Grant M Harris

U.S. Fish and Wildlife Service · Department of the Interior

Technological and methodological advances in remote sensing and machine learning have created new opportunities for advancing wildlife surveys. We assembled a Community of Practice (CoP) to capitalize on these developments to explore improvements to the efficiency and effectiveness of aerial wildlife monitoring from a management perspective. The co...

Climate change shifts ecosystems, altering their compositions and instigating transitions, making climate change the predominant driver of ecosystem instability. Land management agencies experience these climatic effects on ecosystems they administer yet lack applied information to inform mitigation. We address this gap, explaining ecosystem shifts...

Objective The Yaqui Catfish Ictalurus pricei , a species that is endemic to the southwestern United States and west‐central Chihuahua and Sonora, Mexico, is extinct in the United States and extremely endangered in Mexico due to habitat loss and hybridization with nonnative Channel Catfish I. punctatus . To re‐establish populations in the United Sta...

The United States is rapidly expanding production of renewable energy to meet increased energy demands and reduce greenhouse gas emissions. Wind energy is at the forefront of this transition. A central challenge is understanding the nexus between wind energy development and its capacity for negative effects on wildlife causing population declines a...

Biologists commonly use camera traps for estimating species richness to inform conservation actions, steer land protection, and reveal effects of climate change. Long-term studies using short delay periods (≤1 min) and numerous cameras produce voluminous amounts of redundant imagery. Camera-trapping procedures maximizing richness estimates while mi...

Stable or growing populations may go extinct when their sizes cannot withstand large swings in temporal variation and stochastic forces. Hence, the minimum abundance threshold defining when populations can persist without human intervention forms a key conservation parameter. We identify this threshold for many populations of Caprinae, typically th...

Globally, migration phenologies of numerous avian species have shifted over the past half-century. Despite North American waterfowl being well researched, published data on shifts in waterfowl migration phenologies remain scarce. Understanding shifts in waterfowl migration phenologies along with potential drivers is critical for guiding future cons...

Two crane species, whooping cranes ( Grus americana ) and sandhill cranes ( Antigone canadensis ), overwinter along the Texas Gulf Coast. Periodic, extreme drought conditions have prompted concerns that potential freshwater limitations could hinder conservation of cranes, especially endangered whooping cranes. In response, land managers constructed...

The Aransas-Wood Buffalo population (the only non-reintroduced, migratory population) of endangered whooping cranes (Grus americana), overwinters along the Texas Gulf Coast, USA. Understanding whooping crane space use on the wintering grounds reveals essential aspects of this species ecology, which subsequently assists with conservation. Using glob...

Estimating Sample Size for Point-Count Based Distance Sampling

Managing water (e.g., catchments) to increase the abundance and distribution of game is popular in arid regions, especially throughout the southwest United States, where biologists often manage water year-round for desert bighorn sheep (Ovis canadensis nelsoni). Bighorn may visit water when predators (e.g., mountain lions [Puma concolor], coyotes [...

With most of the world’s Caprinae taxa threatened with extinction, the IUCN appeals to the development of simple and affordable sampling methods that will produce credible abundance and distribution data for helping conserve these species inhabiting remote areas. Traditional sampling approaches, like aerial sampling or mark-capture-recapture, are i...

The only self-sustaining population of endangered whooping cranes (Grus americana) requires a network of conservation lands for wintering along the Texas Gulf Coast (USA), so that this increasing population can reach downlisting under the Endangered Species Act (1,000 birds). We identify locations providing the highest quality and most sustainable...

Populations of Caprinae typically inhabit mountainous, remote and occasionally highly vegetated terrain, often making population estimation costly or impractical to pursue. Therefore, many Caprinae populations lack abundance data (Shackleton1997). This problem motivated us to design and test a simple and inexpensive solution for producing credible...

Conservation programs for imperiled fish require a sampling method for quantifying their habitat relationships and their progress toward recovery, via abundance estimation and subsequent monitoring. Depletion sampling is a commonly used method, although the assumptions of homogeneous capture probabilities are tenuous. Recently, Bayesian hierarchica...

Designing wildlife surveys requires biologists to identify their objectives and the accuracy (bias and precision) required to inform them. In southwestern Arizona (USA), abundance estimates and trends for desert bighorn sheep (Ovis canadensis) rely on detection-corrected aerial surveys (group-size estimator), to inform harvest and assess management...

In the original publication, the Electronic Supplementary Material (ESM) was published incorrectly. The correct version of ESM is given in the link below.

Within the U.S. portion of the Central Flyway, the U.S. Fish and Wildlife Service manages waterfowl on numerous individual units (i.e., Refuges) within the National Wildlife Refuge System. Presently, the extent of waterfowl use that Refuges receive and the contribution of Refuges to waterfowl populations (i.e., the proportion of the Central Flyway...

Models of animal density often use coarse landcover categories that homogenize vegetation attributes, thereby limiting specificity of results. Alternatively, models including land surface phenology (LSP) metrics derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery capture continuous time-series data describing plant...

Data describing population abundance, survival, and recruitment informs species conservation status and conservation actions. Acquiring these data remains challenging for rare and endangered species, especially freshwater fish, with ~37% threatened or extinct. The absence of data risks inaction, ineptness and ignorance that can contaminate conserva...

Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes (Grus americana) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping...

Worldwide, approximately half of all freshwater fish are threatened with extinction or lack data sufficient for classifying their conservation status. We focused on three such species endemic to southeastern Arizona, USA and Sonora, Mexico: Yaqui topminnow (Poeciliopsis occidentalis sonoriensis), Yaqui chub (Gila purpurae), and beautiful shiner (Cy...

Data describing population abundance, survival, and recruitment informs species conservation status and conservation actions. Acquiring these data remains challenging for rare and endangered species, especially freshwater fish, with ~37% threatened or extinct. The absence of data risks inaction, ineptness and ignorance that can contaminate conserva...

ContextClimate change alters the vegetation composition and functioning of ecosystems. Measuring the magnitude, direction, and rate of changes in vegetation composition induced by climate remains a serious and unmet challenge. Such information is required for a predictive capability of how individual ecosystem will respond to future climates. Objec...

Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water pro...

Climate often drives ungulate population dynamics, and as climates change, some areas may become unsuitable for species persistence. Unraveling the relationships between climate and population dynamics, and projecting them across time, advances ecological understanding that informs and steers sustainable conservation for species. Using pronghorn (A...

Focusing conservation strategies requires identifying the demographic parameters and environmental conditions affecting the growth of animal populations most. Therefore, we examined relationships between population demographics and winter drought (1950–2011) for endangered whooping cranes (Grus americana ) wintering in Texas, USA. We modeled winter...

Many units of the National Wildlife Refuge System (NWRS) in the Central Flyway of the United States were established to conserve and enhance waterfowl populations. Consistent and continuous monitoring of waterfowl abundance on refuges is critical when evaluating the performance of individual refuges as well as the refuge system on a larger scale. I...

Setting conservation goals and management objectives relies on understanding animal habitat preferences. Models that predict preferences combine location data from tracked animals with environmental information, usually at a spatial resolution determined by the available data. This resolution may be biologically irrelevant for the species in questi...

We used sightability models with aerial counts to estimate regional abundance of desert bighorn sheep (Ovis canadensis) in southwestern Arizona during 1992–2012. Because of incomplete spatial and temporal coverage of surveys, we integrated sightability estimates using Bayesian state-space models. Although some game management units (GMUs) exhibited...

Winter recreation can displace ungulates to poor habitats, which may raise their energy expenditure and lower individual survivorship, causing population declines. Winter recreation could be benign, however, if animals habituate. Moreover, recreation creates trails. Traveling on them could reduce energy expenditure, thereby increasing ungulate surv...

Wildlife biologists often use grid-based designs to sample animals and generate abundance estimates. Although sampling in grids is theoretically sound, in application, the method can be logistically difficult and expensive when sampling elusive species inhabiting extensive areas. These factors make it challenging to sample animals and meet the stat...

Wildlife biologists often use grid-based designs to sample animals and generate abundance estimates. Although sampling in grids is theoretically sound, in application, the method can be logistically difficult and expensive when sampling elusive species inhabiting extensive areas. These factors make it challenging to sample animals and meet the stat...

Wildlife biologists often use grid-based designs to sample animals and generate abundance estimates. Although sampling in grids is theoretically sound, in application, the method can be logistically difficult and expensive when sampling elusive species inhabiting extensive areas. These factors make it challenging to sample animals and meet the stat...

Wildlife populations experience periods of negative growth of varying magnitudes and duration. Understanding these dynamics and a population’s sensitivity to them informs conservation planning, policy decisions, recovery criteria and management triggers, especially when management actions are expensive or risky. Therefore, to inform management and...

Habitat loss and attendant fragmentation threaten the existence of many species. Conserving these species requires a straightforward and objective method that quantifies how these factors affect their survival. Therefore, we compared a variety of metrics that assess habitat fragmentation in bird ranges, using the geographical ranges of 127 forest e...

Habitat loss and attendant fragmentation threaten the existence of many species. Conserving these species requires a straightforward and objective method that quantifies how these factors affect their survival. Therefore, we compared a variety of metrics that assess habitat fragmentation in bird ranges, using the geographical ranges of 127 forest e...

Spatially explicit metapopulation models and metapopulation capacity. (DOCX)

Complete list of Atlantic forest bird species (bold names recommended for reassessment based on habitat fragmentation, due to low metapopulation capacity). (XLSX)

Habitat loss is the principal threat to species. How much habitat remains—and how quickly it is shrinking—are implicitly included in the way the International Union for Conservation of Nature determines a species’ risk of extinction. Many endangered species have habitats that are also fragmented to different extents. Thus, ideally, fragmentation sh...

Networks of automatic cameras are producing many thousands of images over modest time periods. For example, 35 cameras at Sevilleta National Wildlife Refuge in New Mexico, USA have produced more than 1.9m useful images since June, 2009. A US Fish and Wildlife monitoring program is producing about 30,000 images per week. Although image file retrieva...

After a decline in the U.S. population of Sonoran Pronghorn to less than ~ 30 individuals in 2003 the Sonoran Pronghorn Recovery Team determined that recovery efforts should attempt to reintroduce additional populations within historic habitat. With a program to restore Antilocapra americana sonoriensis to the Kofa National Wildlife Refuge in Arizo...

We evaluated the collecting locales of 251 masked bobwhite (Colinus virginianus ridgwayi) specimens in museum collections. Eighteen were from 4 sites in Arizona—all collected by Herbert Brown. The vast majority (93%) of specimens were from the Mexican State of Sonora. We visited and photographed each of the Arizona collection locations and most of...

Habitat fragmentation continues to be a leading threat for our global future. Methods to quantify fragmentation of habitat landscapes, particularly for endangered species, would be especially useful in conservation planning. Using the principles of metapopulation theory, we updated and devised two methods for analyzing fragmented landscapes: metapo...

Background/Question/Methods Rare and cryptic animals inhabiting densely vegetated or complex terrain challenge efforts to count them. Sampling methods often rely on broad, systematic schemes to sample individuals (e.g. photography or DNA), but these approaches grow expensive over large areas. We tested if sampling at focal times and in biologicall...

Background/Question/Methods Habitat fragmentation is one of the primary threats to biodiversity. Satellite imagery is providing increasingly detailed information on habitat distributions, yet efficient techniques for linking these data to species survival are in short supply. Starting with metapopulation theory, we compared two methods of making t...

Field surveys in montane Atlantic forest of Rio de Janeiro state, Brazil, provided a list of 82 bird species in four sitesvisited. Our protocol relied on standardized use of mist nets and observations. The birds recorded include 40 Atlanticforest endemics, three globally and two nationally Vulnerable species, and two regionally Endangered species....

Knowledge of mammal migrations is low, and human impacts on migrations high. This jeopardizes efforts to conserve terrestrial migrations. To aid the conservation of these migrations, we synthesized information worldwide, describing 24 large-bodied ungulates that migrate in aggregations. This synthesis includes maps of extinct and extant migrations,...

The grey-winged cotinga Tijuca condita was first described in 1980 from an old specimen, misidentified as a congener. Field observations came later, from two remote, high-elevation forests in the mountains of Rio de Janeiro, Brazil. Both involved only a few pairs of birds at best, making this species one of the least known in the world. Accurately...

Small geographical range size is the single best predictor of threat of extinction in terrestrial species. Knowing how small a species' range has to be before authorities consider it threatened with extinction would allow prediction of a species' risk from continued deforestation and warming climates and provide a baseline for conservation and mana...

Managers in southern Africa are concerned that continually increasing elephant populations will degrade ecosystems. Culling, translocation and birth control are flawed solutions. An alternative is providing elephants more space but this hinges on identifying landscape preferences. We examined two diverse eco-systems and uncovered similarities in el...

Although there is widespread agreement about conservation priorities at large scales (i.e., biodiversity hotspots), their boundaries remain too coarse for setting practical conservation goals. Refining hotspot conservation means identifying specific locations (individual habitat patches) of realistic size and scale for managers to protect and polit...

Intense deforestation causes massive species losses. These losses occur because the habitats supplanting primary forest are inadequate to sustain viable populations of forest-dependent species. Despite this, certain species do seem to persist within the secondary habitats that replace original forest. This implies that there is a special class of s...