As you might guess, “deer pellet” is just one of those nicer ways of saying poop. And the white-tailed deer produces a prodigious number of them- 13 pellet groups per day on average, scientists have estimated. Each group contains up to 90 round or oval pellets. The lifted tail in the image above signals a pellet group on the way.
Pellets can be classified as firm, soft, or loose depending on what the deer was eating. The firm type is most commonly observed. The other two might lead the uninitiated observer to think there were miniature horses or cattle about.
Besides fertilizing the landscape, pellets are useful for estimating the deer population of a forest. Wildlife biologists and ecologists generally do the counting, though anyone with lots of land and deer on it might find this a useful method.
Pellet count plots are laid out along a transect line, at 100 foot intervals. Each plot has a four foot radius, and the rules require that each pellet group counted must consist of at least 10 pellets, and at least half of them must lie within the plot. After slogging through the woods collecting this sort of data all day, you might wonder if it wouldn’t be easier to just count the deer!
But we’re not done yet – all the data must be plugged into a formula, as follows:
PGC / (PGD x DLO x PSM) = deer per sq. mile
PGC – pellet groups you counted
PGD – pellet groups, per deer, per day (13)
DLO – days since leaves off
PSM – plot area in square miles
Just for the fun of it I decided to find a pellet count plot at Beargrass Creek and try some counting. The site I visited had a dense carpet of wintercreeper and looked great. But the frustrations of data collecting quickly became evident – although the vines were well browsed and pellet groups lay scattered about, none fell within the radius of the plot. However, a group of deer nearby was watching me, so I counted them. Obviously many plots would need to be surveyed to get a good overall picture of population.
Lest you get the idea I am making fun of pellet counting, that is not the case. This method of estimating deer population is one of the tools wildlife managers use to determine if there is a healthy balance of large herbivores to the land they are living on. Annual pellet counts are a particularly good way to assess whether deer numbers are going up or down.
Why does this matter? Carrying capacity can vary quite a bit based on the quality of the habitat, but habitat inevitably declines as deer numbers grow. Just like us, they eat the stuff they like best first, leaving the less preferred and downright unpalatable plants for last. In our forest there are still plenty of mayapples and jack-in-the-pulpit, because both are on the “eat only when starving” list. Solomons’s seal, on the other hand rarely succeeds in producing a flowering stalk that doesn’t get bitten off.
While a pellet count attempts to estimate deer numbers, another type of study, the “browse impact survey” quantifies the impact deer have on forest regeneration. This one will be featured in a future post.