Robert J. Fletcher

University of Florida | UF · Department of Wildlife Ecology and Conservation

Invasive exotic species are spreading rapidly throughout the planet. These species can have widespread impacts on biodiversity, yet the ability for native species, particularly long-lived vertebrates, to respond rapidly to invasions remains mostly unknown. Here we provide evidence of rapid morphological change in the endangered snail kite (Rostrham...

Significance Connectivity, or the degree to which individuals can move across landscapes, is essential for species persistence and the maintenance of biodiversity. While connectivity is increasingly understood for some individual species and landscapes, understanding and predicting connectivity for entire communities remains elusive despite its imp...

International demand for wood and other forest products continues to grow rapidly, and uncertainties remain about how animal communities will respond to intensifying resource extraction associated with woody bioenergy production. We examined changes in alpha and beta diversity of bats, bees, birds, and reptiles across wood production landscapes in...

Balancing the competing, and often conflicting, needs of people and wildlife in shared landscapes is a major challenge for conservation science and policy worldwide. Connectivity is critical for wildlife persistence, but dispersing animals may come into conflict with people, leading to severe costs for humans and animals and impeding connectivity....

Prey can use several information sources (cues) to assess predation risk and avoid predation with a variety of behavioural responses (e.g., changes in activity, foraging, vigilance, social behaviour, space use, and reproductive behaviour). Direct cues produced by predators and indirect cues from environmental features or conspecific and heterospeci...

Maintaining and restoring ecological connectivity will be key in helping to prevent and reverse the loss of biodiversity. Fortunately, a growing body of research conducted over the last few decades has advanced our understanding of connectivity science, which will help inform evidence‐based connectivity conservation actions. Increases in data avail...

As the Anthropocene proceeds, the matrix in which remaining habitats are embedded is an increasingly dominant component of altered landscapes. The matrix appears to have diverse and far-reaching effects, yet our understanding of the causes and consequences of these effects remains limited. We first synthesize the broad range of perspectives on the...

Changes in phenology are occurring from global climate change, yet the impacts of other types of global change on the phenology of animals remain less appreciated. Understanding the potential for synergistic effects of different types of global change on phenology is needed, because changing climate regimes can have cascading effects, particularly...

Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems¹ that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value⁴. Here we present empirically defined thresholds for categorizing the cons...

Rostrhamus sociabilis (Snail Kite) have recently expanded their range in Florida, tracking the invasion of a Pomacea snail (P. maculata), and exhibiting considerable changes in bill size and feeding niche. This range expansion is not aligned with changes in climatic conditions or the distribution of their historic prey (P. paludosa). The Eltonian N...

Background Understanding how to connect habitat remnants to facilitate the movement of species is a critical task in an increasingly fragmented world impacted by human activities. The identification of dispersal routes and corridors through connectivity analysis requires measures of landscape resistance but there has been no consensus on how to cal...

Understanding dispersal is central to interpreting the effects of climate change, habitat loss and habitat fragmentation, and species invasions. Prior to dispersal, animals may gather information about the surrounding landscape via forays, or systematic, short‐duration looping movements away from and back to the original location. Despite theory em...

The functional stability of ecosystems depends greatly on interspecific differences in responses to environmental perturbation. However, responses to perturbation are not necessarily invariant among populations of the same species, so intraspecific variation in responses might also contribute. Such inter-population response diversity has recently b...

Animals are faced with a variety of dangers or threats, which are increasing in frequency with ongoing environmental change. While our understanding of fearfulness of such dangers is growing in the context of predation and parasitism risk, the extent to which non-trophic, interspecific dangers elicit fear in animals remains less appreciated. We pro...

The colonization of suitable yet unoccupied habitat due to natural dispersal or human introduction can benefit recovery of threatened species. Predicting habitat suitability and conflict potential of colonization areas can facilitate conservation planning. Planning for reintroduction of gray wolves (Canis lupus) to the US state of Colorado is under...

The importance of dispersal rates and distances has long been appreciated by ecologists and evolutionary biologists. An emerging field of research is revealing how temporal variation in dispersal can substantially influence ecological and evolutionary outcomes. We review how dispersal rates can temporally vary substantially in many ecosystems, a pa...

Context Dispersal typically consists of three components—departure, transience and settlement—each of which can be influenced by the landscape. A fundamental aspect of dispersal is the dispersal kernel, which describes how the likelihood of settlement varies as a function of the distance from the departure location. Dispersal concepts are often clo...

Many ecologists increasingly advocate for research frameworks centered on the use of 'big data' to address anthropogenic impacts on ecosystems. Yet, experiments are often considered essential for identifying mechanisms and informing conservation interventions. We highlight the complementarity of these research frameworks and expose largely untapped...

Background Understanding how to connect habitat remnants to facilitate the movement of species is a critical task in an increasingly fragmented world impacted by human activities. The identification of dispersal routes and corridors through connectivity analysis requires measures of landscape resistance but there has been no consensus on how to cal...

Habitat loss is often considered the greatest near‐term threat to biodiversity, while the impact of habitat fragmentation remains intensely debated. A key issue of this debate centers on the problem of scale–landscape or patch–at which to assess the consequences of fragmentation. Yet patterns are often confounded across scales, and experimental des...

Megaherbivores play a critical role in the ecology of African savannas and grasslands. In addition, these systems are forecast to experience more frequent and severe droughts as a product of changes in the global climate. Thus, the continued conservation of megaherbivores and their associated ecosystems will require a better understanding of how me...

Fragmentation and scale Although habitat loss has well‐known impacts on biodiversity, the effects of habitat fragmentation remain intensely debated. It is often argued that the effects of habitat fragmentation, or the breaking apart of habitat for a given habitat amount, can be understood only at the scale of entire landscapes composed of multiple...

The once vast and interconnected Everglades wetland ecosystem in Florida underwent a 50% reduction in area in the 1900s, resulting in a highly compartmentalized and managed system where ecological restoration is ongoing. Everglade snail kites (Rostrhamus sociabilis plumbeus, hereafter snail kites) are federally endangered wetland specialists with a...

Understanding how species respond to the environment is essential in ecology, evolution, and conservation. Abiotic factors can influence species responses and the multi‐dimensional space of abiotic factors that allows a species to grow represents the environmental niche. While niches are often assumed to be constant and robust, they are most likely...

Many early successional and disturbance-dependent bird species have declined over the past several decades. Cavitynesting birds in early successional forests are vulnerable because they often require specific habitat characteristics and frequent disturbance events. We examined whether stand age (a proxy for forest succession), stand size, and snag...

Consumers, including megaherbivores and fire, are considered important limiting forces for woody plants and canopy closure in African savannas. However, climatic events like drought can also play a significant role in limiting trees and maintaining tree‐grass coexistence in savannas. The extent to which top‐down control (e.g. megaherbivores) and bo...

Changes in global bioenergy consumption have catalyzed the emergence of forest plantations as an important energy alternative. In the southeastern United States, land cover changes caused by increasing demands for pine trees as a bioenergy feedstock incite associated impacts on local ecosystem services (e.g., water yield). However, water yield impa...

Genetic connectivity lies at the heart of evolutionary theory, and landscape genetics has rapidly advanced to understand how gene flow can be impacted by the environment. Isolation by landscape resistance, often inferred through the use of circuit theory, is increasingly identified as being critical for predicting genetic connectivity across comple...

The natal environment can have long-term fitness consequences for individuals, particularly via 'silver spoon' or 'environmental matching' effects. Invasive species could alter natal effects on native species by changing species interactions, but this potential remains unknown. Using 17 years of data on 2588 individuals across the entire US breedin...

Although matrix improvement in fragmented landscapes is a promising conservation measure, matrix permeability (willingness of an organism to enter the matrix) and movement survival in the matrix are usually aggregated. Consequently, it is unknown which matrix property needs to be improved. It also remains unclear whether matrix upgrading from dispe...

Understanding animal movement often relies upon telemetry and biologging devices. These data are frequently used to estimate latent behavioural states to help understand why animals move across the landscape. While there are a variety of methods that make behavioural inferences from biotelemetry data, some features of these methods (e.g. analysis o...

As Amazon deforestation rates reach the highest levels observed in the past decade, it is extremely important to direct conservation efforts to regions containing preserved forests with a high risk of deforestation. This requires forecasting deforestation, a complex endeavor due to the interplay of multiple socioeconomic and environmental factors a...

Increased agricultural intensification and extensive woody plant encroachment are having widespread effects on the functioning of grass-dominated systems at multiple spatial scales. Yet there is little understanding of how the provisioning of biodiversity-based ecosystem services might be altered by these ongoing changes. One fundamental ecosystem...

In savannas across the planet, encroaching woody plants are altering ecosystem functions and reshaping communities. Seed predation by rodents may serve to slow the encroachment of woody plants in grasslands and savannas. Our goals for this study were to determine if rodents in an African savanna selectively removed seeds of an encroaching plant and...

ContextUnderstanding the relative contributions of spatial and environmental processes on community assembly is a central question in ecology. Despite this long-standing interest, our understanding of how landscape structure may drive spatial processes of community assembly remains poorly understood in part because of the challenge of tracking comm...

Agricultural intensification is a threat to terrestrial ecosystems around the world. Agricultural areas, especially monocultures, create homogenous landscapes for wildlife. However, certain crops, such as sugarcane, are harvested in phases, creating a mosaic of fields in different stages of growth. We investigated changes in avian communities acros...

Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species an...

Small changes in the environment can have large impacts, leading to ‘tipping points’ or ‘threshold’ effects on populations. Identifying such effects can provide practitioners benchmarks to both minimize negative impacts and foster positive benefits for populations. Nonetheless, identifying thresholds can be challenging as they can vary spatially, t...

Bioenergy produced from woody biomass in managed forest systems represents a substantial portion of the global supply of renewable energy. As societies transition to renewable energy and demand for wood-based bioenergy increases, timber-producing forests and other agricultural and marginal lands may transition to bioenergy management regimes. Limit...

1. Understanding animal movement often relies upon telemetry and biologging devices. These data are frequently used to estimate latent behavioral states to help understand why animals move across the landscape. While there are a variety of methods that make behavioral inferences from biotelemetry data, some features of these methods (e.g., analysis...

Landscape connectivity is increasingly promoted as a conservation tool to combat the negative effects of habitat loss, fragmentation, and climate change. Given its importance as a key conservation strategy, connectivity science is a rapidly growing discipline. However, most landscape connectivity models consider connectivity for only a single snaps...

Land‐cover and land‐use change are major drivers of global biodiversity loss. Savannas are experiencing shrub encroachment and land‐use changes that affect animal communities, yet how the effects of shrub encroachment vary with land use remains unclear. We also need to determine which species traits explain the effects of shrub encroachment and lan...

Understanding how the world's flora and fauna will respond to bioenergy expansion is critical. This issue is particularly pronounced considering bioenergy's potential role as a driver of land‐use change, the variety of production crops being considered and currently used for biomass, and the diversity of ecosystems that can potentially supply land...

Human demand for food, fiber, and space is accelerating the rate of change of land cover and land use. Much of the world now consists of a matrix of natural forests, managed forests, agricultural cropland, and urbanized plots. Expansion of domestic energy production efforts in the United States is one driver predicted to influence future land‐use a...

Maintaining the ability of organisms to move between suitable patches of habitat despite ongoing habitat loss is essential to conserving biodiversity. Quantifying connectivity has therefore become a central focus of conservation planning. A large number of metrics have been developed to estimate potential connectivity based on habitat configuration...

Cultivation of bioenergy feedstocks is a growing land‐use world‐wide, yet we have a poor understanding of how bioenergy crop management practices affect biodiversity. This knowledge gap is particularly acute for candidate cellulosic bioenergy feedstocks, such as tree plantations, and for organisms that provide important ecosystem services, such as...

Central-place foragers can be constrained by the distance between habitats. When an organism relies on a central place for thermal refuge, the distance to food resources can potentially constrain foraging behavior. We investigated the effect of distance between thermal refuges and forage patches of the cold-intolerant marine mammal, the Florida man...

Quantifying landscape connectivity is fundamental to better understand and predict how populations respond to environmental change. Currently, popular methods to quantify landscape connectivity emphasize how landscape features provide resistance to movement. While many tools are available to quantify landscape resistance, these do not discern betwe...

Some of the world’s deadliest diseases and greatest public health challenges are zoonoses from wildlife, such as Ebola (Ebolavirus). Due to the increasing number of cases in recent years, it has been widely hypothesized that increasing human population densities and anthropogenic disturbance largely explain outbreaks of Ebola virus disease in human...

Vulnerability to habitat fragmentation Habitat fragmentation caused by human activities has consequences for the distribution and movement of organisms. Betts et al. present a global analysis of how exposure to habitat fragmentation affects the composition of ecological communities (see the Perspective by Hargreaves). In a dataset consisting of 448...

For species with geographically restricted distributions, the impacts of habitat loss and fragmentation on long-term persistence may be particularly pronounced. We examined the genetic structure of Panama City crayfish (PCC), Procambarus econfinae, whose historical distribution is limited to an area approximately 145 km2, largely within the limits...

Habitat connectivity enhances diversity Fragmentation of ecosystems leads to loss of biodiversity in the remaining habitat patches, but retaining connecting corridors can reduce these losses. Using long-term data from a large, replicated experiment, Damschen et al. show quantitatively how these losses are reduced. In their pine savanna system, corr...

Selective logging is the primary cause of tropical forest degradation and is rapidly expanding worldwide. While the impacts of logging on species diversity and distributions are well understood, little is known about the effects of logging on animal behaviours central to individual fitness and population persistence. The song rate of breeding songb...

Predicting connectivity, or how landscapes alter movement, is essential for understanding the scope for species persistence with environmental change. Although it is well known that movement is risky, connectivity modelling often conflates behavioural responses to the matrix through which animals disperse with mortality risk. We derive new connecti...

Understanding and accurately modeling species distributions lies at the heart of many problems in ecology, evolution, and conservation. Multiple sources of data are increasingly available for modeling species distributions, such as data from citizen science programs, atlases, museums, and planned surveys. Yet reliably combining data sources can be...

Context Land-use change is a key driver of pollinator declines worldwide. Plantation forests are a major land use worldwide and are likely to expand substantially in the near term, especially with projected cellulosic biofuel production. But little is known about the potential local and landscape-scale impacts of plantation forestry on bees, the mo...