Aspects of breeding biology of chital (Axis axis) and sambar (Rusa unicolor) in the Western Ghats

Antler cycles are convenient external signs indicating internal changes in reproductive status of male deer. Antler phenology of chital (Axis axis) and sambar (Rusa unicolor) were studied in a deciduous habitat of Mudumalai Tiger Reserve, Western Ghats, using vehicle transects for 2 successive years. Apparent breeding seasonality occurred with the majority of adult stags in hard antlers from May to mid October in chital (>87 %), and October to May in sambar (>68 %). Adult hard antler in chital correlated with mean group size, while sambar showed a weak correlation between adult hard antler and group size. Chitals prefer forming large groups at forest edges and open habitats while sambars prefer dense vegetation cover. Adult hard antlers in chital and sambar showed a weak relation to fawning since most adult females were in oestrus during the peak rutting season. Adult hard antlers in chital associated positively with rainfall and day length while sambar responded weakly to rainfall. We conclude that environmental variables determined species-specific mating strategies in the two deer species.     

Population ecology of free-ranging urban dogs in West Bengal, India

A population of urban free-ranging dogsCanis familiaris Linnaeus, 1758 was studied in Katwa, West Bengal, India. The analysis of changes in the density of the dog population over a period of 4 years revealed a considerable stability of this population. Mean (±SD)₂ seasonal population density was 185±19 dogs/km², ranging from 156 to 214 dogs/km². A sex ratio of 1.37∶1 in favour of male was recorded in this study. High mortality (67%) occurred under the age of 4 months, and 82% mortality occurred within the age of 1 year. Among the adults, 24% mortality under the age of 2.6 year was recorded. Only a single breeding cycle and synchronization of breeding was observed. Immigration was observed as a crucial factor affecting the stability of this population.     

Demography of grey partridges Perdix perdix in Poland in the years 1991–2004: reasons of population decline

Grey partridge Perdix perdix populations were monitored in the years 1991–2004 in ten agricultural areas (100–200 km² each) located in various regions of Poland. Spring density (call counts in March/April) and parameters describing reproductive success (counts of adult and young birds in coveys found in August) were estimated, and annual survival rate of adult birds was calculated. In the 1990s, the mean spring density of grey partridge in Poland showed a threefold decrease. In 1993 (the year of the highest mean density), from 4.6 pairs/km² to 20.0 pairs/km² were found in individual areas; whereas in 2004, there were from 0.4 pairs/km² to 8.3 pairs/km². The mean brood-production rate in individual years ranged from 29% to 49% (overall mean 36.8%), the chick-survival rate from 31% to 56% (43.1%), the young production from 1.6 to 2.8 young per adult (2.32 young/adult) and the annual survival rate of adult birds from 25% to 33% (28.3%). The population decrease in the 1990s was connected with the drop of reproductive success, including both the brood-production rate and the chick-survival rate, as well as with the decline of annual survival rate of adult birds. The decrease of brood-production rate and adult-survival rate probably resulted mainly from increased abundance of nest and incubating female predators (particularly foxes). Fluctuations in chick-survival rate were related to weather conditions, but also slight long-term decline was recorded, probably due to more intensive pesticide use.     

Social and spatial relationships in captive southern white rhinoceros (Ceratotherium simum simum)

Although critical to the conservation of white rhinoceros, captive breeding has proven challenging because of the poor and irregular reproductive health of many captive rhinos, and social interactions may play a significant role. This research investigated the social and spatial relationships of two captive groups of southern white rhinoceros (Ceratotherium simum simum) by examining the frequency of companion changes, the number of space maintenance vocalizations made per hour by each reproductively mature female, and dominant/subordinate interactions. The observed captive rhinos did not change their companionships during the study. They exhibited space maintenance vocalizations and display greater than once per hour, particularly when feeding. Females housed with four calves on 0.033 km² exhibited space maintenance vocalizations more frequently (X±SE = 6.19±0.199/hr) than females housed with one calf and more space (0.06 km², X±SE = 0.55±0.182/hr) and females housed without calves and more space (0.65 km², X±SE = 1.90±0.086/hr). Wider separation of food piles and of females with young calves is suggested to reduce the interpreted spatial stress. The presence of a large number of rhinos in restricted captive space resulted in the formation of herds with dominance hierarchies that were enforced during competition for food and shade. The most subordinate rhino in each of the herds exhibited unusual behaviors such as dung‐kicking and nonestrus urine squirting, and neither has ever reproduced. Suppression of subordinate rhinos might lead to social stress that could negatively impact reproductive success. Zoo Biol 26:487–502, 2007. © 2007 Wiley‐Liss, Inc.     

利用红外相机建立野生水鹿行为谱及PAE编码系统

动物行为谱是动物行为学研究的基础。2015年1月至2016年6月,在四川卧龙自然保护区,利用PAE编码分类系统并结合红外相机所获得的照片和视频数据开展水鹿(Rusa unicolor)行为谱的研究,建立了野生水鹿行为谱及其PAE编码系统。本研究共分辨并记录了野生水鹿的7种姿势,63种动作和74种行为,基本涵盖了水鹿的主要行为,并区别了各种行为在成年雄性、成年雌性和亚成体之间的相对发生频次,分析水鹿的具体行为与环境之间的关联。通过建立野生水鹿的行为谱,能为更深入地开展水鹿行为生态学研究提供基础信息,也为水鹿的保护与管理提供依据。该研究可以推广到其他不易直接观测的野生动物的行为学研究中。     

Density and population structure of the jaguar (<Emphasis Type="Italic">Panthera onca</Emphasis>) in a protected area of Los Llanos,Venezuela, from 1 year of camera trap monitoring

Density is crucial for understanding large carnivore ecology and conservation, but estimating it has proven methodologically difficult. We conducted 1 year of camera trapping to estimate jaguar (Panthera onca) density and population structure in the Los Llanos region of Venezuela on the Hato Piñero ranch, where hunting is prohibited and livestock are excluded from half of ranch lands. We identified 42 different jaguars and determined their sex, age class, and reproductive status. We estimated adult jaguar densities with spatial capture-recapture models, using sex/reproductive state and session as covariates. Models without temporal variation received more support than models that allowed variation between sessions. Males, reproductive females, and nonreproductive females differed in their density, baseline detectability, and movement. The best estimate of total adult jaguar population density was 4.44 individuals/100 km². Based on reproductive female density and mean number of offspring per female, we estimated cub density at 3.23 individuals/100 km² and an overall density of 7.67 jaguars/100 km². Estimated jaguar population structure was 21% males, 11% nonreproductive females, 26% reproductive females, and 42% cubs. We conclude that extending the sampling period to 1 year increases the detectability of females and cubs and makes density estimates more robust as compared to the more common short studies. Our results demonstrate that the Venezuelan Llanos represent important jaguar habitat, and further, they emphasize the importance of protected areas and hunting restrictions for carnivore conservation.     

甘肃兴隆山保护区野生马麝分布、数量特征及影响因素

综合采用样线法、粪堆计数法及重复调查法对甘肃省兴隆山国家级自然保护区的野生马麝(Moschus chrysogaster)进行了种群调查,结合生境分析,确定了其种群分布、数量特征及影响因素。结果表明,兴隆山保护区分布有野生马麝(1159±275)头,平均种群密度为(3.51±0.83)头/km²;各植被类型生境中的野生麝种群数量及密度存在差异,灌丛生境分布有70%的野生马麝种群,达(807±170)头,种群密度为(6.49±1.63)头/km²;针叶林种群密度最大,达(8.85±83.25)头/km²,分布有野生麝(123±45)头;针阔混交林分布最少,仅(41±15)头,种群密度为(5.00±1.84)头/km²;人工林生境无野生马麝分布。保护区各植被类型生境中的野生马麝种群分布差异反映了马麝对适宜生境功能的需求,食物、保温和隐蔽性是制约野生马麝冬季分布和种群数量的关键因素。此外,因生境及人为干扰强度的不同,保护区各区域的野生马麝种群分布存在差异。建议通过减少人为干扰、地表植被管理及人工林管理优化...     

Density of tiger and leopard in a tropical deciduous forest of Mudumalai Tiger Reserve,southern India,as estimated using photographic capture–recapture sampling

Density of tiger Panthera tigris and leopard Panthera pardus was estimated using photographic capture–recapture sampling in a tropical deciduous forest of Mudumalai Tiger Reserve, southern India, from November 2008 to February 2009. A total of 2,000 camera trap nights for 100 days yielded 19 tigers and 29 leopards within an intensive sampling area of 107 km². Population size of tiger from closed population estimator model M_b Zippin was 19 tigers (SE = ±0.9) and for leopards M_h Jackknife estimated 53 (SE = ±11) individuals. Spatially explicit maximum likelihood and Bayesian model estimates were 8.31 (SE = ±2.73) and 8.9 (SE = ±2.56) per 100 km² for tigers and 13.17 (SE = ±3.15) and 13.01 (SE = ±2.31) per 100 km² for leopards, respectively. Tiger density for MMDM models ranged from 6.07 (SE = ±1.74) to 9.72 (SE = ±2.94) per 100 km² and leopard density ranged from 13.41 (SE = ±2.67) to 28.91 (SE = ±7.22) per 100 km². Spatially explicit models were more appropriate as they handle information at capture locations in a more specific manner than some generalizations assumed in the classical approach. Results revealed high density of tiger and leopard in Mudumalai which is unusual for other high density tiger areas. The tiger population in Mudumalai is a part of the largest population at present in India and a source for the surrounding Reserved Forest.     

Population densities,group size and biomass of ungulates in a lowland tropical rainforest forest of the eastern Himalayas

Large ungulate population monitoring is a crucial wildlife management tool as ungulates help in structuring and maintaining the large carnivore populations. Reliable data on population status of major ungulate prey species are still non-existent for most of the protected areas in the Indian part of the eastern Himalayan biodiversity hotspot. Twenty transects were monitored over a period of three years (2009–2011) totaling 600 km with an average length of 2 km. The estimated mean density of ungulates was 17.5 km⁻² with overall density of 48.7 km⁻². The wild pig Sus scrofa had the highest density (6.7 ± 1.2 km⁻²) among all the prey species followed by barking deer Muntiacus muntjak (3.9 ± 0.6 km⁻²), sambar Rusa unicolor (3.8 ± 0.5) and gaur Bos gaurus (3.5 ± 0.9 km⁻²). The estimated total ungulate biomass density was 2182.56 kg km⁻². This prey biomass can support up to 7.2 tigers per 100 km⁻². However, with two other sympatric carnivores sharing the same resources, the actual tiger numbers that can be supported will be lower. The estimated minor prey species was 31 km⁻² significantly 30.6% crop damages were reported by wild pig (p = 0.01) and 35.4% was elephant (p = 0.004). This data on ungulate densities and biomass will be crucial for carnivore conservation in this understudied globally significant biodiversity hotspot.     

Reproductive success of wild Lesser Rheas (Pterocnemia -Rhea- pennata pennata) in north-western Patagonia, Argentina

We studied the reproductive success of a wild Lesser Rhea population (Pterocnemia -Rhea- pennata pennata) during two reproductive seasons (2004/2005 and 2005/2006) in north-western Patagonia, Argentina. The parameters recorded included population and nest density, clutch size, hatching success, chick survival (up to 3 months of age) and percentage of chicks that reached the juvenile stage after the winter. We also estimated the percentage of males that attempted to nest and of those that were successful (those producing at least one chick), daily nest mortality rates (DNMR) at different stages of the nesting cycle and the probability that an egg that has been recently laid will produce a chick. On average, both years pooled, the density of this population of Lesser Rheas was 1.55 ± 0.2 individuals/km² (SE), nest density was 0.17 ± 0.04 per km ² , clutch size was 20.8 ± 6.4 eggs, hatching success was 74.4% ± 11.3, Mayfield’s probability of an egg that will produce a chick was 0.64, chick survival was 65.4% ± 14.5 and percentage of chicks that reached the juvenile stage was 26.3%. Nearly a quarter of Lesser Rhea males in the population attempted to nest during a breeding season, and the DNMR was significantly higher during the laying stage (most nest failures were due to anthropogenic disturbances related to livestock raising activities). Nesting success, hatching success, and chick survival of Lesser Rheas were higher than those of their most closely related species, the Greater Rhea (Rhea americana), whereas the percentage of chicks that reached the juvenile stage was similar due to high winter mortalities of chicks. We suggest that the increase in reproductive effort is a strategy of this species to overcome environmental constraints.     

麋鹿鹿角脱落、群主更替、产仔的年节律及其环境影响因子

本文在2014—2016年三个冬季(12月—翌年2月)收集了北京南海子麋鹿苑半散放麋鹿自然脱落的角,并观察和记录了2015—2017年发情期(5—9月)群主更替和2016—2018年产仔期(3—7月)麋鹿幼仔出生情况,结合2014—2018年年平均气温、季平均气温、月平均气温、年降雨量、雨季开始时间、种群密度等环境因子,对鹿角脱落、群主更替、产仔等繁殖特征的年节律及其环境影响因子进行了研究。结果表明：1)麋鹿鹿角脱落、群主更替、产仔的年节律均存在年际差异。2)鹿角脱落时间为12月开始,1月下旬或2月上旬结束。3)发情期为5月下旬或6月上旬开始,9月上旬结束;2015—2017年发情期时间有延长的趋势。4)产仔期为3月中旬或4月中旬开始,5月下旬或7月下旬结束。5)麋鹿鹿角脱落、群主更替、产仔的年节律存在明显的同步关系,其中鹿角脱落开始时间、鹿角脱落高峰期、鹿角脱落结束时间、第一次发情期开始时间、群主更替高峰期、产仔期开始时间、产仔高峰期、产仔期结束时间与前一年度比较均出现同步提前的现象。6)鹿角脱落年节律存在随着12月平均气温升高而提前的现象;产仔期开始时间和产仔高峰期存在随着前一年9月平均气温的升高而提前的现象。7)鹿角脱落年节律表现出随着年降雨量的增多而提前的现象;第一次发情期开始时间、群主更替高峰期的年节律表现出随着前一年度年降雨量的增多而提前的现象。8)麋鹿鹿角脱落、群主更替、产仔的年节律均不存在随着种群密度升高或降低而提前或延迟的现象。麋鹿繁殖特征的年节律是一个复杂的过程,受气候、营养、种群密度、纬度等环境因子的影响。     

内蒙古贺兰山冬春季岩羊种群现状及保护

为调查内蒙古贺兰山国家级自然保护区内岩羊（Pseudois nayaur alashanicus）的种群现状,通过样线法在2017、2018年冬季,2018、2019年春季进行了调查,利用R 4.0.3中的Distance 1.0.2对样线观测数据进行分析,估测保护区内岩羊的种群数量及密度,分析其种群结构。结果显示,调查共观测到岩羊6299只,其中,2018年冬季种群数量最高,约为2654（2230-3161）只（括号内为95%数量置信区间）,种群密度为3.921（3.293-4.668）只/km²。与2003年同季节的调查数据对比发现,保护区内岩羊的种群数量在15年间增长迅速,岩羊的种群密度累计增长了约53.17%,年平均增长3.54%。岩羊集群形式：混合群（88.03%,80.95%）为岩羊冬、春最主要的集群形式,且混合群的数量冬季多于春季,独羊出现的次数最低（1.99%,2.86%）,不同的集群类型在不同的季节的差异极显著（P<0.001）;岩羊平均群大小：春季为（13.439±12.085）只,冬季为（9.011±8.610）只,调查季节中集群大小多为1-10只,岩羊的不同季节的群大小差异极显著（P<0.001）。种群成体与幼体比在不同季节的变化范围为1.411-2.673,雌雄比在不同季节的变化范围为0.934-1.469,种群结构的季节性差异极显著（P<0.001）。集群类型、群大小及群组成的调查表明,不同季节间岩羊种群结构差异明显。     

The density and stability of birds in shrubland and drainage line woodland in the southern Karoo,South Africa

Comparative surveys of bird species richness and abundance showed that a total of 69 bird species was recorded on 1 km transects (n = 996) through shrubland, with a total estimated density of birds of 32.7 ± 32.8 (S.D.) birds/km², of which resident birds made up 24.4 ± 21.0 birds/km², nomads made up 1.9 ± 11.7 birds/km² and local nomads made up 6.3 ± 20.1 birds/km². There was no correlation in general between total bird numbers or total bird biomass and rain, but numbers and biomass of nomads showed the strongest correlations with rainfall two months previously. A total of 86 species was recorded on 276 surveys along a 1 km stretch of drainage line woodland. Species richness varied from an average of about nine species to 24 species each month, and only showed a marked change during the 'dry' period of 1990 to early 1991. Density of birds in this woodland was 59.2 ± 20.8 birds/km. Biomass of birds was relatively constant throughout the study period, with marked increases in certain months when large species were present.     

Evaluating Methods for Counting Cryptic Carnivores

ABSTRACT Numerous techniques have been proposed to estimate carnivore abundance and density, but few have been validated against populations of known size. We used a density estimate established by intensive monitoring of a population of radiotagged leopards (Panthera pardus) with a detection probability of 1.0 to evaluate efficacy of track counts and camera-trap surveys as population estimators. We calculated densities from track counts using 2 methods and compared performance of 10 methods for calculating the effectively sampled area for camera-trapping data. Compared to our reference density (7.33 ± 0.44 leopards/100 km²), camera-trapping generally produced more accurate but less precise estimates than did track counts. The most accurate result (6.97 ± 1.88 leopards/100 km²) came from camera-trap data with a sampled area buffered by a boundary strip representing the mean maximum distance moved by leopards outside the survey area (MMDMOSA) established by telemetry. However, contrary to recent suggestions, the traditional method of using half the mean maximum distance moved from photographic recaptures did not result in gross overestimates of population density (6.56 ± 1.92 leopards/100 km²) but rather displayed the next best performance after MMDMOSA. The only track-count method comparable to reference density employed a capture-recapture framework applied to data when individuals were identified from their tracks (6.45 ± 1.43 leopards/100 km²) but the underlying assumptions of this technique limit more widespread application. Our results demonstrate that if applied correctly, camera-trap surveys represent the best balance of rigor and cost-effectiveness for estimating abundance and density of cryptic carnivore species that can be identified individually.     

宁夏贺兰山国家级自然保护区岩羊(Pseudois nayaur)种群数量及结构

为了解宁夏贺兰山岩羊的种群现状,2020-2021年的8月和12-1月,在宁夏贺兰山国家级自然保护区运用样线法对岩羊（Pseudois nayaur）进行种群数量调查,利用R 4.0.1中的Distance 1.0.2对样线观测数据进行分析,估测保护区内岩羊的种群数量及密度,分析其种群结构。结果显示,夏季岩羊种群数量为5176（2554-10490）只,种群密度为2.674（1.320-5.420）只/km²;冬季岩羊种群数量为15752（7294-34017）只,种群密度为8.139（3.769-17.58）只/km²;多数观测距离样线垂直距离在0-200 m之内。岩羊主要集群形式：夏季为雌幼群（52.17%）;冬季为混合群（26.60%）。岩羊平均群大小：夏季为（6.261±8.023）只,冬季为（4.064±4.229）只,群大小在不同季节的差异显著（P=0.010）,集群大小多集中于1-5只之间,最大为47只。夏季调查中,雄性个体占比11.27%,雌性个体占比56.74%,幼体/亚成体占比31.99%;冬季调查中,雄性个体占比29.61%,雌性个体占比50.15%,幼体/亚成体占比20.24%;夏季和冬季岩羊组成成分之间差异极显著（P<0.001）。     

Home Range and Population Density of Fishers in Eastern Ontario

Abstract: Fishers (Martes pennanti) were almost extirpated in Ontario, Canada, south of the French and Mattawa rivers by the 1940s but have recolonized much of their former range over the past several decades. We assessed the effect of the current harvest quota on a fisher population in eastern Ontario by estimating home range size and population density from a sample of radiocollared animals. Mean (± SD) adult home ranges (based on annual 95% min. convex polygons) were consistently smaller than those reported in the literature (M: 11 ± 4.4 km²; F: 2.1 ± 0.8 km²), with up to 71% overlap of adjacent intrasexual home ranges. This yielded an estimated adult fisher population density of 32.7/100 km² of suitable habitat, as defined by the habitat composition within observed home ranges. We further estimated that between 2003 and 2005, trappers harvested 17.8-42.3% of the pretrapping population. These results suggest that although current fisher population density is high in our study area compared to reported densities in other areas, harvest rate is also high and an increase in quota is unwarranted.     

Survey of Hylobates agilis albibarbis in a logged peat-swamp forest: Sabangau catchment, Central Kalimantan

Few data are available on gibbon populations in peat-swamp forest. In order to assess the importance of this habitat for gibbon conservation, a population of Hylobates agilis albibarbis was surveyed in the Sabangau peat-swamp forest, Central Kalimantan, Indonesia. This is an area of about 5,500 km² of selectively logged peat-swamp forest, which was formally gazetted as a national park during 2005. The study was conducted during June and July 2004 using auditory sampling methods. Five sample areas were selected and each was surveyed for four consecutive days by three teams of researchers at designated listening posts. Researchers recorded compass bearings of, and estimated distances to, singing groups. Nineteen groups were located. Population density is estimated to be 2.16 (±0.46) groups/km². Sightings occurring either at the listening posts or that were obtained by tracking in on calling groups yielded a mean group size of 3.4 individuals, hence individual gibbon density is estimated to be 7.4 (±1.59) individuals/km². The density estimates fall at the mid-range of those calculated for other gibbon populations, thus suggesting that peat-swamp forest is an important habitat for gibbon conservation in Borneo. A tentative extrapolation of results suggests a potential gibbon population size of 19,000 individuals within the mixed-swamp forest habitat sub-type in the Sabangau. This represents one of the largest remaining continuous populations of Bornean agile gibbons. The designation of the Sabangau forest as a national park will hopefully address the problem of illegal logging and hunting in the region. Further studies should note any difference in gibbon density post protection.     

Historical range and movements of the Elephants in Babile Elephant Sanctuary,Ethiopia

A study on historical range and movement patterns of the African savannah elephants (Loxodonta africana africana) in Ethiopia was made from December 2004 to November 2008. Babile Elephant Sanctuary is one of the strongholds of elephants in the country, where it now supports approximately 27% of the elephant population in Ethiopia. Elephant movement routes and ranges were identified based on interviews of local people and by tracking the animals in the field. Elephants of the Sanctuary were categorized into two distinctive groups or clans based on their movement patterns and their associations to each other. Three major valleys, namely Gobele, Erer and Dakata, were crossed by elephants. Elephants in the population had an estimated annual range of 3014 km². Of this, 85.7% (2583 km²) was inside the Sanctuary and 14.3% (430 km²) outside but adjacent to the Sanctuary. Elephant use outside of the Sanctuary included three different areas: Upper Erer Valley (8 km²), Upper Gobele Valley (48 km²) and west of Gobele Valley (374 km²). The extent of range varied seasonally. During the wet season, elephant range was restricted to Erer Valley and its tributaries (1266 km² and a density of approximately 0.25 animal km^?2), or 42% smaller than the dry season range (1417 km², 0.23 elephant km^?2). Range use was smallest (332 km²) in October to November and from April to May. During the dry season, elephants were found in two distinctive groups, one using Gobele Valley and the other Erer Valley.     

Determinants of age at first reproduction and lifetime breeding success revealed by full paternity assignment in a male ungulate

Age at first reproduction is an important determinant of individual variation in reproductive success in ungulates, but few studies have examined its relationship with later fitness‐related traits in males. We used a long‐term individual based study of a harvested moose population to quantify the individual reproductive performance and survival of males, as well as to examine the determinants of age at first reproduction and consequences of age at first reproduction on lifetime breeding success. The probability that a male successfully reproduced at the age of two was negatively related to the mean age of adult males in the population, but the relationship weakened with increasing population size. Large antlers and large body mass relative to other males in the population increased the number of calves sired at their first successful mating season. In addition, those that successfully reproduced as two year‐olds were more likely to sire calves the next year, making them more productive at a given age compared to those that first reproduced at the age of three or older. We emphasize the importance for males to start reproducing as soon as possible in a harvested population to gain lifetime fitness benefits, as surviving the hunt is a major determinant of reproductive success in this population. We found no costs of early reproduction in males, hence leading to high individual heterogeneity in male reproductive performance. The apparent lack of reproductive costs could partly be explained by the age distribution in the population, individual variation in early‐life body mass and antler size, and differences in probabilities of being hunted of successful and unsuccessful males.     

Hyper‐abundance of Native Wild Pigs (Sus scrofa) in a Lowland Dipterocarp Rain Forest of Peninsular Malaysia1

This study reports extraordinarily high density estimates for the wild pig (Sus scrofa) from an aseasonal tropical forest site within the species'native range. At Pasoh Forest Reserve, a 2500 ha area of lowland dipterocarp rain forest in Peninsular Malaysia, line transects were used to estimate pig density from May to October in 1996 and 1998. In 1996, 44 sightings of S. scrofa consisting of 166 individuals were recorded along 81 km of transects. In 1998, 39 sightings documented 129 individuals along 79.9 km of transects. Estimated population density was 47.0 pigs/km² in 1996 and 27.0 pigs/km²‐ in 1998. Sus scrofa biomass in this forest was estimated at 1837 kg/km² and 1346 kg/ km² in 1996 and 1998, respectively. Differences between years were attributed to changes in the density of young pigs, coincident with a mast‐seeding year of dipterocarp trees in 1996. Pig densities at Pasoh Forest Reserve were much higher than at other forest locations within the species' native range in Europe and Asia. Because Pasoh Forest Reserve is a forest fragment, two factors likely account for the extremely high pig densities: (1) local extinction of natural predators (mainly tigers and leopards) and (2) an abundant year‐round food supply of African oil palm fruits from extensive plantations bordering the reserve.