The paper presents a new interactive technique for correcting CAD/CAM data containing errors. An algorithm is described that can be used to correct surface data containing undesirable discontinuities (''gaps''/ ''holes'', and ''overlaps'') and intersections among surface patches. Such surface problems commonly arise in the aircraft, automobile, and ship industry and make later processing of the data difficult, if not impossible. The new method provides a tool to correct wrong data requiring minimal user interaction. The imput for the scheme can be a set of parametrically defined surfaces (e.i., Bezier, B-spline, or NURBS surfaces) or a set of triangles (or quadrilaterals) discretizing the original geometry. The output is a set of G0 or G1 (tangent plane)continuous, bicubic B-splines surfaces approximating the given data. Each of these B-spline surfaces is constructed using just four user-specified boundary curves.

We present a robust and efficient surface-surface intersection (SSI) algorithm. The algorithm is based on intersecting surface triangulations and improves the resulting linear spline curve approximations of the exact intersection curves by replacing intersecion points of the surface triangulations by exact intersecion points. We use a specialized data structure, the k-d tree, for the efficient intersection of surface triangulations. The resulting intersection curves are guaranteed to lie within a user-specified tolerance.

Seventy-one Chinese ring-necked pheasants were radio-tracked in mixed crops in Sutter County, CA. Weekly survival of 39 wild (4 native and 35 translocated) versus 32 pen-reared birds were compared at 2 sites (~2,000 ha each) during the fall 1996 agricultural harvests. Pheasant survival after 1 week was wild 74% and 79% versus pen-reared 61% and 57% at the Meridian and Nicolaus sites, respectively. Thereafter, pooled sites survival was ~linear with ~1 wild bird dying every 2.8 weeks for 7 weeks and ~1 pen-reared bird death occurred every 4.7 days for 3 weeks. Several relocated and pen-reared pheasants joined wild flocks, and their survival improved with one of each harvested during the 1997 hunting season. Both survived >400 days. All affected pheasants changed their habitat utilization and movement ecology following the harvest of their primary cover and forage crop(s). Chi square analysis of habitat use by 30 wild and 19 pen-reared pheasants demonstrated habitat preferences were greater than its availability (P < 0.01) for milo (planted only in Meridian), weeds, and corn. Their preferences for alfalfa, beets, and safflower were equal to their availability. Rice was preferred when the fields were dry, but overall it was not preferred (P < 0.01). Also, orchards (cleared of ground vegetation for nut harvests) and fallow habitats were not preferred. Movement ecology data were separated by study site because of significant habitat differences. Home ranges (95% utilization areas) using the minimum convex polygon method to compare wild versus pen-reared pheasants averaged 74 and 67 ha at Meridian and 73 and 140 ha at Nicolaus. Daily rooster and hen movements averaged 295 m and 276 m for wild birds and 335 m and 382 m for pen-reared birds at the Meridian and Nicolaus sites, respectively. Results from the first fall pheasant study in California crops demonstrated they preferred the dynamic juxtaposition of grains and weeds for cover, shelter and forage with water. Twenty-nine pheasants (58%) demonstrated habitat preferences for grains– milo, rice, and corn. Pheasant survival was related to post-harvest habitat changes. Their home range, survival, and movements were very similar at both sites although the crop mosaic and habitat relationships were very different. These new results should be included in both public and private pheasant management practices.

Many fossorial species of wildlife cause damage in a variety of land-use settings. Research of these species is challenging because of the complications associated with working underground. Traditional methods of conducting research on fossorial rodents in their natural environments are expensive, labor intensive, and invasive on the landscape. More innovative and effective methods of doing research underground are needed. We evaluated a burrow-probe camera for viewing inside the burrows of California ground squirrels (Spermophilus beecheyi) as part of an anticoagulant baiting study. It was useful for locating carcasses as well as for collecting information on live squirrels and non-target species. We also used burrow cameras to aid in on-going studies of black-tailed prairie dogs (Cynomys ludovicianus) and evaluated their utility in the burrows and dens of other mammals along the front range of Colorado. We will discuss our evaluations of burrow cameras and applications for their use in wildlife damage research.

The National Wildlife Research Center (NWRC) conducted a field study to determine hazards to non-target gallinaceous birds following the use of 2.0% zinc phosphide (Zn3P2) baits for vole control in fall alfalfa. Consultation among the NWRC, USDA Wildlife Services, California Department of Food and Agriculture (CDFA), U. S. Environmental Protection Agency (EPA), and the California Department of Fish and Game produced a 3-phased study. Free-ranging ring-necked pheasants and California quail were studied in alfalfa during the concurrent harvest of other agricultural crops. These data would be used by CDFA to support the re-registration of their label “Rodent Bait Zinc Phos­phide Treated Grain (2.00%)”, EPA Reg. No. CA890027. Phase 1 was a pilot study to determine whether the two test species could be maintained in walled enclosures. Phase 2 was a worst-case-scenario using the test species in alfalfa enclosures during vole control (i.e., simulated field study). Information from the 14-day post-baiting period led to a better understanding of some variables, including the sub-lethal effects that could impact the design of the final phase. During Phase 3 the actual non-target field study was conducted. Results from Phase 1 showed that these species could be maintained in outdoor enclosures using only wing clipping, 1 m-high metal walls, and no covering nets. Phase 2 proved that in outdoor alfalfa enclosures, baiting for vole control was not hazardous to quail but might be to pheasants. Phase 3 concluded that 2.0% Zn3P2 bait when applied per label directions was not hazardous to either wild or pen-reared free-ranging pheasants in fall agricultural areas. This article summarizes the 3-phased study, the resulting data, and conclusions.

This chapter focuses on three computer-aided geometric design (CAGD) techniques that are often needed to ''prepare'' a complex geometry for grid generation. Standard grid generation methods, as discussed in [George '91], [Knupp & Steinberg '93], and [Thompson et al. '85], assume that parametric surfaces are well parametrized and free of undesired discontinuities. We describe CAGD techniques that are extremely helpful for the preparation of complex geometries for the grid generation process.