This textbook introduces the Ada programming language in a manner suitable for students with little or no previous experience of programming. It shows how solutions can be systematically designed and how these solutions can then be implemented on a computer. The early parts of the book concentrate on solving small problems while the later parts show how packages can be used in the construction of reliable large programs. As Ada is a complex and versatile language, no attempt is made to cover it all. The author concentrates on central features such as data types, subprograms, packages, separate compilation, exceptions and files. He provides in addition a large number of complete Ada programs, all of which have been tested on the York Ada compiler. The final version of the Ada language (ANSI/MIL-STD-1815A-1983) is used throughout.

In 1991, a workshop was held to examine the data related to declines in Canadian amphibian populations and associated causes and, in particular, to develop a protocol to address the issue. Participants were invited to present reports on the current status of knowledge on amphibians in Canada, particularly species that appear to be threatened. Summaries of this information are presented in this report, along with the factors that may be contributing to fluctuations in amphibian populations. Methodologies and tribulations involved in accurately assessing amphibian population size and recruitment are given. A framework for environmental monitoring was presented and the data needed, both intensive and extensive, was discussed.

"Several wetland classification schemes have been devised to facilitate waterfowl management in North America. These schemes were developed primarily from vegetational, not hydrological, characteristics of wetlands and so do not consider annual changes in slough responses to climatic variability. Here we provide a hydrological scheme that proves to be consistent with Millar's (1976) ecological classification scheme"--Abstract.

"A positive correlation was found between independent estimates of the density of males and counts of red-wings obtained from the North American breeding bird survey (BBS). Density of males was a useful indicator of the number of red-wings in an area, whereas the BBS was a useful indicator of change in regional population level." --

Bitterbrush [Purshia tridentata (Pursh) DC] plants were burned or clipped, fall and spring, under different soil moisture conditions on two sites in east-central Oregon. Treatments, on plants of an erect growth form on the Juniperus/Artemisia-Purshia site resulted in 38% of the fall-clipped and 40% of the spring-clipped plants sprouting. None of the unwatered fall-burned plants sprouted, nor did any of the fall- burned plants that were watered 24 hours prior to burning. Ten percent of the plants that were watered after fall-burning and 30% of the spring-burned plants sprouted. On the Pinus/Purshia site treatments on plants of a lower-growing, decumbent form of bitterbrush resulted in 69% of the fall-clipped and 90% of the spring-clipped plants sprouting. None of the unwatered, fall-burned plants sprouted although 20% of the plants watered prior to fall-burning and 10% of the plants watered after fall- burning sprouted. Fifty percent of the spring-burned plants sprouted. Within sites, sprouting of clipped plants on either site did not appear to be related to plant size, age, or soil moisture. Burning was more damaging on both sites than clipping and fall-burning more damaging than spring-burning.