Evaluating the costs and sampling adequacy of a vertebrate monitoring program

Ecological monitoring is important for tracking trends in species and ecosystems over time and is the basis of conservation planning and government policy. Given there are increasing constraints on funding opportunities for conservation research there need to be simple approaches to assess the costs and effectiveness of surveys that highlight where methods can be refocussed to address changing management aims. In this study we use data from a vertebrate fauna monitoring program to assess the extent to which the sampling has been effective in recording the total estimated vertebrate species richness, identify which classes, families or functional groups of birds, mammals and reptiles have been under sampled by existing methods and which of the survey methods used were most cost effective. We compiled data collected over six surveys conducted over five years on a conservation reserve in northern Australia as a case study. We used rarefaction curves to examine the rate of species accumulation and sampling adequacy for 15 fauna functional groups representing bird, mammal and reptile taxa. We also compared the cost effectiveness using the relative dollar cost for six survey methods including both observational (active search, bird counts) and trapping (cage, box, funnel and pitfall traps) techniques. In our case study, despite six repeated surveys, with a total estimated cost in excess of $500 000, sampling for six of the 15 targeted fauna groups was insufficient. Multiple survey methods are required to sample taxa such as reptiles and small mammals. Costs per methods were approximately equal when comparing different techniques such as pitfall, cage, Elliott and funnel traps. This study demonstrates that it is straightforward to use simple metrics of survey success to guide, refine and improve monitoring programs.