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OPTIMIZING OBSERVER EFFORT FOR FIELD DETECTION OF REPRODUCTIVE EFFECTS IN BIRDS
Citation:
Etterson, M A. AND R S. Bennett. OPTIMIZING OBSERVER EFFORT FOR FIELD DETECTION OF REPRODUCTIVE EFFECTS IN BIRDS. Presented at SETAC Annual Meeting, Austin, TX, November 9-13, 2003.
Description:
Avian nest survival is best viewed as a Markov process with two absorbing states, death and fledging. We present a column-stochastic Markov chain from which all major Mayfield formulations of daily nest-survival can be derived contingent upon the degree of observer knowledge of events at the nests under study. This new insight into the relationship between different formulations of daily survival probabilities allows us to directly examine the tradeoff between cost and benefits to differing monitoring strategies. This methodology will be valuable in risk assessment to 1) help deterine the sample size and most efficient monitoring regime for field-detection of adverse reproductive effects for a given stressor, and 2) to evaluate the posterior probability of type II errors in completed risk assessments. We demonstrate the suite of methods using Vesper Sparrow as a model species. Preliminary results suggest very large sample sizes monitored at short intervals will be necessary to detect small reductions in daily survival probability.