BEHAVIORAL RESPONSE OF CATTLE EGRETS TO POPULATION CONTROL MEASURES IN HAWAII

We monitored behavior of cattle egrets (Bubulcus ibis) during a population control program to reduce egret-aircraft strike hazards from a small heronry near the Hilo, Hawaii, airport. Results verified that attempts to move egrets from undesirable roost sites should be undertaken before nesting begins. Although possibly compounded by previous treatments, our observations also indicate that 1) egrets may abandon a new roost in response to a few dead egrets placed in clear view around the roost, and 2) shooting at egrets as they attempt to land at a traditional feeding site causes long-term avoidance of the area. Rapid repopulation after control indicates that techniques to move roosts and prevent congregations are more likely than population control to resolve problems.

Hierarchy-Based Access Control in Distributed Environments

Access control is a fundamental concern in any system that manages resources, e.g., operating systems, file systems, databases and communications systems. The problem we address is how to specify, enforce, and implement access control in distributed environments. This problem occurs in many applications such as management of distributed project resources, e-newspaper and payTV subscription services. Starting from an access relation between users and resources, we derive a user hierarchy, a resource hierarchy, and a unified hierarchy. The unified hierarchy is then used to specify the access relation in a way that is compact and that allows efficient queries. It is also used in cryptographic schemes that enforce the access relation. We introduce three specific cryptography based hierarchical schemes, which can effectively enforce and implement access control and are designed for distributed environments because they do not need the presence of a central authority (except perhaps for set- UP).

Landscape-Genetic Analysis of Population Structure in the Texas Gray Fox Oral Rabies Vaccination Zone

In west-central Texas, USA, abatement efforts for the gray fox (Urocyon cinereoargenteus) rabies epizootic illustrate the difficulties inherent in large-scale management of wildlife disease. The rabies epizootic has been managed through a cooperative oral rabies vaccination program (ORV) since 1996. Millions of edible baits containing a rabies vaccine have been distributed annually in a 16-km to 24-km zone around the perimeter of the epizootic, which encompasses a geographic area >4 x 105 km2. The ORV program successfully halted expansion of the epizootic into metropolitan areas but has not achieved the ultimate goal of eradication. Rabies activity in gray fox continues to occur periodically outside the ORV zone, preventing ORV zone contraction and dissipation of the epizootic. We employed a landscape-genetic approach to assess gray fox population structure and dispersal in the affected area, with the aim of assisting rabies management efforts. No unique genetic clusters or population boundaries were detected. Instead, foxes were weakly structured over the entire region in an isolation by distance pattern. Local subpopulations appeared to be genetically non-independent over distances >30 km, implying that long-distance movements or dispersal may have been common in the region. We concluded that gray foxes in west-central Texas have a high potential for long-distance rabies virus trafficking. Thus, a 16-km to 24-km ORV zone may be too narrow to contain the fox rabies epizootic. Continued expansion of the ORV zone, although costly, may be critical to the long-term goal of eliminating the Texas fox rabies virus variant from the United States.

AN OVERVIEW OF DEPREDATING BIRD DAMAGE CONTROL IN CALIFORNIA

To many people, California is synonomous with Disneyland, freeways, Los Angeles smog, Yosemite, the California missions, or for you bird aficionados, the California Condor. But do you think about California when you eat strawberry shortcake? You should -- California leads the nation in strawberry production. How about artichokes? California produces over 98% of the artichokes raised in the United States. Dates? California produces over 99% of the dates in the United States. Yes, California is all of these, and it is much more. California may well be the most diverse state in the United States. Within its 100.2 million acres, California has the lowest place in the U.S. in Death Valley and one of the highest mountains with Mt. Whitney. Because California is such a diverse state and has a wide variety of micro- climates, it supports a uniquely diverse agriculture. Agriculture uses only about 36 million acres of its total 100.2 million acres, and most of the cash return from crops is produced on 8,6 million acres that are irrigated. California produces about 250 crops and livestock commodities (excluding nursery crops) and provides the U.S. with about 25% of its table foods. California leads the nation in the production of 46 commercial crops and livestock commodities; its farmers and ranchers marketed $8.6 billion of crop and livestock products in 1975, and the state’s harvested farm production in 1975 set a new record at 51.1 million tons. HISTORY OF BIRD PROBLEMS Records such as this are not achieved without some risk. Crops growing in Cali- fornia have always had competition from many types of vertebrate pests. The wide variety of crops grown in California and the varied climates and situations in which they are grown has resulted in many different species of birds damaging crops. Birds have compet- ed with man for his crops since the dawn of agriculture. McAtee (1932) cited examples of bird damage that occurred in a wide variety of crops in California during the early 1900s. During the 1920s, many requests for Information and relief from damage caused by a wide variety of birds, culminated in the assignment, in May 1929, of two biologists, S. E. Piper and Johnson Neff, of the former U.S. Bio- logical Survey, to initiate field studies in California. In cooperation with the Cali- fornia Department of Food and Agriculture and County Agricultural Commissioners, the study was to determine the problems and devise control procedures relative to bird depredations. Piper and Neff found such damage as Horned Larks pulling sprouting crops, House Finches disbudding deciduous fruit trees and devouring mature fruit. Blackbirds were a problem in the rice crop. Early controls were varied and, for the most part, lacked effectiveness. Flagging of fields was common to deter Horned Larks. Windmill devices were tried to frighten birds. Shooting to kill birds was common; scarecrows were.used. The six-year study brought forth the basis of most of the depredating bird control techniques still in use in California. At the end of the study, these two biologists compiled a book called “Procedure and Methods in Controlling Birds Injurious to Crops in California.” This was and still is the “Bible” for bird damage control techniques used in California. The thorough investigations conducted by these biologists resulted in techniques that have remained valid in California for over 40 years.

WOLF CONTROL IN BRITISH COLUMBIA, CANADA

Up to 1949, the Fish and Game Branch employed personnel, some of whom were temporary, to attempt control of the extremely high wolf pop¬ulations of the central and northern portions of British Columbia. Coyotes were also very numerous in the central and southern regions and had to be considered because of their depredations. The field men were keen and conscientious but their efforts were not co-ordinated. Control areas were severely restricted in size as techniques were not adaptable enough and because of a lack of manpower. Eventually, sheepmen went out of business entirely over wide areas, cattlemen were subjected to huge annual losses, and sportsmen were very concerned. However, stock losses constituted the major complaint and resulted in ranchers demanding action* Two major changes came out of this. First, the bounty on wolves was raised and second, the present Predator Control Division was formed. The administration was convinced that a force of experienced, fully-trained field staff under a single supervision would be far more effective than bounty payments. Unfortunately, bounties were in vogue during that time and forced the necessity of proving the worth of organized controls before any consideration could be given to the elimination of the bounty system.