Ron J. Johnson

17. Influences of shelterbelts on wildlife management and biology

Abstract Shelterbelts provide benefits to wildlife in several ways, including protection from wind and adverse weather, escape or refuge cover, food and foraging sites, reproductive habitat and travel corridors. At least 108 species of birds and 28 species of mammals are known to use shelterbelt habitats. In agricultural areas, 29 species of birds, benefit substantially, 37 moderately and 42 very little or accidentally. At least 57 species of birds have been recorded using shelterbelts during the breeding season and, of these, 28 are known to have nested in them at densities from about 0.3–186 nests ha−1. Shelterbelts have helped maintain or extend the ranges of several small mammal and bird species. For enhancement of wildlife benefits, shelterbelts should be designed to provide the needs of the wildlife most desired and be of sufficient size and complexity to provide wildlife needs throughout the year, including winter food and weather protection appropriate for local climatic conditions. Numbers and diversity of wildlife are usually positively correlated with shelterbelt area and length of perimeter, diversity of vegetation and vegetation complexity. Variation in type of vegetation (e.g. several species of deciduous and coniferous trees, shrubs, grasses, and forbs), in addition to well-developed canopy and understory layers, are desirable. Snags provide nesting and foraging sites for many species; management options include topping snags to leave 4–5-m stumps and providing nest boxes. Overgrazing seriously degrades the benefits of shelterbelts to wildlife, particularly for species that utilize the understory layer. Shelterbelts provide only a portion of most wildlife needs, and thus should be viewed in relation to other nearby resources so that all needs of desired wildlife are met. Adjacent food resources are of particular importance to some wildlife species. Wildlife associated with shelterbelts may provide economic, educational, recreational and aesthetic benefits. In contrast, some species may cause damage or nuisance problems in adjacent areas. Overall, these problems are minor/or can be controlled. Relationships among wildlife, shelterbelts and people are not well studied, so numerous research opportunities and needs exist.

Influences of Trees on Abundance of Natural Enemies of Insect Pests: A Review

In this article we review the use of natural enemies in crop pest management and describe research needed to better meet information needs for practical applications. Endemic natural enemies (predators and parasites) offer a potential but understudied approach to controlling insect pests in agricultural systems. With the current high interest in environmental stewardship, such an approach has special appeal as a method to reduce the need for pesticides while maintaining agricultural profitability. Habitat for sustaining populations of natural enemies occurs primarily at field edges where crops and edge vegetation meet. Conservation and enhancement of natural enemies might include manipulation of plant species and plant arrangement, particularly at these edges; and consideration of optimum field sizes, number of edges, and management practices in and near edges. Blending the benefits of agricultural and forestry (windbreak) systems is one promising approach to field edge management that has additional benefits of wind protection and conservation of desirable wildlife species.

ASSESSING MIGRATION OF RUBY-THROATED HUMMINGBIRDS (ARCHILOCHUS COLUBRIS) AT BROAD SPATIAL AND TEMPORAL SCALES

ABSTRACT. Phenological patterns in birds appear to be temperature-dependent in part, and global temperatures are undergoing change. Many studies of bird phenology are conducted at broad temporal but local spatial scales, making it difficult to assess how temperature affects bird migration across landscapes. Recently, networks of “citizen science” volunteers have emerged whose collective efforts may improve phenology studies as biases associated with such efforts are recognized and addressed. We compared mean Rubythroated Hummingbird (Archilochus colubris) first arrival dates from Journey North (2001–2010) with data from the North American Bird Phenology Program (1880–1969). Ruby-throated Hummingbirds arrived earlier in the more recent period throughout the eastern United States; these advances, however, varied by latitude from 11.4 to 18.2 days, with less pronounced changes above 41°N. Warmer winter and spring temperatures in North American breeding grounds were correlated with earlier arrivals at lower latitudes in our recent period. Surprisingly, Ruby-throated Hummingbirds arrived later at high latitudes (42–43°N) during warmer winters and later at both mid- and high latitudes (38–39, 41–44°N) during warmer springs, which perhaps indicates extended migratory stopovers below 40°N during these years. Overall, weather variables predicted arrival dates better in the recent than in the historical period. Our results document spatial variability in how warming temperatures affect hummingbird arrivals and add credence to the hypothesis that spatial differences in arrival patterns at high versus low latitudes could exacerbate asynchrony between some birds and their food resources and modify associated ecosystem services such as pollination and insect pest suppression.

Global Perspectives on Birds in Agricultural Landscapes

Earth is home for about 10,000 bird species. They inhabit all continents and interface with agroecosystems worldwide. Bird migrations across continents and nations make birds a truly global phenomenon of broad but complex conservation appeal. Global agricultural expansion during the past 200 years and intensification in the last 50 have been key drivers in global habitat loss and in declines of about 60% of the birds listed on the IUCN red list. Agricultural intensification is a continued concern as is expansion in tropical areas such as Latin America. Maintaining field-edge and set-aside habitats and using lower-intensity practices in production areas are important options for sustaining bird populations globally. Many key threats to birds in agroecosystems are global but specific impacts and management options may differ among geographical areas. Global climate change creates uncertainties for agriculture and birds, including impacts on bird migration and nesting, and concerns about synchrony between birds, habitats, and food resources. Climate change adds to other existing challenges of habitat loss and fragmentation, urbanization, migration barriers, and uncertain food resources. The push for biofuels has resulted in production intensification and habitat losses, especially removal of set-aside lands. Wildlife-friendly farming approaches can facilitate bird movement in fragmented agroecosystems and can provide important habitat for agricultural species and migratory birds. Wildlife-friendly and land sparing approaches are currently being debated toward the goal of sustaining biodiversity and food production. Global influences from social and political systems affect agroecosystems, people, and birds.

Reviving a Legacy Citizen Science Project to Illuminate Shifts in Bird Phenology

Climate change has been of high interest to both the scientific community and the public at large since the phenomenon was first suggested. Subsequently, and with growing evidence of its impending ramifications, numerous studies have attempted to illuminate climate change impacts on bird migration. Migration is a key event in the annual cycle in the reproductive success of birds, and changes in migration in response to climate may indicate that species populations are at risk. Previous studies report earlier arrival dates in response to climate change in many bird species, although specific mechanisms are often difficult to explain at broad spatial and temporal scales. Using a newly revived dataset of historical migration cards for over 870 species and spanning 90 years throughout North America, we are developing an historical baseline of bird arrival dates to compare with contemporary records. Here we chronicle the history and reemergence of the North American Bird Phenology Program. We present two case studies illustrating how data from this program has been used to model historical arrival dates of Ruby-Throated Hummingbird (Archilochus colubris) and Purple Martin (Progne subis) throughout eastern North America. Our results show the importance of considering spatial and temporal variability in understanding patterns of bird spring arrivals.

Directing Nest Site Selection of Least Terns and Piping Plovers

Abstract Endangered Interior Least Terns (Sterna antillarum athalassos) and threatened Piping Plovers (Charadrius melodus) nest in Nebraska at gravel mines where they are vulnerable to disturbance and nest loss. Conflicts occur when their nesting and protected status delay mining activities. The possibility of shifting nesting from active to inactive mining areas by using a deterrent (mylar flagging), an attractant (gravel and driftwood spread on bare sand), and a control (untreated sand) was evaluated. Experimental plots (mean 0.36 ha) were established at 18 different gravel mines, twelve in 2000 and seven (one repeat) in 2001 along the Platte and Elkhorn rivers prior to nesting season. Of 117 tern nests, 73% were in attractant, 2% in deterrent, and 26% in control plots. Of 23 plover nests, 61% were in attractant, 9% in deterrent, and 30% in control. Colonies used plots containing less vegetation and more driftwood than unused plots. Within control plots, both tern and plover nests were surrounded by more large (>15 mm) gravel and less coarse sand than was available at random points. Within attractant plots, substrate at the nest did not differ from random points. In all plots, Least Tern nests were more likely to have driftwood by the nest than was available at random points. Hatching rates did not differ between attractant and control plots. To attract Least Terns and Piping Plovers, sand covered with 15% small gravel, 5-10% large gravel, <3% vegetation, and about ten pieces driftwood/1,000 m2 was found to be effective. As deterrents, mylar streamers 7 m long, 30 mm wide, and 0.025 mm thick, attached to 1 m poles arranged in a 7 m grid were used. The combination of attractant and deterrent treatments provided a mechanism to protect nesting birds and avoid conflicts.

Bird dispersal recordings: an overview

Bird damage control often involves dispersing birds from areas where they cause problems. Dispersal techniques have been used at airfields, rural and urban bird roosts, livestock facilities, fruit orchards, grain fields, and other locations. Certain avian vocalizations have evolved as alarm or distress calls, and these calls can be exploited as a means of dispersing birds. The behavioral response to such calls, however, varies. Certain species may disperse with the appropriate call, whereas others show little or no reaction. The efficacy of this technique is not well documented at present, but its potential for development as a management tool seems great. Visual warning signals may increase the effectiveness of bird dispersal recordings by decreasing the habituation rate, increasing realism, or decreasing the fright threshold of the birds causing problems, or by a combination of these factors. Habitat manipulation, which reduces the attractiveness of an area to birds, complements dispersal efforts. It appears that a combination of management techniques is the most effective strategy. In addition, pretreatment evaluation of the problem and situation plus records of field results are helpful parts of a dispersal effort. Evolutionary, theoretical, and applied aspects of bird communication are discussed as they relate to bird dispersal, the repellency of recorded sounds, habituation rate, and effects of regional dialects. A review of the vocalization and hearing ranges of birds is included; this may help define the frequency and type of sounds most likely to disperse birds. The characteristics of recording and broadcasting equipment are detailed in relation to component selection, and suggestions are made for effective use. A section on field application of bird dispersal recordings provides guidelines for duration and spacing of playbacks and recommends using an integrated approach. Continued refinement of bird dispersal recordings and associated techniques can increase considerably our effectiveness in solving bird damage problems.

A farm-scale biodiversity and ecosystem services assessment tool: The healthy farm index

Farm management focused on maximizing biomass production results in biological simplification and ultimately a degraded production potential for the future. Despite the large and growing body of evidence pointing to the need to restore biodiversity to farm systems, incorporation of biodiversity and ecosystem services into local agricultural land-use decision-making remains limited. The lack of planned and associated biodiversity may reduce resiliency of local managed ecosystems and add management costs; however, the tradeoff for individual landowners of greater diversity is increased management complexity and uncertainty. To assist farmers in managing biodiversity and to encourage ecological thinking, we developed the Healthy Farm Index, a farm-scale tool that complements existing farm assessment tools by integrating multiple metrics and outputs suitable for applied decision-making and annual evaluation. In this article, we describe the impetus for the index development and the structure of the index and through a case study apply the index and discuss its varied outputs and applications.

Assessment of Squirrel-Caused Power Outages

Squirrel-caused power outages in Lincoln and Omaha, Nebraska, were evaluated by examining company power outage reports and by consulting with power company representatives. Reports showed that squirrel-caused outages at pole-mounted transformers were most prevalent during May, June, and October (48% of total) and between 1 and 4 h after sunrise (38%), patterns that coincide with squirrel dispersal or morning activity periods. In Lincoln, 1980 and 1981, squirrels caused 177 outages per year, which was 24% of all outages and 90% of animal-caused outages. Estimated minimum annual costs were

Using species distribution models to define nesting habitat of the eastern metapopulation of double-crested cormorants

23 364 for repairs, public relations, and lost revenue while meters were not running. In Omaha, 1985 and 1986, squirrels caused 332 outages per year, costing at least