« PreviousContinue »
subsistence as about five or six times the average amount found in the stomachs. It is evident that we can not compute the consumption of plant lice by the same formula, as these minute, soft-bodied insects are so delicate that they are digested in a small fraction of the time required for hard insects and seeds. To get a proper idea of the number of meals of plant lice taken in a day we must consult the actual records of some of the Winston-Salem birds. In most cases it is evident that the birds ate about as many aphides at one time of day as another. This is well illustrated by the records of the goldfinch and the chipping sparrow, as follows:
Record of aphides eaten by the goldfinch and the chipping sparrow.
In the case of the chipping sparrow we have specimens representing more hours of the day than for any other species. The record shows that at all hours from 10 a. m. to 5 p. m., excepting one unrepresented and one showing only a few aphides eaten, chipping sparrow stomachs contained large numbers of plant lice in good enough condition for counting. The fact that they were not far digested proves that they were recently swallowed, certainly within an hour.
We are justified, therefore, in considering that at least one meal of plant lice is taken each hour; probably several are. At the time of year the stomachs were collected, birds, if they so desired, could feed during a period of about 14 hours per day. We are distinctly on the safe side, therefore, in reckoning one meal of aphides to each of 10 hours in the day. If, therefore, we multiply by 10 the average number of aphides eaten per meal by the birds of any species, we shall arrive at the daily consumption per individual. We are further justified in regarding the proportion of aphis-eating birds to be
the same for all the individuals of a species on the farm as among the individuals whose stomachs were examined. Hence the daily consumption of plant lice per individual, multiplied by the proper proportion of the birds of each species, will give the total daily destruction of aphides per species. As the number of aphides that can be counted is in nearly every case far under the number actually represented in the stomach, and as we reckon 10 meals when probably more than 14 are taken, it must be admitted that our estimates are conservative.
In addition to the aphides destroyed by the birds present throughout the investigation, we must reckon those taken by the transient flocks of siskins and titlarks. To be on the safe side we will assume that during their brief visits these birds consumed only half as many meals per day as the other species. It will be more accurate also to use the averages of the other species as to the number of birds. eating plant lice (61 per cent) and the number of aphides consumed (75.9 per cent) rather than the higher records for each of those birds which are based upon single stomach examinations. Upon this basis their records are as follows:
Estimated number of aphides eaten by the pine siskin and the titlark.
The birds frequenting about 100 acres of grainfields near WinstonSalem, N. C., from March 29 to April 4, 1909, certainly destroyed about 1,000,000 grain aphides daily. These birds are all members of the sparrow family and are not usually given much credit as destroyers of insects.
A flock of about 5,000 titlarks spent part of one day on the farm, and it is probable that in that time they ate more than a million grain aphides.
It must be admitted that these numbers, representative of migration time, are far above the possibilities of the normal bird population of the farm. It is true, on the other hand, that nearly all of the sparrows had been abundant on the farm and carrying on their good work since very early spring. What is more important, this is the season of the year when the aphides are freest from other natural checks, and the repressive influence of the birds therefore has its maximum value. The grain aphides can reproduce at a temperature about 16° F. below that which will permit the increase of their most important parasite. This means that in the vicinity of WinstonSalem the plant lice can breed unmolested for about a month in spring, probably from about the 10th or 15th of February to a corresponding date in March.
Sparrows are abundant throughout this period and their destruction of 10,000 aphides per acre per day, the rate ascertained in 1909, reduced by an incalculable number the aphis infestation in the grain-growing region of North Carolina. All of the birds found preying upon the aphides at Winston-Salem are common in winter throughout the Southern States, in all of which they no doubt render equally important service to grain crops.
NATIONAL FOREST TIMBER FOR THE SMALL
By WILLIAM B. GREELEY,
In Charge of Silviculture, Forest Service.
USERS OF NATIONAL FOREST TIMBER.
Three thousand small logging operators and users of timber are now supplied with their raw material by the National Forests, through purchase from the United States; 25,000 more obtain timber for their own needs without charge. The small operator is the industrial agent sought by the Forest Service to manufacture the timber on the National Forests and distribute it to the consumers. At the same time the utilization of the Forests requires many large operators. Numerous bodies of timber can not be developed without large investments of capital or logged without a business organization and equipment of corresponding scale. The physical conditions on the National Forests afford opportunity for business enterprises of every size, from the shake maker, equipped with a wagon and half a dozen tools, who buys, fells, and rives a single tree, to the large lumber company, which must construct and operate a twoband sawmill and 50 or 60 miles of logging railroad for the development of a large body of timber, which without this equipment would be wholly inaccessible. Good administration of the National Forests requires the encouragement of all classes of operators-the small logger or millman, wherever he is able to put the stumpage of the Government upon the market in the form of commercial products; the larger lumberman, where the resources of the Forests can not be put to use without his business organization and capital.
HOW THE PRINCIPLE WORKS.
The sales on the Deerlodge National Forest, of central Montana, show how this principle actually works. This Forest supplies 119 timber operators, one of which is a large company, logging in the higher valleys near the Continental Divide, where extensive investments are required for flumes, roads, and other equipment beyond the means of the individual operator. The rest are small loggers, cutting
in the lower, more accessible regions, where the timber can be marketed by short flumes or hauled out by wagon or sled. The combined annual output is 16,000,000 feet of scale timber, 6,000 cords of fuel wood, and 336,000 pieces of mine props, poles, and lagging, practically all of which is used in the great copper mines of Butte.
PROPORTION OF SMALL OPERATIONS.
Small operators handle the bulk of timber cut from the National Forests; 99 per cent of the 5,772 sales made last year were for amounts under $5,000 in value, and 97 per cent were for amounts under $1,000. Operators of this class cut, all told, 273,935,000 board feet, or 63 per cent of the total amount removed from the Forests under sales during the year. While the large operator must be encouraged to exploit the less accessible areas where costly improvements are necessary, the small logger and millman will continue to be the chief customer of the public in the disposal of its timber.
OPPORTUNITIES FOR THE SMALL OPERATOR.
The National Forests afford opportunities of two broad classes to the small timber operator. He may either supply some local market which is more or less isolated from the competitive lumber trade, or he may cut and sell timber for wider consumption where the kind of products or the logging conditions of the locality may make him a successful competitor of the large lumberman, or give him a distinct place in the industry in cooperation with large operators or manufacturers. The first, cutting for near-by industries or communities, is distinctly and almost exclusively a field for the small operator. Such purchasers now cut annually 213,000,000 board feet for local supply. For the lumberman of limited capital this is the best chance offered. Not only do local market and industrial conditions favor the small operator in this field, but the future of his business, in so far as the available supply of timber is concerned, is directly protected by the National Forests. A permanent supply of timber ample for all local needs, and hence for a permanent local industry engaged in its logging and manufacture, is the first concern of the Forest Service. It is worth while to show how this supply is maintained.
LOCAL USES PROVIDED FOR.
The timber resources of the National Forests, aggregating 600,000,000,000 feet of merchantable material, besides large areas of young growth not yet of commercial size, are administered by natural units determined by topography, markets, and transportation facilities. The amount of wood produced annually on each unit by the growth