In Installment Two of Ask a Naturalist, we direct the attention of our experts away from seasonal changes in flora and insect life (the focus of Installment One) to the lives and activities of the animals that surround us, inhabiting our woods and our imaginations. Our experts build a framework for enhanced appreciation, establishing facts, telling stories from the creature perspective and debunking myths wherever they find them. Where possible, we once again keep the focus on subjects of seasonal relevance, hoping to provide our readers with tools and perspectives to understand our natural environment and its inhabitants better.
This month’s experts come to us from a variety of local institutions and organizations: the Mohonk Preserve, Bard College, New Paltz’s Mill Brook Preserve and New York’s Department of Environmental Conservation.
How do squirrels organize their nut hoards and remember how to find them?
It was president Theodore Roosevelt who lamented a nature writer who “endows a red squirrel with check pouches.” We should pay closer attention to nature, be better observers. Chipmunks, not squirrels, have cheek pouches. Squirrels famously “squirrel away” their food to live on through the winter, since they do not hibernate.
Right now, our most common squirrel, the Eastern gray squirrel, is busy feeding for winter, but also creating caches of acorns, nuts and berries to eat later when snow covers the ground. They bury their stash about one inch in the ground, often, researchers have found, organizing the food by size and type, and perhaps even taste. This method of “spatial chunking,” along with a keen sense of smell, helps the squirrel to find the food later, when snow blankets the ground.
Despite how common these rodents are, the lives of squirrels remain often unnoticed. And they prefer it that way. As they go about burying their food, they often “fake-bury” nuts: They dig a hole, pretend to throw a nut in there then run off to a secret stash location. This “deceptive caching” is no doubt a way to throw off others – especially other squirrels – who might be watching.
– Susan Fox Rogers
Associate professor of Nonfiction Writing, Bard College
When and why do deer lose their antlers?
To answer that, let’s start with another question: Why do deer have antlers? Males (bucks) of our native whitetail deer (Odocoileus virginianus) rely on antlers to help establish their dominance over other bucks. Adult bucks sometimes battle over does (female deer), using their antlers as weapons as they crash headfirst into one another. On rare occasions their antlers can get tangled together, and if the bucks can’t separate themselves, they’ll die of starvation. Antlers also function as a signal to does of how strong and healthy a buck is. This is because antler growth is reliant on good genes, good diet and age. Antler growth can be inhibited by disease or injury. Only a strong, mature buck will grow the heavy rack with lots of points that is so coveted by trophy-hunters.
Antler growth typically takes off in early spring as days lengthen and temperatures warm. Antlers are actually bone tissue, and while they are growing, they are covered with a soft, hairy layer of skin called velvet. This velvet supplies blood and nutrients to the fast-growing antler bone tissue. In early fall, the buck’s testosterone levels rise, and this causes his antlers to harden and the velvet to dry out and strip off. Now his antlers are tough, hardened weapons, and they won’t grow any bigger this year. Mating season (or “rut”) begins, and if he’s successful, his antlers will help him find a mate and pass on his genes to future generations.
In early winter, rutting season ends, and his antlers have done their job. Another change in hormones causes the antlers to drop off one at a time. This can happen as early as December or as late as March, but in our area, it typically occurs around January or February. The buck’s neck, which became swollen during the rut in order to help support the weight of his antlers and cushion the force of ramming his weapons into others, shrinks back down to its pre-rut size. Now the buck’s main concerns are finding enough food to survive the winter, and avoiding predators who are trying to do the same thing. If he’s lucky, he’ll make it to spring, at which point the whole process starts all over.
Antler growth is energetically expensive. This helps explain why only mature bucks sport huge trophy racks. For young deer, it’s more important to prioritize body size over antler size, as even the largest rack won’t help a scrawny buck survive, much less mate. Once a buck has reached his full size, his body can afford to expend more energy on antler growth. Because antlers are bone, they require a lot of calcium, and this is a precious nutrient in nature. When these calcium-rich antlers drop off, they don’t just go to waste there on the forest floor. They get recycled by other animals, including mice, chipmunks, squirrels or even foxes and coyotes, who gnaw and ingest the nutrients they contain.
Want to look for deer sheds next time you’re out in the woods? They’re hard to find, but it’s quite a treat when you do get lucky. Look from January through April for the best chance of finding them. Try to focus on areas where you know deer spend a lot of time, especially places where they bed down. It will be easier to find sheds in areas without a lot of thick cover, so start with easy terrain like fields and meadows before heading into the woods. Even if you don’t find antlers, you can enjoy the fresh air and the pleasure that comes with being out in nature!
– Elizabeth Long
Director of Conservation Science
Mohonk Preserve
www.mohonkpreserve.org
What do shrews eat?
Recently, through my bedroom window, I heard high-pitched squeaking and I looked out to see a tiny creature struggling in the grass. My daughter was standing over it, almost reaching the same high pitch. “It’s a mouse! I think it’s injured!” It was mouse-ish, but its body wasn’t quite right. Then I saw its long pointy snout, many long whiskers and tiny eyes. A shrew! It’s easily mistaken for a mouse, although it is in the order Eulipotyphla, not the order Rodentia. “What does it eat?” she gushed. She wanted to boost its chances, my empathetic nature girl.
First, some background: There are a whopping 385 species of shrew worldwide, a number of which are in New York. We have the red-toothed shrew, smoky shrew and masked shrew, just to name a few. A little north of here in the boreal forests, there is the rare pygmy shrew, one of the smallest mammals on earth. An adult weighs two to three grams (a packet of Domino sugar is 3.5 grams).
Besides what they eat, how they eat is worth mentioning. Some use poisonous venom to subdue prey, from worms to mice. A mealworm can be paralyzed for up to 15 days to keep a fresh meal handy (not nearly enough poison to harm a human, thankfully). A partly aquatic species we have in New York has the ability to walk on water. The tiny hairs on their feet trap air bubbles to make this feat possible. This surely helps it catch prey and escape predators as well. Another helpful predator deterrent is its musky odor that is unpleasant to some, notably foxes, which love to feast on small mammals.
So, they’ve got a lot going for them, but they also have to be nonstop eating machines. They have very high metabolisms. Some shrews have a heart rate that reaches 1,500 beats per minute: faster than a hummingbird. If they don’t eat in a few hours, they will die. My daughter was right; it needed food stat.
While their diet is somewhat varied, they are known as insectivores. Before my daughter could find it a cricket, it scampered away. Good thing, too: An owl has begun hanging out in one of our trees. And I don’t believe they mind the smell. My first look at the jawbone of a shrew was in an owl pellet. So if her shrew friend shows itself again, she might want to tame it.
– Julie Seyfert-Lillis
Executive director
Mill Brook Preserve, New Paltz
http://millbrookpreserve.org
Are bobcats making a comeback in the mid-Hudson Valley?
The bobcat is a rarely seen member of the cat family that occurs throughout New York, except for Long Island. Since this species is so elusive, they are very difficult to monitor. One of the ways that the Department of Environmental Conservation (DEC) monitors the bobcat population is through tracking harvest. There are hunting and trapping seasons for bobcats in certain areas of New York, including the Hudson Valley. Any bobcat taken during these seasons must be reported and tagged with a special pelt seal. DEC biologists track these harvest trends to get a sense of the bobcat population. Over the past ten years, the number of bobcats harvested in the Hudson Valley has remained fairly stable, with a slight decline in the past few years.
In addition, in 2013, DEC started a public furbearer sighting survey. Anyone who sees a bobcat can report the sighting on the DEC’s website. The DEC uses these sighting indices as an additional way to monitor the bobcat population.
The number of reported bobcat sightings in the Hudson Valley has been on the rise in recent years, but that may be the result of more people becoming aware that the DEC is interested in hearing about these sightings. To help us get a better handle on the bobcat population in the Hudson Valley and the rest of New York, keep your eyes open for these neat cats and report any sightings that you have here: www.dec.ny.gov/animals/30770.html.
– New York State Department of Environmental Conservation
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