March 6, 1889.] 



Garden and Forest. 



Ill 



foremost artists in planning great public parks — the most 

 difficult of all the landscape-gardener's tasks — as does Mon- 

 sieur Andr6 in his more practical hand-book called "L Art des 

 Jardins." But it is pleasant to see that with all the wealth of 

 material from which he had to choose, dealing with times old 

 and new, American artists and their work were esteemed 

 worthy of so considerable a share of attention and praise. 



Conifers Injured by Squirrels. 



That squirrels have the habit of biting off the cones of 

 coniferous trees in order to get at the seeds more easily, is well 

 known, but why quantities of the twigs, tips and buds of these 

 trees are sometimes found upon the ground in winter and 

 spring seems not to have been generally understood. Com- 

 plaints on this subject have often been made by people living 

 near Boston, and attention has been particularly directed to the 

 Norway Spruce. In some cases bushels, of tips, from two to 

 four inches long, could be gathered under two or three of 

 these trees. High winds, disease, insects, birds, squirrels and 

 other agencies have been suggested, but proof seemed to be 

 wanting to substantiate any theory. That it did not result from 

 strong winds during cold weather was proved by the fact that 

 the trouble was local, as the ground under some Spruces would 

 be thickly strewn with the tips, while other trees only a few 

 rods away were quite free from evidence of injury. Neither, 

 on careful examination, could any trace of disease, or the work 

 of borers or other insects be found. 



The injuries have been noticed in other parts of the country, 

 and in the Gardeners' Monthly for 1885 there are several notes 

 concerning it. The editor, p. 166, considers the " matter mys- 

 terious," and says that " mice or squirrels cannot do it, as the 

 twigs are not cut by teeth, but broken, as examination by a lens 

 clearly shows." . 



On page 227 Professor W. A. Buckhout gives several good 

 reasons for supposing it was the work of squirrels, but he had 

 not seen them do it, and, in addition to the Norway Spruce, he 

 mentions similar injuries to Pimis rigida. The editor men- 

 tions specimens received from New Hampshire which " were 

 broken off at a bud — disarticulated as it were — which a squir- 

 rel could not do," and he further thinks " that after the rodent 

 has cut the branch, and drying commences, disarticulation of 

 the side branches results." 



At the end of a note (p. 276) from a correspondent at Lexing- 

 ton, Kentucky, who complains of similar injuries to Norway 

 Spruces there, for which he can give no reason, the editor 

 says : " On our grounds (Germantown, Pennsylvania) we have 

 no squirrels, and yet the trees are so thickly strewn with 

 branches — broken at the articulation, not cut by teeth — that the 

 ground surface beneath the trees is covered." 



Several years ago I noticed gray squirrels cutting off twigs of 

 Norway Spruce in the winter or early spring, but not until very 

 recently have I had what seems to be positive proof that they 

 do all the mischief. After having carefully Avatched them at 

 the work I think there is not the least doubt that besides cutting 

 off the twigs at any place, they can also, and naturally do, 

 " disarticulate " the branches at the point where the lastseason's 

 growth began. In this vicinity a very large proportion of the 

 twigs cut from the Spruces are severed at the " articulation," 

 probably because the squirrels generally find it the most con- 

 venient place. As the squirrels reach forward and grasp the 

 little side branchlets to draw them towards themselves, they 

 find the branchlets bend most readily at, or close to, the base 

 of the year's growth, and at the same place a small space is 

 left clear of the sharp-pointed leaves, at once giving an open- 

 ing and a weak point at which to sever it, which the squirrels 

 do quickly and neatly with their sharp incisors. " Disarticula- 

 tion of the side branches" would not naturally take place after 

 drying imtil long after the leaves had fallen and the branches 

 had begun to decay. 



The object of the squirrels in cutting off the twigs is to 

 enable them to get at the terminal and lateral buds, the heart 

 of which they dexterously extract and eat while they have a 

 comfortable foot-hold on a strong branch. For the same 

 reasons they cut the nuts from trees and retire to a safe 

 place before eating. Many buds are eaten without cutting off 

 the twigs. Both the red and gray squirrels cut the twigs of 

 Spruces, and I have seen the two species at work on the same 

 trees at the same time. 



They seem to prefer the Norway to either the native Black 

 or White Spruces when growing side by side, probably because 

 in the former the branches are more supple, and the leaves 

 less sharp and rigid. 



On calm days, when the squirrels are at work, most of the 

 twigs which they cut off and drop may be caught and lodged 



by their leaves among the branches of the trees, and being 

 blown to the ground during strong winds, their appearance in 

 large quantities after a storm is accounted for. On the flat, 

 sprayed branches, on the upper part of a large tree, I found 

 little heaps of the detached twigs. Although walnuts and 

 hickories were not aVjundant, there was a good crop of acorns 

 and other tree-seeds the past season, and it its difficult to say 

 why the squirrels eat the spruce-buds, as their doing so does 

 not appear to be from necessity. 



If the attack should be made upon the same trees for a 

 number of years it would naturally result in giving the 

 branches a tufted and deformed appearance, if not proving a 

 very serious or fatal injury. 



Near the Arnold Arboretum there are some European 

 Larches, the slender, pendulous twigs of which have been bit- 

 ten off by squirrels in the spring, for several years at least, 

 and the branches are covered with numerous knotty swellings 

 and tufts, which are quite conspicuous, especially in winter. 



I have found only one authority who has seen and recorded 

 this habit in our squirrels. Dr. C. Hart Merriam, in his work 

 on " The Vertebrates of the Adirondack Region," in the article 

 on the red squirrel, p. 116, says : He eats the little buds that 

 may be found scattered sparingly along the small branches of 

 the Spruce, and, in order to obtain them easily, bites off the 

 terminal twigs and drags them back where the limb is large 

 enough to aHow him to sit comfortably on his haunches while 

 feeding. Under single trees, both in the great forest and on 

 our own lawn, I have found enough twigs to fill a bushel 

 basket. The injury thus done is sometimes very extensive." 



In European journals there are frequent notices of injuries 

 to Conifers caused by squirrels ; but, in some instances at 

 least, the attacks are of a different and more serious kind. A 

 writer in the Journal of Forestry (London) for January, 1881, 

 p. 578, says of them : " After a severe winter, during which a 

 scarcity of seeds has been experienced, tfiese animals betake 

 themselves to the young woods, and do great damage by nip- 

 ping buds from the extremities of the branches, thus causing 

 the trees to become bushy and straggling in the top ; they also 

 in the early spring and summer months denude many Pine 

 trees of their bark, commencing their attacks at two to five 

 feet from the top, sometimes peeling all around and some- 

 times in patches; in the former case, the heavy winds will cause 

 the trees to break; but, as regards the latter, the injury, if not 

 severe, will in time heal over, although usually producing 

 what is subsequently known as a flaw in timber. ... In like 

 manner squirrels attack deciduous trees, such as the Beech 

 and Plane, thus frequently causing the tops to die. ... In 

 woods where there is a good mixture of Spruce Fir, their 

 depredations will be found to be of the most serious nature." 



By far the most serious charge that I have seen against the 

 squirrels, in connection with their injuries to Conifers, occurs 

 in the Bulletin de la Societe d'Acclimatatiojt de France, April, 

 1881, p. 253, where M. Ed. R^nard gives an account of the 

 ravages caused by squirrels on the Pines in the forest of Ram- 

 bouillet. Here the writer relates that previous to the year 

 1874 there were no squirrels known in the forest of Rambouil- 

 let ; but about this time they were introduced, having escaped 

 from a neighboring chateau. 



At first their presence in the woods gave pleasure ; then he 

 says : " But one day, after a strong gust of wind, I saw on 

 the ground, to my astonishment, a considerable quantity of the 

 leaders {fleches) of Pines from two to three metres in height. 

 I did not know to what to attribute this devastation, which I 

 soon knew must be the work of the squirrels ; they had 

 gnawed entirely around the bark of the Conifers, and the dead 

 tops of my trees were thrown down and strewed on the 

 ground." 



The destruction of the squirrels was ordered, and over 200 

 Avere killed in the year, and the injuries decreased. Later, 

 however, a new invasion of squirrels from another forest de- 

 stroyed some thousands of trees of Pinics sylvestris, by com- 

 pletely girdling the stems several metres from the ground, 

 causing the trees to have a spreading form, and destroying 

 their value for timber. 



Acorns having been scarce the preceding year, he thinks 

 that the squirrels, in the absence of other winter food, were 

 obliged to eat the bark. 



The trouble had increased to such an extent from year to 

 year, the squirrels attacking fruit-trees as well as Conifers, 

 that the forest administrators had established a reward of 

 half a franc each for all squirrels killed. 



I do not know that the squirrels have been found to peel the 

 bark of Pines in this country, but it is not improbable that 

 they would do so in times of scarcity of other food. 



In the spring they sometimes bite through the bark of 



