Geology topics

Tom Smith

Publications and source records attributed to Tom Smith.

7 recordsLinked to original sources

USGS2022

Efficacy of bear spray as a deterrent against polar bears

Although there have been few attempts to systematically analyze information on the use of deterrents on polar bears ( Ursus maritimus ), understanding their effectiveness in mitigating human-polar bear conflicts is critical to ensuring both human safety and polar bear conservation. To fill this knowledge gap, we analyzed 19 incidents involving the use of bear spray on free-ranging polar bears from 1986 to 2019 in Canada, Russia, and the United States to evaluate the effectiveness of bear spray as a polar bear deterrent. We found that bear spray was an effective deterrent in close-range encounters with polar bears, stopping undesirable behavior in 18 of 19 incidents. Bear spray effectively deterred both curious and aggressive polar bears, including polar bears attempting to attack people. The mean distance between user and bear at the time of spraying was 2 m (min–max = 0.2–10.0 m, mode = 1 m), though bears were usually first seen at greater distances. Bear spray was successfully deployed against polar bears in all 4 seasons. Wind affected spray performance in 1 of 19 of incidents. In 8 of 14 bear spray incidents, other deterrents were used without success before bear spray was used effectively to deter polar bears. No humans or polar bears were killed or injured in any of the incidents in which bear spray was used. We also analyzed 54 polar bear attacks and attempted attacks on humans where bear spray was not carried. The data suggest that in 93% of those incidents, the use of bear spray might have saved the lives of both the people and bears involved if it had been available and used. Our analysis improves our understanding of the effectiveness of bear spray for polar bear conflict mitigation.

Wildlife Society Bulletin↗

USGS2022

Where land and sea meet: Brown bears and sea otters

In Katmai National Park, Alaska, USA, we have seen changes in the number of brown bears and sea otters. The number of animals of a species a habitat can support is called carrying capacity. Even though bears live on land and sea otters live in the ocean, these two mammals share coastal habitats. Bears eat salmon, other fish, plants, clams, and beached whales. Sea otters feed on clams and other marine invertebrates. All these foods are influenced by the ocean. Recently, we have seen fewer bears but more sea otters! What changed? Many things, but several observations point to the ocean. There are fewer salmon, whales, and clams, so bears rely more on plants for food. Fewer clams mean sea otters must work harder to find food. Our studies are helping us to understand how and why carrying capacity for a given species may change over time.

Alaska↗

USGS2018

Den phenology and reproductive success of polar bears in a changing climate

Synchrony between reproduction and food availability is important in mammals due to the high energetic costs of gestation and lactation. Female polar bears ( Ursus maritimus ) must accumulate sufficient energy reserves during spring through autumn to produce and nurse cubs during the winter months in snow dens. Adequate time in a den is important to optimize cub development for withstanding harsh Arctic spring conditions and to synchronize emergence with peak prey availability, which occurs in May and June. During 1985–2013, den phenology was investigated using temperature data collected on satellite collars deployed on adult female polar bears in the southern Beaufort Sea (SB) and Chukchi Sea (CS). We examined relationships between den phenology, reproductive success (cub production and post-emergence survival), and environmental factors (weather and sea-ice conditions). Females observed with cubs emerged later and remained in dens on average 15.0 ± 7.6 ( SE ) days longer than females seen without cubs. Females occupying land-based dens, where estimated snowfall was greater, had higher reproductive success. Recently, female polar bears have increased land-based denning in the SB. Females in CS emerged later from dens than SB females, consistent with better female body condition and higher cub survival in the CS. During years with a greater area of autumn sea ice, reproductive success was higher at land-based versus sea-ice dens, suggesting continued decline in sea ice could negatively affect recruitment. However, further research is needed to better understand mechanistic relationships. Because females emerging later from dens had higher reproductive success, den duration could be a useful metric in population monitoring.

Journal of Mammalogy↗

USGS2014

Downscaled climate projections for the Southeast United States: evaluation and use for ecological applications

Climate change is likely to have many effects on natural ecosystems in the Southeast U.S. The National Climate Assessment Southeast Technical Report (SETR) indicates that natural ecosystems in the Southeast are likely to be affected by warming temperatures, ocean acidification, sea-level rise, and changes in rainfall and evapotranspiration. To better assess these how climate changes could affect multiple sectors, including ecosystems, climatologists have created several downscaled climate projections (or downscaled datasets) that contain information from the global climate models (GCMs) translated to regional or local scales. The process of creating these downscaled datasets, known as downscaling, can be carried out using a broad range of statistical or numerical modeling techniques. The rapid proliferation of techniques that can be used for downscaling and the number of downscaled datasets produced in recent years present many challenges for scientists and decisionmakers in assessing the impact or vulnerability of a given species or ecosystem to climate change. Given the number of available downscaled datasets, how do these model outputs compare to each other? Which variables are available, and are certain downscaled datasets more appropriate for assessing vulnerability of a particular species? Given the desire to use these datasets for impact and vulnerability assessments and the lack of comparison between these datasets, the goal of this report is to synthesize the information available in these downscaled datasets and provide guidance to scientists and natural resource managers with specific interests in ecological modeling and conservation planning related to climate change in the Southeast U.S. This report enables the Southeast Climate Science Center (SECSC) to address an important strategic goal of providing scientific information and guidance that will enable resource managers and other participants in Landscape Conservation Cooperatives to make science-based climate change adaptation decisions.

Open-File Report↗

USGS2009

Black and Brown Bear Activity at Selected Coastal Sites in Glacier Bay National Park and Preserve, Alaska: A Preliminary Assessment Using Noninvasive Procedures

A number of efforts in recent years have sought to predict bear activity in various habitats to minimize human disturbance and bear/human conflicts. Alaskan coastal areas provide important foraging areas for bears (Ursus americanus and U. arctos), particularly following den emergence when there may be no snow-free foraging alternatives. Additionally, coastal areas provide important food items for bears throughout the year. Glacier Bay National Park and Preserve (GLBA) in southeastern Alaska has extensive coastal habitats, and the National Park Service (NPS) has been long interested in learning more about the use of these coastal habitats by bears because these same habitats receive extensive human use by park visitors, especially kayaking recreationists. This study provides insight regarding the nature and intensity of bear activity at selected coastal sites within GLBA. We achieved a clearer understanding of bear/habitat relationships within GLBA by analyzing bear activity data collected with remote cameras, bear sign mapping, scat collections, and genetic analysis of bear hair. Although we could not quantify actual levels of bear activity at study sites, agreement among measures of activity (for example, sign counts, DNA analysis, and video record) lends support to our qualitative site assessments. This work suggests that habitat evaluation, bear sign mapping, and periodic scat counts can provide a useful index of bear activity for sites of interest.

Open-File Report↗

USGS2005

Brown bear habituation to people - Safety, risks, and benefits

Recently, brown bear ( Ursus arctos ) viewing has increased in coastal Alaska and British Columbia, as well as in interior areas such as Yellowstone National Park. Viewing is most often being done under conditions that offer acceptable safety to both people and bears. We analyze and comment on the underlying processes that lead brown bears to tolerate people at close range. Although habituation is an important process influencing the distance at which bears tolerate people, other variables also modify levels of bear-to-human tolerance. Because bears may react internally with energetic costs before showing an overt reaction to humans, we propose a new term, the Overt Reaction Distance, to emphasize that what we observe is the external reaction of a bear. In this paper we conceptually analyze bear viewing in terms of benefits and risks to people and bears. We conclude that managers and policy-makers must develop site-specific plans that identify the extent to which bear-to-human habituation and tolerance will be permitted. The proposed management needs scientific underpinning. It is our belief that bear viewing, where appropriate, may promote conservation of bear populations, habitats, and ecosystems as it instills respect and concern in those who participate.

Wildlife Society Bulletin↗

USGS2001

Tampa Bay Integrated Science Pilot Study: wetland characterization

Coastal wetlands in Tampa Bay consist of mangrove forest and tidal salt marsh. Wetlands buffer storm surges, provide fish and wildlife habitat, and enhance water quality through the removal of water-borne nutrients and contaminants. Substantial areas of both mangrove and salt marsh have been lost to agricultural, residential and industrial development in this urban estuary. Wetlands restoration has been initiated in Tampa Bay. Baseline studies on the current condition of wetlands and historical and prehistorical information is needed for successful restoration planning and evaluation. A major objective of this component of the Tampa Bay pilot program was to characterize wetlands in Tampa Bay beginning with areas that differ in their degree of human-induced disturbance ( Fig. 1 ). The Alafia River area is urbanized, industrialized and dredged, whereas the Terra Ceia area has a history of agricultural use with associated soil berms and mosquito ditches, but has not been farmed for at least 20 years ( Fig. 2 ).

Open-File Report↗