Wildlife & Remote Sensing
How remote sensing comes together with wildlife
How is remote sensing used when it comes to wildlife management, conservation, and general observations? With the variety of ways data can be remotely sensed, the method used depends on the situation and the data that needs to be aquired.
The most common use for satellite imagery appears to be habitat mapping. This is an important part of conservation, as habitat protection goes hand in hand with the protection of a species. As technology improves, a greater number of scientists are beginning to use remote sensing in a greater variety of ways.
Mineral deposits in the Andes Mts
Low altitude aerial photography is just one of the many ways that allow for the measure of population estimates. Aerial photography involves flying over an area of interest and taking photos of large areas. Individuals in the photos are then counted. It is however, difficult to determine if all the individuals are available to be photographed.
The estimate of a population size can then be compared to past estimates to determine if the population is increasing, decreasing, or if it remains unchanged. Most formal approaches to population management include a monitoring program, which is usually focused on abundance (Williams et al. 2002).
Drones are now changing the way aerial photography is being captured. As the machines are smaller and quieter than a plane or helicopter, it allows the user to get closer to the subject without being intrusive. The use of a drone is significantly cheaper than renting a helicopter or plane. The use of a drone is also significantly safer, as light aircraft crashes are the number one killer of wildlife biologists.
Aerial photography may be one of the oldest forms of remote sensing, but it is still an ever evolving and valuable tool.
Biologist Peter Bente arranges aerial photos of the Western Arctic Caribou Herd. Tens of thousands of animals are photographed and counted.
Landsat is the oldest continuous Earth record ever, making it is easy to find and use hisctorical Landsat data/images. Monitoring dynamic habitats, whether naturally occuring or man-made, can even be used to aid in the conservation of rare and endangered species.
An excellent example of this can be found in a case study by Bartel and Sexton in 2009: Monitoring habitat dynamics for rare and endangered species using satellite images and niche-based models.
This study uses the St Francis' satyr butterfly, to show that satellite imagery (22 years of Landsat TM images were used in this study) can be used in combination with ground observations to predict potential species distribution into unoccupied habitat. This is key information that is often left out in species recovery plans. Knowing the potential distribution of a rare and endangered species can be used to aid in conservation efforts.
St. Francis Satyr Butterfly
Image Credit Melissa McGraw
Similar to the St Francis' satyr butterfly case study mentioned previously, Ned Horning used MODIS imagery from the TERRA satellite, combined with field observations to map the full range of chamelion habitat on Madagascar. MODIS was well suited to the task with its wide range of view. Very little time was spent putting smaller images together to create a complete image of Madagascar.
Terra also provided almost daily coverage of the area. This allowed them to see changes on the island across the seasons, and to more accurately map the various ecosystems. The frequent visits also helped to overcome the clouds which sometimes blocked the view of the MODIS sensor.
The Terra imagery was also combined with other remotely sensed environmental observations including; topography data from NASA's Shuttle Radar Topography Mapping Mission, as well as precipitation observations from NOAA's satellites.
MODIS image
to the left.
Maps created by
Robert Simmons
Monitoring the ice in the Arctic (and Antacrtic) is a very important task. While the freezing and thawing of the sea ice is a seasonal event, the overall decrease in ice formation is indicitive of climate change. This of course is placing pressure on the wildlife that depend on the ice, such as the polar bear. With less ice forming, and more ice melting, it is becoming increasingly difficult for polar bears to hunt for food, causing many to starve.
Unique polar microbial communities are also at stake. These communites are very important as they form much of the base of the Artic food chain. In one way or another, those that live in the Arctic will be impacted by the loss of sea ice.
RADARSAT is, and has been, used to observe these changes in the ice to include observing fractures in large ice shelves and traking the ice islands. RADARSAT is well suited for this type of near real time monitering as it is uninhibited by cloud cover.
RADARSAT-1 Image of the Ward Hunt Ice Shelf Fracture
Population Counts
Habitat Mapping
Habitat mapping is an important tool used to aid in conservation efforts. Being able to predict where wildlife travel through or migrate to allows for a more complete habitat protection and species management plan. There are several satellite based sensors that are capable of habitat mapping, two of which are mentioned below. Using satellites is a much more cost effective method as opposed to hiring workers to traverse the area in question and record habitat types. In many cases, such as Landsat, the imagery is free.
Coral reefs are a very dynamic and extremely fragile ecosystem. Such a wide variety of life depends on the reefs. Yet these reef based ecosystems are crumbling. Warming of the oceans plus pollutants in the water make for a toxic mix.
Being that the coral reef ecosystem is so dynamic and unique, no one sensor is well suited enough to detect all the attributes that make up the reef system. But the necessary information can be pulled from many of the sensors and combined as needed.
Imagery from Landsat TM can be used to detect algal blooms (which can smother an ecosystem) and suspended sediment concentraion. MODIS can detect sea surface temperature (which coral reefs are sensitive to). AVHRR and ASTER can also be used to detect SST, along with UV radiation (which leads to coral bleaching) and even cloud cover.
With the extinction of so many species hanging in the balance, it is important to monitor the coral reefs. Such careful monitoring may allow for preventative measure to be taken before the reefs are lost