Double-check in Lizard Age Estimation:Use of Phalanx Bone and Keratin Claw Sheath Lamellas

Dear Editor,The problem of age estimation in amphibians and reptiles with annual fluctuations of growth pattern has been considered to be mostly solved since the skeletochronological method was introduced(Kleinenberg and Smirina,1969).This method is based on counting the number of lines of arrested growth(LAGs)—cyclical growth marks that are usually formed annually and characterized by different optical aspects within the tubular bones.

On the road to Mandalay: contribution to the Microhyla Tschudi, 1838(Amphibia: Anura: Microhylidae) fauna of Myanmar with description of two new species

We prese nt a morphological and molecular assessment of the Microhyla fauna of Myanmar based on new collections from central (Magway Division) and northem (Kachin State) parts of the country. In total, six species of Microhyla are documented, including M. berdmorei, M. heymonsi, M. butleri, M. mukhlesuri and two new species described from the semi-arid savarma-like plains of the middle part of the Irrawaddy (Ayeyarwady) River Valley. We used a 2 481 bp long 12S rRNA- 16S rRNA fragment of mtDNA to hypothesize gen ealogical relati on ships within Microhyla. We applied an in teg rati ve taxonomic approach combining molecular, morphological, and acoustic lines of evidenee to evaluate the taxonomic status of Mya nmar Microhyla. We dem on strated that the newly discovered populations of Microhyla sp. from the Magway Division represent two yet undescribed species. These two new sympatric species are assigned to the M. achatina species group, with both adapted to the seas on ally dry environments of the Irrawaddy Valley. Microhyla fodiens sp. nov. is a stout-bodied species with a remarkably enlarged shovel-like outer metatarsal tubercle used for burrowing and is highly diverge nt from other know n congeners (P-distancea8.8%). Microhyla irrawaddy sp. nov. is a small-bodied slender frog reconstructed as a sister species to M. kodial from southern India (P-distance=5.3%);however, it clearly differs from the latter both in external morphology and advertisement call parameters. Microhyla mukhlesuri is reported from Myanmar for the first time. We further discuss the morphological diag no sties and biogeography of Microhyla species recorded in Myanmar.

Do Larger and Older Individuals Occupy Better Areas in the Colony of Qinghai Toad-headed Agamas?

Group living reduces the chances of predation.This is also true for burrowing animals,which use burrows as refuges to escape predators.Living in the center of a colony is the safest because it offers access to the greatest number of burrows;however,it is stressful due to frequent aggressive interactions there.We predicted that larger and older animals should occupy areas of a colony with a higher density of burrows than smaller and younger ones.To test this prediction,we observed individually marked Qinghai toad-headed agamas(Phynocephalus vlangalii)from a single colony late in the breeding season when females were gravid.Density of burrows was the highest and distance between them the shortest in the center of the colony.Aggressive encounters were more frequent in the central part of the colony than on its periphery.We found a negative correlation between body size and distance to the center of the colony for females,but not for males.There was no such correlation between age of individuals and distance to the center of the colony.Females in this species likely compete with other females and males for central burrows in the colony even after mating season finishes.We suggest that gravid females likely compete for the dense burrows within the central part of the colony mainly due to their relatively lower sprint speed and higher probability of being caught by a predator if they are not refuged in a burrow.

A new species of Nanohyla(Anura:Microhylidae)from the lowland forests of southern Vietnam

DEAR EDITOR,We describe a new species of Nanohyla from the Song Hinh Protected Forest in Phu Yen Province,southern Vietnam,based on an integrative taxonomic approach.The new species represents a divergent lineage(16S rRNA gene uncorrected P-distance>5.3%),which clearly differs from any other Nanohyla species based on a series of morphological characters,most notably the presence of white spots on the top of its head.Morphologically,Nanohyla albopunctata sp.nov.is characterized by small body size(male snout-vent length(SVL)18.2-20.2 mm);moderately slender body habitus;rounded snout;distinct tympanum;rounded canthus rostralis;loreal region slightly concave;skin on dorsum tubercular,ventral surfaces smooth;mid-vertebral skin ridge and dorsomedial stripe absent;superciliary tubercles absent.

Effects of temperature and resource abundance on small- and large-bodied cladocerans: Community stability and species replacement

Understanding when small- or large-bodied cladocerans dominate zooplankton communities has received considerable debate over the past 50 years. While a large body of research has proposed that large-bodied species are superior competitors over small-bodied species, other studies have shown that small-bodied species can dominate at least under some environmental conditions. We tested the hypothesis that dominance by small- and large-bodied cladocerans varied in response to the coupled effects of food supply and temperature. Laboratory experiments with poly- and monocultures of small- and large-bodied cladocerans were performed at three temperatures (16°C, 22°C and 27°C) and with varying amounts of food supply. The results of the experiments showed that the small-bodied species (Ceriodaphnia quadrangula) dominated at low food supply and higher temperature, while the large-bodied species (Daphnia magna and Daphnia pulex) in contrast dominated at lower temperature and higher food supply. Furthermore, although there were variations in the relative biomass of the small- and large-bodied cladocerans in the polycultures, C. quandrangula replaced the two larger Daphnia species when they declined in biomass at low food supply. Species replacement in response to temperature and food supply helped to maintain the relatively constant level of total cladoceran biomass in the polycultures which was the most pronounced at the intermediate temperature. We suggest that the observed changes in dominance were similar to facilitative replacement rather than competitive exclusion. Physiological processes such as clearance rates can help to promote the succession of large- and small- bodied populations within a community along gradients of temperature and food availability.

Topology in Biology: Singularities and Surgery Transformations in Metazoan Development and Evolution

The review presents a topological description and interpretation (analysis) of some events in metazoan development and evolution through the use of well-known mathematical concepts and theorems (using topological approach). It is the topological language that can provide strict and adequate description of various phenomena in developmental and evolutionary transformations. Topological singularities inevitably arising and transforming during early development destroy the preexisting pattern of symmetry. The symmetry breaking of preexisting spatial pattern plays a critical role in biological morphogenesis in development and evolution. Some events of early development are interpreted in terms of symmetry breakdown and related to well-known mathematical theorems. A topological inevitability of some developmental events through the use of classical topological concepts is discussed. The topological approach makes it possible to consider the succession of spherical surgeries, which change the topological genus of an animal body surface. We model the biological shape as a set of smooth, closed, oriented surfaces—membrane or epithelial layers. Membrane and epithelial surfaces are boundary layers, interfaces between a living structure and its environment, ensuring metabolism. Toroid forms as well as fractal structures in metazoans can be considered as functionally optimized biological design and attractors in biological morphogenesis. The epithelial surface is an interface between the internal medium of an organism and the outside environmental medium;topological and fractal transformations during metazoan evolution and development increase this interface, ensuring better adaptation of organism to the environment. Fractal structures as well as toroid forms can be considered as a functionally optimized design in Metazoa. Topological methodology reveals a certain set of topological rules constraining and directing biological morphogenesis during evolution and development.

Analysis of Diagnostic Efficiency of Excretory-Secretory Antigens for <i>Trichinella spiralis</i>and <i>Trichinella nativa</i>in ELISA

The comparative studies of diagnostic efficiency of excretory-secretory antigens of Trichinella spiralis and Trichinella nativa were performed using blood sera of rats from Wistar line experimentally infected with Arctic trichinellae. For animal infection and antigen preparation Trichinella from muscles of wild carnivorous mammals from Arctic regions of Russia were used. When antigen from T. nativa larvae was used to analyze titers of sera of rats experimentally infected with Arctic Trichinella, a significant increase in efficacy ofELISAwas detected. E.g., sera of rats infected with trichinellae from ringed seals retained in ELISA with T. nativa antigen values higher than diagnostic level at titers of 1:6400 - 1:12800, while titer of those same sera when using T. spiralis antigen was no higher than 1:200 - 1:400.

Pine wilt disease: a short review of worldwide research

This article summarizes the results of the research papers presented at the International Symposium on pine wilt disease （IUFRO Working Party Meeting 4.04.03） held in July 2009, at Nanjing, China. The general topics covered were on pine wilt disease （PWD）, its causal organism, the pinewood nematode （PWN） Bursaphelenchus xylophilus, plus other PWN-associated microorganisms that play a significant role in PWD such as bacteria （e.g. Pseudomonasfluorescens）. Most of the papers that are reviewed are based on work on PWD-PWN in East Asia and Russia. Specific topics covered include： 1） the fundamental conceptions of PWD development, 2） pathogenicity, 3） host-parasite relationships including the histopathology of diseased conifers and the role of toxins from bacteria-nematode ecto-symbionts, 4） PWN life cycle and transmission, 5） B. xylophilus dissemination models, 6） associations （with other nematodes）, 7） diagnostics, 8） quarantine and control of the PWN and 9） biocontrol of the PWN.

A new species of the genus Theloderma Tschudi, 1838 (Amphibia： Anura： Rhacophoridae) from Tay Nguyen Plateau, central Vietnam

A new species of small tree frog from a primary montane tropical forest of central Vietnam, Tay Nguyen Plateau, is described based on morphological, molecular, and acoustic evidence. The Golden Bug-Eyed Frog, Theloderma auratum sp. nov., is distinguishable from its congeners and other small rhacophorid species based on a combination of the following morphological attributes： （1） bony ridges on head absent; （2） smooth skin completely lacking calcified warts or asperities; （3） pointed elongated tapering snout; （4） vocal opening in males absent; （5） vomerine teeth absent; （6） males of small body size （SVL 21.8-26.4 mm）; （7） head longer than wide; ED/SVL ratio 13%-15%; ESL/SVL ratio 16%-20%; （8） small tympanum （TD/EL ratio 50%-60%） with few tiny tubercles; （9） supratympanic fold absent; （10） ventral surfaces completely smooth; （11 ） webbing between fingers absent; （12） outer and inner metacarpal tubercles present, supernumerary metacarpal tubercle single, medial, oval in shape; （13） toes half-webbed： I 2-21/4 II 11/^-23/~ III 2-31/4 IV 3-11/2 V; （14） inner metatarsal tubercle present, oval; outer metatarsal tubercle absent; （15） iris bicolored; （16） dorsal surfaces golden-yellow with sparse golden-orange speckling or reticulations and few small dark-brown spots; （17） lateral sides of head and body with wide dark reddish-brown to black lateral stripes, clearlyseparated from lighter dorsal coloration by straight contrasting edge; （18） ventral surfaces of body, throat, and chest greyish-blue with indistinct brown confluent blotches; （19） upper eyelids with few （3-5） very small flat reddish superciliary tubercles; （20） limbs dorsally reddish-brown, ventrally brown with small bluish-white speckles. The new species is also distinct from all congeners in 12S rRNA to 16S rRNA mitochondrial DNA fragment sequences （uncorrected genetic distance P〉8.9%）. Advertisement call and tadpole morphology of the new species are described. Our molecular data showed Theloderma auratum sp. nov. to be a sister species of Th. palliatum from Langbian Plateau in southern Vietnam.

Population response of rodents to control with rodenticides

We summarize theoretical approaches and practice of rodent pest control in Russia and former USSR during last 50 years. We review literature as well as original data to understand mechanisms of rodent populations recovery after chemical control campaigns in urban areas, agricultural lands and natural foci of plague. Laboratory and field experiments indicate that inherent individual variation in behavioural, physiological and life-history traits provides survival of heterogeneous mix of individuals in residual population with increased resistance to poisonous baits and high reproductive potential that leads to fast recovery of a population. In a series of field experiments with various rodent and lagomorph species （Mus musculus, Rattus norvegicus, Meriones unguiculatus, M. meridianus, M. tamariscinus, Ochotona pallasii ） we have shown that patterns of recolonization of depopulated area and mechanisms of population recovery vary among species and depend on species-specific social organization. After control territorial and group-living species demonstrated an increase in mobility and affiliative and marking behaviour and a decrease in intraspecific aggression. The rate of recolonization of treated areas was high due to redistribution of survived individuals and immigration by neighbors. Population recovered to original level due to increased breeding performance and fecundity of both survived residents and immigrants. In contrast, socially-independent species exhibited minor changes in behaviour. Recolonization was mainly due to better survival and recruitment of youngs, so the rate of recolonization was low. Species-specificity of behavioural compensation mechanisms to control should be considered when developing ecologically based rodent management strategies

Soil respiration in paludified forests of European Russia

Soil respiration studies in paludified forests of the European part of Russia are quite rare in comparison with those of open peat bogs,which make long-term observations in this region highly relevant.In this study,soil CO2 emissions were measured by the close chamber method in different microlandscapes of paludified forests.For four summer seasons with different environments,soil respiration ranged from 1078 to 248 mg CO2 m^-2 h^-1 in a paludified spruce forest site with coarse woody debris to 659–820 mg CO2 m^-2 h^-1 in a paludified boggy pine forest.The most intensive soil respiration was observed during the hot summer of 2013 and the lowest in the hot and humid summer of 2016.Annual total soil CO2 emissions in paludified forests in 2015–2016 were approximately 2000–3000 g CO2 m-2.During the year,the lowest CO2 emission values were observed from November to April(14–84 mg CO2 m^-2 h^-1)and the maximum were in July and August(522–1205 mg CO2 m^-2 h^-1).The contributions of CO2 emissions in the cold November–April period were 6–8.5%.The impacts of temperature on soil respiration were higher(r2=0.45–0.57)than those of groundwater levels(r^2=0.17–0.49).Soil respiration in the paludified spruce forest and in the pine bog generally were higher than emissions from ecosystems with similar hydrothermal conditions in the boreal zone.

Impacts of late Quaternary environmental change on the long-tailed ground squirrel(Urocitellus undulatus)in Mongolia

Impacts of Quaternary environmental changes on mammal faunas of central Asia remain poorly understood due to a lack of comprehensive phylogeographic sampling for most species.To help address this knowledge gap,we conducted the most extensive molecular analysis to date of the long-tailed ground squirrel （Urocitellus undulatus Pallas 1778） in Mongolia,a country that comprises the southern core of this species＇ range.Drawing on material from recent collaborative field expeditions,we genotyped 128 individuals at two mitochondrial genes （cytochrome b and cytochrome oxidase Ⅰ;1797 bp total）.Phylogenetic inference supports the existence of two deeply divergent infraspecific lineages （corresponding to subspecies U.u.undulatus and U.u.eversmanni）,a result in agreement with previous molecular investigations but discordant with patterns of range-wide craniometric and external phenotypic variation.In the widespread western eversmanni lineage,we recovered geographically-associated clades from the：（a） Khangai,（b） Mongolian Altai,and （c） Govi Altai mountain ranges.Phylogeographic structure in U.u.eversmanni is consistent with an isolation-by-distance model;however,genetic distances are significantly lower than among subspecies,and intra-clade relationships are largely unresolved.The latter patterns,as well as the relatively higher nucleotide polymorphism of populations from the Great Lakes Depression of northwestern Mongolia,suggest a history of range shifts into these lowland areas in response to Pleistocene glaciation and environmental change,followed by upslope movements and mitochondrial lineage sorting with Holocene aridification.Our study illuminates possible historical mechanisms responsible for U.undulatus genetic structure and contributes to a framework for ongoing exploration of mammalian response to past and present climate change in central Asia.

Ecology and social behavior of the tamarisk gerbil Meriones tamariscinus: insights from long-term research in the wild and semi-natural environments

The present review provides a compilation of the published data on the ecology and social behavior of tamarisk gerbils. Both field studies anddirect observations under semi-natural conditions provide evidence that the tamarisk gerbil is a nocturnal herbivorous rodent that lives in highlyseasonal habitats and displays seasonal fluctuations in reproduction and spatial organization. A typical feature of the tamarisk gerbils’ spatialorganization is higher mobility of males during the breeding season (as compared with the nonbreeding period) and formation of temporaryaggregations of males competing for access to receptive females;the composition of these aggregations was variable and depended on thereproductive condition of the females. Females tend to occupy exclusive home ranges irrespective of their reproductive condition. The matingsystem of the species can be defined as scramble competition polygyny with some features of polygynandry and promiscuity. The tamariskgerbil has distinct features of a solitary species and its social structure is primarily based on aggressive interactions or mutual avoidance ofconspecifics resulting in a dominance hierarchy among males and site-dependent dominance among females during the breeding season. Bythe end of the breeding season, males become less mobile and occupy nearly exclusive home ranges, consistent with solitary living. The mainfeatures of the spatial and social organization of this species, which distinguish it from other solitary rodents, are the higher mobility of malesand the formation of temporary multimale–multifemale aggregations during the breeding season. Overall, the data presented expand our understanding of socioecology of gerbils.

Previously unknown behavior in parasitic cuckoo females:male-like vocalization during migratory activity

Background:In the last decade,enigmatic male-like cuckoo calls have been reported several times in East Asia.These calls exhibited a combination of vocal traits of both Oriental Cuckoo(Cuculus optatus)and Common Cuckoo(Cuculus canorus)advertising calls,and some authors therefore suggested that the enigmatic calls were produced by either Common×Oriental Cuckoo male hybrids or Common Cuckoo males having a gene mutation.However,the exact identity of calling birds are still unknown.Methods:We recorded previously unknown male-like calls from three captive Oriental Cuckoo females,and compared these calls with enigmatic vocalizations recorded in the wild as well as with advertising vocalizations of Common and Oriental Cuckoo males.To achieve this,we measured calls automatically.Besides,we video-recorded captive female emitting male-like calls,and compared these recordings with the YouTube recordings of calling males of both Common and Oriental Cuckoos to get insight into the mechanism of call production.Results:The analysis showed that female male-like calls recorded in captivity were similar to enigmatic calls recorded in the wild.Therefore,Oriental Cuckoo females might produce the latter calls.Two features of these female calls appeared to be unusual among birds.First,females produced male-like calls at the time of spring and autumn migratory activity and on migration in the wild.Because of this,functional significance of this call remained puzzling.Secondly,the male-like female call unexpectedly combined features of both closed-mouth(closed beak and simultaneous inflation of the‘throat sac')and open-mouth(prominent harmonic spectrum and the maximum neck extension observed at the beginning of a sound)vocal behaviors.Conclusions:The Cuculus vocalizations outside the reproductive season remain poorly understood.Here,we found for the first time that Oriental Cuckoo females can produce male-like calls in that time.Because of its rarity,this call might be an atavism.Indeed,female male-like vocalizations are still known in non-parasitic tropical and apparently more basal cuckoos only.Therefore,our findings may shed light on the evolution of vocal communication in avian brood parasites.

Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation:effects of individual characteristics,environment,and maternal investment

Juvenile survival is a key life-history influence on population dynamics and adaptive evolution.We analyzed the effects of individual chara-cteristics,early environment,and maternal investment on juvenile survival in a large solitary hibernating rodent-yellow ground squirrel Spermophilus fulvus using Cox mixed-effects models.Only 48%of weaned pups survived to dispersal and 17%survived to hibernation.Early life expectancy was primarily determined by individual characteristics and,to a lesser extent,by the early environment.The strongest and pos-itive predictor of juvenile survival was body mass which crucially affected mortality immediately after weaning.Males suffered higher mortality than females after the onset of dispersal;however,the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both sexes.Later emerged juveniles had lower life expectancy than the earliest pups.The overall effect of local juvenile density was positive.Prolonged lactation did not enhance juvenile survival:Pups nursed longer survived shorter than the young nursed for a shorter period.Our findings support the hypothesis that females of S.fulvus cannot effectively regulate maternal expenditures to mitigate the effects of unfavorable conditions on their offspring.The strategy to deal with seasonal time constraints on life history in female S.fulvus suggests an early termination of maternal care at the cost of juvenile quality and survival.This female reproductive strategy corresponds to a"fast-solitary"life of folivorous desert-dwelling S.fulvus and other solitary ground squirrels with prolonged hibernation.

Acoustic complexity of pup isolation calls in Mongolian hamsters: 3-frequency phenomena and chaos

Studying pup isolation calls of wild rodents provides background for developing new early-life animal models for biomedical research and drug testing.This study discovered a highly complex acoustic phenotype of pup isolation calls in 4–5-day-old Mongolian hamsters Allocricetulus curtatus.We analyzed the acoustic structure of 5,010 isolation calls emitted in the broad range of frequencies(sonic,below 20 kHz,and ultrasonic,from 20 to 128 kHz)by 23 pups during 2-min isolation test trials,1 trial per pup.In addition,we measured 5 body size parameters and the body weight of each pup.The calls could contain up to 3 independent fundamental frequencies in their spectra,the low(f0),the medium(g0),and the high(h0),or purely consisted of chaos in which the fundamental frequency could not be tracked.By presence/absence of the 3 fundamental frequencies or their combinations and chaos,we classifed calls into 6 distinctive categories(low-frequency[LF]-f0,LF-chaos,high-frequency[HF]-g0,HF-h0,HF-g0+h0,and HF-chaos)and estimated the relative abundance of calls in each category.Between categories,we compared acoustic parameters and estimated their relationship with pup body size index.We discuss the results of this study with data on the acoustics of pup isolation calls reported for other species of rodents.We conclude that such high complexity of Mongolian hamster pup isolation calls is unusual for rodents.Decreased acoustic complexity serves as a good indicator of autism spectrum disorders in knockout mouse models,which makes knockout hamster models prospective new wild animal model of neurodevelopmental disorders.

Ecology and social behavior of the social vole Microtus socialis: A generalized review

The present review is a compilation of the published data on the ecology and social behavior of the social vole.Field studies provide evidence that these voles live in family groups consisting of 1 adult male,1 or 2 breeding females,and their offspring(1 or 2 litters).The social vole is capable of year-round reproduction,but in arid regions,the voles demonstrate seasonality in breeding.The mating system of this species may be defined as behavioral monogamy.A typical feature of the space use system is territoriality characterized by a locus-dependent dominance in relationships between neighboring breeding pairs as well as family groups.The family group social organization may be defined as consistent relationships without a dominant hierarchy.Social voles are cooperative in defending their territories,constructing burrows,digging underground tunnels,maintaining nests,and raising young.Cooperation appears to enhance the survival of family groups of this species under the extreme climaticconditionsof Central Asia.

A new aberrant species of the genus Sphaerostoma (Trematoda: Opecoelidae) from the Amur River basin

A new freshwater opecoelid species,Sphaerostoma tamarae sp.nov.,is described from Rhynchocypris percnura mantschurica caught in the Syumnyur River(Amur River basin,Russia).This parasite species differs from all other congeners in the distribution of the vitelline follicles(restricted to the hindbody)and the morphology of the ventral sucker(strongly protuberant).Molecular phylogenetic analysis based on 28S rRNA gene sequences and the morphological analysis allow to tentatively assign the new species to the genus Sphaerostoma,without closing the question regarding the true genus affiliation of this species.In addition,the authors provide an argument for renaming the Plagioporinae to the Sphaerostomatinae.

Red River barrier and Pleistocene climatic fluctuations shaped the genetic structure of Microhyla fissipes complex （Anura： Microhylidae） in southern China and Indochina

South China and Indochina host striking species diversity and endemism. Complex tectonic and climatic evolutions appear to be the main drivers of the biogeographic patterns. In this study, based on the geologic history of this region, we test 2 hypotheses using the evolutionary history of Microhyla fissipes species complex. Using DNA sequence data from both mitochondrial and nuclear genes, we first test the hypothesis that the Red River is a barrier to gene flow and dispersal. Second, we test the hypothesis that Pleistocene climatic cycling affected the genetic structure and population history of these frogs. We detect 2 major genetic splits that associate with the Red River. Time estimation suggests that late Miocene tectonic movement associated with the Red River drove their diversification. Species distribution modeling （SDM） resolves significant ecolo- gical differences between sides of the Red River. Thus, ecological divergence also probably promoted and maintained the diversification. Genogeography, historical demography, and SDM associate patterns in southern China with climate changes of the last glacial maximum （LGM）, but not Indochina. Differences in geography and climate between the 2 areas best explain the discovery. Responses to the Pleistocene glacial-interglacial cycling vary among species and regions.

Social structure and space use of Amur tigers(Panthera tigris altaica)in Southern Russian Far East based on GPS telemetry data

To better understand the spatial structure of Amur tigers(Panthera tigris altaica)at the southern edge of their range we fitted 14 tigers(6♀♀and 8♂♂)with 15 GPS-Argos collars between 2008 and 2011 in 2 study sites:the Ussuriskii Reserve of southern Sikhote-Alin and the Land of the Leopard National Park in southwest Primorye,Russian Far East.Fixed kernel estimates of male home ranges were larger than those of female home ranges(P<0.05[mean 95%fixed kernel♀=401±205 km2;mean 95%fixed kernel♂=778±267 km2]).The home range size of females varied greatly,but on average was similar to estimates derived from earlier work further north.Low overlap of adjacent home ranges suggested that females retained exclusive territories.Real core areas of females overlapped only slightly,and remained stable over multiple years.The home ranges of adult males were smaller than those of males to the north,and in contrast to previous studies,high overlap among males indicated the absence of territoriality.Nonetheless,real core areas of males did not overlap,suggesting some spatial separation.In comparison to other tiger populations and other areas of the Russian Far East,the sex ratio in our 2 study areas was highly skewed towards males.We believe this skewed sex ratio resulted in the dissolution of territoriality of males due to an inability to defend individual females,with males resorting to scramble competition for mates.Continued monitoring of these sites to determine whether shifts in the sex ratio might result in a return to male territoriality would provide confirmation of our tentative hypothesis.