Book Chapters by Travis Longcore
Journal Articles by Travis Longcore
A s diurnal creatures, humans have long sought methods to illuminate the night. In pre-industrial... more A s diurnal creatures, humans have long sought methods to illuminate the night. In pre-industrial times, artificial light was generated by burning various materials, including wood, oil, and even dried fish. While these methods of lighting certainly influenced animal behavior and ecology locally, such effects were limited. The relatively recent invention and rapid proliferation of electric lights, however, have transformed the nighttime environment over substantial portions of the Earth's surface. Ecologists have not entirely ignored the potential disruption of ecological systems by artificial night lighting. Several authors have written reviews of the potential effects on ecosystems or taxonomic groups, published in the "gray" literature (
PLoS ONE, 2012
Avian mortality at communication towers in the continental United States and Canada is an issue o... more Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action.
International Journal of Remote Sensing, 2007
Nightsat is a concept for a satellite system capable of global observation of the location, exten... more Nightsat is a concept for a satellite system capable of global observation of the location, extent and brightness of night-time lights at a spatial resolution suitable for the delineation of primary features within human settlements. Based on requirements from several fields of scientific inquiry, Nightsat should be capable of producing a complete cloud-free global map of lights on an annual basis. We have used a combination of high-resolution field spectra of outdoor lighting, moderate resolution colour photography of cities at night from the International Space Station, and high-resolution airborne camera imagery acquired at night to define a range of spatial, spectral, and detection limit options for a future Nightsat mission. The primary findings of our study are that Nightsat should collect data from a near-synchronous orbit in the early evening with 50 to 100 m spatial resolution and have detection limits of 2.5E 28 Watts cm 22 sr 21 mm 21 or better. Although panchromatic low-light imaging data would be useful, multispectral low-light imaging data would provide valuable information on the type or character of lighting; potentially stronger predictors of variables, such as ambient population density and economic activity; and valuable information to predict response of other species to artificial night lighting. The Nightsat mission concept is unique in its focus on observing a human activity, in contrast to traditional Earth observing systems that focus on natural systems.
Environmental Management, 2000
Arthropod communities from several habitats on and adjacent to the El Segundo dunes (Los Angeles ... more Arthropod communities from several habitats on and adjacent to the El Segundo dunes (Los Angeles County, CA) were sampled using pitfall and yellow pan traps to evaluate their possible use as indicators of restoration success. Communities were ordinated and clustered using correspondence analysis, detrended correspondence analysis, two-way indicator species analysis, and Ward's method of agglomerative clustering. The results showed high repeatability among replicates within any sampling arena that permits discrimination of (1) degraded and relatively undisturbed habitat, (2) different dune habitat types, and (3) annual change. Canonical correspondence analysis showed a significant effect of disturbance history on community composition that explained 5-20% of the variation. Replicates of pitfall and yellow pan traps on single sites clustered together reliably when species abundance was considered, whereas clusters using only species incidence did not group replicates as consistently. The broad taxonomic approach seems appropriate for habitat evaluation and monitoring of restoration projects as an alternative to assessments geared to single species or even single families.
European Journal of Wildlife Research, 2012
Global economic and population growth increase the extent and intensity of artificial night light... more Global economic and population growth increase the extent and intensity of artificial night lighting. From an ecological perspective, this is light pollution, which causes changes in reproductive physiology, migration and foraging of many species and ultimately leads to loss of biodiversity. Some seabirds are intimately linked with the light features of their environments because they are nocturnally active. We report light-induced groundings of Cory's shearwater (Calonectris diomedea) during a 2-year study (2008 and 2009) in São Miguel Island, in the Azores archipelago, and investigate the spatial correlation of locations of grounded birds with an annual composite of remotely sensed stable lights. Results indicate that 16.7% of fledglings are attracted to lights. The exposure of shearwater colonies in the study area to artificial night lighting is low overall. Four colonies account for 87% of the grounded birds. The distance each bird was found from the closest colony was best explained by the ratio of the satellite-measured light levels at the grounding spot to the light levels at the assigned colony of origin. These results demonstrate that satellite-observed nighttime lights are sufficient to assess risk to marine birds at the scale of oceanic islands and indicate their utility for monitoring the effectiveness of programs to manage lighting to reduce risk for these species and conducting global assessments of species vulnerability. To minimize the impact on Cory's shearwater and other marine birds, we recommend measures such as reduction and control of lighting intensity near colony locations, while continuing and re-enforcing rescue campaigns.
Avian Conservation and Ecology, 2013
This special feature of Avian Conservation and Ecology contains a Special Issue of ten articles d... more This special feature of Avian Conservation and Ecology contains a Special Issue of ten articles describing extent and character of avian mortality in Canada associated with human activities. These include estimates of mortality resulting from mowing and other mechanical operations, industrial forestry, domestic cats, collisions with windows, wind turbines, power lines and vehicles, bycatch in commercial fisheries, and both offshore and terrestrial oil and gas exploration and production. These articles contain sector-based assessments of the annual magnitude of the number of eggs or active nests destroyed and number of birds killed as a consequence of a wide range of human activities, excluding habitat development and hunting. This Special Issue represents an unprecedented snapshot of the state of knowledge for such sources of mortality for an entire country at a specific time. Needless to say, numbers of such avian mortalities that can be attributed to humans are large and unevenly distributed among species and different activities.
Wetlands, 2010
Vast resources are devoted annually to watershed management and wetland restoration. Historical w... more Vast resources are devoted annually to watershed management and wetland restoration. Historical wetland losses are often cited as a motivation for prioritizing ambitious wetland restoration efforts. However, analysis of historical conditions is often underutilized in the planning process. In this paper we demonstrate historical ecological analysis of the San Gabriel River watershed in southern California. We integrate multiple disparate data sources collected at different spatial and temporal scales to describe historical wetland extent and distribution. We compare historic wetlands to contemporary conditions to calculate wetland losses. From the results of this analysis, we conclude that the widely held view of southern California as naturally dry and desert-like with mainly ephemeral and intermittent streams may be an over generalization. Historically, the San Gabriel watershed has supported complex expanses of channels, ponds, sloughs, seeps, marshes, and seasonal wetlands that alternated between wet and dry conditions on multi-year to decadal cycles. We estimate that >86% of historical wetlands have been lost since ca. 1870, with the greatest losses occurring to palustrine alkali meadows in the lower floodplain. Despite the extensive losses, the analysis reveals areas of the watershed conducive to wetland re-establishment and provides insight into the most appropriate wetland types to prioritize for specific watershed settings.
European Journal of Wildlife Research, 2012
Global economic and population growth increase the extent and intensity of artificial night light... more Global economic and population growth increase the extent and intensity of artificial night lighting. From an ecological perspective, this is light pollution, which causes changes in reproductive physiology, migration and foraging of many species and ultimately leads to loss of biodiversity. Some seabirds are intimately linked with the light features of their environments because they are nocturnally active. We report light-induced groundings of Cory's shearwater (Calonectris diomedea) during a 2-year study (2008 and 2009) in São Miguel Island, in the Azores archipelago, and investigate the spatial correlation of locations of grounded birds with an annual composite of remotely sensed stable lights. Results indicate that 16.7% of fledglings are attracted to lights. The exposure of shearwater colonies in the study area to artificial night lighting is low overall. Four colonies account for 87% of the grounded birds. The distance each bird was found from the closest colony was best explained by the ratio of the satellite-measured light levels at the grounding spot to the light levels at the assigned colony of origin. These results demonstrate that satellite-observed nighttime lights are sufficient to assess risk to marine birds at the scale of oceanic islands and indicate their utility for monitoring the effectiveness of programs to manage lighting to reduce risk for these species and conducting global assessments of species vulnerability. To minimize the impact on Cory's shearwater and other marine birds, we recommend measures such as reduction and control of lighting intensity near colony locations, while continuing and re-enforcing rescue campaigns.
Cities, 2013
Revitalization of urban alleys, underway in cities and towns in North America, Europe, and other ... more Revitalization of urban alleys, underway in cities and towns in North America, Europe, and other regions, can be seen as a manifestation of a broader movement among city agencies, planners, and community groups to expand green urban infrastructure and promote sustainability. This article analyzes alley greening programs in seven cities in the United States using the lens of sustainability planning. Study results indicate that most alley greening programs are narrowly oriented toward stormwater management. An in-depth exploration of the alley greening program in the city of Los Angeles illustrates how a more robust commitment to sustainability -through the adoption of goals related to environmental protection, economic development, and social equity -might be actualized in the context of alley greening efforts. The article also considers the role of collaboration in developing integrative sustainability programs around alleys.
With the listing of the quino checkerspot butterfly, Euphydryas editha quino, as a federally enda... more With the listing of the quino checkerspot butterfly, Euphydryas editha quino, as a federally endangered species, research into its ecology and conservation is necessary to allow for recovery planning and management. We review systematics, distribution, natural history, and conservation prospects, with reference to pertinent literature about other E. editha subspecies. Additional information is presented from museum specimens and ongoing research on the species.
Nightsat is a concept for a satellite system capable of global observation of the location, exten... more Nightsat is a concept for a satellite system capable of global observation of the location, extent and brightness of night-time lights at a spatial resolution suitable for the delineation of primary features within human settlements. Based on requirements from several fields of scientific inquiry, Nightsat should be capable of producing a complete cloud-free global map of lights on an annual basis. We have used a combination of high-resolution field spectra of outdoor lighting, moderate resolution colour photography of cities at night from the International Space Station, and high-resolution airborne camera imagery acquired at night to define a range of spatial, spectral, and detection limit options for a future Nightsat mission. The primary findings of our study are that Nightsat should collect data from a near-synchronous orbit in the early evening with 50 to 100 m spatial resolution and have detection limits of 2.5E 28 Watts cm 22 sr 21 mm 21 or better. Although panchromatic low-light imaging data would be useful, multispectral low-light imaging data would provide valuable information on the type or character of lighting; potentially stronger predictors of variables, such as ambient population density and economic activity; and valuable information to predict response of other species to artificial night lighting. The Nightsat mission concept is unique in its focus on observing a human activity, in contrast to traditional Earth observing systems that focus on natural systems.
Journal of Insect Conservation, 2001
Before, during and after habitat restoration from 1984 to 1994, we monitored population size of t... more Before, during and after habitat restoration from 1984 to 1994, we monitored population size of the federally listed endangered El Segundo blue butterfly, Euphilotes bernardino allyni (Shields). In the subsequent formalization of a recovery plan for the species, the U.S. Fish and Wildlife Service established several recovery criteria, including a requirement of 'a scientifically credible monitoring plan' to track population size annually. To avoid detrimental effects of the extensively used mark-release-recapture method on the delicate El Segundo blue butterfly, which would conflict with protection afforded by the Endangered Species Act, we chose instead to perform transect counts to estimate relative population size. Herein, we analyze the results of our transect counts by three different methods, developed by or modified from Pollard, Watt et al. and Zonneveld. Qualitatively, the three methods, which have different assumptions, produced similar results when applied to the same data. Zonneveld's model estimates death rate in addition to an index of population size, thus providing more information than the other two methods. The El Segundo blue butterfly's sedentary nature and the close relationship of its adult and early stages to one foodplant permits extrapolation of the index of population size based on transect counts, to an estimate of actual population size. Our data document butterfly numbers increasing from 1984 to 1989, but then declining until the end of our observations in 1994. Based on analysis of our El Segundo blue butterfly data, we propose an implementation of a scientifically credible monitoring plan.
With the listing of the quino checkerspot butterfly, Euphydryas editha quino, as a federally enda... more With the listing of the quino checkerspot butterfly, Euphydryas editha quino, as a federally endangered species, research into its ecology and conservation is necessary to allow for recovery planning and management. We review systematics, distribution, natural history, and conservation prospects, with reference to pertinent literature about other E. editha subspecies. Additional information is presented from museum specimens and ongoing research on the species.
Environmental Management, 2007
Management of ecological reserve lands should rely on the best available science to achieve the g... more Management of ecological reserve lands should rely on the best available science to achieve the goal of biodiversity conservation. “Adaptive Resource Management” is the current template to ensure that management decisions are reasoned and that decisions increase understanding of the system being managed. In systems with little human disturbance, certain management decisions are clear; steps to protect native species usually
Avian Conservation and Ecology
This special feature of Avian Conservation and Ecology contains a Special Issue of ten articles d... more This special feature of Avian Conservation and Ecology contains a Special Issue of ten articles describing extent and character of avian mortality in Canada associated with human activities. These include estimates of mortality resulting from mowing and other mechanical operations, industrial forestry, domestic cats, collisions with windows, wind turbines, power lines and vehicles, bycatch in commercial fisheries, and both offshore and terrestrial oil and gas exploration and production. These articles contain sector-based assessments of the annual magnitude of the number of eggs or active nests destroyed and number of birds killed as a consequence of a wide range of human activities, excluding habitat development and hunting. This Special Issue represents an unprecedented snapshot of the state of knowledge for such sources of mortality for an entire country at a specific time. Needless to say, numbers of such avian mortalities that can be attributed to humans are large and unevenly distributed among species and different activities.
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Book Chapters by Travis Longcore
Journal Articles by Travis Longcore