30 



THE CANADIAN SPORTSMAN AND NATURALIST. 



ruticilla ; red-eyed and yellow-throated vireos, 

 Virio olivaceus; and V. jlavifrons ; wood- 

 peckers, Picib^e ; blue bird, Sialia stalls: 

 cat-bird, Galeoscoptes Carol) 'nensis ; brown 

 thrush, Sarporhynchus rut'us ; sparrows^ 

 Frixgji.id.e .- cuckoos, Coccidje ; nuthatch, 

 Siita Garolinensis ; chickadee, Parus ,atrica- 

 pillus : kin-lets, Sylvid.e ; meadow-lark, 

 Siwrnella magna ; Baltimore oriole, Icterus 

 Baltimore; wren, Troglodytes redon ; black- 

 birds, Icterid.e ; and especially the Robin, 

 (Turdus migrator his) as a great fruit thief, 

 destroying a far greater quantity than it would 

 eat, therefore, should not be protected by legis- 

 lation. I trust the above extract will induce 

 readers of the Canadian Sportsman and 

 Naturalist to give their experience respect 

 ing tbe usefulness of Insectivorus birds to 

 farmers, fruit-growers, and gardeners. 



E. D. W. 

 Montreal, March 28th, 1881. 



Tbe above-named birdsare all insectivorous, 

 but tbe question regarding their being benefi- 

 cial to agriculture is a matter which we have 

 always contended, was overstretched. Mr. 

 S. A. Forbes, an American naturalist, has 

 examined tbe stomachs of 150 birds of the 

 Thrush family, with quite unexpected results. 

 " Forty-one of these were Rollins ; thirty-seven 

 Cat-birds ; twenty-eight Brown Thrushes ; eight 

 Alice's Thrushes ; six Swainson's Thrushes, 

 and one Wilson's Thrush. They were shot in 

 various months from March to September and 

 during four successive years. The number of 

 specimens is, of course, too small to allow con- 

 clusive generalization ; but as no equal number 

 of specimens bas been previously studied with 

 equal care, it will probably be fair to state some 

 of the result as hypotheses, more or less proba- 

 ble, but requiring verification by further study. 

 The most fruitful peculiarity of tbe method 

 used was the careful estimate, for each speci- 

 men (after a critical microscopical examination 

 of the contents of the stomach), of tbe relative 

 amounts of all tbe elements of tbe food, and tbe 

 subsequent averaging of these ratios for the 

 specie.-. By tins means I determined thebith- 

 erto unsuspected fact that the family is inordi- 

 nately destructive to predaceous beetles (Har- 

 palini), seven per cent of the food of the 150 

 specimens consisting of these highly beneficial 

 insects. When we remember that one preda- 

 ceous insect must destroy many times its own 

 bulk of other insects during its life, we see tbe 

 importance of this fact in respect to the economi- 

 cal value of these birds. Between the Tcrdidje, 



and other families, lean make only the follow- 

 ing crude comparison. Of the 150 Thrushes 

 examined, forty-six- per cent, had taken Cara- 

 bine, while of 194 birds of other families in 

 whose stomachs insects were found, less than 

 five per cent, had eaten these Coleoptera. The 

 worst sinner in this respect was tbe Hermit 

 thrush ; while the Alice thrush and the Wood 

 thrush had eaten comparatively few. Curiously 

 the ratio of Carabine continued undiminished 

 during the fruit season when the total of insect 

 food fell away very rapidly. "For example, the 

 Cat-birds ate in May, June and July, eighty- 

 seven per cent., sixty-four per cent., and 

 eighteen per cent., respectively, of insect food, 

 while tbe Carabid.e for those months averaged 

 seven per cent., six per cent., and ten percent., 

 the corresponding fruit record standing nothing, 

 thirty per cent, and seventy one per cent. The 

 following genera were distinguished among the 

 Carabine Scarites, Dyschirius, Platynus, 

 Pvarlhrus, Pterosticlms, Amara, Brachylobus, 

 Geopinus, Agonoderus, Anisodactylus, Brady- 

 eellus, Harpalus, and Stenolophus. The 

 absence of all, or nearly all, the specially 

 protected genera is noticeable ( unless the 

 obscure colour of many is reckoned a special 

 protection.) A single Cicindela (C. lecontei) 

 was found in tbe stomach of a Cat-bird. It 

 is further interesting to notice the apparent 

 specific difference in the food of allied species, 

 occupying tbe same ground at the same time 

 and drawing their food from tbe same sources 

 of supply. The Robin and the Cat-bird differed 

 materially in the number of ants and myriopods 

 destroyed, the,. former eating very few of either 

 (one per cent, and two per cent, respectively). 

 The Brown thrush departs from all tbe other 

 members of bis family in his fondness (?) per- 

 haps it is stern necessity which forces him to 

 this miserable shift), for insects and fragments 

 of grain picked from the droppings of stock. 

 Twenty-eight per cent, of the food of those shot 

 in April was derived from this source, and 

 another eight per cent, consisted of carrion 

 beetles (Sii.phine). This bird was further 

 distinguished from the Robin (as is the Cat- 

 bird also), by tbe absence of the larva of Bibo 

 albipennis Say which made over half the food 

 of the Robin in March. It is important to 

 recall, as throwing light on tbe question of 

 fixity of food habits over large areas, that 

 Professor Jenks, now of Brown University-, 

 found nine tenths of the food Of a large number 

 of Robins whose stomachs were examined by/ 

 him in Massachusetts, in March and April, 

 1858, to consist of this same larva." 



