Janet M. Ruth — Page 2

USGS2005

Advancing migratory bird conservation and management by using radar: An interagency collaboration

Migratory birds face many changes to the landscapes they traverse and the habitats they use. Wind turbines and communications towers, which pose hazards to birds and bats in flight, are being erected or proposed across the United States and offshore. Human activities can also destroy or threaten habitats critical to birds during migratory passage, and climate change appears to be altering migratory patterns. The U.S. Fish and Wildlife Service (USFWS) and other agencies are under increasing pressure to identify and evaluate movement patterns and habitats used during migration and other times. Few tools for deciphering migratory travels exist, but radar-based studies of movements and habitat use patterns in songbirds, waterfowl, and bats hold promise. The U.S. system of over 150 Doppler weather radars provides continental coverage, similar to the scale of bird migration. Although data stored from weather radar represent perhaps the second largest biological data archive in the world, use of those data is currently limited to technically savvy biologists who can handle the obscure data formats. Complementary mobile radar units and thermal and acoustic monitoring are also used in site-specific studies. Efforts to advance bird conservation and management through the use of radar arose independently in several USFWS/USGS collaborations. Recently, this coalition of scientists and resource managers identified the need to work together more closely to foster radar-related research and software development. U.S. Geological Survey (USGS) scientists at Fort Collins Science Center, National Wetlands Research Center, Northern Rocky Mountain Science Center, and Patuxent Wildlife Research Center, as well as USFWS Migratory Bird biologists across the country, are collaborating with university partners to develop a suite of products for managers. The goals are to identify migratory pathways and stopover sites for conservation, mitigation, and landscape planning; convey the importance of functional landscapes and unobstructed airspaces for migrating wildlife; enable use of radar by the wider biological, wind power, and related communities; and simplify the analysis of radar data. The long term focus is to use radar technologies to better understand movement patterns and habitat associations of migratory birds and other wildlife. Land managers and industry may use the knowledge and tools developed to optimize the siting of energy projects, other facilities, and migratory bird habitat projects. The complementary endeavors, not all of which are funded, concentrate on four fundamentals: (1) develop software, in collaboration with National Oceanic and Atmospheric Administration (NOAA) scientists, that enables biologists to access unfiltered weather data and integrate it into standard geographic information systems; (2) develop artificial intelligence-based filters that separate bird from nonbird radar echoes; (3) determine characteristics of bird migration in terms of altitude, speed and direction, daily movements, seasonality, and associations with habitats and landforms; and (4) examine specific movement patterns in relation to towers, wind generation facilities, and tall obstructions. Many technical issues make this work difficult, including complex data structures, massive data sets, digital recognition of birds, large areas not covered by weather radar, and model validation; however, progress will only be furthered by tackling the challenge. The new coalition will meets its goals by: (1) facilitating a productive collaboration with NOAA, Department of the Interior bureaus, state wildlife agencies, universities, power companies, and other potential partners; (2) building and strengthening scientific capabilities within USGS; (3) addressing key migratory bird management issues; and (4) ensuring full funding for the collaborative effort.

Open-File Report↗

USGS2000

Cassin's Sparrow (Aimophila cassinii) status assessment and conservation plan

Executive Summary Cassin’s Sparrow ( Aimophila cassinii ) is a grassland species endemic to the southwestern U.S. and northern Mexico. Its behavior and ecology have been shaped by these arid ecosystems and the health of its populations is dependent on the availability of grasslands that contain a shrub component. Populations of many grassland birds have experienced dramatic declines due to the loss and deterioration of grassland habitats, and there has been concern about the trends in Cassin’s Sparrow populations. Without better information about population trends, ecology, and effects of management activities, and without a stronger emphasis on grassland management, Cassin’s Sparrows and other grassland species may continue to experience declines. Little information exists about historic Cassin’s Sparrow population levels, and current population estimates for states in the breeding range are unknown. Significant survey-wide declines are documented by the Breeding Bird Survey (BBS) between 1966 and 1996. However, closer examination of these data suggest that the survey-wide trends are driven by population declines in the Edwards Plateau and South Texas Brushlands in Texas. No other areas within the core of its range or on the periphery show consistent, significant trends. In fact, there is consensus that in the core of its range in New Mexico Cassin’s Sparrow remains the most abundant breeding bird in grasslands with a shrub component. Understanding of population patterns in this species is complicated by large yearly fluctuations in distribution and numbers at any particular location, apparently in response to precipitation. This is particularly obvious in the periphery of its range. These dramatic fluctuations have hampered a clear assessment of population status, and our understanding has been confounded by the fact that the timing of BBS data collection does not always coincide with the peak breeding season of this species. The lack of information about the Cassin’s Sparrow’s status, ecology, and response to management activities, and the apparent declines indicated by BBS data, have been cause for concern. Habitat disturbance and degradation, mainly due to grazing and rangeland management practices such as shrub control, fire management, and planting of exotics, pose threats to Cassin’s Sparrow populations, as does habitat conversion through suburban development and agriculture. There is evidence that heavy grazing negatively affects populations, but the information is primarily available from the southwestern portion of its range (Arizona) and may not be applicable throughout the Cassin’s Sparrow’s entire range. Any management practice that results in complete removal of the shrub component, or loss of grass cover and an increase in shrub density beyond a threshold preferred by the species, also poses a threat. Lack of standardized or coordinated studies of Cassin’s Sparrow ecology and response to management practices in different geographic portions of its range has made it difficult to assess its status and make specific management recommendations. Limited data are available from the wintering grounds, and from its range (both breeding and wintering) in Mexico. The greatest needs are for determining of the causes of significant declines where they occur, determining of the effects of various management activities on Cassin’s Sparrow throughout its range, improved assessments of population and trends, and a better understanding of the annual population and distribution dynamics of this species, which shows such dramatic annual distributional fluctuations.

Wyoming, Nebraska, Kansas, Oklahoma,Texas, New Mex↗