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1.
Forest edges are dynamic zones characterized by the penetration (to varying depths and intensities) of conditions from the surrounding environment (matrix) into the forest interior. Although edge effects influence many tropical organisms, they have not been studied directly in primates. Edge effects are particularly relevant to lemurs because of the highly fragmented forest landscapes found in Madagascar. In this study, data are presented regarding how the densities of six lemur species (Avahi laniger, Cheirogaleus major, Eulemur rubriventer, Hapalemur griseus griseus, Microcebus rufus, and Propithecus diadema edwardsi) varied between six 500-m interior transects and six 500-m edge transects in the Vohibola III Classified Forest in SE Madagascar. Diurnal (n = 433) and nocturnal (n = 128) lemur surveys were conducted during June-October 2003 and May-November 2004. A. laniger, E. rubriventer, and H. g. griseus exhibited a neutral edge response (no differences in densities between habitats). M. rufus and P. d. edwardsi had a positive edge response (higher densities in edge habitats), which may be related to edge-related variations in food abundance and quality. Positive edge responses by M. rufus and P. d. edwardsi may ultimately be detrimental due to edge-related anthropogenic factors (e.g., hunting by local people). The negative edge response exhibited by C. major (lower densities in edge habitats) may result from heightened ambient temperatures that inhibit torpor in edge habitats.  相似文献   

2.
I investigated how transect type (trails vs. cut transects) and seasonality influenced density estimates for 5 lemur taxa (Avahi laniger, Cheirogaleus major, Eulemur rubriventer, Hapalemur griseus griseus, and Microcebus rufus) in the Vohibola III Classified Forest in SE Madagascar. I surveyed tree height and diameter and lemur populations from June 1 to December 28, 2004 along 2 1250-m trails local people used and 2 1250-m transects cut parallel to the trails in primary rain forest. Despite dendrometric variations within and between trails and transects, only density estimates of Hapalemur griseus griseus differed significantly by transect type. The spatial variation may be a result of removal by local people of giant bamboo, which is the main food for Hapalemur griseus griseus, along trails. Conversely, seasonality influenced density estimates for Cheirogaleus major, Eulemur rubriventer, Hapalemur griseus griseus, and Microcebus rufus. The temporal variations may be related to seasonal torpor for Cheirogaleus major and increased detection probabilities during periods of fruit exploitation for Eulemur rubriventer, Microcebus rufus, and Hapalemur griseus griseus. Transect type and seasonality did not affect density estimates for Avahi laniger, which may be related to the highly folivorous and low-energy diet of the nocturnal lemur. Researchers surveying lemurs along line transects should be aware that transect selection may influence density estimates for Hapalemur griseus griseus and that seasonality may influence density estimates for Cheirogaleus major, Eulemur rubriventer, Hapalemur griseus griseus, and Microcebus rufus.  相似文献   

3.
I present data on variations in Eulemur fulvus rufus and Lepilemur mustelinus densities as well as tree characteristics (height, diameter and stem frequency) between edge and interior forest habitats in southeastern Madagascar. Line transect surveys were conducted from June 2003 to November 2005 in edge and interior forest habitats in the Vohibola III Classified Forest. Although E. f. rufus densities were significantly lower in edge habitats than in interior habitats, density estimates for L. mustelinus did not differ significantly between habitats. Trees in edge habitats were significantly shorter, had smaller diameters and had lower stem frequencies (for those >25 cm in diameter) than trees in interior habitats. Spatial characteristics of food abundance and quality may explain lemur density patterns in Vohibola III. Low E. f. rufus densities may reduce seed dispersal in edge habitats, which has important consequences for the long-term viability of forest ecosystems in Madagascar.  相似文献   

4.
In order to assess the status of lemurs along the lower reaches of the Mahavavy in north-west Madagascar, we carried out transect line sampling at Anjamena between April and August 1995. These data were complemented by additional absence–presence surveys conducted in 1994 and 1995 in many of the remaining forested areas of the region. This is the first study of lemur population density estimates for the faunal subregion between the rivers Mahavavy and Betisboka. Six sympatric lemurs are found at Anjamena: Cheirogaleus medius, Eulemur fulvus rufus, E. mongoz, Lepilemur sp., Microcebus murinus and Propithecus verreauxi coronatus. Data suggest that in some parts of the region large numbers of lemurs may still be found (E. f. rufus 121 individuals per km2, E. mongoz (45), Lepilemur sp. (110), M. murinus (85) and P. v. coronatus (173)). No density data are provided for C. medius. In conclusion, as high lemur population densities may still be found and, in particular, P. v. coronatus is not known to exist in any protected area, Anjamena could serve as an important addition to the protected area system of north-west Madagascar.  相似文献   

5.
Four forest areas were censused in southeastern Madagascar from June–August 1995 to estimate local population densities and habitat conditions for two threatened subspecies of brown lemur (Eulemur fulvus collaris and Eulemur fulvus albocollaris). Survey transects varied in length (1–3.5 km) and in surveillance frequency (three to seven times). Additional test surveys were conducted at the Parc National de Ranomafana to compare transect methods in an area with known population densities of Eulemur fulvus. Based on these tests, we demonstrate that the use of existing trails for transects can result in a close estimate of local population size, although more replications and longer transects increase precision. Results from regional surveys indicate considerably smaller population densities for E. f. albocollaris (0.086 animals/ha). In contrast, E. f. collaris densities were relatively high (.107 animals/ha) at Midongy‐Sud. We also noted variation among sites in the density of lianas, which was positively correlated with local population density (a possible indication of habitat degradation). More generally, habitats in E. f. albocollaris's range suffered from fragmentation, reduction in forest area, logging, and potentially greater hunting pressure. Based on these results, it is apparent that more immediate steps are necessary to preserve E. f. albocollaris populations and habitats. Am. J. Primatol. 47:51–60, 1999. © 1999 Wiley‐Liss, Inc.  相似文献   

6.
The Fandriana-Marolambo forest corridor is one of the largest (ca. 250,000 ha) and least explored tracts of unprotected forest in southeast Madagascar. Although published range maps show continuous distributions for many lemurs throughout the region, there are few data on lemur community structure in the corridor. We aimed to determine lemur community structure, with its ecological correlates (altitude, agriculture, selective logging, and hunting), in the Fandriana-Marolambo forest corridor. We surveyed 7 sites and sighted 4 nocturnal taxa (Avahi laniger, Cheirogaleus major, Lepilemur mustelinus, and Microcebus rufus) and 6 diurnal taxa (Eulemur rubriventer, E. fulvus rufus, E. f. fulvus, Propithecus diadema edwardsi, Hapalemur griseus griseus, and Varecia variegata variegata). Composition of the lemur community was broadly similar to that of nearby protected areas (Ranomafana and Mantadia National Parks). However, we sighted no Hapalemur aureus, H. simus, or Indri indri, and observed Propithecus diadema edwardsi and Varecia variegata variegata at only 1 site each. We sighted an apparent hybrid form of Eulemur fulvus fulvus and E. f. rufus that may represent a new hybrid zone for lemurs. After testing for spatial autocorrelation, lemur diversity correlates negatively with altitude and agricultural intensity. Though the Government of Madagascar is assessing the corridor as a new national park, we suggest conservation plans for local lemurs are complicated by population isolation and lack of data on minimum viable size of the proposed protected area.  相似文献   

7.
Primate populations, including Madagascar’s lemurs, are threatened worldwide and conservationists need accurate population estimates to develop targeted conservation plans. We sought to fill knowledge gaps for three lemur taxa —white-fronted brown lemur (Eulemur albifrons); eastern woolly lemur (Avahi laniger); and Allocebus/Microcebus, a category combining observations of hairy-eared dwarf lemurs (Allocebus trichotis) and mouse lemurs (Microcebus spp.)— in northeastern Madagascar by estimating their density, examining how their encounter rates and densities vary across three different forest types, and monitoring trends in encounter rates and densities at resurveyed sites, using data from surveys at six forest sites over a 4-year period (2010–2013). Landscape density for white-fronted brown lemur, eastern woolly lemur, and Allocebus/Microcebus was 21.5 (SE 3.67), 57.7 (SE 9.17), and 39.1 (SE 9.55) individuals/km2, respectively. There was no difference in density estimates at intact and intermediately degraded forest sites; however, we encountered white-fronted brown lemurs more often in intact forest (1.64 ± SE 0.40 individuals/km) than in intermediately degraded and degraded forest (0.15 ± SE 0.06 and 0.16 ± SE 0.06 individuals/km). In addition, we encountered white-fronted brown lemurs at lower rates in 2013 (0.15 ± SE 0.06 individuals/km) compared to 2010 (0.82 ± SE 0.12 individuals/km) at a resurveyed site. Our findings emphasize that primate researchers must account for variation in how lemur encounter rates and densities differ between intact and degraded forests, and although we observed a decline in white-fronted brown lemur encounter rate at our resurveyed site, we caution that changes in lemur encounter rates may simply reflect lower detection rates rather than lower density. Future research should focus on using conventional distance sampling techniques, which are infrequently used in primate studies, to provide more robust density estimates as a way to accurately assess trends and the effects of anthropogenic pressures on lemur populations.  相似文献   

8.
We investigated how greater dwarf lemur (Cheirogaleus major) densities, ambient air temperature, and dendrometrics (tree height and diameter) varied along forest edge-interior gradients in the Vohibola III Classified Forest in SE Madagascar. We also assessed if spatial variations in densities of Cheirogaleus major provide indirect evidence of increased predation pressure in the transition zone between edge and interior forest habitats, i.e., an ecological trap. We conducted diurnal temperature surveys (N = 394) and nocturnal surveys of Cheirogaleus major (N = 182) over 2 yr along 4 1250-m transects that ran perpendicular to the forest edge in Vohibola III. We did not see Cheirogaleus major from May to mid-September, and the highest sighting frequency occurred during October–November. Cheirogaleus major exhibited a negative edge response because densities ranged from low levels in edge habitats to higher levels in the forest interior. After we tested for spatial autocorrelation, edge-related variations in densities of Cheirogaleus major covaried most strongly with tree diameter. Edge responses of Cheirogaleus major may reflect spatial variations in fruit and liana abundance, though data are needed on the precise relationship between tree diameter and food production to confirm the relationship. Edge-related variations in densities of Cheirogaleus major may also provide indirect evidence of an ecological trap. Testing and controlling for spatial autocorrelation should be important components of future studies of primate conservation biology and ecology.  相似文献   

9.
Sucking lice and ticks were collected from live-trapped eastern rufous mouse lemurs, Microcebus rufus Geoffroy, in and around the periphery of Ranomafana National Park, southeastern Madagascar, from 2007 to 2009. Samples of 53 sucking lice (Insecta: Phthiraptera: Anoplura) and 28 hard ticks (Acari: Ixodidae) were collected from 36 lemur captures representing 26 different host individuals. All of the lice were Lemurpediculus verruculosus (Ward) (6 males, 46 females, 1 third instar nymph). Only the holotype female was known previously for this louse and the host was stated to be a "mouse lemur." Therefore, we describe the male and third instar nymph of L. verruculosus and confirm M. rufus as a host (possibly the only host) of this louse. All of the ticks were nymphs and consisted of 16 Haemaphysalis lemuris Hoogstraal, 11 Haemaphysalis sp., and 1 Ixodes sp. The last 2 ticks listed did not morphologically match any of the Madagascar Haemaphysalis or Ixodes ticks for which nymphal stages have been described.  相似文献   

10.
In this study, I tested two hypotheses regarding the relationship of ecological variables (size, density, and distribution of patches) and infant developmental patterns to lemur social structure using two prosimian primates in Ranomafana, Madagascar: the rufous lemur (Eulemur fulvus rufus) and the red-bellied lemur (Eulemur rubriventer). Three predictions regarding the general effects of patch size and subgroup size on lemur feeding rates were supported: (1) Rufous lemurs used large patches; red-bellied lemurs used smaller patches; (2) larger subgroups of rufous lemurs used larger patches; and (3) rufous lemur feeding rates decreased significantly with increases in subgroup size and patch size, whereas size and patch size had no significant effect on red-bellied lemur feeding rates. However, food item size (fruit) had a more significant effect on rufous and red-bellied lemur feeding rates than either patch size or subgroup size. When similar-sized fruits were compared, rufous lemur feeding rates on small fruit were most affected by patch size, yet feeding rates on medium-sized fruit were most affected by subgroup size. Neither lemur species used patches in consistent ways seasonally. During periods of food abundance, rufous lemurs used many small, common, and clumped patches. In food scarcity periods, they used fewer, larger, rarer, and less clumped patches; groups migrated when food became most scarce. Red-bellied lemurs also used patches in variable ways, but these patterns were not linked with food availability. Finally, infant development patterns differed between lemur species; red-bellied lemur males cared for offspring and infants reached developmental landmarks faster than rufous lemur infants. Therefore, red-bellied lemur group size may be constrained by the need for additional infant care by other group members. In contrast, rufous lemur group size may be constrained by patch availability during the most critical period of food scarcity. © 1996 Wiley-Liss, Inc.  相似文献   

11.
Extensive areas of forest are cleared every year to establish new agricultural land in the tropics, resulting in a catastrophic loss in habitat for the world’s primates. A prominent example of this process is Madagascar, where an increasing demand for arable land has led to the once-forested landscape to be now dominated by agricultural areas used for the cultivation of food and cash crops. Despite the prominence of these plantations throughout Madagascar, their suitability as a habitat to support endemic lemur populations remains unclear. Here, we assessed lemur presence in vanilla plantations, Madagascar’s principal export crop, within the northeastern Sava region with the use of line transects. We confirmed the presence of five lemur species, four of which were nocturnal cheirogaleids, in these vanilla plantations. Intensively farmed vanilla plantations and those in existing stands of vegetation supported at least one species of lemur. Furthermore, lemurs were significantly more likely to be present in plantations grown close or adjacent to natural forest fragments, compared to more intensively farmed, anthropogenic sites. In comparison, we observed eight lemur species in natural forest fragment sites in close proximity to the vanilla plantation sites, four of which we did not observe in any of the plantation sites. Our results provide evidence of lemurs using vanilla plantations and show that vanilla plantations may act as extensions of suitable habitat for lemurs, suggesting that they may also function as matrices between isolated forest fragments through which gene flow can occur. These are important and encouraging findings for both lemur conservation and for sustainable agroforestry undertaken by local farming communities.  相似文献   

12.
Pronounced seasonality, with temperatures dropping as low as 5 degrees C during the dry season, has led to the hypothesis that Malagasy lemurs face cold stress and respond to this by inactivity and social thermoregulation, i.e. resting in tight body contact with conspecifics. Compared to anthropoids, lemur groups are comprised of an unusually high number of males, leading to an even or slightly male-biased adult sex ratio. According to one hypothesis, females may benefit from these surplus males in their groups if males huddle with females. The results of this study on redfronted lemurs (Eulemur fulvus rufus) in Kirindy Forest, Madagascar revealed that the animals indeed responded to cold ambient temperatures by increased inactivity and the formation of huddling groups. However, surplus males did not participate more frequently than expected in huddling groups with females and females do not, therefore, benefit from the high number of males in their groups by increased social thermoregulation.  相似文献   

13.
In this paper, I provide data on the possible effects of group size and seasonal changes in food availability on the activity and habitat use patterns of two species of prosimian primate: the rufous lemur (Eulemur fulvus rufus) and the red-bellied lemur (Eulemur rubriventer). General and subtle seasonal differences were observed between lemur species in (1) group size and composition, (2) activity profiles, and (3) habitat use. Rufous lemur groups were larger (mean = 8 individuals) and contained more adults than red-bellied lemur groups (mean = 3 individuals). The overall degree and distribution of diurnal activity differed between lemur species and varied within species with seasonal changes in food availability. In general, rufous lemurs traveled more often than red-bellied lemurs. During food scarcity, both species increased the amount of time spent feeding, although peak feeding and traveling times differed. Both species also preferred horizontal substrates; however, during food scarcity, red-bellied lemurs used terminal branches more often while feeding than rufous lemurs. In addition, red-bellied lemurs used the lower middle story forest and rested in taller, upper canopy trees more often than rufous lemurs. Differences in activity and habitat use patterns between lemur species were more related to seasonal changes in food availability than overall differences in group size. These behavioral patterns may represent different strategies used by each lemur species to avoid directly competing for similar resources during times of food scarcity. © 1996 Wiley-Liss, Inc.  相似文献   

14.
We used species‐area relationships (SARs) to investigate the effects of habitat loss on lemur biogeography. We measured species richness via visual surveys on line transects within 42 fragments of dry deciduous forest at the Ambanjabe field site in Ankarafantsika National Park, Madagascar. We measured human disturbance and habitat characteristics within 38 of the 42 fragments. We measured the distance between each fragment and the nearest settlement, continuous forest, and nearest neighboring fragment. We fit 10 candidate SAR models to the data using nonlinear least squares regression and compared them using Akaike's Information Criterion (AIC). To determine how habitat characteristics, as well as area, influenced species richness, we ran a hierarchical partitioning procedure to select which variables to include in generalized additive models (GAMs) and compared them using AIC. Contrary to expectations, we found that lemurs form convex SARs, without a “small island effect”, and with the power model being the most likely SAR model. Although we found that four variables (area, survey effort, and total human disturbance, and mean tree height) independently contributed greater than 10% of the variation in lemur species richness, only area was included in the most likely model. We suggest that the power model was the most likely SAR model and our inability to detect a “small island effect” are the result of Microcebus spp. being edge tolerant and capable of dispersing through matrix, scale issues in the study design, and low γ‐diversity in the landscape. However, more study is needed to determine what role human disturbance plays in influencing species richness in lemurs.  相似文献   

15.
The population of brown lemurs has rapidly grown since their founders were introduced to the Berenty Reserve. The founders consist of two species (Eulemur fulvus rufus and E. collaris). To characterize the behavior of the population and to examine whether these characteristics affect population growth, I investigated the habitat use and social structure of the population of brown lemurs at Berenty (Berenty Eulemur). Behavior data were collected focusing on horizontal and vertical habitat use, activity rhythms, and intergroup relationships. These data were compared with the data of E. fulvus in other areas, with the previous studies done at Berenty, and with data on Berenty Lemur catta. Berenty Eulemur maintained a home range size comparable to E. f. rufus in the western deciduous dry forest, but was found at a lower level of the forest and had larger overlapping home ranges. Berenty Eulemur use food resources earlier in the morning than L. catta, intergroup conflict was avoided by vocal communication, and Berenty Eulemur made suitable use of their limited habitat. I suggest that a number of behavioral characteristics of Berenty Eulemur may contribute to their population growth.  相似文献   

16.
Ambatorongorongo Mountain lies at the historical intersection betweenhumid, spiny, and littoral forests in southeastern Madagascar. We report theresults of surveys of the herpetofauna and lemurs occurring in Malahelo Forest,a small (<25 ha) forest fragment lying on the western slope ofAmbatorongorongo Mountain. There are at least 41 reptile, 11 amphibian, and 7lemur species in this forest, including several that are endemic to southeasternMadagascar and are at severe risk of extinction. The species richness of theMalahelo fauna is comparable to that of even the largest forest reserves in theregion. We also evaluate the similarity of the Malahelo herpetofauna to that ofnearby humid, spiny, and littoral forests to assess the biogeographic affinitiesof its amphibians and reptile assemblages. Both groups contain speciescharacteristic of each of the three surrounding forest types, but thebiogeographic patterns appear to differ for amphibians and reptiles. Overall,the herpetofauna and lemurs of the Malahelo Forest indicate that it is a remnantof a biogeographic transition zone between the major forest types ofsoutheastern Madagascar. The combination of high species richness, regionalendemics, and unique herpetofaunal and lemur assemblages should make MalaheloForest a high conservation priority, and we give recommendations for protectingwhat remains of this important transitional forest.  相似文献   

17.
Predator–primate interactions are understudied, yet predators have been shown to influence primate behavior, population dynamics, and spatial distribution. An understanding of these interactions is important for the successful management and conservation of these species. Novel approaches are needed to understand better the spatial relationships between predators and primates across changing landscapes. We combined photographic surveys of predators and humans with line-transect sampling of lemurs across contiguous and fragmented forests in Madagascar to 1) compare relative activity; 2) estimate probability of occupancy and detection; 3) estimate predator–primate and local people–primate co-occurrence; and 4) assess variables influencing these parameters across contiguous and fragmented forests. In fragmented (compared to contiguous) forest sites endemic predator and lemur activity were lower whereas introduced predator and local people activity were higher. Our two-species interaction occupancy models revealed a higher number of interactions among species across contiguous forest where predator and lemur occupancy were highest. Mouse lemurs show evidence of “avoidance” (SIF < 1.0) with all predator species (endemic and introduced) in contiguous forest whereas white-fronted brown lemurs show “attraction” (SIF > 1.0) with feral cats and local people in contiguous forest. Feral cats demonstrated the highest number of interactions with lemurs, despite their distribution being limited to only contiguous forest. Distance to forest edge and distance to nearby villages were important in predicting predator occupancy and detection. These results highlight the growing threat to endemic predators and lemurs as habitat loss and fragmentation increase throughout Madagascar. We demonstrate the effectiveness of a novel combination of techniques to investigate how predator species impact primate species across a gradient of forest fragmentation.  相似文献   

18.
The alarming rate of deforestation in Madagascar is driving some endemic primates to extinction. Surprisingly, anthropogenic habitat disturbance is not always deleterious. The effect of disturbance on lemur abundance may be related to diet, with frugivorous species more prone to population declines than folivores or insectivores. To test the effects of disturbance on lemur abundance and group size, we surveyed 2 sites within contiguous forest at Ranomafana National Park, 1 lightly disturbed primary forest (Vato) and 1 heavily logged forest (Tala). We quantified forest structure variables along 6 survey routes and conducted 68 diurnal and 42 nocturnal lemur surveys. Canopy closure, canopy height, and understory visibility were greater in Vato than in Tala. We encountered 2 frugivorous lemurs (Eulemur rufifrons, Varecia variegata) and 1 folivore (Avahi peyrierasi) significantly more frequently in Vato than in Tala, whereas the opposite was true for the insectivorous Microcebus rufus. Rates did not differ statistically for 1 frugivore (Eulemur rubriventer) and 2 folivores (Propithecus edwardsi, Hapalemur griseus). Comparisons across the 6 survey routes suggest that the abundance was heterogeneous within as well as between sites. Neither group size nor composition differed between sites. Encounter rates for Varecia variegata were positively related to canopy closure, and encounter rates for Avahi peyrierasi were positively related to canopy height. Encounter rates for Microcebus rufus were negatively related to canopy closure, height, and understory visibility. Similar to other studies, the results suggest that some lemurs, including folivores, may cope with anthropogenic disturbance better than others, including some frugivores. Lemur abundance is heterogeneous, though, even on small spatial scales.  相似文献   

19.
The white-collared lemur (Eulemur cinereiceps) is found in southeastern Madagascar. This species is endangered due to the loss and fragmentation of its natural habitat and hunting. Eighteen nuclear microsatellite loci were isolated from genomic DNA derived from an animal from Mahabo Forest in Madagascar. Population genetic parameters were estimated from a population of white-collared lemur sampled at Vevembe Forest 7 years apart to evaluate the potential utility of this marker suite.  相似文献   

20.
Locomotor diversity among lemurids has been ignored by placing most species into a category of arboreal quadrupeds. Recent field studies have shown that leaping behaviors comprise a relatively large amount of their travel. In this contribution I detail a study of captive lemurs locomoting on a designed support network and/or in outdoor enclosures. Associations between support context, leaping behaviors, and landing kinematics are detailed for Hapalemur griseus, Eulemur rubriventer, Eulemur fulvus, Eulemur mongoz, and Varecia variegata. In-air body position, including the amount and location of trunk flexion, coupled with the extent of shoulder and hip flexion dictates limb use at landing. Limb strike pattern when landing onto the same support type varies interspecifically. The kinematic variation in leaping behaviors may well have implications for functional analyses of the postcranium. © 1996 Wiley-Liss, Inc.  相似文献   

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