Laser Imaging Sensor Assists Ivory-Billed Woodpecker Hunt
COLLEGE PARK & GREEN BELT, Md., Aug. 8, 2006 -- Using a laser imaging sensor capable of providing a detailed measurement of the structure of dense forests, researchers hope to prove once and for all that the ivory-billed woodpecker is not extinct.
A team from the University of Maryland and NASA Goddard Space Flight Center in Greenbelt, Md., are imaging areas of habitat suitable for the ivory-billed woodpecker, one of the largest and most regal members of the woodpecker family, which was thought to have gone extinct about 60 years ago with the loss of much of its habitat.
An artist's rendering of what an ivory-billed woodpecker looks like. (Image: George M. Sutton/Cornell Lab of Ornithology)
The researchers just completed two weeks of flights over delta regions of the lower Mississippi River using an aircraft carrying NASA's Laser Vegetation Imaging Sensor (LVIS), which gets detailed views of vegetation in dense forests, as well as information about the terrain beneath the forest canopy. They are now working to analyze the data taken during the flights and translate it into maps of canopy cover, biomass and other measures of forest structure that will be used to identify areas where ivory-billed woodpeckers are most likely to be found. The mapping project is latest step in a more than two-year effort to find irrefutable evidence that the bird survives.
"Through numerous studies, we have shown the effectiveness of the data generated by lidar for many scientific uses, including carbon sequestration, fire modeling and prediction, and habitat characterization," said LVIS project researcher Ralph Dubayah, a Maryland geography professor. "Lidar (light detection and ranging) provides measures of the vertical structure of the canopy and ground. This sets it apart from other remote sensing systems, such as Landsat, that provide detailed horizontal information, but can say very little, for example, about whether a green patch of forest is short or tall. We know that for habitat characterization and suitability, the vertical structure of the canopy is of paramount importance to many species, including the ivory-bill."
LVIS images from the ivory-billed project are not yet available. This image from a previous project shows a 3-D view of trees and other vegetation in the tropical forest of La Selva, Costa Rica. The color indicates the amount of laser energy reflected from trees and leaves back to the sensor onboard the aircraft. (Image: John Weishampel, University of Central Florida)
The LVIS contains lasers that send pulses of energy to the ground. Photons of light from the lasers bounce off leaves, branches and the ground and reflect back to the instrument. By analyzing these returned signals, scientists receive a direct measurement of the height of the forest's leaf covered canopy, the ground level below and everything in between.
"LVIS is aiding this search effort far beyond what aircraft photos or satellite images can provide," said Woody Turner, NASA program scientist. "We're trying to understand the environment where these birds live or used to live, using features like thickness of the ground vegetation and tree-leaf density, in combination with other factors such as closeness to water and age of the forest, to determine where we might find them."
The latest possibility that the species actually survives was first raised in February 2004, when a kayaker reported spotting the woodpecker along the Cache River in Arkansas. The sighting spawned an intensive year-long search in the Cache River and White River national wildlife refuges, involving more than 50 experts and field biologists working together as part of the Big Woods Conservation Partnership, led by the Cornell University's Cornell Laboratory of Ornithology and The Nature Conservancy.
In April 2005, that team published a report in the journal Science that at least one male ivory-bill still survived. Their findings included multiple sightings of the elusive woodpecker, audio recordings and frame-by-frame analyses of brief blurry video footage. However, some scientists have challenged whether it really was the ivory-billed woodpecker that actually was spotted. In May, a six-month search of eastern Arkansas led by the Cornell Lab of Ornithology, with support from Audubon Arkansas, failed to find further evidence of the bird. .
The red border shows the forested area in the White River Wildlife Reserve of Arkansas where researchers flew in June and July 2006 to identify a possible habitat for the ivory-billed woodpecker. (Image: NASA)
The Maryland/Goddard mission is designed to provide habitat maps that search teams will use, beginning this fall, for new efforts to find evidence of the bird's survival.
"The three-dimensional maps of canopy structure obtained during these flights will aid greatly in the continued search for the ivory bill," said Maryland scientist Michelle Hofton, who is in charge of planning and deployment for the mission, and of processing the data generated. "These lidar maps reveal the uniqueness of the forests, and verify the importance of continuing to preserve such areas as habitat for the ivory-billed woodpecker, and other bird and animal species."
Funded mainly by the US Fish and Wildlife Service and the US Geological Survey, the project is just one example of a broad range of lidar applications, according to NASA Goddard's Bryan Blair, principal investigator for the LVIS instrument.
"This field campaign using LVIS data to support ground activities is an excellent example of an application of lidar data," Blair said. "Some projects use LVIS data as a part of an effort to develop approaches that fuse different types of remote sensing data and apply this combined data to a scientific research problem or, as in this case, to an operational application such as monitoring bird habitat."
The researchers previously used the laser instrument to study wildlife habitats in "old-growth" forests in the western United States and in tropical rain forests. For more information, visit: www.umd.edu or www.nasa.gov
- An acronym of light detection and ranging, describing systems that use a light beam in place of conventional microwave beams for atmospheric monitoring, tracking and detection functions. Ladar, an acronym of laser detection and ranging, uses laser light for detection of speed, altitude, direction and range; it is often called laser radar.
- 1. A generic term for detector. 2. A complete optical/mechanical/electronic system that contains some form of radiation detector.
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