Tracking deer births from space
NASA's extensive web of satellites hasbeen used for everything from spotting shipwrecks to helping farmers combat draught, but a new project has turned them towards something a little different yet – analyzing deer populations. Making use of the Terra and Aqua probes, the project studied the animals' environment to accurately predict their fawning season.
The easiest way to know when deer willstart giving birth is to pay attention to their surroundings. In thelate stages of pregnancy, and in the early part of a fawn's life, adoe needs access to plenty of rich vegetation. Birth rates hit a peakjust a little before the height of plant growth every year, sogaining a better understanding of exactly when that's occurring canhelp predict when fawning season is about to begin.
Biologists and land managers alreadytrack deer populations, in part so that they can determine how manyhunting permits to issue, but the data provided by the new project isfar more precise, allowing for close estimations of the start andpeak of the season for individual regions.
The project makes use of a systemdesigned to track the health of vegetation, known as the NormalizedDifference Vegetation Index (NDVI). The index is designed to measurehow plants absorb and reflect back light, with increased levels ofreflected infrared light indicating healthier vegetation. On a basiclevel – the greener the landscape appears, the healthier it is.
The project focused on a large regionstretching from southern Idaho to central Arizona, which was splitinto three separate zones. Using the Moderate Resolution ImagingSpectroradiometer (MODIS) instruments on NASA's Terra and Aquasatellites, the researchers measured the NDVI every day for an entirecalendar year.
The collected data revealed a lot aboutthe region, showing that greenness peaks later in southern latitudesthan in more northern areas – something that the researchersattributed largely to consistent moisture from snowmelt nourishingthe roots of mountainous vegetation.
With the southern latitudes relyingmore on rainfall starting in the late summer, the vegetation becomeshealthier, or more green, at a later date. That difference translatesdirectly to dear birthing trends, with does beginning to give birthlater in the more southern regions.
The project is a good example of howsatellite data can have a significant impact back home. Deer have asignificant economic impact in the US, not least thanks to their rolein hunting. Tracking their population trends helps us betterunderstand and predict any changes that may occur as regionalclimates shift or events such as droughts occur.
Full details of the project werepublished online in the journal PLOS One.