Habitat use,abundance, and persistence of Neotropical migrant birds in a habitat matrix in northeast Belize

ABSTRACT To ensure adequate protection of nonbreeding habitats used by Neotropical migratory landbirds, we must first address questions about habitat use and quality. On the Yucatan peninsula, migrants use many habitats, several of which remain unstudied, and methodological differences preclude interhabitat comparisons based on studies to date. We used distance sampling along line transects in six habitats in northeast Belize to examine use of previously unstudied habitats (e.g., salt marsh) by Neotropical migrants and to permit comparison across habitats. We calculated unadjusted and adjusted (for detectability) density estimates for individual migrant species and for all species combined to generate hypotheses about habitat quality based on the assumption that density and quality are positively correlated. Adjusted density estimates for all migrants were highest in black mangrove habitat (1799 ± 110 ind/km²), intermediate in three forest types and milpa (range 598–802 ind/km²), and lowest in salt marsh (207 ± 32.3 ind/km²). By combining density estimates with habitat availability in our study region, we estimated that evergreen forest and black mangrove supported 70% and 9% of the region's migrant population, respectively. At the species level, five of the 10 most common species had habitat preferences (>50% detections in one habitat). Given the diversity of habitat preferences among species and apparent seasonal movements, our results indicate that Neotropical migrants in northeast Belize are dependent on a matrix of interconnected habitats.     

The size of savannah Africa: a lion’s (Panthera leo) view

We define African savannahs as being those areas that receive between 300 and 1,500 mm of rain annually. This broad definition encompasses a variety of habitats. Thus defined, savannahs comprise 13.5 million km² and encompass most of the present range of the African lion (Panthera leo). Dense human populations and extensive conversion of land to human use preclude use by lions. Using high-resolution satellite imagery and human population density data we define lion areas, places that likely have resident lion populations. In 1960, 11.9 million km² of these savannahs had fewer than 25 people per km². The comparable area shrank to 9.7 million km² by 2000. Areas of savannah Africa with few people have shrunk considerably in the last 50 years and human population projections suggest they will likely shrink significantly in the next 40. The current extent of free-ranging lion populations is 3.4 million km² or about 25 % of savannah area. Habitats across this area are fragmented; all available data indicate that between 32,000 and 35,000 free-ranging lions live in 67 lion areas. Although these numbers are similar to previous estimates, they are geographically more comprehensive. There is abundant evidence of widespread declines and local extinctions. Under the criteria we outline, ten lion areas qualify as lion strongholds: four in East Africa and six in Southern Africa. Approximately 24,000 lions are in strongholds, with an additional 4,000 in potential ones. However, over 6,000 lions are in populations of doubtful long-term viability. Lion populations in West and Central Africa are acutely threatened with many recent, local extinctions even in nominally protected areas.     

Status and distribution of the Black-cheeked Lovebird,Zambia

Dodman, T., Katanekwa, V., Aspinall, D. & Stjernstedt, R. 2000. Status and distribution of the Black-cheeked Lovebird, Zambia. Ostrich 71 (1 & 2): 228–234.

A survey of the Black-cheeked Lovebird Agapornis nigrigenis in 1994 resulted in much new information. About 10 000 live in mopane Colophospermum mopane woodland in south-west Zambia. They are localised with a high dependence on mopane woodland with permanent standing water. Some birds may also occur in the eastern part of Namibia's Caprivi strip, in the northern tip of Botswana and in the western tip of Zimbabwe. However, its status here is confused by the presence of feral lovebirds of more than one species. The core distribution is a disjointed belt of mopane woodland between the Zambezi and Kafue rivers. The distribution outside the dry season is wider and allied to the availability of ripening crops close to patches of mopane woodland or riverine forest. The total area of mopane woodland utilised is approximately 4 550 km². The habitat is dynamic, reflecting gradual desiccation in the area. There are less permanent water sources available now than earlier this century and distribution has been affected by the successive drying up of a number of ephemeral rivers. Low availability of water in the dry season has probably been the principal factor causing lovebirds to desert the Bovu and Sinde rivers. Lovebirds are well-known by local people as they descend on crops, notably sorghum and millets. The general transition of these crops to maize in the second half of this century may have had an earlier impact on lovebird numbers and distribution. There was extensive trapping between the 1920s and 1960s, principally for the pet bird trade. This trade is uncommon now, though a few isolated incidences occur. Lovebirds are still trapped for food and some are killed as pests, but these activities probably have no serious long-term impacts on the population at present trapping levels.     

Low leopard populations in protected areas of Maputaland: a consequence of poaching,habitat condition,abundance of prey,and a top predator

Identifying the primary causes affecting population densities and distribution of flagship species are necessary in developing sustainable management strategies for large carnivore conservation. We modeled drivers of spatial density of the common leopard (Panthera pardus) using a spatially explicit capture–recapture—Bayesian approach to understand their population dynamics in the Maputaland Conservation Unit, South Africa. We camera‐trapped leopards in four protected areas (PAs) of varying sizes and disturbance levels covering 198 camera stations. Ours is the first study to explore the effects of poaching level, abundance of prey species (small, medium, and large), competitors (lion Panthera leo and spotted hyenas Crocuta crocuta), and habitat on the spatial distribution of common leopard density. Twenty‐six male and 41 female leopards were individually identified and estimated leopard density ranged from 1.6 ± 0.62/100 km² (smallest PA—Ndumo) to 8.4 ± 1.03/100 km² (largest PA—western shores). Although dry forest thickets and plantation habitats largely represented the western shores, the plantation areas had extremely low leopard density compared to native forest. We found that leopard density increased in areas when low poaching levels/no poaching was recorded in dry forest thickets and with high abundance of medium‐sized prey, but decreased with increasing abundance of lion. Because local leopard populations are vulnerable to extinction, particularly in smaller PAs, the long‐term sustainability of leopard populations depend on developing appropriate management strategies that consider a combination of multiple factors to maintain their optimal habitats.     

Line Transect and Triangulation Surveys Provide Reliable Estimates of the Density of Kloss’ Gibbons (Hylobates klossii) on Siberut Island, Indonesia

Estimating population densities of key species is crucial for many conservation programs. Density estimates provide baseline data and enable monitoring of population size. Several different survey methods are available, and the choice of method depends on the species and study aims. Few studies have compared the accuracy and efficiency of different survey methods for large mammals, particularly for primates. Here we compare estimates of density and abundance of Kloss’ gibbons (Hylobates klossii) using two of the most common survey methods: line transect distance sampling and triangulation. Line transect surveys (survey effort: 155.5 km) produced a total of 101 auditory and visual encounters and a density estimate of 5.5 gibbon clusters (groups or subgroups of primate social units)/km². Triangulation conducted from 12 listening posts during the same period revealed a similar density estimate of 5.0 clusters/km². Coefficients of variation of cluster density estimates were slightly higher from triangulation (0.24) than from line transects (0.17), resulting in a lack of precision in detecting changes in cluster densities of <66 % for triangulation and <47 % for line transect surveys at the 5 % significance level with a statistical power of 50 %. This case study shows that both methods may provide estimates with similar accuracy but that line transects can result in more precise estimates and allow assessment of other primate species. For a rapid assessment of gibbon density under time and financial constraints, the triangulation method also may be appropriate.     

Habitat use and densities of co‐existing migrant Willow Warblers Phylloscopus trochilus and resident eremomelas Eremomela spp. in Zimbabwe

Capsule Migrant Willow Warblers occupy more woodland types and occur at higher densities than ecologically‐similar resident Afrotropical warblers.

Aims To compare population densities of Willow Warblers and eremomelas in adjacent acacia, mopane and miombo woodlands, and assess the abundance of potential invertebrate prey in each habitat type, in order to investigate whether Palearctic migrants use more open habitats and are more flexible in habitat use than their Afrotropical counterparts in the same feeding guild.

Methods Using distance sampling we carried out four replicated sets of point counts in acacia woodland and three sets of counts in miombo and mopane between December 1999 and February 2000. We noted the tree species in which we saw warblers foraging and took beating‐tray samples of potential arthropod prey present on tree foliage in each of the three habitats.

Results Willow Warbler density in acacia woodland increased from 1.80 ± 0.54 (se) birds/ha in early December to 7.15 ± 1.41 birds/ha in late January after influxes of later arrivals. Densities of Willow Warblers in miombo and mopane were much lower (1.14 ± 0.28 and 0.38 ± 0.23 birds/ha, respectively) and did not show significant changes. Burnt‐necked Eremomelas averaged 0.74 ± 0.34 birds/ha in acacia woodland, and in miombo densities of Green‐capped and Yellow‐bellied Eremomelas were 0.23 ± 0.17 and 0.34 ± 0.26 birds/ha, respectively. Densities in mopane were too low to estimate reliably. Willow Warblers and Green‐capped Eremomelas showed some apparent preferences in tree species used for foraging but differences in tree use were not obviously related to the abundance of arthropod taxa present as potential prey.

Conclusion Willow Warblers occupied more habitats at greater density than similar Afrotropical warblers. They appear to favour acacia, but their settlement patterns and the reasons for disparities between densities of immigrants and residents are unclear.     

Lions in a coexistence landscape: Repurposing a traditional field technique to monitor an elusive carnivore

Throughout Africa, lions are thought to have experienced dramatic population decline and range contraction. The greatest declines are likely occurring in human‐dominated landscapes where reliably estimating lion populations is particularly challenging. By adapting a method that has thus far only been applied to animals that are habituated to vehicles, we estimate lion density in two community areas in Kenya''s South Rift, located more than 100 km from the nearest protected area (PA). More specifically, we conducted an 89‐day survey using unstructured spatial sampling coupled with playbacks, a commonly used field technique, and estimated lion density using spatial capture‐recapture (SCR) models. Our estimated density of 5.9 lions over the age of 1 year per 100 km² compares favorably with many PAs and suggests that this is a key lion population that could be crucial for connectivity across the wider landscape. We discuss the possible mechanisms supporting this density and demonstrate how rigorous field methods combined with robust analyses can produce reliable population estimates within human‐dominated landscapes.     

Density-dependent habitat selection and partitioning between two sympatric ungulates

Theory on density-dependent habitat selection predicts that as population density of a species increases, use of higher quality (primary) habitat by individuals declines while use of lower quality (secondary) habitat rises. Habitat partitioning is often considered the primary mechanism for coexistence between similar species, but how this process evolves with changes in population density remains to be empirically tested for free-ranging ungulates. We used resource-selection functions to quantify density effects on landscape-scale habitat selection of two sympatric species of ungulates [moose (Alces alces) and elk (Cervus canadensis manitobensis)] in Riding Mountain National Park, Manitoba, Canada (2000–2011). The density of elk was actively reduced from 1.2 to 0.4 elk km^?2 through increased hunting effort during the period of study, while moose density decreased without additional human influence from 1.6–0.7 moose km^?2. Patterns of habitat selection during winter by both species changed in accordance to expectations from density-dependent habitat-selection theory. At low intraspecific density, moose and elk did not partition habitat, as both species selected strongly for mixed forest (primary habitat providing both food and cover), but did so in different areas segregated across an elevational gradient. As intraspecific density increased, selection for primary habitat by both species decreased, while selection for secondary, lower quality habitat such as agricultural fields (for elk) and built-up areas (for moose) increased. We show that habitat-selection strategies during winter for moose and elk, and subsequent effects on habitat partitioning, depend heavily on the position in state space (density) of both species.     

Prey and tigers on the forgotten trail: high prey occupancy and tiger habitat use reveal the importance of the understudied Churia habitat of Nepal

Tigers are globally threatened and their conservation relies on intact habitat that supports key large prey. The Churia habitat is relatively unknown even though it occupies a significant portion of the forested landscape of the Terai Arc, which stretches over 1000 km in a narrow band across Nepal and India, parallel to the Himalayas. To address this lack of detailed information relevant to tiger conservation, we used sign surveys to estimate occupancy probability for 5 focal prey species of tigers (gaur, sambar, chital, wild pig, and barking deer), and assess tiger habitat use within 537 km² of the understudied Churia habitat in Chitwan National Park (CNP), Nepal. Multi-season occupancy models allowed us to make seasonal (winter vs. summer) inferences regarding changes in occupancy or habitat use based on covariates influencing occupancy and detection. We found that sambar had the largest spatial distribution occupying 431–437 km², while chital had the smallest at 100–158 km² across both seasons. The gaur population showed the most seasonal variation occupying from 413 to 318 km², suggesting their migration out of the Churia in summer and moving in during winter. Wild pigs showed the opposite trend occupying from 444 to 383 km²; suggesting moving into Churia in summer and out in winter. Barking deer were widespread in both seasons (329–349 km²). Tiger habitat use (\({{\hat{\varPsi } }}({\text{SE}})\)) was higher in winter 0.63 (0.11) than in summer 0.54 (0.21), but confidence intervals overlapped and area used was similar across seasons, 337 km² (winter) to 291 km² (summer). Available habitat, distribution of water sources, and human disturbance were the most common variables influencing spatial distribution of prey and habitat use of tigers at different spatial scales. Overall, we found high prey occupancy and tiger habitat use, suggesting the Churia is valuable habitat for ungulates and tigers. Given that this habitat accounts for 639 km² within CNP and 7642 km² across the entire Terai Arc, the Churia should no longer be neglected in global tiger conservation planning.     

In the absence of a “landscape of fear”: How lions,hyenas, and cheetahs coexist

Aggression by top predators can create a “landscape of fear” in which subordinate predators restrict their activity to low‐risk areas or times of day. At large spatial or temporal scales, this can result in the costly loss of access to resources. However, fine‐scale reactive avoidance may minimize the risk of aggressive encounters for subordinate predators while maintaining access to resources, thereby providing a mechanism for coexistence. We investigated fine‐scale spatiotemporal avoidance in a guild of African predators characterized by intense interference competition. Vulnerable to food stealing and direct killing, cheetahs are expected to avoid both larger predators; hyenas are expected to avoid lions. We deployed a grid of 225 camera traps across 1,125 km² in Serengeti National Park, Tanzania, to evaluate concurrent patterns of habitat use by lions, hyenas, cheetahs, and their primary prey. We used hurdle models to evaluate whether smaller species avoided areas preferred by larger species, and we used time‐to‐event models to evaluate fine‐scale temporal avoidance in the hours immediately surrounding top predator activity. We found no evidence of long‐term displacement of subordinate species, even at fine spatial scales. Instead, hyenas and cheetahs were positively associated with lions except in areas with exceptionally high lion use. Hyenas and lions appeared to actively track each, while cheetahs appear to maintain long‐term access to sites with high lion use by actively avoiding those areas just in the hours immediately following lion activity. Our results suggest that cheetahs are able to use patches of preferred habitat by avoiding lions on a moment‐to‐moment basis. Such fine‐scale temporal avoidance is likely to be less costly than long‐term avoidance of preferred areas: This may help explain why cheetahs are able to coexist with lions despite high rates of lion‐inflicted mortality, and highlights reactive avoidance as a general mechanism for predator coexistence.     

Occupancy,density, and activity patterns of a Critically Endangered leopard population on the Kawthoolei-Thailand border

Large carnivores have been largely extirpated from Southeast Asia due to deforestation, habitat fragmentation, and poaching. Estimating the density of endangered carnivore populations, and identifying relationships between species occupancy and both environmental and anthropogenic factors, is essential for effective conservation planning. Recently, the IUCN conservation status of the Indochinese leopard (Panthera pardus delacouri) was upgraded to “Critically Endangered.” We surveyed Kweekoh Wildlife Sanctuary in Kawthoolei, an area administered by the Karen ethnic group in eastern Myanmar, to quantify (1) leopard population density using spatially explicit mark-resight (SMR) models, (2) leopard occupancy as influenced by important ecological variables, and (3) potential differences in activity between melanistic and spotted leopard morphs. Leopard density was estimated to be 1.39 ± SE 0.22/100 km². Leopard occupancy (ψ = 0.43; 95% credible interval: 0.26–0.67) increased further from roads, at relatively higher elevations, and in areas with higher relative abundance of wild boar. Leopard activity was cathemeral, with higher activity during night hours, and significant overlap (Δ = 0.84; 95% confidence interval: 0.71–0.96) between melanistic and spotted morphs. However, melanistic leopards were more active during twilight hours than spotted individuals whose activity did not significantly vary throughout the day. Indochinese leopard density estimates in Kweekoh were among the lowest reported from Southeast Asia. Leopard occupancy was highest in the sanctuary's core areas, suggesting the presence of negative anthropogenic impacts along the sanctuary borders. We suggest our low density estimates warrant immediate and decisive conservation action, including better protection for leopards, their habitat, and their prey.     

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.     

Comparative performance of four survey methods for assessing Lilian’s Lovebird abundance in Liwonde National Park,Malawi

Monitoring abundance of threatened species is important for conservation planning. Lilian’s Lovebird Agapornis lilianae is a near-threatened small parrot found in mopane Colophospermum mopane woodland. Its population has not been investigated in any part of its range. We investigated the abundance and density of the Lilian’s Lovebird in Liwonde National Park, Malawi. Both distance sampling (line and point transects) methods and total counts (waterhole and flyway counts) were applied. The point count method gave very low numbers and was discontinued after the first year. Line transects conducted during the wet season had the highest density estimates of 17 ± 4.8 lovebirds km?2 of mopane woodland. However, number of observations per transect in each year were low. Waterhole counts had the lowest density estimates (10 ± 3.5 lovebirds km?2). Flyway counts gave an intermediate estimate (13 ± 3.0 lovebirds km?2). The total population of Lilian’s Lovebirds in Liwonde National Park is therefore estimated to be about 4 000 individuals. The use of line transect counts at the end of the rainy season is recommended for continued monitoring of Lilian’s Lovebirds abundance in Liwonde National Park.     

Spatial variation in density of American black bears in northern Yellowstone National Park

The quality and availability of resources are known to influence spatial patterns of animal density. In Yellowstone National Park, relationships between the availability of resources and the distribution of grizzly bears (Ursus arctos) have been explored but have yet to be examined in American black bears (Ursus americanus). We conducted non-invasive genetic sampling during 2017–2018 (mid-May to mid-July) and applied spatially explicit capture-recapture models to estimate density of black bears and examine associations with landscape features. In both years, density estimates were higher in forested vegetation communities, which provide food resources and thermal and security cover preferred by black bears, compared with non-forested areas. In 2017, density also varied by sex, with female densities being higher than males. Based on our estimates, the northern range of Yellowstone National Park supports one of the highest densities of black bears (20 black bears/100 km²) in the northern Rocky Mountains (6–12 black bears/100 km² in other regions). Given these high densities, black bears could influence other wildlife populations more than previously thought, such as through displacement of sympatric predators from kills. Our study provides the first spatially explicit estimates of density for black bears within an ecosystem that contains the majority of North America's large mammal species. Our density estimates provide a baseline that can be used for future research and management decisions of black bears, including efforts to reduce human–bear conflicts.     

Characteristics of African wild dog natal dens selected under different interspecific predation pressures

To successfully reproduce, many carnivorous mammals need access to suitable den sites. Den site selection is often based on fitness related criteria like escape from predators, food availability and shelter from extreme weather conditions. African wild dogs are cooperative breeders that use a den to give birth to their offspring. They often co-exist with lions and spotted hyenas, both of which are known to kill African wild dog pups. Little is known about den site selection by African wild dogs. In this study, we compared vegetation characteristics and distribution of roads and waterholes around den sites and random sites, in areas with high and low lion and spotted hyena densities. In both areas, African wild dogs selected den sites in closed woodland with little visibility, which is likely to reduce detection by predators, increase the likelihood of escape when detected, and might provide shelter from extreme weather conditions. In the high predator density area, African wild dogs seemed to spatially avoid predators by selecting den sites in this type of habitat relatively further away from waterholes and roads. African wild dogs have high energetic costs of gestation. Therefore, even when predation risk is relatively low, they are likely to try to maximise their fitness by choosing a den site in habitat that will provide optimal protection for their offspring, leaving little additional options to respond to a higher predation pressure.     

Integration of ground survey and remote sensing derived data: Producing robust indicators of habitat extent and condition

The availability of suitable habitat is a key predictor of the changing status of biodiversity. Quantifying habitat availability over large spatial scales is, however, challenging. Although remote sensing techniques have high spatial coverage, there is uncertainty associated with these estimates due to errors in classification. Alternatively, the extent of habitats can be estimated from ground‐based field survey. Financial and logistical constraints mean that on‐the‐ground surveys have much lower coverage, but they can produce much higher quality estimates of habitat extent in the areas that are surveyed. Here, we demonstrate a new combined model which uses both types of data to produce unified national estimates of the extent of four key habitats across Great Britain based on Countryside Survey and Land Cover Map. This approach considers that the true proportion of habitat per km² (Z_i) is unobserved, but both ground survey and remote sensing can be used to estimate Z_i. The model allows the relationship between remote sensing data and Z_i to be spatially biased while ground survey is assumed to be unbiased. Taking a statistical model‐based approach to integrating field survey and remote sensing data allows for information on bias and precision to be captured and propagated such that estimates produced and parameters estimated are robust and interpretable. A simulation study shows that the combined model should perform best when error in the ground survey data is low. We use repeat surveys to parameterize the variance of ground survey data and demonstrate that error in this data source is small. The model produced revised national estimates of broadleaved woodland, arable land, bog, and fen, marsh and swamp extent across Britain in 2007.     

Estimating abundance of mountain lions from unstructured spatial sampling

Mountain lions (Puma concolor) are often difficult to monitor because of their low capture probabilities, extensive movements, and large territories. Methods for estimating the abundance of this species are needed to assess population status, determine harvest levels, evaluate the impacts of management actions on populations, and derive conservation and management strategies. Traditional mark–recapture methods do not explicitly account for differences in individual capture probabilities due to the spatial distribution of individuals in relation to survey effort (or trap locations). However, recent advances in the analysis of capture–recapture data have produced methods estimating abundance and density of animals from spatially explicit capture–recapture data that account for heterogeneity in capture probabilities due to the spatial organization of individuals and traps. We adapt recently developed spatial capture–recapture models to estimate density and abundance of mountain lions in western Montana. Volunteers and state agency personnel collected mountain lion DNA samples in portions of the Blackfoot drainage (7,908 km²) in west-central Montana using 2 methods: snow back-tracking mountain lion tracks to collect hair samples and biopsy darting treed mountain lions to obtain tissue samples. Overall, we recorded 72 individual capture events, including captures both with and without tissue sample collection and hair samples resulting in the identification of 50 individual mountain lions (30 females, 19 males, and 1 unknown sex individual). We estimated lion densities from 8 models containing effects of distance, sex, and survey effort on detection probability. Our population density estimates ranged from a minimum of 3.7 mountain lions/100 km² (95% CI 2.3–5.7) under the distance only model (including only an effect of distance on detection probability) to 6.7 (95% CI 3.1–11.0) under the full model (including effects of distance, sex, survey effort, and distance × sex on detection probability). These numbers translate to a total estimate of 293 mountain lions (95% CI 182–451) to 529 (95% CI 245–870) within the Blackfoot drainage. Results from the distance model are similar to previous estimates of 3.6 mountain lions/100 km² for the study area; however, results from all other models indicated greater numbers of mountain lions. Our results indicate that unstructured spatial sampling combined with spatial capture–recapture analysis can be an effective method for estimating large carnivore densities. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Western lowland gorilla density and nesting behavior in a Gabonese forest logged for 25 years: implications for gorilla conservation

The tropical forests of the Congo Basin constitute biodiversity refuges that still hold large numbers of species, including endemic and endangered vertebrates. Along with several key species, the critically endangered western lowland gorilla (WLG) potentially contributes to forest dynamics through seed dispersal. Considering the extensive influence of timber harvesting on tropical forest ecosystems, the survival of gorilla populations in logged forests might prove critical for forest ecosystem conservation. We estimated WLG density, through a nest count survey, in a forest in southeast Gabon that has been logged for 25 years. Nesting behavior and habitat use were described and we applied generalized linear models to identify the factors that influence gorilla day and night habitat use. The estimated density of weaned gorillas, 1.5 gorillas km^?2, is comparable with estimates from some protected areas and other sustainably managed sites within their range. Habitat type had the greatest influence on nest site distribution. We observed a preference for nesting in open terra firma forest, and open habitats in general, which supports the findings of previous studies. Habitat use during the day was strongly influenced by habitat type and human activities, and to a lesser degree by functional and non-functional roads, and rivers. Our results support the suggestion that logged forests are suitable habitats for WLG if hunting and poaching are controlled. We recommend collaborations between timber operators and scientists to improve the conservation potential of tropical forests and enhance the wildlife-management aspects of logging practices.     

New insights into the distribution and conservation status of the Golden-White Tassel-Ear Marmoset <Emphasis Type="Italic">Mico chrysoleucos</Emphasis> (Primates,Callitrichidae)

Among the 13 Mico species recognized by the IUCN Red List of Threatened Species, six are listed as “Data Deficient”. The geographic range of most of the Mico species has been estimated from only a few records. We report new localities and the geographic extension of Mico chrysoleucos. In addition, we confirmed the presence of the species in two distinct protected areas. We modeled the habitat suitability of M. chrysoleucos using the maximum entropy method and including new records obtained by the authors in the state of Amazonas, Brazil. From the total area of occurrence calculated for the species, 22.8% is covered by protected areas and indigenous lands. The annual mean deforestation rate estimated between 2000 and 2015 was 2.95%, and the total area deforested by 2015 was 3354 km² or 8.6% of the total distribution limits of the species. The habitat lost between 2000 and 2015 was 3.2% (1131 km²) of the total potential distribution, while the habitat loss area legally protected was 31 km², and the habitat loss in settlements was equal to 691 km². Our results extend the geographic distribution of the species about 100 km farther south, with the Maracanã River being a possible geographic barrier for the species. The significantly low rate of habitat loss inside protected areas and indigenous land, when compared to unprotected areas, points out the importance of these areas to M. chrysoleucos conservation. The species is relatively wide-ranging, legally protected, and resilient to regional anthropic threats. However, the hydroelectric schemes and the improvement of the road system in southern Amazonia pose an imminent threat to the species.     

Evidence for density-dependent habitat occupancy at varying scales in an expanding bird population

Understanding factors shaping the spatial distribution of animals is crucial for the conservation and management of wildlife species. However, few studies have investigated density-dependent habitat selection in wild populations in non-equilibrium conditions and at varying spatial scales. Here, we investigated density-dependent habitat selection at varying spatial scales in an increasing white stork Ciconia ciconia population using a long term data set in western France. During a 16-year study period, the breeding population density increased from 0.66 nests per 100 km² to 6.6 nests per 100 km². At the beginning of the colonisation of the area settlement probability of storks was mainly positively affected by grasslands located near wetlands. Areas with intensive or moderately intensive agriculture were extremely unlikely to be occupied by breeding birds. However, selection for the initially preferred habitats faded as stork density increased although the proportions of habitat types remained unchanged. At the same time selection for initially less favoured habitats had increased. Moreover, we found that the spatial scale of selection for each foraging habitat variable was consistent over time. Our results suggest that snapshot analyses of resource selection in populations at high density may be misleading for population conservation or management. In contrast, a longitudinal approach to resource selection can be a valuable tool for understanding resource limitation.