192 FOOD HABITS AND REQUIREMENTS 



published rwords of the birds eating snakes. The 17-inch green snake mentioned by Judd is 

 an example. A slightly smaller garter snake was found in a grouse crop b\ the Investigation. 

 A nunilxT of scales from the same species were likewise identified in two other birds. 



Four other vertebrates also have been recorded. Bones from a small unidentified bird were 

 found in a grouse shot May 23, 1933 in the Adirondacks and feather remains in that of a 

 Catskill bird. Even more mystifying were the cottontail hairs found in two other gizzards. 

 It is more easily explained but equally interesting that another individual had fed to a slight 

 extent upon small finger-nail clams ( Sphaerium ), and that twice mussels have been recog- 

 nized. These mollusks are more or less common along the marshy shorelines of certain Adi- 

 rondack lakes. Snails also were taken by 75 birds, mostly chicks. 



There are a few plants in which the grouse exhibits a little-suspected interest. The leaves 

 of pondweed ( Potainogeton), stalks of sedge (Cyperus), seeds of spikerush ( Eleocharis), bits 

 of moss and traces of fungi and of mushrooms, have all been identified once or twice. 



There are in addition miscellaneous items among which might be iiu-iitioncd: long-dead 

 leaves, birch curls, bits of glass and an inch-long roofing nail (the latter |)uncturing the giz- 

 zard and killing the bird). Lead shot seems rarely to be picked U]). though one case of what 

 appeared to be lead poisoning was investigated. 



Gravel Consumption 



Seed-eating birds in general pick up bits of gravel and other hard particles to aid in 

 grinding their food in their unusually strong muscular stomach called the gizzard. It is the 

 function of this organ to pulverize the food before passing it on for digestion in the intestines. 

 As a mechanical aid in this process the grouse, like its near relatives, usually keeps a small 

 supply of gravel or other hard objects in its gizzard. 



The number of these gizzard stones in a grouse is usually greater than one would suspect. 

 In iNew York birds, they are present in amounts varying from a trace to nearly one-half the 

 total bulk, the average being about 12 per cent, or one-ninth of the contents. It is possible 

 that gravel is necessary to efficient gizzard action, but its absence for short periods at least 

 seems to make little difference. With buds, twigs and hea\ y-coated seeds the breaking down 

 action may be quite successful even in the absence of gravel. In such cases it is not un- 

 common to find a number of hard seeds which, it has been suggested, may act in somewhat 

 the same capacity as grit. If such action does take place, it is of short duration in the 

 ruffed grouse, for seeds in the gizzard seldom show much evidence of long-continued wear. 

 Pebbles, on the other hand, even the resistant granite. riia\ be retained until they are smooth 

 as though hand-polished. 



The presence of grit in the gizzard, bulli in ficciiicncN of occurrence and in amount, 

 seems to be inlhjcnced more or less by the weather. b\ llic lialiitiil ;iiul b\ the fond which 

 the grouse happens to be eating. Most birds want grit at all seasons of the year. This 

 In noticeable al winlcr feeding stations, both for grouse and for pheasants where grit, as 

 well as food, is taken. Whenever winter blankets the coverts with snow. gr;i\fl is hard to 

 obtain and grouse ma\ retain the fall-secured sup|)l\. This tna\ explain wh\ gravel makes 

 up <jnly about nine i)er cent of the gizzard contents al that lime of the \ear. There is also 



a difference in relative volume of grit according In lln- l\i f fncid eaten. In winter the 



food items (niaitd\ buds and twigs) bulk large, whereas the more compact foods of sum- 

 mer take up coinparati\c!y small space: in the former period the gravel occupies a rather 

 smaller proportion and in the latter period a larger j)roportion of the total stomach con- 



