Fernanda Michalski

Disturbance‐Mediated Mammal Persistence and Abundance‐Area Relationships in Amazonian Forest Fragments

Few researchers have investigated the synergistic effects of tropical forest fragmentation and disturbance on species persistence and abundance. We examined effects of both forest-patch metrics and forest disturbance in determining richness and abundance of midsized to large-bodied mammal species in a highly fragmented Amazonian forest landscape. Twenty-one forest fragments, ranging from 2 to 14,480 ha, and two continuous forest sites were sampled based on sightings, tracks, line-transect censuses, armadillo burrow censuses, and camera trapping. Patch occupancy of 37 species recorded ranged from 4% to all forest sites surveyed. Forest fragment size was the strongest predictor of species persistence, explaining 90% of the variation in species richness. Information-theoretic analysis confirmed that fragment area was the most important explanatory variable for the overall species richness and abundance of mammal species, followed by surface fires, which affected the abundance of seven species. Large mammal species were typically absent from fragments <100 ha, whereas some ubiquitous species were favored by fragmentation, exhibiting hyperabundance in small patches. Our findings highlight the importance of large (>10,000 ha), relatively undisturbed forest patches to maximize persistence and maintain baseline abundances of Neotropical forest mammal species.

Habitat patch size modulates terrestrial mammal activity patterns in Amazonian forest fragments

Abstract Understanding how environmental change influences the behavior of organisms is central for both ecological understanding and species conservation. We used camera traps to monitor the diurnal variation in activity of 3 ubiquitous terrestrial mammals in neotropical forests—nine-banded armadillos (Dasypus novemcinctus), common opossums (Didelphis marsupialis), and red-rumped agoutis (Dasyprocta leporina)—across a fragmented forest landscape of the southern Brazilian Amazon. Results from a total of 3,086 camera-trap days distributed across 21 forest patches (ranging in size from 2 to 14,480 ha) and 2 undisturbed continuous forest areas were used to test the effects of a series of abiotic and forest disturbance variables on species activity. An information theoretic analysis revealed significant predictors of the temporal distribution of activity that varied among species. Habitat fragmentation affected the activity of both nocturnal species, but effects of habitat patch area depended on interactions with disturbance variables for the common opossum. Of the 3 species investigated, D. novemcinctus exhibited the greatest variation in activity in relation to forest patch size. Armadillos were strictly nocturnal in forest areas >1,000 ha, whereas their foraging activity switched to a cathemeral pattern, with up to 60% of all photos recorded during the day in smaller forest patches (<1,000 ha). In contrast, the time since forest patches had been isolated was the only significant predictor of activity patterns for agoutis, a diurnal species exhibiting a bimodal activity pattern. Our results support the hypothesis that behavioral plasticity is an important determinant of species persistence in small forest remnants dominated by edge effects.

Terrestrial mammal responses to edges in Amazonian forest patches: A study based on track stations

Abstract Examining edge effects is imperative to developing effective conservation and management strategies in fragmented landscapes as they are a key component of how landscape change influences habitat quality. Although medium- to large-bodied mammals are recognised as key components of tropical forests, their responses to forest edges remain poorly documented. Here, we describe how five species of medium- to large-bodied terrestrial neotropical mammals respond to forest-pasture edges along 17 forest patches (ranging in size from 5–4714 ha) and two continuous areas of Amazonian forest in Alta Floresta, Brazil. Tracks from two rodent (Dasyprocta agouti and Agouti paca) and three ungulate species (Tayassu tajacu, Mazama gouazoubira and Tapirus terrestris) were recorded over 4900 sand track station nights during a 4-month study period. When species occurrences were compared between patch size classes we found a significant interaction between patch size and distance from the nearest forest edge only for ungulates. We discuss the cost-effectiveness of monitoring protocols for large terrestrial mammals in tropical forests based on sand track stations, and how edge effects and patch size can modulate species abundance and distribution.

Successful carnivore identification with faecal DNA across a fragmented Amazonian landscape

The use of scat surveys to obtain DNA has been well documented in temperate areas, where DNA preservation may be more effective than in tropical forests. Samples obtained in the tropics are often exposed to high humidity, warm temperatures, frequent rain and intense sunlight, all of which can rapidly degrade DNA. Despite these potential problems, we demonstrate successful mtDNA amplification and sequencing for faeces of carnivores collected in tropical conditions and quantify how sample condition and environmental variables influence the success of PCR amplification and species identification. Additionally, the feasibility of genotyping nuclear microsatellites from jaguar (Panthera onca) faeces was investigated. From October 2007 to December 2008, 93 faecal samples were collected in the southern Brazilian Amazon. A total of eight carnivore species was successfully identified from 71% of all samples obtained. Information theoretic analysis revealed that the number of PCR attempts before a successful sequence was an important negative predictor across all three responses (success of species identification, success of species identification from the first sequence and PCR amplification success), whereas the relative importance of the other three predictors (sample condition, season and distance from forest edge) varied between the three responses. Nuclear microsatellite amplification from jaguar faeces had lower success rates (15–44%) compared with those of the mtDNA marker. Our results show that DNA obtained from faecal samples works efficiently for carnivore species identification in the Amazon forest and also shows potential for nuclear DNA analysis, thus providing a valuable tool for genetic, ecological and conservation studies.

No Return from Biodiversity Loss

In their Letter “Brazilian Law: Full Speed in Reverse?” (16 July, p. [276][1]), J. P. Metzger and coauthors highlight the precarious plight of the Brazilian Forest Act (Codigo Florestal), embattled by new legislative reform that will effectively condemn old-growth remnants and forest regrowth

Assessing Sampling Biases in Logging Impact Studies in Tropical Forests

The ecological responses of tropical forest wildlife to selective timber extraction have received considerable attention in the last few decades, yet there is little consensus among the large number of studies about the most appropriate sampling design. Here, we reviewed 26 years of tropical forest logging literature to evaluate the relationship between sampling design and the quality of information reported, which varied greatly among 75 studies. Most studies (88%) failed to include a pre-logging baseline condition in the sampling design, and the temporal scale of post-logging studies was generally inadequate. Studies also usually failed to report key information on study areas; only half of the articles reported some information on the spatial scale of the study, and only one-third presented some quantitative metric to describe forest habitat structure. Additionally, most studies (64%) failed to report the type of forest management and almost half (45%) did not describe the intensity of timber harvest in the logged areas. These sampling and reporting biases in logging studies hugely undermine the comparability among studies. We conclude with some general guidelines to maximize comparability among studies, and to enhance the potential usefulness of future logging studies for wildlife conservation strategies in tropical forest regions.

The bush dog Speothos venaticus and short-eared dog Atelocynus microtis in a fragmented landscape in southern Amazonia.

The bush dog Speothos venaticus and the short-eared dog Atelocynus microtis are categorized as Near Threatened on the IUCN Red List. I document the occurrence of these two little known canids in a fragmented landscape in southern Amazonia (around Alta Floresta, Mato Grosso state, Brazil) using interviews and two extensive camera-trapping surveys. From a total of 144 interviews conducted during 2001–2002 in forest fragments and continuous forest sites, bush and short-eared dogs were confirmed in only eight (5.6%) and 14 (9.7%) forest sites, respectively. Two camera-trapping surveys, conducted in 2003–2004 and 2007–2008, with a total of 6,721 camera-trap days, recorded two photographs of bush dogs and seven of short-eared dogs, in three continuous forest sites. On the basis of the large sampling effort it appears that these two elusive species occur at low densities in the study region. The continued presence of these species in an agricultural frontier with high deforestation rates makes this information of relevance for long-term conservation initiatives in this region and in other Neotropical agricultural frontiers.

Implications of faecal removal by dung beetles for scat surveys in a fragmented landscape of the Brazilian Amazon

Monitoring rare and elusive species for effective management and conservation is particularly challenging and often demands the development of specialized techniques. Scat surveys have been applied to monitor a variety of rare species but relatively little attention has been given to the development of appropriate sampling designs. To determine if scat surveys could be applied to compare the distribution of species across three habitats of a fragmented region in the Brazilian Amazon, the removal of human (n = 27) and jaguar (n = 27) scat samples in forest, riparian corridor and pasture habitats was recorded for 24 hours. Dung beetles were responsible for removing the majority of samples (71%) and a generalized linear mixed effect model revealed significant influence of habitat and scat type on removal probability, with forest and riparian corridors having higher removal compared with samples in pasture habitats. Although non-invasive scat surveys can potentially address fundamental broad-scale conservation and management questions, our results demonstrate that scat surveys in the tropics must account for differences in scat removal rates between habitats and target species before conclusions can be drawn regarding patterns of habitat use.

Activity pattern of Cuniculus paca (Rodentia: Cuniculidae) in relation to lunar illumination and other abiotic variables in the southern Brazilian Amazon

Understanding what influences the activity of organisms is important for both ecological understanding and species conservation. Using data from 2,707 camera trap days distributed across 24 forest sites, we present quantitative analyses of the activity pattern of Cuniculus paca (Linnaeus, 1766) in southern Amazonia. We compared the activity pattern of this species across four designated subsets of the 24-hours diel cycle (dawn, dusk, day and night). Using linear regression models we tested the influence of season, temperature and rainfall on the activity patterns of C. paca (paca). We also evaluated the nocturnal photos of paca (N = 111) as a function of the degree of lunar illumination in order to test the prediction that pacas minimize their activity during moon phase when illumination is brighter. Pacas were not recorded during the day but were active at dawn, dusk and night time. We found differences in the influence of the abiotic variables on the nocturnal activity of pacas in the study area. There was no significant difference between the observed (expressed as the frequency of total counts of independent photos over the five classes of lunar illumination) and the expected activity of pacas, based on the frequency of days in the lunar cycle with different classes of lunar illumination, whereas lunar illumination had a weak negative influence on the timing of paca activity (i.e. pacas were active closer to sunset with increasing lunar illumination). However, the timing of nocturnal activity in pacas was not influenced by season, temperature or rainfall. Our findings highlight the ecological plasticity of this Neotropical rodent which has a key function in the maintenance of Neotropical forests.

Ecological Relationships of Meso-Scale Distribution in 25 Neotropical Vertebrate Species

Vertebrates are a vital ecological component of Amazon forest biodiversity. Although vertebrates are a functionally important part of various ecosystem services they continue to be threatened by anthropogenic impacts throughout the Amazon. Here we use a standardized, regularly spaced arrangement of camera traps within 25km2 to provide a baseline assessment of vertebrate species diversity in a sustainable use protected area in the eastern Brazilian Amazon. We examined seasonal differences in the per species encounter rates (number of photos per camera trap and number of cameras with photos). Generalized linear models (GLMs) were then used to examine the influence of five variables (altitude, canopy cover, basal area, distance to nearest river and distance to nearest large river) on the number of photos per species and on functional groups. GLMs were also used to examine the relationships between large predators [Jaguar (Panthera onca) and Puma (Puma concolor)] and their prey. A total of 649 independent photos of 25 species were obtained from 1,800 camera trap days (900 each during wet and dry seasons). Only ungulates and rodents showed significant seasonal differences in the number of photos per camera. The number of photos differed between seasons for only three species (Mazama americana, Dasyprocta leporina and Myoprocta acouchy) all of which were photographed more (3 to 10 fold increase) during the wet season. Mazama americana was the only species where a significant difference was found in occupancy, with more photos in more cameras during the wet season. For most groups and species variation in the number of photos per camera was only explained weakly by the GLMs (deviance explained ranging from 10.3 to 54.4%). Terrestrial birds (Crax alector, Psophia crepitans and Tinamus major) and rodents (Cuniculus paca, Dasyprocta leporina and M. acouchy) were the notable exceptions, with our GLMs significantly explaining variation in the distribution of all species (deviance explained ranging from 21.0 to 54.5%). The group and species GLMs showed some novel ecological information from this relatively pristine area. We found no association between large cats and their potential prey. We also found that rodent and bird species were more often recorded closer to streams. As hunters gain access via rivers this finding suggests that there is currently little anthropogenic impact on the species. Our findings provide a standardized baseline for comparison with other sites and with which planned management and extractive activities can be evaluated.