A Ruffed Grouse’s nest is pretty basic – just a shallow bowl on the forest floor, created by the hen grouse tossing leaves over her shoulder and having them fall on her back, slip down to the ground and form a bowl. Ruffed Grouse lay anywhere from 9 to 14 eggs at intervals of 25 to 30 hours, which means it takes about two weeks for a hen to lay an average clutch of 11 eggs. Each of her eggs weighs about 4 percent of her body weight — the entire clutch will be equal to about half of her weight. Once incubation starts (when the last egg is laid) the hen’s behavior goes from wandering around and feeding voraciously, to sitting on the nest and barely moving. Because of this behavior, as well as her cryptic coloration, an incubating Ruffed Grouse hen is much more likely to see you before you see her. She will stay motionless on her nest, even in the face of danger, hiding her eggs. Once she is certain she has been spotted, she will fly off the nest, exposing her eggs. Foxes, crows, ravens, chipmunks, skunks, bobcats and raccoons are some of the predators responsible for the loss of 25% – 40% of grouse nests each year. After the precocial Ruffed Grouse chicks hatch during the first two weeks of June, they will be led away from the nest site by the hen. Within 24 hours they will be feeding on insects and within a week they may double their weight! (Thanks to Ginny Barlow for photo op.)
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The most prominent courtship behavior of male wild turkeys (toms) consists of two displays: gobbling and strutting. Both begin in late February in northern New England, before the females (hens) are receptive, but by late March the males begin to reap the fruits of their labor. The gobbling of the males attracts females or competing males over considerable distances. The tom turkey begins to “strut” only after a hen appears. While strutting, he fans his tail, lowers his wings with the primaries dragging on the ground/snow, elevates the feathers on his back and throws his head backward as he appears to glide around a female. If she is receptive, she assumes a “sexual crouch” on the ground, signaling to the male that he may mount her. (Thanks to Chiho Kaneko for this photograph.)
A trail of ruffed grouse tracks in the snow led me to the spot where two grouse had bedded down for the night behind a fallen tree. With snow too shallow to burrow into, this was as protected a location as they could find. More often than not, a grouse defecates in its night roosting site before leaving in the morning. Grouse scat comes in two forms, one a dry, fibrous cylindrical pellet with a white-wash of uric acid at one end, and the other a softer, darker brown plop. The vast majority of a grouse’s diet (buds, twigs, leaves, catkins) goes directly through its digestive system and forms the dry, courser scat. Finer (and more nutritious) material such as the cambium layer of woody plants enters the caeca, two specialized pouches, before passing through the large intestine. The caeca contain bacteria which break down cellulose and produce the more digested, and therefore more liquefied, scat. Sometimes the two kinds of scat are deposited separately and sometimes, as in the bed on the right in the photograph, together. (Thanks to Dr. Alcott Smith who clarified grouse digestion for me.)
When the snow on the ground is 10” or more deep, and the night is very cold, ruffed grouse often seek shelter from the elements by diving into the snow and spending the night there. Sometimes they burrow five or ten feet into the snow, but sometimes, as in this case, they stay pretty much where they landed, perhaps a foot or so deep in the snow bank. This adaptive behavior not only hides them from predators, but serves to insulate the bird, as it rarely goes below 20 degrees F. in the cavity, regardless of how cold the air is. More often than not, the grouse defecates during its stay in the snow (dark matter in photograph). When leaving its snow cave, sometimes a grouse will burst out of the snow as it flies away, but as you can see from the groove in the snow in this photograph, this grouse chose to travel by foot.
The Ruffed Grouse has both behavioral and physical strategies for dealing with the cold, snow and ice of New England winters. Three of the physical changes that take place in the fall are evident by looking closely at a grouse’s legs, feet and beak. The feathers on its legs grow thicker and further down towards its feet, to provide better insulation. Small comb-like growths of skin, called pectinations, develop along either side of each toe. These increase the surface area of a grouse’s foot, and serve as snowshoes in deep snow. They also help the grouse cling to icy branches while it quickly snips off poplar and other buds at either end of the day. And on its beak, feathers expand downward to cover its nostrils, slowing the cold air and giving it a chance to warm up before it is inhaled by the grouse.
Some birds, especially those that eat seeds, buds, leaves and nuts, such as ruffed grouse, eat food very rapidly, faster than it can be passed through the digestive system. These birds usually have a pouch-like crop where food is stored to be digested later, when the birds are not out in the open, susceptible to predators. (see 10-24-12 Naturally Curious post) This rapid consumption and storage of food by grouse, often at dawn and dusk, is referred to as “budding.” Examining the contents of road-killed grouse crops is one way of learning more about this adaptive behavior. Assuming some of my readers might (?) share my curiosity about the diet of grouse, I occasionally post the contents of a grouse crop I’ve recently examined. My most recent dissection revealed that the grouse had switched from its herbaceous summer diet to its more woody winter diet — its crop contained no less than 232 male birch flower buds, or catkins. (Disclaimer: This crop was not that of the grouse that was the subject of the 11-9-12 post.)
Ruffed grouse, also known locally as partridge, are so well camouflaged that sometimes the only glimpse you get of them is when they explode right in front of you in an attempt to fly away from you. Occasionally, however, one will allow you more than a cursory look (and an opportunity to photograph it up close). This often happens when someone is running an engine, be it lawn mower, wood splitter or 4-wheeler. Upon hearing the sound, a grouse may walk rapidly towards it and linger in the vicinity for hours. Perhaps the occasional female grouse mistakes the sound of an engine for the alluring drumming of a male grouse, as the drumming sounds uncannily like a lawn mower starting up!