Gauthreaux, Sidney A. Jr. 1992. The use of weather radar to monitor long-term patterns of
trans-Gulf migration in spring. pp. 96-100 In: J. M. Hagan and D. W. Johnston (eds.)
Ecology and conservation of neotropical migrant landbirds. Pp. 96-100.
Smithsonian Institution Press, Washington, DC.
WSR-57 radars are operated at eight weather stations around the northern and eastern coasts
of the Gulf of Mexico. These radars are capable of detecting the migration of birds across the Gulf and through the coastal areas from Brownsville, Texas around the northern Gulf to Key West, Florida. Film records from the radar stations exist for 33 years (1957-1990) and can be used to quantify the day-to-day and year-to-year patterns of spring migration across the Gulf. The methods of analysis are discussed and preliminary findings suggest a decline in the amount of trans-Gulf migration and changes in the seasonal timing of the flights since the mid-1960s.
Leshem, Yossi and Sidney A. Gauthreaux, Jr. 1996. Proposal to develop a global network to predict bird movements on a real–time and daily scale by using radars. Bird Strike Committee Europe BSCE–23/WP 50. London, May 13–17, 1996.
Civilian air traffic as well as military flights have increased significantly during the last decades. Military aircraft now fly at low altitudes and high velocities during day and night, using fire zones in several countries. The cost of commercial and military aircraft has increased two fold during the last decades. For these reasons, the potential for damage caused by birds has increased dramatically. We propose to develop a global network of radar to predict bird movement on a real-time and daily scale through the use of a network of regional radar systems.
A network of regional radar systems should be developed in the Middle East, around the Mediterranean Sea, in Western, Northern, and Eastern Europe, in Asia, and in Africa which will provide together a global network as currently in place in the USA for weather prediction by NEXRAD WSR-88D radar. It should be proposed by BSCE to the European Market, leading insurance companies, and others to develop the system which can significantly reduce the number of air collisions in order to save lives and billions of dollars.
Russell, Kevin R., David S. Mizrahi and Sidney A. Gauthreaux Jr. 1998. Large-scale mapping of Purple Martin migratory roosts. Journal of Field Ornithology 69:316–325.
Recent advances in remote sensing technologies Allow researchers to inventory and
study bird populations at large spatial scales. We used National Weather Service WSR-88D
weather surveillance radar images acquired from the Internet to detect and map the locations of
Purple Martin (Progne subis) pre-migratory roosts across the eastern United States. Purple
Martins form a distinctive ring or annulus on radar during predawn departures from roosts,
allowing mapping of roost sites based on this signature. Overall, we identified 33 roosts sites in
13 states. Although most roost sites were confined to the southeastern United States, sites as far
north as Missouri and Kentucky, and as far west as central Texas and Oklahoma were detected.
Seventy-three percent (24/33) of roosts were clearly associated with bodies of water such as
lakes and rivers. We found that using Internet-acquired radar images for bird studies had
limitations when compared to direct acquisition of images from WSR-88D radar stations or
through contracts with WSR-88D product providers. However, the increased expertise and
financial investment associated with these methods make Internet-acquired radar data an
attractive alternative for rapid assessment of roost locations and dynamics over large
Gauthreaux, Sidney A. Jr. and Carroll G. Belser. 1998. Displays of Bird Movements on the WSR–88D: Patterns and Quantification. Weather and Forecasting 13:453–464.
The WSR-88D can readily detect birds in the atmosphere in both clear air and precipitation
mode, and echo reflectivities of 30-35 dBZ may be realized during heavy migration events or
when birds are departing from a roosting site. This paper describes the appearance of birds on
base reflectivity, base velocity, and vertical azimuth display wind profile products, and presents
a calibration curve that relates decibel values of reflectivity to bird migration traffic rates. The
recognition of bird displays in WSR-88D is essential for accurate interpretation of data gathered
by the radar and its use in the development of forecasts. The findings also document the
importance of the WSR-88D as a remote sensing tool for biological studies of birds and insects
in the atmosphere and the application of such information in the avoidance of bird-aircraft
Gauthreaux, Sidney A. Jr., David S. Mizrahi, and Carroll G. Belser. 1998. Bird Migration and Bias of WSR–88D Wind Estimates. Weather and Forecasting 13:465–481.
Migrating birds can greatly influence base velocity, velocity azimuth display (VAD), and VAD wind profile products of the WSR-88D. We document this by comparing estimates of wind velocity and direction from these products with corresponding radiosonde and pilot balloon data. Mean absolute differences between wind velocities estimated from base velocity products and the corresponding radiosonde data were significantly greater on days with bird migration than on days with no migration. Even low-density migrations can increase VAD wind velocities relative to winds measured simultaneously by balloon. Because birds usually migrate with following winds, wind directions measured by VAD are less affected, but in some cases the difference can be as much as 128. Consequently, when winds aloft are nearly calm and variable in direction, the data in the VAD wind profile and base velocity products may pertain almost exclusively to migrating birds.
Russell, Kevin R. and Sidney A. Gauthreaux Jr. 1999. Spatial and temporal dynamics of a purple martin pre–migratory roost. Wilson Bull. 111(3): 354-362
We used simultaneous WSR-88D radar (NEXRAD) and direct visual observations to investigate the spatial and temporal dynamics of a Purple Martin (Progne subis) pre-migratory roost in South CaroIina. The timing of mass flights of martins from and to the roost was related to levels of ambient light. Each morning, the birds first departed approximately 40 min before sunrise independent of date, with peak departures occurring about 10 min before sunrise. The time of evening flights was more variable, but peak movement of birds into the roost consistently occured at sunset. Purple Martins exited the roost in organized, annular departures (3600) that were visible on radar up to 100 km away from the roost but returned to the roost over an extended period in scattered flocks. During morning departures we recorded flight speeds up to 13.4 m/s. Radar echoes corresponding to martin flights were recorded farther from the roost, and flights from and to the roost occurred later and earlier, respectively, in response to increased cloud cover. The departures of birds from the roost appeared to be displaced by winds aloft. At the peak of the roosting season in late July, the total roost population was estimated to be at least 700,000 birds.
Gauthreaux, Sidney A. Jr. and Carroll G. Belser. 1999. Bird Migration in the region of the Gulf of Mexico. The Ostrich. Proceedings of the International Ornithological Congress XXII, Durban, South Africa, 16–22 August 1998 In: Adams, N.J. & Slotow, R.H. (eds)
Proc. 22 Int. Ornithol. Congr., Durban: 1931-1947. Johannesburg: BirdLife South Africa.
Since the turn of the century considerable debate has surrounded the flight strategies of migratory birds in the vicinity of the Gulf of Mexico. Cooke (1904) and Lowery (1945) suggested that many species fly across the Gulf in spring. In contrast, Williams (1945) proposed that most birds migrated around the Gulf. Lowery (1946,1951) subsequently documented the evening departure of migrants from Yucatan Mexico. Since the mid-1960s radar studies of bird migration along the northern Gulf coast show that trans-Gulf migration occurs regularly from mid-March to late-May. The timing and point of arrival of each trans-Gulf migration is strongly dependent on atmospheric steering currents and weather over the Gulf. Since 1992 the use of new doppler weather surveillance radars on the northern Gulf coast has facilitated the study of flight speeds and directions of migrants in the Gulf of Mexico region. Data from these radars show that in spring circum-Gulf migrants may fly NE from the coasts of Brownsville, TX and Tamaulipas, Mexico, cross the northwestern Gulf, and make landfall on the upper Texas and southwestern Louisiana coast when winds are favourable for such a flight. In the fall, migrants occasionally depart southward from the northern Gulf coast, turn WSW offshore, and make landfall on the lower Texas coast. These flights, like those in spring, are strongly dependent on wind patterns over the Gulf.