American robin

Abstract: The vast area occupied by the Robin during the breeding season indicates its toleration of a wide variety of habitats. In the norther portion of its range it pushes out beyond the limit of trees where it nests in low bushes. The factors limiting the northward distribution are not clearly evident. Vegetation is important, certainly as nesting cover and perhaps as food. Along the southern limit of the breeding range the species is extending its range. In certain parts of Texas and California the Robin has moved into new areas following the establishment of a water supply by man. In the southeastern states the species is pushing steadily nearer to the Gulf of Mexico and the Atlantic Ocean, having recently reached these bodies of water in certain regions. No change in the environment seems to have preceded or accompanied this extension in the latter region. In areas where the Robin is a common nesting bird it inhabits many diverse types of environment. The changes which man introduces seem usually to favor it. Dense forests are not unsuitable to this bird, nor are Robins absent from the treeless plains of the prairie states, but in both of these environments inhabited areas are more frequently selected than unpopulated ones. It is in the suburban areas that the requirements of the Robin are best filled. Open lawns are very productive feeding grounds and the shade trees growing about houses and along streets are used successfully as nesting sites. The fact that this bird thrives in and about villages and towns is responsible for its great increase in numbers during the period that man has settled throughout its range. The habitat must furnish sufficient food for the adults and their young. Many foods are eaten by Robins, but they must be relatively soft. Grains and other hard fruits cannot be digested. The habitat must provide water for in arid regions Robins occur only about sources of water. The cover requirements

Abstract: ABSTR•CT.--American Robins (Turdus migratorius) displayed four classes of approach to a Screech Owl (Otus asio): silent approach, vocal approach, mobbing, and attacking. Mobbing and attacking were confined to the breeding season. Mobbing first appeared in March and reached a maximum duration per mobbing bird in May and a maximum frequency in June. Mobbing and attacking were most often performed by pairs of robins or by single birds. These responses were directed at a Screech Owl located on the territory of the pair or individual. Silent approach and vocal approach occurred at all times of the year. During the breeding season, birds approached a Screech Owl located on a territory other than their own, observed the owl being mobbed, but joined in mobbing only if the owl flew. Outside the breeding season, robins gathered in large mobile flocks. Birds in such flocks sometimes approached a Screech Owl but did not mob. I suggest that the contexts in which these responses occurred indicate that mobbing and attacking are beneficial for robins only when birds are confined to territories or home ranges. The presence of young on territories further increases the amount of parental mobbing. Received 20 August 1980, accepted 4 November 1981.

Abstract: Abundance of birds and their tick parasites were estimated in a residential community located in Westchester County, NY, where Lyme disease is endemic. In total, 36 bird species (416 captures) were collected, of which 25 species (69%) were parasitized by ticks. Ixodes dammini Spielman, Clifford, Piesman & Corwin composed 96.4% of the 1,067 ticks found on birds. The bird species most heavily parasitized was house wren, Troglodytes aedon Vieillot (11.1 Ixodes dammini per bird). Relative density estimates of birds, using fixed circle radius counts, revealed dominance by the American robin, Turdus migratorius L. (29.3%), followed by the common grackle, Quiscalus quiscula (L.) (9.3%). Bird density estimates were combined with tick abundance data to calculate an importance value for each bird species as a host for immature I. dammini. The American robin was most important, accounting for 72.7% of all larval I. dammini found on birds, followed by the common grackle (8.2%) and the house wren (5.9%). Both the American robin and house wren are reservoir competent for the Lyme disease spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner and therefore may contribute to the risk of Lyme disease for humans. During August when larvae were most prevalent, 39% of the American robins and 70% of the common grackles were observed on lawns. These species are probable contributors to nymphal I. dammini populations found on lawns.

Abstract: The familiar sight of the American Robin (Turdus migratorius) foraging for earthworms on a lawn has not prompted a detailed investigation of the sensory mechanisms and environmental clues employed by the birds when finding worms, although several workers have commented on and made speculations about this behavior. Tyler (in Bent, 1949) has supplied a good general description of the behavior of robins foraging for worms. Polyak (1957) and Allen (1934) assume that robins are definitely employing vision to find worms. Bent (1949) mentions the possible use of hearing while foraging but thinks that vision is the more important