Delmarva Fox Squirrel Photomonitoring
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At times, CBFO needs to determine if Delmarva fox squirrels (DFS) occupy a particular forest parcel. Because we only need to know if they are present, we use a technique known as photomonitoring instead of traditional trapping methods. This technique is non-invasive, and allows us to confirm the presence of this endangered species without going through the rigors of a full trapping effort. The camera simply takes a photo of any animal that breaks a harmless, invisible, infrared beam.
However, when we are lucky enough to get a photo of DFS, we can’t tell individuals apart or how old they are. This is because most Delmarva fox squirrels look almost exactly alike. On rare occasions, we may get an individual with markings that can be used to identify future photos of this individual. Most commonly, we simply record whether or not the parcel is occupied, and can follow up with a trapping effort to estimate how many squirrels are actually there.
Because we use corn for bait, we get plenty of photos of other local wildlife. This “bycatch” does not usually interfere in our monitoring effort, unless they steal the bait. Raccoons are great thieves, and also our most common visitor, other than the fox squirrel.
Though it is easy to tell the difference between a DFS and a deer on film, sometimes we get common gray squirrels (the kind you have in your backyard) attempting to impersonate DFS. Though DFS and GS look very similar, the following are some consistent differences that help us tell them apart on film.
Visit the photo page for larger images for the DFS
•DFS are bigger. Delmarva fox squirrels are almost 1.5 times bigger than gray squirrels.
•DFS have fluffier tails. Delmarva fox squirrels tail hair is about 1.5 times longer than gray squirrels; as a result, their tail looks much longer and fluffier.
• DFS are silver. Although gray squirrels have “gray” in their name, they look browner than DFS on film, due to brown coloring on their cheeks, along their spine, and on their sides (just in between the white belly and gray back). DFS look more silver gray, usually with little or no dark markings.
Photomonitors have been used in a number of DFS research studies, and its future as a monitoring tool looks bright.