SEASONAL, HABITAT AND SEX-SPECIFIC PATTERNS OF FOOD UTILIZATION BY RED-WINGED BLACKBIRDS (Agelaius phoeniceous) IN EASTERN ONTARIO AND THEIR ECONOMIC IMPORTANCE

Crop depredation by red-winged blackbirds (Agelaius phoeniceus) causes serious economic losses to agricultural crops each year in both Canada and the United States. The concentration of vulnerable, monocultural crops, particularly corn, during periods when large flocks of blackbirds congregate in roosting areas prior to migration has invariably led to heavy feeding pressure (Stone et al., 1972; Wiens and Dyer, 1975; Tyler et al., 1978). Efforts to reduce damage levels by mechanical and chemical dispersal agents have been largely unsuccessful, at least in terms of a long-term solution to the problem. Recently, the lethal control of blackbird populations using surfactants has been proposed. However, the potential repercussions of the removal of substantial numbers of birds from northern breeding areas are virtually unknown (Robertson et al., 1978). Much of the research dealing with the feeding ecology of red-winged blackbirds has been limited to fall and winter periods when large aggregations of birds are actively involved in crop depredation (Goddad, 1969; Williams, 1976; Dolbeer et al., 1978) or pose a potential health hazard (Monroe and Cronholm, 1976). However, what is not known is the degree to which the removal of deleterious weed seed and insect pests cited in several studies (Bird and Smith, 1964; Mott et al., 1972; Robertson et al., 1978) might be of potential value to agriculture. The issue of whether the benefits derived from redwing foraging compensate for the negative aspects associated with crop depredation and health hazards remains largely unresolved. The present study attempted to evaluate the pest status of this species using diet information derived from food habits analysis conducted during the residency of red- winged blackbirds in a northern breeding area. By determining how the feeding ecology of red-winged blackbirds varies on a seasonal basis, among different breeding habitats and between sexes, we hoped to determine more realistically which segments of the population might be responsible for the greatest benefits or detriments and, thereby, more accurately evaluate the economic impact of the species as a whole. To achieve this aim, the study provides an accurate description of the common insects and weed pests utilized by redwings. By determining the relative proportions of those items known to be detrimental, we hoped to illustrate, at least qualitatively, the degree to which redwing foraging is comprised of both beneficial and harmful components.

THE MONK PARAKEET IN NEW YORK

Attention was focused on the Monk Parakeet (Myiopsitta monachus) in New York State in 1971 when the first successful breeding record was documented for the state although Monk Parakeets had been noticed in New York and New Jersey since 1968 (Bull, 1971). Since 1971 awareness of the bird’s potential for becoming an established species in New York has spread through several segments of the state’s populace. This awareness has been created primarily through two articles in the magazine published by the New York State Department of Environmental Conservation (DEC), The Conservationist (Trimm, 1972) (Trimm, 1973); several articles in popular magazines, Parade, Yankee, Sports Afield; journals, American Birds and Kingbird; county cooperative extension bulletins and newsletters; and in numerous newspapers throughout the Northeast. The Monk Parakeet is about 12 inches long (Mourning Dove size), weighs about 90 grams, and is native to Argentina and other temperate regions of South America. The bird is pale green with a soft gray forehead and breast, some blue on the flight feathers and a flesh-colored bill. They are gregarious throughout the year. The Monk Parakeet differs from other members of the parrot family in that it builds large communal nests of sticks. Each pair of parakeets has its own private compartment with a downward-pointing tunnel entrance from the inner unlined compartment. The nest is used as sleeping quarters year round and live twigs cut by the bird are continually added to the structure (Bump, 1971). A brief review of the bird’s history in New York shows that the bird remained a mere curiosity until 1972. At that time, because the population seemed to be increasing and because information gleaned from the literature and from those with first-hand experience with the bird in its native haunts of South America indicated that the bird posed a serious potential agricultural problem, several prominent individuals, birding and conservation societies, and state and federal agencies took the position that the bird should be retrieved or removed from the wild.