian woodlands, followed by Acacia‐dominated woodland and Brachystegia‐dominated woodland. Browsing occurrence was negatively related to distance from permanent water and diameter at breast height(DBH). A larger number of trees, sampled at random and covering a larger portion of the reserve would provide more reliable estimates of browsing and related factors. Knowledge of time‐ and site‐specific factors affecting elephant browsing can be used to forecast future habitat transformations and manipulate the range of the elephants within the reserve.     

Variation in the Composition of Milk of Asian Elephants (Elephas maximus) Throughout Lactation

We investigated milk nutrient composition from three Asian elephant cows over the first 3 years of lactation, including two consecutive lactations in one cow. Body mass gain is presented for three calves during the first year. Milk samples (n = 74) were analyzed for dry matter (DM), fat, crude protein (CP), sugar, ash, calcium (Ca), phosphorus (P), and potassium (K); gross energy (GE) was calculated. Concentrations of most nutrients changed over lactation: DM, fat, CP, Ca, P, and GE were positively correlated to calf age; sugar was negatively correlated to calf age. GE doubled between birth (1 kcal/g) and 2 years of age (2 kcal/g). After accounting for calf age, GE, fat, Ca, and P concentrations differed among the cows. Milk composition also differed between two lactations from the same cow. When milk nutrients were expressed on a mg per kcal basis, the pattern changes: CP, Ca, and P remained relatively constant over lactation on a per energy basis. Calf mass quadrupled over the first year of life; mass gain was linear at 0.9 kg/day. Asian elephant milk composition is variable, both across lactations and between cows, complicating efforts to determine representative values for comparative studies and for the formulation of elephant milk formulas. The fact that CP, Ca, and P were all relatively constant when expressed on a per energy basis may be of biological significance. The increase in nutrient density over lactation undoubtedly limits maternal water loss, reducing the volume of milk necessary to support the calf. Zoo Biol 32:291–298, 2013. © 2012 Wiley Periodicals, Inc.     

Using presence‐only modelling to predict Asian elephant habitat use in a tropical forest landscape: implications for conservation

Aim Asian elephants, Elephas maximus, are threatened throughout their range by a combination of logging, large scale forest conversion and conflict with humans. We investigate which environmental factors, both biotic and abiotic, constrain the current distribution of elephants. A spatially explicit habitat model is constructed to find core areas for conservation and to assess current threats. Location Ulu Masen Ecosystem in the province of Nanggroe Aceh Darussalam on the island of Sumatra, Indonesia. Methods A stratified survey was conducted at 12 sites (300 transects) to establish the presence of elephants. Presence records formed the basis to model potential habitat use. Ecological niche factor analysis (ENFA) is used to describe their niche and to identify key factors shaping elephant distribution. An initial niche model was constructed to describe elephant niche structure, and a second model focused on identifying core areas only. To assess the threat of habitat encroachment, overlap between the elephants’ optimal niche and the occurrence of forest encroachment is computed. Results Elephants were recorded throughout the study area from sea level to 1600 m a.s.l. The results show that the elephant niche and consequently habitat use markedly deviates from the available environment. Elephant presence was positively related to forest cover and vegetation productivity, and elephants were largely confined to valleys. A spatially explicit model showed that elephants mainly utilize forest edges. Forest encroachment occurs throughout the elephants range and was found within 80% of the elephants’ ecological niche. Main conclusions In contrast to general opinion, elephant distribution proved to be weakly constrained by altitude, possibly because of movement routes running through mountainous areas. Elephants were often found to occupy habitat patches in and near human‐dominated areas. This pattern is believed to reflect the displacement of elephants from their former habitat.     

Population structure and behaviour of crop-raiding elephants in Kibale National Park, Uganda

We examined patterns of crop raiding by elephants across gender and age classes in relation to elephant life history and sociobiology and estimated the quantitative contribution of crops to elephant diet in Kibale National Park (KNP). Elephant dung‐boli sizes were used to estimate age and sex, while the presence of crop remains in the dung of crop‐raiding elephants was used as evidence of repeated raiding. To estimate the expected proportion of elephants raiding per age class, the age distribution of raiders was compared with the age distribution of all KNP elephants. Elephants raiding crops were predominantly males. They began raiding in expected proportions at 10–14 years while a higher than expected proportion raided crops at 20–24 years. These results suggest that crop raiding is initiated at an age when male elephants leave their families and a large proportion of elephants raid when they are approaching reproductive competition. Evidence from dung of crop raiders, suggests that repeated raiding increases with age. Crop raiders derived 38% of their daily forage from the short time spent raiding, consistent with expectations of foraging theory. Males may be more likely to learn crop raiding because they are socially more independent and experience intense mating competition than females.     

Human disturbance and the activity patterns and temporal overlap of tapirs and jaguars in reserves of NW Belize

Human disturbance from tourism and other non-consumptive activities in protected areas may be stressful to wildlife. Animals may move away in space or time to avoid human interaction. For species of particular conservation concern, such as Baird's tapirs (Tapirus bairdii) and jaguars (Panthera onca), a better understanding of how they respond to different levels and types of disturbance is needed in order to manage human visitation to parks in ways that minimize negative outcomes for wildlife. We describe the overlap in activity patterns of tapirs, jaguars, and humans at logged and unlogged sites and at places with low versus high human visitation using camera survey data from protected areas of NW Belize, 2013–2016. Tapirs were nocturnal in all study sites, with > 80% of all tapir detections occurring between 1900 hr and 0500 hr. Their activity patterns were not different in unlogged versus logged sites and did not change with increased human traffic. Jaguars were cathemeral across sites but had more nocturnal activity at the site with the most human impact. Activity pattern overlap between tapirs and jaguars did not differ significantly between logged and unlogged sites, nor between areas with low and high human activity. Human traffic increased from 2013 to 2016 at most of the study locations. In conclusion, this camera trap dataset suggests that non-consumptive human disturbance does not alter the activity patterns of tapirs and jaguars in protected areas lacking hunting pressure.     

Severe drought and calf survival in elephants

Climate change in Africa is expected to lead to a higher occurrence of severe droughts in semi-arid and arid ecosystems. Understanding how animal populations react to such events is thus crucial for addressing future challenges for wildlife management and conservation. We explored how gender, age, mother's experience and family group characteristics determined calf survival in an elephant population during a severe drought in Tanzania in 1993. Young males were particularly sensitive to the drought and calf loss was higher among young mothers than among more experienced mothers. We also report high variability in calf mortality between different family groups, with family groups that remained in the National Park suffering heavy calf loss, compared with the ones that left the Park. This study highlights how severe droughts can dramatically affect early survival of large herbivores and suggests that extreme climatic events might act as a selection force on vertebrate populations, allowing only individuals with the appropriate behaviour and/or knowledge to survive.     

Anthropogenic driven range expansion of Asian elephant Elephas maximus in an agricultural landscape and its consequences in South West Bengal,India

Alterations of the geographical ranges of animals have become a reason for interactions with humans, leading to various consequences. We describe the pattern of range expansion of Asian elephants (Elephas maximus) and implications for human-elephant interactions in the agricultural landscape of South West Bengal, India. We enquired about past and current sightings of Asian elephants from local people to gather information on range expansion from the 1950 s to 2018. We also collected the records of human deaths and injuries by elephants from 2010 to 2018 from the records of the Forest Department. We employed an occupancy framework to understand the probability of the occurrence of elephants in the landscape from 2010 to 2018. The range of elephants in the landscape increased from ∼ 1200 km² in the 1950–60 s to ∼ 13200 km² by 2010–18. The calculated probability of use of grid cells was 36 % and the forest edge had a high influence on the space usage by the elephants. Elephants occurred in an average of 26 grid cells per month, and the number of grid cells with elephants did not differ between the months. A total of 640 attacks on humans occurred, which significantly varied between the years. The probability of elephant occurrence in a grid cell was the major determinant factor for the elephant attacks on humans. Although people respect elephants, there is a sense of intolerance towards them if they enter the crop fields, owing to the small land holdings and the incapacity to endure the monetary losses of the farmers.     

A lifetime at depth: vertical distribution of southern elephant seals in the water column

Although numerous studies have addressed the migration and dive behaviour of southern elephant seals (Mirounga leonina), questions remain about their habitat use in the marine environment. We report on the vertical use of the water column in the species and the potential lifetime implications for southern elephant seals from Marion Island. Long-term mark-resight data were used to complement vertical habitat use for 35 known individuals tagged with satellite-relay data loggers, resulting in cumulative depth use extrapolated for each individual over its estimated lifespan. Seals spent on average 77.59% of their lives diving at sea, 7.06% at the sea surface, and 15.35% hauled out on land. Some segregation was observed in maximum dive depths and depth use between male and female animals—males evidently being physiologically more capable of exploiting increased depths. Females and males spent 86.98 and 80.89% of their lives at sea, respectively. While at sea, all animals spent more time between 300 and 400 m depth, than any other depth category. Males and females spent comparable percentages of their lifetimes below 100 m depth (males: 65.54%; females: 68.92%), though males spent 8.98% of their lives at depths in excess of 700 m, compared to females’ 1.84% at such depths. Adult males often performed benthic dives in excess of 2,000 m, including the deepest known recorded dive of any air-breathing vertebrate (>2,133 m). Our results provide a close approximation of vertical habitat use by southern elephant seals, extrapolated over their lifespans, and we discuss some physiological and developmental implications of their variable depth use.     

How selective are elephants as agents of forest tree damage in Bwindi Impenetrable National Park,Uganda?

Elephants are locally concentrated in Bwindi Impenetrable National Park. Vegetation damage attributable to elephants appears to be increasing and may result in the modification of the forest. We examined the implied selectivity of stem damage due to elephants. We followed 26.84 km of recent elephant trails and used 122 plots to document tree damage in relation to species, stem sizes and locations. Of 897 trees (DBH ≥2 cm), 542 (60.4%) were intact, 22 (2.5%) debarked, 274 (30.5%) toppled and 172 (19.2%) had broken branches. Small trees were more likely to be pushed over or have their branches broken, whereas large trees were more commonly debarked. The species most frequently selected for damage included mid‐successional species such as Newtonia buchananii, Myrianthus holstii and Chrysophyllum albidum. These species may be vulnerable to increasing elephant numbers. Our analyses using general linear models indicate that elephants are selective concerning where, how and what tree stems they damage. We found a higher incidence of elephant damage per‐tree stem in open areas than in more closed areas, suggesting feedback in which elephants maintain open habitats that may be conducive for other species such as mountain gorillas. More work is needed to better determine how changing elephant numbers may influence Bwindi's conservation values.     

Skeletal development in the African elephant and ossification timing in placental mammals

We provide here unique data on elephant skeletal ontogeny. We focus on the sequence of cranial and post-cranial ossification events during growth in the African elephant (Loxodonta africana). Previous analyses on ossification sequences in mammals have focused on monotremes, marsupials, boreoeutherian and xenarthran placentals. Here, we add data on ossification sequences in an afrotherian. We use two different methods to quantify sequence heterochrony: the sequence method and event-paring/Parsimov. Compared with other placentals, elephants show late ossifications of the basicranium, manual and pedal phalanges, and early ossifications of the ischium and metacarpals. Moreover, ossification in elephants starts very early and progresses rapidly. Specifically, the elephant exhibits the same percentage of bones showing an ossification centre at the end of the first third of its gestation period as the mouse and hamster have close to birth. Elephants show a number of features of their ossification patterns that differ from those of other placental mammals. The pattern of the initiation of the ossification evident in the African elephant underscores a possible correlation between the timing of ossification onset and gestation time throughout mammals.     

Activity budgets and the relationship between feeding and stereotypic behaviors in Asian elephants (Elephas maximus) in a Zoo

Activity budgets were studied in eight Asian elephants (Elephas maximus) at Chester Zoo (UK) for 35 days, between January and November 1999. Recordings were made between 10:00 and 16:00 hr (with most behavior frequencies calculated between 10:00 and 14:00 hr). The elephants exhibited variation in activity depending on their age, sex, the time of day and the time of year. Only the five adult cows exhibited stereotypic behavior, with frequencies ranging from 3.9 to 29.4% of all observations. These elephants exhibited individual, diurnal and seasonal variation in stereotypic behavior. This has implications for studies that use short sampling periods and may make comparisons of data collected at different times of the day or year invalid. The six adult elephants spent 27.4–41.4% of the time feeding (between 10:00 and 14:00 hr), 22.9–42.0% standing still, 6.1–19.2% walking and 3.9–9.6% dusting. The hypothesis that the frequency of stereotypic behavior in adult cow elephants was negatively correlated with the frequency of feeding behavior was tested and was found to be true. Stereotypic behavior increased in frequency toward the end of the day—while waiting to return to the elephant house for food—and elephants spent more time stereotyping during the winter months than during the summer months. Elephants were inactive (i.e. exhibited behaviors other than locomotion) for between 70.1 and 93.9% of the time. Creating more opportunities for elephants to exhibit foraging behavior and the introduction of greater unpredictability into management regimes, especially feeding times, may reduce the frequency of stereotypic behavior and increase general activity levels. Zoo Biol 28:79–97, 2009. © 2008 Wiley-Liss, Inc.