Experimental analysis of retreat‐site selection by thick‐tailed geckos Nephrurus milii

Abstract Although animals use habitats non‐randomly in the wild, complex correlations among environmental features mean that proximate influences on habitat selection can be identified only by experimental manipulation of potential cues. Thick‐tailed geckos Nephrurus milii are large lizards that are widely distributed through southern Australia. These nocturnally active animals typically spend daylight hours under surface rocks. We presented captive geckos with alternative retreat‐sites (rock crevices) differing in attributes potentially relevant to habitat selection. The lizards showed strong preference for shelter‐sites that enhanced thermoregulation (warm rather than cool) and that reduced the animal's vulnerability to predators (narrow crevices with small openings and not containing the scent of a predatory snake). Horizontal rather than sloping crevices were also preferred. Overall crevice size and thickness of the overlying rock did not influence retreat‐site selection in the laboratory, but could be important in the field because of their influence on thermal regimes under rocks. The present study supports the idea that nocturnal reptiles base their selection of diurnal shelters on multiple aspects related to the fitness consequences of occupancy of alternative available retreat‐sites.     

Factors affecting retreat‐site selection by coppertail skinks (Ctenotus taeniolatus) from sandstone outcrops in eastern Australia

Abstract Coppertail skinks (Ctenotus taeniolatus) are medium‐sized diurnal lizards that are widespread in eastern Australia. Field surveys on sandstone outcrops in the Sydney region showed that these animals use available rocks non‐randomly: coppertails were found under large, sun‐exposed rocks on deep soil. Choice trials in the laboratory documented selection of retreat sites that were warm, with substrate preferences shifting in a diel cycle. Lizards selected retreats with rock substrates during the day but with sandy substrates at night. Rocky retreats attain higher temperatures during daylight hours, but burrows in sand beneath rocks may provide greater protection against ingress by nocturnal predators. During fieldwork we rarely found lizards under rocks with either ants or centipedes, suggesting that coppertails may avoid these predatory invertebrates. Tongue‐flick trials showed that the lizards could discriminate among common ant species based on chemosensory cues, but apparently could not detect centipede chemical cues. In experimental trials, the lizards did not avoid retreat sites scented by either ants or centipedes. Our data thus suggest that retreat‐site selection in coppertails is driven by abiotic cues (rock size, sun exposure and substrate type) that may confer fitness benefits in terms of thermoregulation and predator avoidance, with biotic cues playing a less important role.     

Using Artificial Rocks to Restore Nonrenewable Shelter Sites in Human‐Degraded Systems: Colonization by Fauna

Many animals spend much of their time within retreat sites underneath loose surface rocks and may be highly selective in terms of the physical characteristics of the sites that they use. If such shelters are eliminated by anthropogenic activities, such as rock removal for landscaping, the only way to restore these nonrenewable habitats may be to replace them with artificial rocks. To construct artificial rock habitats, we need to understand which rock attributes are important for faunal use and develop methods to mimic these important natural retreat site characteristics. Based on our prior understanding of rocky retreat sites used by reptiles in sandstone outcrops of southeastern Australia, we constructed realistic‐looking artificial rocks from fiber‐reinforced cement and evaluated (1) the degree to which they mimicked natural retreat sites in both thermal regime and three‐dimensional crevice structure and (2) their colonization by fauna after deployment in the field. Our results demonstrate that thermal regimes and crevice structures beneath the artificial rocks were similar to those beneath natural rocks. In addition, 100% of the artificial rocks were colonized (by 45 invertebrate, six lizard, and two snake species, including the endangered Broad‐headed snake, Hoplocephalus bungaroides) after only 40 weeks. Together, these results suggest that restoring degraded habitats for rock‐dwelling species is feasible and can provide a rapid means of enhancing shelter‐site availability for such species.     

Site vegetation characteristics are more important than landscape context in determining bird assemblages in revegetation

The effectiveness of revegetation in providing habitat for fauna is expected to be determined both by within‐site factors and attributes of the landscape in which a revegetation site occurs. Most studies of fauna in revegetation have been conducted in landscapes that have been extensively cleared, modified or fragmented, and in Australia, predominantly in the southern temperate zone. We investigated how within‐site vegetation attributes and landscape context attributes were related to bird species richness and composition in a chronosequence of post‐mining rehabilitation sites within an otherwise intact landscape in tropical northern Australia. Our working hypothesis was that bird species richness in rehabilitating sites would be positively related to site vegetation structure and landscape context including (1) proximity to woodland and (2) the proportion of woodland within a 500‐m buffer of rehabilitation sites. Within each of 67 sites, we sampled vegetation once and surveyed for birds eight times over 16 months. Landscape context variables were calculated using GIS. There were large differences between bird assemblages of woodland and rehabilitation sites and between age classes of rehabilitation. Bird assemblages were strongly related to site vegetation attributes across all rehabilitation sites. Proximity to woodland was only related to bird assemblages in rehabilitation sites older than 4 years old. We conclude that the relative importance of landscape context and site variables at any point in time will be a function of how closely vegetation within the revegetation site matches the habitat resource requirements of individual species.     

Environmental factors affecting patterns of distribution and co‐occurrence of two competing raptor species

Habitat selection is a complex process, that is affected by several factors, including habitat characteristics, environmental conditions, and both intra‐ and interspecific interactions. We analysed habitat preferences of two top avian predators, Peregrine Falcon Falco peregrinus, a medium‐sized diurnal raptor, and Eagle Owl Bubo bubo, a large nocturnal raptor. These two species are known to compete for preferred nest‐sites, and proximity to cliffs with Eagle Owls may reduce Peregrine breeding output through predation of young Falcons. We investigated the environmental factors affecting occurrence and coexistence of the two species and the potential role of habitat suitability in favouring co‐occurrence in 3519 km² of the central pre‐Alps of Italy, where the two species breed on cliffs and sometimes co‐occur on the same cliff. Peregrines settled on long, steep and favourably orientated cliffs in woodland landscapes close to urban areas. Eagle Owls settled on topographically similar cliffs, but in lower rainfall areas compared with cliffs occupied by Peregrines and cliffs unoccupied by either species. Sites where the two species co‐occurred were characterized by more horizontally extended cliffs compared with sites of exclusive occurrence of each species. An analysis of relative habitat suitability revealed that sites where the two species co‐occurred had the highest predicted probability of occupancy for both species, suggesting that those sites should be regarded as high‐quality sites. Breeding productivity of Eagle Owls was negatively affected by the co‐occurrence of Peregrines, whereas the effect of Eagle Owl proximity on Peregrine productivity varied according to cliff suitability for the Peregrines. Habitat selection had fitness consequences for Eagle Owls because breeding productivity increased with cliff length. Environmental conditions, particularly climatic factors, could allow the widespread coexistence of these competing raptors at the landscape scale, whereas at the local scale co‐occurrence could take place only on larger cliffs. These were preferred sites for both species, presumably because breeding at such sites offsets the costs of settling close to the competitor species.     

Local versus landscape determinants of butterfly movement behaviors

Large-scale patterns of animal distributions and abundances may be determined by mechanisms that act at local or landscape scales. We studied the movement behaviors of four species of bottomland butterflies in a natural setting to examine the determinants of movement behavior across different scales. We tested the relative importance of three landscape attributes: drainage slope, boundary type, and stream proximity, and local habitat attributes related to food plants and plants that influence habitat structure. Across species, we tested the relative importance of organism size and habitat specificity to explain response variation. In general, butterfly responses to landscape features were more universal than responses to local features. Specifically, results from this study showed that drainage slope did not influence movement behaviors but boundary type, stream proximity, and host plant abundance all influenced movement patterns. Responses to local features varied by species and often complemented landscape effects on movement. Responses to all features were not related to butterfly size, but did vary in accordance with butterfly host plant specificity. These behaviors help to explain landscape-level variation in population distribution among species.     

Factors affecting breeding habitat selection in a cliff-nesting peregrine Falco peregrinus population

We studied factors affecting breeding habitat selection in a population of cliff-nesting peregrines Falco peregrinus across multiple spatial levels (cliff site, cliff context and land-use of the surrounding landscape), over a 2,100 km² study area in the Alps (Italy and Switzerland). We detected 30 breeding pairs (density: 1.43 territorial pairs/100 km²), whose territories were uniformly distributed over the study area. We compared 15 habitat features characterising occupied cliffs and 30 randomly selected unoccupied cliffs by means of stepwise forward logistic regression and hierarchical partitioning. The logistic regression analysis showed that occupied cliffs were longer (horizontal length), steeper, and had a greater extension of urban areas in the surrounding landscape compared to non-occupied cliffs. The model had a discrimination ability of 0.95. Hierarchical partitioning indicated that the logistic regression model was appropriate. Neither the distance of cliffs to the nearest site occupied by a potential competitor and predator, the eagle owl Bubo bubo, which occurred at a low density (0.67 pairs/100 km²), nor the distance to the nearest site occupied by peregrines had any effect on the cliff suitability model. Therefore, habitat selection in cliff-nesting peregrines was mainly influenced by cliff site features and surrounding landscape characteristics, whereas the proximity to conspecifics and to an intraguild predator had no apparent effects on peregrine settlement in our study population.     

The social elite: Habitat heterogeneity,complexity and quality in granite inselbergs influence patterns of aggregation in Egernia striolata (Lygosominae: Scincidae)

Habitat heterogeneity, structural complexity and habitat quality are key features of the environment that drive species' distribution and patterns of biological organization. Traditionally, pattern‐based studies have focused on faunal responses to biological systems. However, the influence of non‐biological environments such as insular rock outcrops on patterns of vertebrate distribution is conceivably as important, but has received less attention. Granite inselbergs are a naturally heterogeneous and spatially‐limited habitat. As such, they provide an opportunity for investigating whether environmental attributes influence social behaviour in animals that use these kinds of habitat, particularly lizards that are well adapted to saxicoline environments. We applied ecological theory to investigate the influence of habitat heterogeneity, structural complexity and habitat quality on patterns of home‐site occupancy in the crevice skink Egernia striolata (Lygosominea: Scincidae) from insular granite outcrops located within fragmented agricultural landscapes. We compared home‐site occupancy among solitary juveniles, solitary adults and lizard aggregations. We found significant differences in home‐site occupancy between aggregations and solitary lizard outcrop attributes measured at multiple spatial scales. The probability of a home‐site being occupied by an aggregation increased where large rock masses were present, on northern aspects near the core of the outcrop and in structurally variegated landscapes. Significantly more aggregations occupied home‐sites surrounded by high boulder cover and crevice microhabitat. We provide evidence that geophysical attributes of granite inselbergs and landscape context can influence patterns of lizard aggregation. Thus, we clearly document the environmental correlations of variability in sociality among subpopulations of Egernia striolata.     

River Otter Latrine Site Selection in Arid Habitats of Western Colorado,USA

ABSTRACT River otters (Lontra canadensis) select specific habitat features when establishing latrines, but no studies have described latrine features in arid and semiarid environments. We developed a model describing those habitat features that influence otter latrine site selection on rivers in arid and semiarid watersheds of western Colorado, USA. River otters selected latrine sites with the presence of beaver (Castor canadensis) activity, large prominent rocks, adjacent to deeper water, with shading over the site, and rock or cliff overstory. Our model provides a robust predictive tool for identifying river otter latrine sites in arid environments of southwestern North America.     

Predictive models of habitat preferences for the Eurasian eagle owl Bubo bubo: a multiscale approach

Habitat preference of eagle owls Bubo bubo were examined through comparing habitat composition around 51 occupied cliffs and 36 non-occupied cliffs in Alicante (E Spain). We employed Generalized Linear Models to examine patterns of habitat preference at three different spatial scales: nest site (7 km²), home range (25 km²), and landscape (100 km²). At the nest site scale, occupied cliffs were more rugged, had a greater proportion of forest surface in the surroundings, and were further from the nearest paved road than unoccupied cliffs. Additionally, probability of having an occupied cliff increased when there was another occupied territory in the surroundings. At both the home range scale and the landscape scale, high probabilities of presence of eagle owls were related to high percentages of Mediterranean scrubland around the cliffs, which are the preferred habitat of European rabbits Oryctolagus cuniculus , the main prey of the owls. We suggest a hierarchical process of habitat selection in the eagle owl concerning suitable trophic resources at the broadest scales and adequate sites for breeding and roosting at the smallest scale. However, it should be noted that some structural features such as the proximity of roads were not necessarily avoided by the owls, but their presence were possibly constrained by systematic killing of individuals. Our paper provides new evidence for the requirement of multi-scale approaches to gain insight into both the different limiting factors for the persistence of populations and the role of individual perception of the environment in the evolution of habitat selection.     

流域景观类型及配置对大型底栖动物完整性的影响

通过对滦河流域66个河段大型底栖动物采集和生境指标监测,基于大型底栖动物完整性评价和13种景观指数构建,探讨了不同景观指数对于大型底栖无脊椎动物完整性的解释能力。景观指数类型包括流域及欧式距离缓冲区土地利用百分比、水流路径缓冲区土地利用百分比、局部区域土地利用百分比和基于水流路径的反距离权重指数。基于多元线性逐步回归模型,根据调整R2(Square of the coefficient)来判断不同指数的解释能力。研究结果表明基于水流路径的反距离权重指数对于大型底栖动物完整性的解释能力最好,其次为基于水流路径的缓冲区和局部区域的土地利用百分比指数,全流域及欧氏距离缓冲区内土地利用百分比解释能力最差。农田是影响大型底栖动物完整性最重要的景观类型,距离河流越近的农田对大型底栖动物完整性的影响越大,因此流域及河岸带农田的控制和管理对于滦河流域大型底栖动物完整性的恢复具有重要的作用。     

Use of forest fragments by blue-winged macaws (<Emphasis Type="Italic">Primolius maracana</Emphasis>) within a fragmented landscape

Parrots are the most threatened group of birds in the world, mainly because of the reduction and fragmentation of their natural habitats. However, few studies have investigated the dynamics of parrot populations in disturbed landscapes on a broad scale. In this paper, we studied the ecological interactions of the vulnerable blue-winged macaw (Primolius maracana) in a fragmented landscape surrounding a large protected park in southeastern Brazil. We sampled 36 forest fragments that varied in size, characteristics, degree of isolation and type of surrounding matrix in order to assess the importance of habitat features on the maintenance of these birds. Blue-winged macaws were recorded in 70% of the satellite remnants that were sampled, which included large and small blocks of forest. These areas were used as sites for feeding, nesting or overnight rests, and also provided connectivity for birds’ displacements. However, the frequency of macaw visits varied among the remnants, and this was related to habitat features such as patch size, human use of surrounding land, and the proximity to the protected park, to urban areas and to the birds’ roosting areas. In general, landscape-scale parameters explained more of the variation in the frequency of visits by macaws than did patch-scale parameters. These results demonstrate the importance of landscape mosaics for the survival of blue-winged macaws.     

A comparison of spatially explicit landscape representation methods and their relationship to stream condition

1. Biodiversity, water quality and ecosystem processes in streams are known to be influenced by the terrestrial landscape over a range of spatial and temporal scales. Lumped attributes (i.e. per cent land use) are often used to characterise the condition of the catchment; however, they are not spatially explicit and do not account for the disproportionate influence of land located near the stream or connected by overland flow. 2. We compared seven landscape representation metrics to determine whether accounting for the spatial proximity and hydrological effects of land use can be used to account for additional variability in indicators of stream ecosystem health. The landscape metrics included the following: a lumped metric, four inverse‐distance‐weighted (IDW) metrics based on distance to the stream or survey site and two modified IDW metrics that also accounted for the level of hydrologic activity (HA‐IDW). Ecosystem health data were obtained from the Ecological Health Monitoring Programme in Southeast Queensland, Australia and included measures of fish, invertebrates, physicochemistry and nutrients collected during two seasons over 4 years. Linear models were fitted to the stream indicators and landscape metrics, by season, and compared using an information‐theoretic approach. 3. Although no single metric was most suitable for modelling all stream indicators, lumped metrics rarely performed as well as other metric types. Metrics based on proximity to the stream (IDW and HA‐IDW) were more suitable for modelling fish indicators, while the HA‐IDW metric based on proximity to the survey site generally outperformed others for invertebrates, irrespective of season. There was consistent support for metrics based on proximity to the survey site (IDW or HA‐IDW) for all physicochemical indicators during the dry season, while a HA‐IDW metric based on proximity to the stream was suitable for five of the six physicochemical indicators in the post‐wet season. Only one nutrient indicator was tested and results showed that catchment area had a significant effect on the relationship between land use metrics and algal stable isotope ratios in both seasons. 4. Spatially explicit methods of landscape representation can clearly improve the predictive ability of many empirical models currently used to study the relationship between landscape, habitat and stream condition. A comparison of different metrics may provide clues about causal pathways and mechanistic processes behind correlative relationships and could be used to target restoration efforts strategically.     

Retreat site selection and social organization in captive electric fish, Apteronotus leptorhynchus

Gymnotiform fish use their electric organ discharge for electrolocation and communication. They are active nocturnally and seek retreat sites during the day. We examined retreat site selection in Apteronotus leptorhynchus by assessing their preference for retreat tubes that differed in opacity and dimension. Isolated fish preferred opaque to clear tubes, long and narrow diameter tubes to short, wide diameter tubes, and open-ended to closed tubes. We also assessed how groups of fish distributed themselves in tubes according to sex and electric organ discharge frequency under four conditions: (1) unlimited tube availability, (2) limited tube availability, (3) variation in tube opacity, and (4) variation in tube dimension. When tube availability was unlimited, fish generally preferred to occupy tubes alone. However, females, but not males, often cohabited tubes with consexuals. When tube availability was limited, females were more often than males found outside of tubes. When tubes varied by opacity and dimension, fish clustered most commonly in preferred tube types (opaque and long tubes). Males with the highest electric organ discharge frequencies usually occupied the most preferred tube type. Thus, fish have clear preferences in selecting retreat sites and groups of fish reveal their dominance relationships when presented with variation in retreat sites.     

Greater Sage-Grouse Nesting Habitat: The Importance of Managing at Multiple Scales

Abstract: Considering habitat selection at multiple scales is essential to fully understand habitat requirements and management needs for wildlife species of concern. We used a hierarchical information-theoretic approach and variance decomposition techniques to analyze habitat selection using local-scale habitat variables measured in the field and landscape-scale variables derived with a Geographic Information System (GIS) for nesting greater sage-grouse (Centrocercus urophasianus) in the Powder River Basin (PRB), Montana and Wyoming, USA, 2003–2007. We investigated relationships between habitat features that can and cannot be mapped in a GIS to provide insights into interpretation of landscape-scale—only GIS models. We produced models of habitat selection at both local and landscape scales and across scales, yet multiscale models had overwhelming statistical and biological support. Variance decomposition showed that local-scale measures explained the most pure variation (50%) in sage-grouse nesting-habitat selection. Landscape-scale features explained 20% of pure variation and shared 30% with local-scale features. Both local- and landscape-scale habitat features are important in sage-grouse nesting-habitat selection because each scale explained both pure and shared variation. Our landscape-scale model was accurate in predicting priority landscapes where sage-grouse nests would occur and is, therefore, useful in providing landscape context for management decisions. It accurately predicted locations of independent sage-grouse nests (validation R² = 0.99) and showed good discriminatory ability with >90% of nests located within only 40% of the study area. Our landscape-scale model also accurately predicted independent lek locations. We estimated twice the amount of predicted nesting habitat within 3 km of leks compared to random locations in the PRB. Likewise we estimated 1.8 times more predicted nesting habitat within 10 km of leks compared to random locations. These results support predictions of the hotspot theory of lek placement. Local-scale habitat variables that cannot currently be mapped in a GIS strongly influence sage-grouse nest-site selection, but only within priority nesting habitats defined at the landscape scale. Our results indicate that habitat treatments for nesting sage-grouse applied in areas with an unsuitable landscape context are unlikely to achieve desired conservation results.     

Hot rocks or no hot rocks: overnight retreat availability and selection by a diurnal lizard

I used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards ( Sceloporus occidentalis). In watersheds of northern California (USA), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. Rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available retreat sites on meadows during the first 5 h of inactivity. Only cobble and sand substrates provided retreats with temperatures within the preferred daily active range (32–36°C) during the inactive period for these lizards (1900–0900 hours). Females on a cobble bar used rocks as retreats on >90% of nights during the breeding season whereas females on a meadow used wood (>70% of nights) and burrows (>25% of nights). In contrast to females, cobble bar males used rocks significantly less frequently (<70%) and slept in the open air significantly more frequently (25% vs. <1%). Cobble bar females further, showed a significant preference for cobbles 15 cm thick, whereas the rocks used by males did not differ significantly in thickness from those measured in randomly placed transects. Rocks 15 cm thick were the warmest retreats commonly available on this habitat type. Thus, thermal microenvironments available to and chosen by gravid female lizards differ considerably between river and non-river habitats.     

Towards indicators of butterfly biodiversity based on a multiscale landscape description

The conservation of biodiversity has gained prominence in ecological research for the last decades. Conservation actions require a measure of biodiversity such as species richness, but its assessment is very difficult, even for small areas and therefore the search for surrogates (i.e. indicators) of biodiversity has emerged as an active research topic. We investigated the relationships between butterfly species richness and landscape structure and composition in two pine plantation sites in Southwest France. We assessed the correlation between butterfly species richness and a set of 15 landscape metrics computed for 18 land-uses at 10 different spatial scales. Spatial scales were accounted for by computing landscape metrics for circular buffers with radius ranging from 100 to 1000 m. The joint use of the Partial Least Squares Regression (PLSR) and a stepwise regression procedure revealed strong correlations between butterfly species richness and various landscape metrics in both study sites. The selected landscape metrics differed from one site to another and mostly involved measures of landscape fragmentation. We found a very strong effect of the spatial scale of investigation upon the perception of the landscape–butterfly richness relationship. Our main conclusions are that (i) certain landscape attributes can potentially serve as indicators for butterfly species richness at the landscape scale; (ii) future indicators of biodiversity based on landscape features should consider various spatial scales.     

Central place foraging in a human-dominated landscape: how do common cranes select feeding sites?

Human infrastructure and disturbance play an important role when animals select resources in human-modified landscapes. Theory predicts that animals trade food intake against costs of movement or disturbance to optimize net energy gain and fitness, but other necessary resources may also constrain the decisions, e.g. when animals repeatedly need to return to a central location, such as a nest, waterhole or night roost. Central place foraging theory states that the probability of occurrence of an animal decreases with the distance to the central location while selectivity for food items or foraging sites providing high net energy gain should increase with distance. We studied foraging patterns of common cranes Grus grus feeding in an agricultural landscape adjacent to a wetland to which they return for night roost. We used availability of spilled grains on harvested fields and distance to human settlement as proxy for site quality (i.e. increased likelihood of increased net energy gain with increased food availability and less disturbance). As predicted by theory, our results clearly show that cranes were more likely (more than twice as high resource selection function scores) to select foraging sites close to roosts. However, contrary to predictions, the selection of high quality sites in terms of high food availability decreased with distance to roost sites. Nevertheless, our results indicate that cranes were more likely to select sites with low risk of human disturbance far from roost sites, and were more tolerant to disturbance close to roost sites. How different species respond to the local and environmental conditions will increase the understanding of the species’ resource requirement, and also where in the landscape to prioritize conservation or management actions (e.g. mitigation of human disturbance and crop damage prevention to sustain agricultural production).     

A regional study of Holocene climate change and human occupation in Peruvian Amazonia

Aim  To investigate the influence of Holocene climatic and human-induced changes on a region of high biodiversity in southern Peruvian Amazonia.
Location  Four palaeoecological records from separate lakes within a lake district close to the modern city of Puerto Maldonado, Peru.
Results  The lakes provide a palaeoecological record spanning the last 8200 years. A mid-Holocene dry event is documented in all of the records that extend back > 6000 years. The dry event appears to have lasted from c . 7200 yr bp until c . 3300 yr bp . The onset of wetter conditions coincides with the formation of the youngest of the four lakes. The earliest occupation of these sites is inferred from the presence of charcoal at 7200 yr bp , and the first crop pollen is found at 3630 yr bp . Lakes that were regularly occupied were colonized soon after they formed. A reduction in charcoal concentration and the absence of crop pollen after c . 500  bp in all lakes is consistent with site abandonment following conquest.
Main conclusions  The mid-Holocene dry event is suggested to be part of a time-transgressive drying that tracked from north to south in both the Andes and the Amazon lowlands. The last millennium may represent the period of highest sustained lake levels within the Holocene. The proximity of the four lakes allows a landscape-scale analysis of the spatial extent of human disturbance centred on a known site of human occupation and reveals the highly localized nature of pre-Columbian anthropogenic disturbance in Amazonian landscapes. Inferences regarding widespread pre-Columbian landscape modification by indigenous peoples must take into account key site attributes, such as seasonality and proximity to rivers.     

Multi-scale turtle dove nest habitat selection in a Mediterranean agroforestry landscape: implications for the conservation of a vulnerable species

Determination of factors affecting nest habitat selection is a major topic in avian ecology, with strong implications for conservation purposes especially for the species with unfavorable status. The turtle dove (Streptopelia turtur) is a vulnerable species that has undergone a rapid and serious decline across its distribution range. I investigated the effect of different variables at two spatial scales (10-m radius, nest site; and 100-m radius, landscape) on the probability of presence of turtle dove nests in an agroforestry system of Central Morocco. Topography, habitat structure, human disturbance, and land use parameters were measured at nests (n?=?70) and random points (n?=?70) at both scales. Generalized linear model analyses showed that, at the nest site scale, tree height best explained occurrence of turtle dove nests (with nest occurring preferentially in smaller trees). At the landscape scale, nest occurrence probability decreased with elevation and distance to the nearest forest edge, and increased with forest cover and distance to the nearest habitation. Comparison of explanatory power of the single-scale models showed that the most relevant scale was the nest site level, followed by landscape scales, but the model including both nest-scale and landscape-scale variables was best. The variation partitioning analysis confirmed this pattern. In study area, the turtle dove nest habitat selection process occurs within a relatively small scale, but the joint effect of variables at the two scales is relevant. From a practical perspective, it would be interesting to reproduce the same experimental approach on other Mediterranean breeding habitats (agricultural and other forest habitats) to find out if this species would adopt the same nest habitat selection pattern.