Seasonal Dynamics, Habitat Relationships, and Management of Avifauna in Farmstead Shelterbelts

Abstract

Seasonal dynamics and habitat relationships of avian populations and communities in farmstead shelterbelts were studied during 1978-80 in southern Minnesota. Eighty-seven species of birds were recorded, 14 of which were classified as being highly important; omnivores and granivores were predominant. Species richness (S) and species diversity (H') were similar in spring and summer, but were lower in autumn and winter. Species evenness (J') seldom varied among seasons, and no consistent pattern in total individuals of all species combined (N) occurred over seasons. Shelterbelts were segregated into 3 types based primarily on stability of S, J', and N during autumn and winter. Extent of perimeter and length of shelterbelts were associated more often with avian variables than was area of shelterbelts. Distance to wooded and oldfield habitats, distance to and number of proximal buildings, and percentage of croplands and pastures surrounding shelterbelts were important to associated avifauna. A concentration effect occurred in isolated shelterbelts; the greater the isolation, the more likely that certain species were encountered in a shelterbelt due to the paucity of similar habitat in the vicinity. Picea, Pinus, Populus, Ulmus, Acer, Fraxinus, and Lonicera were related to abundances of several avian species. Management recommendations include establishing shelterbelts that are >0.6 ha in area and 8 rows in width. Proper spacing within and between rows should be considered and a diversity of plantings should be used. Mowing and cultivation should be discontinued after the shelterbelt becomes established. Snags should be retained as nesting and foraging sites. Croplands, rather than pastures, should be positioned near shelterbelts. No-tillage or minimum tillage systems, a few rows of standing crops, food plots, and artificial feeders at farm homes are suggested. Shelterbelts can be designed to provide protection and beauty to the farmstead aswell as to benefit a variety of farmland avifauna. J. WILDL. MANAGE. 47(1):85-104 Farmstead shelterbelts are man-made habitats created by planting rows of trees and shrubs (hereafter also termed plantings) on the windward sides of farm homes and buildings. In intensively farmed regions of the Midwest, these small wooded islands (generally <1 ha) provide protection against wind and drifting snow, reduce energy and feed costs, and afford aesthetic beauty to farmsteads (Smith and Scholten 1980). Further, shelterbelts are of considerable importance to birds and other wildlife (Popowski 1976, Martin 1978). However, as a result of larger farms, increased mechanization, use of pivot irrigation systems, and other recent trends in the agricultural industry, the availability of farmstead shelterbelts and other permanent wildlife habitat is restricted (Vance 1976). For example, Griffith (1976) estimated that farmstead shelterbelts, field windbreaks, and other wooded habitats comprise <3% of the total area in the Great Plains. Aspects of the ecology of avifauna associated with farmstead shelterbelts have been examined. Rotzien (1963) and Yahner (1981) studied winter use of shelterbelts by birds. Weiser and Hlavinka (1956), Martin (1978, 1980), Martin and Vohs (1978), and Cassel and Wiehe (1980) investigated breeding and migratory communities in these habitats. Avian use of vertical strata and plantings during the annual cycle has been detailed (Yahner 1981b). Nest densities and nest-site selection also have been examined (Field 1971, Martin 1978, Yahner 1982a). Studies of avian communities in a variSPresent address: Forest Resources Laboratory, School of Forest Resources, The Pennsylvania State University, University Park, PA 16802. J. Wildl. Manage. 47(1):1983 85 This content downloaded from 157.55.39.215 on Tue, 30 Aug 2016 04:48:53 UTC All use subject to http://about.jstor.org/terms 86 AVIFAUNA IN FARMSTEAD SHELTERBELTS * Yahner ety of habitats usually have been conducted only during the breeding season, with little reference to nonbreeding times of the year (Kricher 1975); yet seasonal monitoring of bird communities is necessary for a better understanding of populations and habitat relationships (Dickson 1978). The objectives of my study were to (1) document seasonal trends in the dynamics of avian populations and community structure in farmstead shelterbelts, (2) examine the relationships between the habitat features describing dimensions, vegetation, and proximal land-uses of shelterbelts and the avian populations and communities using these habitats, and (3) develop effective management recommendations for landowners and agencies that either establish new or renovate older shelterbelts. I thank H. Scholten of the College of Forestry, University of Minnesota and C. L. Wilcox of the Rosemount Agricultural Experiment Station for cooperation with all aspects of the research. M. W. Weller and J. R. Kitts, Department of Entomology, Fisheries, and Wildlife, University of Minnesota and H. Scholten provided helpful comments on the manuscript. This study was supported by the Minnesota Agricultural Experiment Station and by grants from the Graduate School of the University of Minnesota, the National Rifle Association of America, and the Max McGraw Wildlife Foundation. This is Paper 11,826 of the Minnesota Agricultural Experiment Station, Scientific Journal Series, University of Minnesota, St. Paul.